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A phytosociological study of fir and spruce forests on the plateau of Cape Breton Island, Nova Scotia Smith, Richard T. 1974

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A PHYTOSOCIOLOGICAL STUDY OF FIR AND SPRUCE FORESTS ON THE PLATEAU OF CAPE BRETON ISLAND, NOVA SCOTIA I by RICHARD T. SMITH B . S c , A c a d i a U n i v e r s i t y , 1970 A THESIS SUBMITTED IN OF THE REQUIREMENTS MASTER OF PARTIAL FULFILLMENT FOR THE DEGREE OF SCIENCE i n the Department o f Botany We a c c e p t t h i s t h e s i s as conforming to the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA November 1974 In presenting th is thes is in pa r t i a l fu l f i lment of the requirements for an advanced degree at the Un ivers i ty of B r i t i s h Columbia, I agree that the L ibrary shal l make it f ree ly ava i l ab le for reference and study. I fur ther agree that permission for extensive copying of th is thes is for scho la r ly purposes may be granted by the Head of my Department or by h is representat ives . It is understood that copying or pub l ica t ion of th is thes is for f inanc ia l gain sha l l not be allowed without my wri t ten permission. Department of BOTANY The Univers i ty of B r i t i s h Columbia Vancouver 8. Canada Date April 17, 1975 ABSTRACT . The present study was designed to: a) employ phytosociological methods to characterize the major spruce and f i r forests of the Cape Breton Plateau, b) measure specific climatic and edaphic factors and relate these to the forest vegetation and c) assess the boreal nature of the Plateau forests through comparisons with boreal forests in neighbouring regions of eastern Canada. Climatic measurements were made from June to late August during a two year period. These included continuous recordings of temperature and wind and weekly measurements of precipitation. Daily maximum and minimum temperatures and weekly precipitation were used for climatic characterization of the area and for comparison with D.O.T. meteorological data at Cheticamp and Ingonish Beach in the lowlands of Cape Breton. Soils were sampled, where possible, in each forest stand. Profiles were described and samples were taken for quantitative analysis of texture, nitrogen, phosphorus, carbon, pH, available water, and exchangeable calcium, potassium, magnesium and sodium. Vegetation study resulted in the recognition of three forest associations. The most widespread of these i s the Abies balsamea - Diyopteris spinulosa - Hylocomium vmbratvm. or upland f i r association. This i s the most productive of the three associations. It forms the climatic climax of the area, and occurs on the better-drained soils of low ridges. Stands of this type have relatively closed tree canopies in which Abies balsamea is predominant and i i Betula papyvifera occurs frequently but with low densities. Shrub layers are poorly developed because of poor light conditions, and the herb and bryophyte layers are moderately to well developed. The Picea mariana - Plevjrozivm scnvebevi or black spruce association i s common, and develops both on poorly-drained organic soils in low lying areas, and on thin stony soils on ridges. Tree growth i s very poor in these areas. Stands of this type lack a well-defined tree canopy and are chracterized by dense growths of stunted, wind pruned Picea mariana which rarely exceed 3 m in height. Low shrub species, many of which also occur in raised bogs, are abundant, while herb and bryophyte growth is poor. The third forest type recognized i s the Abies balsamea -Osrrunda cinnamomea - Sphagnum cavillaceum or swamp f i r association. This has a rather limited distribution and occurs low lying sheltered areas, on poorly drained organic soils. Site conditions here are poorer for tree growth than are those of the upland f i r association, and Abies balsamea, the dominant species, forms an open canopy with lower densities and higher numbers of standing dead trees than in upland f i r stands. Beneath the open canopy, light conditions are . favourable, and the shrub, herb and bryophyte layers are well developed. The forest soils studied are acid and have low levels of total nitrogen and exchangeable calcium, sodium, potassium and magnesium. Although differences among the soils of the three associations for the chemical factors analysed were few, the organic soils beneath the swamp f i r and the black spruce stands of low lying areas have high moisture contents and probably are poorly aerated. This could be responsible for poor ,tree growth in these areas. i i i Earlier workers have noted that the coniferous forests on the Plateau differ from the mixed climatic climax forests of the lowland areas of Cape Breton, and have suggested that climatic rather than edaphic factors are responsible. In the present study, comparisons of climate for the two areas corroborated this view, indicating that summer maximum and minimum Plateau temperatures are several degrees lower than those of the lowland areas. A second opinion is that although the Plateau forests have . been classified as similar to those of the remainder of Nova Scotia, they are more boreal in nature. In the present study the Plateau forest associations were found to be f l o r i s t i c a l l y richer than boreal forests in Newfoundland and southeastern Quebec, but because they contain most of the major species of the boreal forest types, i t is concluded that they should be considered a southern extension of the boreal forest. i v ACKNOWLEDGEMENTS Gratitude i s expressed for invaluable assistance given by a number of persons during completion of the present study. The wardens of the Cape Breton Highlands National Park were very cooperative and their assistance in solving l o g i s t i c problems during the summer f i e l d seasons i s greatly appreciated. Thanks are also expressed to James Roy and Paul Forwood for care taken in the gathering of data. Preparation of the f i r s t draft of this paper was greatly aided by the assistance of Sherran Johnson. Finally, I am deeply in debt to my supervisor, Dr. Charles B e i l , who generously provided patient instruction and guidance throughout a l l stages of the study. CONTENTS Page I. INTRODUCTION 1. O b j e c t i v e s 1 2. Previous I n v e s t i g a t i o n s 2 3. The Study Area . . . 3 I I . METHODS 1. Vegetation Sampling 17 2. Vegetation A n a l y s i s . 17 3. S o i l A n a l y s i s 21 4. C l i m a t i c Measurements 22 I I I . THE CLIMATE OF THE PLATEAU 1. Temperatures 25 2. P r e c i p i t a t i o n . . . 29 3. Wind . . . 32 4. R e l a t i v e Humidity 35 5. D i s c u s s i o n . . 35 IV. DESCRIPTIONS OF THE FOREST ASSOCIATIONS 1. The Upland F i r A s s o c i a t i o n . '. 44 2. The Black Spruce A s s o c i a t i o n 49 3. The Swamp F i r A s s o c i a t i o n 53 4. S u c c e s s i o n a l Communities 57 5. D i s c u s s i o n 60 6. Comparison of the P l a t e a u A s s o c i a t i o n s w i t h B o r e a l F o r e s t s i n Eastern Canada 68 . v i ( Page V. FOREST SOILS 1. Morphological C h a r a c t e r i s t i c s . . . . . 80 2. Ph y s i c a l and Chemical C h a r a c t e r i s t i c s . 89 3. Discussion 105 VI. AUTECOLOGY OF MAJOR TREE SPECIES 1. Abies balsamea (Balsam F i r ) . 106 2. Picea maviana (Black Spruce) . 108 3. Picea glauca (White Spruce). . . 119 4. Betulo. papyrifera (White Birch) i 2 0 5. Discussion 121 VII. FINAL DISCUSSION 128 VIII. SUMMARY. . • 133 IX. CONCLUSIONS. -143 X. LITERATURE CITED 145 XI. APPENDICES 149 LIST OF TABLES Table Page 1. Climate summaries for D.O.T. stations i n northern Cape Breton 8 2. Description of vegetation layers 18 3. The Domin-Krajina scale of cover abundance . 19 4. Location and description of meteorological station's 23 5. Daily maximum and minimum temperatures at Plateau and D.O.T. stations. 26 6. Daily temperature ranges for the Cape Breton Plateau and D.O.T. stations 30 7. P r e c i p i t a t i o n t o t a l s for the Cape Breton Plateau . . . . . . 31 8. Wind measurements on the Cape Breton Plateau 34 9. D i s t r i b u t i o n of constant species among forest associations '. 61 10. Physical and chemical cha r a c t e r i s t i c s of upland f i r s o i l s 88 11. Physical and chemical c h a r a c t e r i s t i c s of swamp f i r s o i l s . 90 12. Physical and chemical ch a r a c t e r i s t i c s of black spruce s o i l s i n depressions 92 13. Physical and chemical c h a r a c t e r i s t i c s of black spruce s o i l s on ridges . 94 14. Mensurational data for major tree species. . . . 109 v i i i LIST OF FIGURES Figure Page 1. The Plateau from the Lox-zlands 4 2. The Plateau from McKenzie Mountain '. . . . 4 3. Map of the study area 6 4. Maximum and minimum temperatures at Plateau station 01. .. . 28 5. Maximum and minimum temperatures at Plateau station 02. . . 28 6. Maximum and minimum temperatures at Plateau station 11. . . 28 7. Precipitation totals at Cape Breton Plateau climatic stations . 33 8. Maximum and minimum temperatures at Cheticamp, N.S. ; . . . 39 9. Maximum and minimum temperatures at Ingonish Beach, N.S 39 10. Maximum and minimum temperatures at Buchans, Newfoundland 41 11. Precipitation totals at D.O.T. stations . . . 42 12. The upland f i r association 45 13. Understory vegetation in an unshaded area 47 14. Understory vegetation in a shaded area 47 15. Dryopteris spinuZosa in an upland f i r stand 48 16. Black spruce stands developed around open peat bogs . . . . 50 17. Black spruce stand showing wind-trimmed trees . . 50 18. Black spruce stand showing the abundance of low shrubs. . . 52 19. A stand of the swamp f i r association 56 20. A successional community in which Abies balsamea i s dominant 58 i x F i g u r e Page 21. A s u c c e s s i o n a l community i n which Betv.la papyrifara i s dominant 58 22. A s o i l p r o f i l e i n an up l a n d f i r s t a n d 81 23. A s o i l p r o f i l e i n a swamp f i r s t a n d . . 83 24. D i s t r i b u t i o n o f Abies bo.lsamea among stem d i a m e t e r c l a s s e s m 25. Graph o f age v s . D.B.H. o f Abies balsamea . . . . . . . . . 113 26. R e g r e s s i o n o f h e i g h t v s . D.B.H. d a t a f o r Abies balsamea i n t h e swamp f i r a s s o c i a t i o n 114 27. R e g r e s s i o n o f h e i g h t v s . D.B.H. d a t a f o r Abies balsamea. i n the up l a n d f i r a s s o c i a t i o n 115 28. D i s t r i b u t i o n o f s t a n d i n g dead Abies balsamea among d i a m e t e r c l a s s e s 117 1 I. INTRODUCTION 1. Objectives Although several studies have been made of the Cape Breton Plateau f o r e s t s , knowledge of them i n many ways s t i l l remains d e f i c i e n t . For the most part, i n v e s t i g a t o r s have recognized forest communities on the Plateau on the basis of tree species composition, giving inadequate consideration to c h a r a c t e r i s t i c s of understory vegetation. Environmental f a c t o r s have been poorly investigated. Forest s o i l s of the area have been poorly studied, and only Nichols (191S) and Comeau (1971) gathered weather data. F i n a l l y , although several writers have suggested that the Plateau vegetation i s s i m i l a r to the boreal forests of eastern Canada and should be classed as part of the same, no de t a i l e d comparisons have been made between Plateau forests and neighbouring boreal regions. The present study was designed to employ phytosociological methods to q u a n t i t a t i v e l y and q u a l i t a t i v e l y characterize the structure and composition of forest associations on the Plateau. Furthermore, t h i s information i s related to data obtained from analyses of s o i l s and climate, and e c o l o g i c a l r e l a t i o n s h i p s determining the i d e n t i t y of forest communities are examined. Results from t h i s study are compared with those of vegetation studies i n Newfoundland (Damman, 1964), southeastern Quebec (Linteau, 1955), and Labrador (Wilton, 1964). 2. Previous Investigations Few vegetation studies have been conducted on the Cape Breton Plateau. One of the e a r l i e s t was a forest survey by Macoun (1898) i n which only very general c h a r a c t e r i s t i c s of the forest vegetation were noted. In a l a t e r study (Fernow et ^1. , 1912) the Plateau f o r e s t s were examined as part of an economic study of the forests of Nova Scotia. The f i r s t d e t a i l e d vegetation study of the area was conducted by Nichols (1918). This included the recognition and d e s c r i p t i o n of plant communities and associations, which were rel a t e d to climate and topography, and placed i n a general f o r e s t c l a s s i f i c a t i o n scheme. Several l a t e r i n v e s t i g a t i o n s include those of H a l l (1949) and Killam (1951) i n which po l l e n p r o f i l e s from peat bogs on the Plateau were examined i n an attempt to determine the sequence of plant communities since g l a c i a t i o n . The present Plateau f o r e s t s were studied by C o l l i n s (1950, 1951) from a se r i e s of p l o t s located along transects, i n which a number of quantitative measurements such as density, frequency and coverage were made. McDonald (1958) c a r r i e d out a s i m i l a r study of the forests located on the upper slopes leading to the Plateau. The most recent study i s an e c o l o g i c a l analysis of plant associations occurring i n raised bogs on the Plateau (Comeau, 1971) i n which phytosociological methods were used and both c l i m a t i c and edaphic factors were considered i n r e l a t i o n to the vegetation. 3 3. The Study Area Location and Physiography . ; 2 Cape Breton, a large i s l a n d of over 10,000 km , forms the northeastern t i p of Nova Scotia and i s centered around a point at approximately 46°N and 61°W. I t i s bordered by the A t l a n t i c Ocean on the south and east, and the Gulf of St. Lawrence and Northumberland S t r a i t on the north and west r e s p e c t i v e l y . Its northernmost t i p i s situated approximately 80 km southwest of Newfoundland. The is l a n d i s composed of two peninsulas, a smaller south-eastern portion formed of gently r o l l i n g lowlands and steeply folded uplands, and a northeastern peninsula composed of a large c e n t r a l tableland or plateau surrounded by coastal lowlands near sea l e v e l i n elevation. The Plateau, over 30,000 ha i n area, slopes upward from an average elevation of about 90 m i n the southern part of the i s l a n d to an average of over 450 m at the northern end, and has been considered a r e s i s t a n t fragment of an upland region once extensive throughout the Maritime Provinces (Goldthwaite, 1924). From the Lowlands the top of the Plateau appears rather f l a t ( F i g. 1), but i s i n fa c t composed of low ridges and broad shallow v a l l e y s (Fig . l f c ) . Near the edge of the Plateau t h i s type of topography i s frequently interrupted by steep walled gorges eroded by streams draining the int e r i o r ^ (Fig.2 ) . The sides of the Plateau are steep and often bear large areas of t a l u s . The area selected f o r study i s located on the northern part of the Plateau p a r t l y within the Cape Breton Highlands National Park. Here the Plateau reaches i t s maximum height and has an average elevation of 4a Figure 1. The Plateau as seen from the lowlands showing the apparent evenness of the summit. ( Photo by Roy ) Figure 2. The Plateau as seen from McKenzie Mountain showing stream dissection. ( Photo by Roy ) 4b 5 about 450 m. Vegetation was studied i n two locations t o t a l l i n g approximately 10,000 ha. The f i r s t was centered around the headwaters of the Big Southwest Brook, the second near the head of the Red River (Fig. 3 ) . Geology and S o i l s The most recent Geological Survey map of the area (Neale, 1963) described the bedrock as a combination of r e s i s t a n t Precambrian quartz and feldspar s c h i s t s and c h l o r i t e gneisses, together with l o c a l i z e d pockets of limestone. These make up most of the bedrock of the Plateau; the remainder consist of various hybrid rocks formed from l a t e r igneous intrusions into the Precambrian formations. Although Fernald (1925) regarded the Plateau as one of the few areas i n eastern Canada to remain i c e - f r e e during the Pleistocene epoch, most writers have since held that the area was gl a c i a t e d . Hichox (1962) found deposits suggesting the Cape Breton highlands formed the center of a l a t e r e t r e a t or l o c a l readvance of the continental i c e sheet, and Neale (1963) noted an abundance of g l a c i a l t i l l on the Plateau. The Plateau s o i l s have been poorly studied, but i n general can be classed as shallow, stony Podzols and organic peats (Cann et al. , 1963). They are considered r e l a t i v e l y u n f e r t i l e , frequently poorly drained, and are derived from a t h i n layer of sandy loam g l a c i a l t i l l . \. Climate The A t l a n t i c Provinces are situated such that frequent meetings take place between continental a i r from the west, southward moving cold a i r from Labrador, and moist a i r from the A t l a n t i c Ocean. Consequently, NORTHERN CAPE BRETON ISLAND t I M H O -S c » l * I X.5 Kilo<n*tcrj to I c« or 1:40.000 U^tonmt P M K B.unrfor^ ? = L » ^ ^ ^ ^ c Kilor»»t»r« Stu<J«j A r e a s l l l l l Cllma+lf fti&'tien* ® Contour XnWv&l l»0 M»*re» Ol Figure 3. Map of northern Cape Breton showing the Study Area. storms are frequent and temperature f l u c t u a t i o n s are common. (Chapman and Brown, 1966). Winter seasons are cold and snowy but frequently interrupted by warm periods, summers are cool with common foggy i n t e r v a l s , and growing seasons are often delayed i n the spring by the passage of cold a i r from the Labrador current. The two meteorological stations nearest the study area are located at Ingonish Beach on the east coast of northern Cape Breton and Cheticamp on the west coast. Both stations are at lowland elevations; Ingonish Beach has an elevation at 4.5 m and Cheticamp i s at sea l e v e l . Ten-year summaries of temperature for Ingonish Beach and p r e c i p i t a t i o n for both areas (Canadian Department of Transport, 1964, 1965) (Table 1) indic a t e that at Ingonish Beach the mean annual maximum temperature i s 51.8°F (10.5°C), the mean annual minimum temperature i s 35.1°F (1.7°C), and the mean annual average i s 43.1°F (6.1°C). February i s the coldest month at t h i s l o c a t i o n , with a mean average temperature of 22.3°F (-5.6°C) and July i s the warmest month at 65.6°F (18.3°C). Mean minimum temperatures are below freezing for f i v e months of the year. The east coast at Ingonish Beach receives more p r e c i p i t a t i o n than the west coast at Cheticamp. On an annual basis, Ingonish Beach receives an average of 53.7 i n (136.3 cm) of r a i n , 126.1 i n (320.3 cm) of snow, and has an average t o t a l p r e c i p i t a t i o n of 66.3 i n (168.3 cm). At Cheticamp the yearly average i s 29.2 i n (74.1 cm) of r a i n , 118.3 i n (300.5 cm) of snow, and 41.0 i n (104.1 cm) of t o t a l p r e c i p i t a t i o n . In January, the wettest month of the year at both l o c a t i o n s , Ingonish Beach receives an .average t o t a l p r e c i p i t a t i o n Table 1. Ten-Year Climatic Summaries for D.O.T. Stations in Northern Cape Bre Location Mean Annual Max. Temp. (•°c) Mean Annual Mean Annual Min. Temp. Average ( °C) Temp. ( °C) No. of Months Mean Annual with Mean . Rain (cm.) Min. Temp. Below ( °C) Mean Annual Mean Annual Snow (cm.) Total Pre-cipitation (cm.) Cheticamp N.S. 46 38'N lat. 61 Ol'W long. elev. 0 m. 74.1 300.5 104.1 Ingonish Beach 46 38'N lat. 60 25*W long. elev. 4.5 m. 10.5 1.7 1.7 5.0 136.3 320.3 168.3 00 (80 i n , 20.3 cm) almost double that of Cheticamp (4.43 i n , 11.2 cm). Few quantitative data have been c o l l e c t e d for the climate of the Plateau; no permanent weather stations e x i s t there, and records are l i m i t e d to those reported i n vegetation studies. From temperatures recorded over a five-day period i n August, 1917, Nichols (1918) reported that the mean d a i l y maximum on the Plateau (74°F) was higher than the coastal Lowlands at Ingonish (71°F) and the mean d a i l y minimum (48°F) was lower than at Ingonish (56°F). He further noted that d a i l y temperatures on the Plateau showed a larger mean range (26°F) than the coastal Lowlands (15°F). Nichols believed freezing temperatures occurred on the Plateau during a l l months of the year and noted that i n 1915, t h e ' f i r s t f r o s t on the Plateau occurred on September 8, 18 days e a r l i e r than i n the Lowlands. Nichols did not measure p r e c i p i t a t i o n , but suggested from observations that the Plateau received more r a i n and snow than the coast. He noted that the Plateau had frequent fogs created by low clouds, but several measurements with atmometers indicated that on c l e a r days evaporation rates were higher on the Plateau than at Ingonish. He believed t h i s d i f f e r e n c e was due to high winds, a common feature of weather on the Plateau. More recent climatic* measurements were reported by Comeau (1971) who found that temperature data c o l l e c t e d from a 77-day period from June to September i n 1970 showed that both the average weekly maximum and the average weekly minimum temperatures on the Plateau were several degrees centigrade lower than those at coastal Lowland stations Cheticamp and Ingonish Beach. His data did not, however, indic a t e great differences i n d a i l y temperature ranges among the three areas. Comeau reported that p r e c i p i t a t i o n on the Plateau during t h i s period amounted to 41.12 cm, 79% f a l l i n g i n August. The lowland areas received l e s s at t h i s time, 38.53 cm f a l l i n g at Ingonish Beach and 28.15 cm at Cheticamp. Comeau suggested these differences i n climate between the Plateau and Lowland areas were large enough to produce differences i n vegetation. Forest C l a s s i f i c a t i o n of the Area The forests of much of Nova Scotia have been considered t r a n s i t i o n a l between the boreal coniferous f o r e s t s of northern Canada and the deciduous forests of the northern United States (Nichols, 1918, 1935). This i s because of the presence i n Nova Scotia of boreal tree species such as Picea glauca, Abies balsamea, and Betula papyrifera,. and species such as Acer saccharum, Fagus grandifolia, and Ulmus americana, c h a r a c t e r i s t i c of the Deciduous Forest Region. Nichols (1935) termed t h i s t r a n s i t i o n a l region the Hemlock-White Pine -Northern Hardwoods Region. Nichols (1918) believed that the Cape Breton Plateau forests were d i s t i n c t from those of the rest of Nova Scotia, c o n s t i t u t i n g a I: southern extension of the boreal Northeastern Evergreen Coniferous Forest Climatic Formation. This, he reported, was shown by the absence on the Plateau of many species such as Fagus grandifolia, Acer saccharum, and Quercus rubra, which were common i n the Lowlands of northern Cape Breton. 11 H a l l i d a y (1937) and Rowe (1959, 1972) both placed the Cape Breton Plateau forests i n the Acadian Forest Region, a unit s i m i l a r to Nichols' Hemlock-White Pine - Northern Hardwoods Region. H a l l i d a y did not recognize any boreal c h a r a c t e r i s t i c s among the Plateau f o r e s t s , noting the conclusions of Macoun (1898) who considered the forests d i s t i n c t l y non-boreal, a f t e r f i n d i n g no plants shared i n common with Labrador. Rowe, however, reported the Plateau f o r e s t s were boreal i n nature, and were s i m i l a r to the New Brunswick Upland Section of the Acadian Forest Region and the Gaspe Section of the Boreal Forest Region. C o l l i n s (1951) found that the Plateau f o r e s t s were characterized by a dominance of boreal tree species and a small t o t a l species number, two features he considered t y p i c a l of boreal f o r e s t s . He noted the Plateau f o r e s t s were s i m i l a r to boreal forests on I s l e Royale, described by Cooper (1913) and i n Labrador (Hustich, 1949; Hare, 1950), and should be classed as part of the Boreal Forest Formation. In a c l a s s i f i c a t i o n of the Maritime Provinces into ecoregions and zones, Loucks (1961) regarded the Cape Breton Plateau as a d i s t i n c t ecoregion, forested by a mixture of Picea mariana, Picea glauca, Abies balsamea, and Betula payrifera, s i m i l a r to the boreal forests of Quebec and Newfoundland and the northern taiga of the Soviet Union. ( In summary, although the Plateau forests appear i n major forest' c l a s s i f i c a t i o n s (Halliday, 1937; Rowe, 1959, 1972) as part of the t r a n s i t i o n a l Acadian Forest Region, most authors have considered the vegetation to be very s i m i l a r to that of the Boreal Forest Region. 12 Since the forests of the Cape Breton Plateau have been regarded by many as similar to the Boreal Forest Region, yet were classified as part of the Acadian Forest Region, a comparison between boreal forests in eastern Canada and those of the Plateau i s desirable. This warrants a review of literature describing general features characteristic of eastern boreal forests and of studies of boreal forests in regions near northern Cape Breton. General Characteristics of  Boreal Forests in Eastern Canada Boreal forests extend in northern Canada as a wide belt of vegetation from Newfoundland to the Rocky Mountain foothills. These regions are characterized by long harsh winters and short cool summers, and the forests are made up of a few hardy dominants and have low total species numbers (Hare, 1954). In eastern Canada the boreal forest is bordered in the north by the arctic tree line and in the south by the Great Lakes - St. Lawrence Region (Rowe, 1959). According to Hare (195o), dominant tree species of boreal forests east of Manitoba include Pioea glauca, Picea mariana, Larix laricina, Abies balsamea, and in restricted areas, Pinus banksiana. Deciduous species are usually abundant only in successional stands. These include Betula papyrifera, Populus tremuloides, Populus balsamifera, and several Alniis species. According to Rowe (1959), in southeastern sections of the boreal forest, Abies balsamea, Picea glauca, and Betula papyrifera are the most abundant tree species on well drained mineral soils. Abies balsamea is commonly the dominant species here whereas forests occurring on poorly drained mineral and organic s o i l s are dominated by Pioea mariana. Larix laricina i s usually present on these s i t e s but i n smaller numbers. In northern regions of Quebec and Ontario, where c l i m a t i c conditions are more severe, P. mariana i s dominant i n most areas and P. glauca, A. balsamea and B. papyrifera are r e s t r i c t e d to the most favourable s i t e s such as r i v e r v a l l e y s (Rowe, 1959). Hare (1950) suggested plant associations could be recognized i n boreal f o r e s t s only with d i f f i c u l t y , since the t o t a l number of species i s small and s o i l s are highly v a r i a b l e . He suggested instead the recognition of three broad s t r u c t u r a l types among boreal forests east of Manitoba. The most northerly of these i s the forest Tundra Ecotone, a region in. which tundra and boreal forest meet i n northern Labrador and Quebec. Permafrost i s common here, and f o r e s t s , l i m i t e d to the most favourable areas, are composed mostly of Piaea mariana. Immediately south of t h i s zone i s the Open Boreal Woodland Zone, characterized by stands of widely spaced Piaea mariana. This type resembles savannah vegetation i n appearance and has a ground vegetation dominated by lichens and ericaceous shrubs. Hare suggested t h i s p e c u l i a r stand structure i s produced by the h o r i z o n t a l rooting habit of the trees, a response to conditions i n which temperatures i n a l l but the upper layers of s o i l are too low for moisture extraction. The most southerly of the three i s the Main Boreal Forest Zone, i n which production i s the highest and stands are composed of closed tree layers dominated by Abies balsamea, Picea mariana, and Picea glauea. The southern boundary of the zone i s marked by an i n t r u s i o n of non-boreal species such as Thuja oooidentalis, Pinus strobus, Fraxinus nigra, and Betula lutea. 14 Hare (1950) found that while no correlation appeared between these zones and moisture regions, they did correspond to thermal efficiency or potential evapotranspiration (P.E.) (Thornthwaite, 1948). The northern border of the Forest-Tundra Ecotone followed a P.E. isopleth of 12.0 to 12.5 in and the southern boundary of the Main Boreal Forest zone was similar to a P.E. of 18.5 in to 19.0 in. LaRoi (1967) examined the vasular flora of 60 stands in 24 sections of the Boreal Forest Region recognized by Rowe (1959). He reported that the number of constant species was small, and although 291 species were recorded, only 6% occurred in 60% or more of the stands. Stands dominated by Picea glauca and Abies balsamea generally contained more species than those dominated by Picea mariana, and species diversity was greatest in south-central stands north of the Great Lakes. In spruce-fir stands Abies balsamea was common east of Saskatchewan, Picea glauca was present throughout, and Betula papyrifera was an important associate east of the Rocky Mountain foot-h i l l s and south of Great Slave Lake. Populus tremuloides and Populus balsamifera occurred in most of the spruce-fir stands west of central Ontario, and Picea mariana, although a frequent subdominant of central stands was uncommon in eastern and western areas. Pinus banksiana was found in only four stands, located in Saskatchewan and in Ontario. Black spruce stands east of Manitoba commonly had Abies balsamea as an associate. Picea glauca, however, was rare in stands of this type in the Atlantic Provinces. 1 5 Eastern Boreal Forest Studies  Newfoundland Damman (1964) c a r r i e d out an e c o l o g i c a l study of the f o r e s t s of the E x p l o i t s River i n c e n t r a l Newfoundland, an area c l a s s i f i e d by Rowe (1959) as part of the Boreal Forest Region. The study employed phytosociological methods i n which,five associations were described and subdivided into various subassociations. His r e s u l t s presented f l o r i s t i c composition and c h a r a c t e r i s t i c species groups for each type, estimates of cover-abundance for each species, descriptions of s o i l p r o f i l e s , and a discussion of e c o l o g i c a l r e l a t i o n s h i p s among the plant communities. Southeastern Quebec Linteau (1955) constructed a s i t e c l a s s i f i c a t i o n of the f o r e s t s of southeastern Quebec, north of the St. Lawrence River, i n the Boreal Forest Region. S i t e types were recognized according to dominant species i n various vegetation l a y e r s , and were described i n d e t a i l using species abundance, presence (frequency) and s o c i a b i l i t y as w e l l as l i s t s of species. These types were r e l a t e d to a number of s i t e conditions including s o i l s and were grouped into s i x major u n i t s . Labrador A broad c l a s s i f i c a t i o n of the f o r e s t s of Labrador was made by Wilton (1964) i n which, through a modification of an e a r l i e r work (Hustich, 1949), f i v e f o rest types were recognized. Wilton's objective 16 was to c r e a t e a c l a s s i f i c a t i o n o f p r o d u c t i v i t y t y p e s , c o r r e l a t e d w i t h s i t e c o n d i t i o n s , f o r the e n t i r e a r e a , r a t h e r than make a d e t a i l e d e c o l o g i c a l d e s c r i p t i o n o f p l a n t communities. D e s c r i p t i o n s o f h i s f o r e s t types a r e c o n s e q u e n t l y b r o a d , and c o n s i s t of d e s c r i p t i o n s of s i t e c o n d i t i o n s , s t r u c t u r a l c h a r a c t e r i s t i c s , and l i s t s o f common s p e c i e s . These t h r e e s t u d i e s t h e n , p r e s e n t f a i r l y d e t a i l e d d e s c r i p t i o n s of b o r e a l f o r e s t communities. In f o l l o w i n g s e c t i o n s , t h e s e a r e compared w i t h r e s u l t s of the p r e s e n t s t u d y , i n an attempt t o judge c l a i m s t h a t the P l a t e a u f o r e s t s s h o u l d be c l a s s e d as p a r t o f t h e B o r e a l F o r e s t Region. 17 I I . METHODS 1. Vegetation Sampling A preliminary survey of the study area was made prior to sampling. This indicated the presence of three broad forest types distinguished by topographic position, physiognomy, and dominant species. Stands that were topographically and f l o r i s t i c a l l y uniform and were free from extensive disturbance were selected for study from these types. In addition to these, three disturbed areas with successional vegetation were examined. Stands were sampled using single plots subjectively located in areas representative of the stand as a whole. Stands with well developed tree layers were sampled with plots measuring 20 m by 20 m, and those lacking tree layers with 10 m by 10 m plots. 2. Vegetation Analysis Seven vegetation layers were recognized, based on height and physiognomy (Table 2). The extent of development of each layer was determined by an estimate of total percentage cover. Species were listed for each layer and were rated with the 11-point Domin-Krajina scale of cover-abundance (Becking, 1957) (Table 3). These figures were converted to percentage cover using the mid-point of each cover-abundance class. Tree species densities were determined by layer, and various Table 2 . Description of Vegetation Layers. Physiognomy Code Height Limits Trees A l •, 9 m or greater A2 3.5 m to 9 m Shrubs B l 1. 8 m to 3.5 m B2 30 cm to 1.8 m Herbs and Dwarf Shrubs C less than 30 m Bryophytes and Lichens Dw growing on wood Dh growing on humus Table 3. The Domin-Krajina Scale of Cover-Abundance (Becking, 1957). Class Cover-Abundance Limits Class Midpoint (% coverage) + single occurrence 0.5% 1 seldom, cover negligible 1.0% 2 very scattered, cover negligible 2.0% 3 scattered, cover to 5% of plot 2.5% 4 common, cover 5% to 10% 7.5% 5 often, cover 10% to 20% 15.0% 6 very often, cover 20% to 30% 25.0% 7 abundant, cover 30% to 50% 40.0% 8 abundant, cover 50% to 75% 62.5% 9 abundant, cover 75% to 95% 85.0% 10 abundant, cover 95% to 100% 97.5% 20 tree measurements were made including the D.B.H. (diameter at breast height) of a l l trees and determinations of ages and heights of trees selected from the range of diameter classes. In addition, densities of standing dead and wind-thrown trees were noted. F l o r i s t i c a l l y similar stands were grouped subjectively into associations. Descriptions of these are presented in association tables (Appendix I) in which species are l i s t e d , by layer, in order of decreasing constancy. Constancy is an expression of the frequency with which a species was found in a particular association. Species of equal constancy are arranged in decreasing order of average cover-abundance. Computation of these averages was such that only stands in which a particular species occurred were included, thus avoiding exceptionally low values for species with low constancy. In addition to the above tables, a summary table (Table 9 ) is presented in which constant species (those occurring in 70% or more stands) are arranged such that for each association characteristic species groups are formed. Vascular plants were identified by Dr. C. E. Be i l , University of British Columbia, and the author. Nomenclature for these follows Roland and Smith (1969). Bryophytes excluding species of Sphagnum were identified by Dr. R. R. Ireland, National Museum of Canada, Ottawa, and Dr. C. E. Beil. Sphagnum species were determined by Dr. J. H. Sparling, University of Toronto. Moss nomenclature i s according to Crum et at. (1973) and liverworts were named according to Schuster (1953). Several lichen determinations were made by Dr. C. E. Be i l , and follow Hale and Culberson (1970). A reference collection of vascular plants collected in the f i r s t f i e l d season are housed at the E. C. Smith Herbarium Acadia University, N.S.; those collected in the second season are located with the bryophytes and lichens at the University of British Columbia. 3. Soil Analysis Soil samples were taken by horizon from a single pit dug in each vegetation plot, and profiles were described and classified according to the Canadian System of Soil Classification (Canada Dept. of Agriculture, 1970). Samples were air dried, sieved, and the less than 2 m fraction retained for analysis. A l l analyses, aside from those designated otherwise, were performed by the author. Selected s o i l samples were analysed for total nitrogen ( %) and total phosphorus (ppm) using a Technicon Auto Analyzer preceded by wet ashing in sulphuric acid and hydrogen peroxide. These determinations were made by the soils laboratory, Nova Scotia Dept. of Agriculture, Truro, N.S. The exchangeable cations sodium, magnesium, potassium, and calcium were gravimetrically extracted from 50 g s o i l samples using neutralized 1 N sodium acetate solutions (Jackson, 1958). Cation concentrations were measured with an atomic absorption spectrophotometer (Perkin-Elmer, Model 303) and expressed as meq/100 g of s o i l . Cation Exchange Capacities were determined for several s o i l samples according to the sodium saturation method (Jackson, 1958). These results were expressed as meq/100 g of s o i l . Percent organic matter was determined as the loss of weight following ignition of s o i l samples at 400°C. Selected samples collected 22 i n 1970 were analyzed by the S o i l s Laboratory, Nova Scotia Department of A g r i c u l t u r e ; determinations for those taken i n 1971 were made by the author. S o i l pH readings were made with a pH meter (Radiometer, Model 25) on 1 : 2.5 s o i l : water suspensions prepared from lOg s o i l samples. Texture analyses were c a r r i e d out on selected s o i l s using the hydrometer method (Bouyoucos, 1951). U.S.D.A. te x t u r a l classes were used i n which the l i m i t s for sand are 2.00 mm to 0.55 mm, s i l t , 0.05 mm to 0.002 mm and clay, l e s s than 0.002 mm. A s o i l ' s a b i l i t y to r e t a i n water i n a form usable by plants was measured as percent a v a i l a b l e water, the differe n c e between permanent w i l t i n g percentage and f i e l d capacity (Buckman and Brady, 1960). A pressure plate extractor was used to determine both of these, subjecting s o i l s f o r 48 hours to one t h i r d atmosphere of pressure f o r f i e l d capacity, and 15 atmospheres for permanent w i l t i n g percentage. 4. Climatic Measurements Several c l i m a t i c stations were established on the Plateau during the 1970 and 1971 f i e l d seasons. The locations of these (Fig. 3 ) were as near as possible to the sampling d i s t r i c t . Since the number of monitoring instruments was l i m i t e d , each s t a t i o n d i f f e r e d s l i g h t l y as to the types of measurements made (Table 4 ) . Results from the Plateau stat i o n s were compared with those from Department of Transport s t a t i o n s along the coast of northern Cape Breton and i n Central Newfoundland (Table 4 ) . i Temperatures were monitored continuously on the Plateau with 23 Tabled . Location and Description of Meteorlogical Stations Location Cheticamp, N.S. (DOT Station) Ingonish Beach, N.S. (DOT Station) Cape Breton Plateau Station 01 (open bog) Cape Breton Plateau Station 03 ( f i r f o r est) Cape Breton Plateau Station 11 (open bog) Buchans, Newfoundland (DOT Station) Glenwood, Newfoundland (DOT Station) Elevation 46°33'N 0 m 61°01'W 46°38'N 4.5 m 60°24'W 46°43'N 480 m 60°39'W 46°42'N 480 m 60°36'W 46°60'N 405 m 60°40'W 48°45'N 270 m 56°50'ti 49°00'N 60 m 54°50'W Period of Measurement continuous continuous June-August 1970 - 77 days June-August 1970 - 77 days June-August 1970 - 62 days June-August 1971 - 54 days June-August 1971 - 54 days June-August 1971 - 54 days continuous continuous Parameters d a i l y precip., d a i l y min., max., mean temp. d a i l y precip., d a i l y min., max., mean temp. continuous temp., weekly precip., weekly wind velo-c i t y , t o t a l wind. continuous precip., weekly precip. d a i l y max., min. temp., occasional r e l . humid. continuous temp., weekly precip., weekly wind velo-c i t y , t o t a l wind. weekly precip., weekly max., min. temp. weekly precip., weekly max., min. temp. d a i l y precip., d a i l y max., min. temp. d a i l y precip., d a i l y max., min. temp. Cape Breton Plateau 46°42'N 510 m Station 02 60°36'W (open heath barren) Cape Breton Plateau 46°50'N 225 m Station 12 60°24'W (open heath barren) Cape Breton Plateau 46°45'N 420 m Station 13 60°51'W (open heath barren) the thermographs housed at ground level in Stevenson screens. Precipitation was measured weekly in stainless steel rain gauges, and cumulative miles of wind were recorded with a totalizing anemometer placed at a height of 2 m above ground level. These wind data were supplemented with weekly measurements of wind velocity. The present project was, in 1970, undertaken as part of a broad study of the Plateau, which included other vegetation types. Weather monitoring during this period was a cooperative effort and consequently some of the data summarized below was also presented by Comeau (1971). 25 I I I . THE CLIMATE OF THE PLATEAU The r e g i o n a l c l i m a t e of ah area i s an important aspect of environment f o r v e g e t a t i o n . Factors such as temperature regimes, p r e c i p i t a t i o n , and r e l a t i v e humidity p l a y c r u c i a l r o l e s i n the determination of s i t e c o n d i t i o n s under which v e g e t a t i o n develops. A study of c l i m a t i c c o n d i t i o n s on the Cape Breton P l a t e a u i s p a r t i c u l a r l y v a l u a b l e from the viewpoint that d i f f e r e n c e s i n v e g e t a t i o n between the Platea u and Lowland areas of Cape Breton have been a t t r i b u t e d to cl i m a t e ( N i c h o l s , 1918; C o l l i n s , 1950; Comeau, 1971). In a d d i t i o n to the summaries of temperature, wind and p r e c i p i t a t i o n presented below, the o r i g i n a l r e s u l t s of c l i m a t i c measurements are given i n Appendix III. 1. Temperatures A summary of d a i l y maximum and minimum temperatures on the Pla t e a u during the summers of 1970 and 1971 (Table 5) i n d i c a t e s that the lowest temperatures of the three-month period were recorded i n June (0°-C i n 1970, 3°C i n 1971) and the highest f o r 1970 i n J u l y (31°C) and f o r 1971 i n August (28°C). Mean maximum temperatures f o r the s t a t i o n s i n 1970 are highest i n J u l y and n e a r l y equal i n June and August (Table 5) w h i l e those f o r s t a t i o n 11 i n 1971 are lowest i n June and highest i n August. Means of d a i l y minimums are lowest i n June f o r both years, and, w i t h the exception of s t a t i o n 03, are highest i n August. Table 5 Summaries of Daily Maximum and Minimum Temperatures at Plateau Stations and D.O.T, . Stations at Ingonish Beach, Cheticamp, and Buchans Monthly Monthly Mean Mean Month Location (°C) Location (°C) June 1970 C.B. Plateau Daily Max. 19.0 Cheticamp, N.S. Daily Max. 20.4 (17 days) Station 01 Daily Min. 8.8 Daily Min. 11.4 C.B. Plateau Daily Max. 20.6 Ingonish Beach, N.S. Daily Max. 21.5 Station 02 Daily Min. 10.0 Daily Min. 11.6 C.B. Plateau Daily Max. 20.5 Buchans, Nfld. Daily Max. 20.0 Station 03 Daily Min. 8.7 Daily Min. 7.7 June 1971 C.B. Plateau Daily Max. 15.3 (06 days) Station 11 Daily Min. 8.1 July 1970 C.B. Plateau Daily Max. 21.7 Cheticamp, N.S. Daily Max. 23.1 (31 days) Station 01 Daily Min. 11.9 Daily Min. 14.9 C.B. Plateau Daily Max. 22.1 Ingonish Beach, N.S. Daily Max. 24.5 Station 02 Daily Min. 12.2 Daily Min. 14.5 Buchans, Nfld. Daily Max. 21.9 Daily Min, 11.4 (26 days) C.B. Plateau Daily Max. 22.7 Station 03 Daily Min. 12.7 July 1971 C.B. Plateau Daily Max. 21.2 (31 days) Station 11 Daily Min. 12.2 August 1970 C.B. Plateau Daily Max. 20.7 Cheticamp, N.S. Daily Max. 22.6 (29 days) Station 01 Daily Min. 12,6 Daily Min. 15.3 C.B. Plateau Daily Max. 21.2 Ingonish Beach, N.S Daily Max. 23.8 Station 02 Daily Min. 13.4 Daily Min. . 15.5 Buchans, Nfld. Daily Max. 21.4 Daily Min. 12.2 (21 days) C.B. Plateau Daily Max. 19.1 Station 03 Daily Min, 12.3 August 1971 C.B. Plateau Daily Max. 22.0 (16 days) Station 11 Daily Min. 15.0 27 Mean maximum and mean minimum temperatures vary only slightly among the three stations established in 1970. These were compared using Duncan's New Multiple Range Test (Steel and Torrie, 1960) and were not found to be significantly different (a = 0.05). Differences between means for the 1970 and 1971 stations are larger, but may be related to the fact that only six days of June and 16 days of August were used for measurement in 1971. Temperature regimes for the areas studied can be further characterized and compared by examining the frequency with which temperatures of various groups occurred. Frequencies are determined for each of 12 three-degree classes, for both daily maximum and minimum temperatures. Frequencies are expressed as a percentage of the total number of days involved at each location. Figures 4 and 5 show that the most frequent groups of maximum temperatures at both stations 01 and 02 in 1970 are those including temperatures from 16°C to 21°C, which occurred with a frequency of 50.7% at station 01 and 43.7% at station 02. Maximum temperatures below 19°C were slightly more frequent at station 02 (32.7%) than at station 01 (29.9%) and maximums above 25°C also occurred more often at station 02 (31.5%) than at station 01 (22.1%). Minimum temperatures from 7°C to 12°C were most common at station 01, where they occurrjed on 41.6% of a l l days, while at station 02 a slightly higher group was most frequent (13°C to 18°C), with a frequency of 48.6%. Minimum temperatures below 10°C were more frequent at station' 01 (36.4%) than at station 02 (29.1%), as were minimums above 15°C (station 01, 28.6%; station 02, 26.4%). 28 , T»mp*ratvro Class** I E3 M IV V VI VII VIM IS SI Xlt Tcm^oratvre C l a o t « « 2 s 18 IS 2* n r , rVSastmwfn | 1 n r i i | Minimum Figure 4. X Frequency of Dally Maximum and Minimus Temperatures at Plateau Station 01 i n Various Classes Figure 6. 2 Frequency of Daily Kaxinua and Minimus Temperatures at Plateau Station 11 i n Various Classe 19 H >: to M -•* " t • » t J -f i » -H Temperature Ctoitoft i i m rv v vi vn. viu ix X xt xa Explanation of Figure* Maxknvm Mfrtrmwai Figure 5. 2 Frequency of Dally Maximum and Kintoua T^opcratui^ at Plateau Station 02 i n Various Classes Class Tecperat-re I bilow 0 II 0 - 3 III 4 - 6 IV 7 - 9 V 10 - 12 VI 13 - 15 VII 16 - 18 VIII 19 - 21 12 22 - 24 X 25 - 27 SI 2 8 - 3 0 XII abora 30 29 Maximum temperatures between 19°C and 25°C formed the most frequent group at station 11 i n 1971, with a 56.6% occurrence (Figured). Maximum temperatures below 19°C at t h i s station (28.4%) were s l i g h t l y lower i n frequency than at station 02, but simi l a r to 01. Maximum temperatures above 25°C occurred much less frequently at station 11 (15.1%) than at either of the 1970 stations. The most frequent minimum temperatures at station 11 were those from 10°C to 15°C, occurring with a frequency of 50.9%. Minimums below 10°C occurred on fewer days (21.5%) at th i s station than at stations i n 1970, while those above 15°C had a frequency of 27.5%, similar to those of 1970. Averages of d a i l y temperature ranges, or the differences between d a i l y maximum and minimum temperatures (Table 6 ) from 1970 stations are highest i n June i n which means vary from 10.1°C to 11.8°C among the three stations. August mean ranges are the lowest, varying from 6.7°C to 8.0°C. Daily temperature ranges varied considerably, ranges at station 02 varying i n June from 4.0°C to 23.0°C, i n July from 1.0°C to 19°C and i n August from 1.0°C to 14.°C. Mean ranges did not d i f f e r considerably among the three 1970 stations. Mean temperature ranges for June and August at station 11 i n 1971 are lower than those for 1970, but these differences again may be produced by the fact that few days of these months were'monitored i n 1971. The mean range for July at station 11 i s similar to those of 1970. ! 2. P r e c i p i t a t i o n P r e c i p i t a t i o n t o t a l s for the three-month period i n 1970 (Table 7 ) varied considerably between stations 01 and 02; the former 30 Table 6. Summaries of Daily Temperature Ranges at Plateau Stations and D.O.T. Stations at Ingonish Beach, Cheticamp, and Buchans Year Month Station Mean Range (°C) Location Mean Range (°C) 1970 June 01 10.1 Cheticamp, N.S. 9.0 02 10.5 Ingonish Beach, N. S. 9.8 03 11.8 Buchans, N f l d . 12.5 1971 11 7.1 1970 July 01 9.8 Cheticamp, N.S. 8.2 02 9.9 Ingonish Beach, N. S. 10.0 03 9.8 Buchans, N f l d . 10.3 1971 11 9.0 1970 August 01 8.0 Cheticamp, N.S. 7.0 02 7.8 Ingonish Beach, N. S. . 8.3 03 6.7 Buchans, Nfld. 9.9 1971 11 7.0 I 31 Table 7. P r e c i p i t a t i o n Totals at Plateau Stations and D.O. T. Stations at Ingonish Beach, Cheticamp, and Buchans from June to August Year No. of Days Station Total P r e c i p i t a t i o n (cm) Station Total P r e c i p i t a t i o n (cm) 1970 79 01 40.90 Ingonish Beach, N.S. 38.48 79 02 30.50 Cheticamp, N.S. 26.26 44 11 31.32 Buchans, Nfld . 37.40 1971 44 44 12 13 28.17 28.70 I 32 received 40.90 cm, the latter only 30.50 cm. In 1971 a l l stations received similar amounts of precipitation. These were similar to that of station 02 in 1970, but as the 1971 period of measurement was 33 days shorter than that of 1970, total precipitation for the two years may have differed. The distributions of r a i n f a l l recorded at station 01 in 1970 and at 11 in 1971 (Figure 7) were not uniform. In 1970 relatively l i t t l e rain was received in July and early August, and 70% of the total f e l l within a 14-day period in August. In 1971, a peak in r a i n f a l l in early July was followed by a period of relatively low precipitation for the remainder of the month, and a rise similar to that of 1970 occurred during the middle of August. Rainfall distributions at other Plateau stations were similar to those mentioned above. 3. Wind In the 17-day measurement period of June, 1970, a total of 4700.9 km of wind was measured at station 01 (Table 8 ), equivalent to an average of 334.1 km per day or 13.0 km per hour. A number of spot wind velocities were determined; of those taken in June, the highest was 28.7 km per hour. 9013.1 km were recorded at this station in July, equal to an average of 300.1 km per day, or 12.4 km per hour. The maximum measured velocity for this month was 25.1 km/hr. Wind I, measurements in August, 1970 resembled those of July. Wind was recorded for only six days in June 1971 at station 11 (Table 8 ); during this period the mean per day was 236.2 km and per .i hour was 9.7 km. Much less wind blew in July 1971 than in July of the 16 i June July August 13 to 19 to 27 to 6 to 13 to 6 to 13 to 19 to F i g u r e 7. Weekly P r e c i p i t a t i o n T o t a l s a t Cape Breton P l a t e a u C l i m a t i c S t a t i o n s . 00 w j i 34 Table 8. Summaries of Wind Measurements on the Cape Breton Plateau, at stations 01 (1970) and 11 (1971) during June to August Month Station No. of Days Mean per day ' , (Km) Mean per hr (Km) Maximum per hr (Km) Monthly Tot a l (Km) June 01 17 334.1 13.0 28.7 4700.9 11 06 236.2 9.7 16.3 2126.2 July 01 31 300.1 12.4 25.1 9013.1 11 31 224.6 9.3 19.3 6739.3 August 01 29 270.5 12.1 27.4 8925.8 11 16 262.4 11.3 19.3 3675.6 previous year; in 1971 a total of 6739.3 km was recorded, equivalent to 224.6 km/day, or 9.3 km/hr. The maximum spot reading for this period was 19.7 km/day. The mean wind per day and per hour for August 1971 was only slightly lower than that of the previous year. 4. Relative Humidity The only relative humidity readings taken on the Plateau during the study period were those made by Comeau (1971) twice daily beneath an Abies balsamea canopy over a 21-day period in June and July of 1970. Morning readings averaged 81.7% and ranged from 41.0% to 93.0%, while evening readings averaged 72.4% and varied from 42.0% to 93.0%. Although daily weather conditions were not recorded, low cloud banks were commonly present on the Plateau as dense fog. L i t t l e additional precipitation was measured at these times, but exposed vegetation nevertheless appeared to receive considerable amounts of moisture. 5. Discussion The preceding results show that during the three-month period in 1970, minimum temperatures were lowest in June and highest in August, while maximum temperatures were highest in July. Although temperature means did not differ greatly between the two stations in 1970, frequencies of maximum and minimum temperature groups did. Both very low and high daily maximum temperatures were more common at station 02 than at station 01, but low and high minimum temperatures were more frequent at station 01. In other words, over the three month 36 period of measurement, maximum temperatures at s t a t i o n 01 were generally more stable than at s t a t i o n 02, where extremes were more common. The reverse was true for minimum temperatures. Stations 01 and 02 d i f f e r e d markedly i n terms of l o c a t i o n ; 01 was located i n a raised bog, and 02 on a dry barren area. Thermographs were located at ground l e v e l , hence differences i n heat conductivity of the two areas may have strongly affected the temperatures recorded. Although high maximum and low minimum temperatures were s l i g h t l y l e s s frequent i n 1971 than i n 1970, temperatures were generally s i m i l a r . The differences that were observed may have been produced by d i f f e r e n c e s i n l o c a t i o n , the measurement s i t e i n 1970 being located i n a much larger bog than that used i n 1971. This may also have accounted for d i f f e r e n c e s i n wind speeds recorded i n the two areas. P r e c i p i t a t i o n on the Plateau during both years was very unevenly d i s t r i b u t e d ; most of the r a i n f a l l i n g i n the three-month period did so during a short period i n August. Such i r r e g u l a r i t i e s i n d i s t r i b u t i o n could create r e l a t i v e l y dry conditions during low r a i n f a l l periods, followed by rapid runoff and erosion i n some areas at times of high r a i n f a l l . Mean wind v e l o c i t i e s were generally highest i n June and lowest i n August. Differences, however, were les s than three km per hour. High wind v e l o c i t i e s are probably more c r i t i c a l during winter months, when exposed vegetation i s subjected to d r i f t i n g snow and i c e b l a s t i n g . Extensive damage of t h i s type i s common i n vegetation i n and around raised bogs on the Plateau (Nichols, 1913). Tne r e s u l t s of t h i s study describe aspects of the Plateau climate for the summers of 1970 and 1971, but are not n e c e s s a r i l y 37 t y p i c a l . In addition, no quantitative information as to winter c l i m a t i c conditions e x i s t . A long-term, year-round study would be necessary for a clear understanding of the climate of the area. Comparisons with Lowland Cape  Breton and Newfoundland Both Nichols (1918) and Comeau (1971) suggested the climate of the Plateau i s d i f f e r e n t from that of Lowland stations at Ingonish Beach and Cheticamp on the coast, and Loucks (1962) believed the Plateau to be c l i m a t i c a l l y s i m i l a r to Buchans, Newfoundland. It seems appropriate, then, to compare the r e s u l t s for the Plateau presented above with records for the same period from D.O.T. stations at these lo c a t i o n s . Since the period of measurement on the Plateau i n 1970 was longer than that of 1971, the r e s u l t s from the former year are used f o r comparisons. These comparisons must, however, be treated with regard given to the fact that while instruments on the Plateau were located at ground l e v e l , those at D.O.T. stations were positioned at a height of 4 f t . Geiger (1965) suggested that such differences i n height could, depending upon weather conditions, produce differences of several degrees i n temperature. Adjustments cannot be made to data c o l l e c t e d on the Plateau, since apparently temperature discrepancies are not consistent. In s p i t e of this*problem, i t does seem worthwhile to compare c l i m a t i c measurements from the Lowland areas of Cape Breton and centr a l Newfoundland with those of the Plateau. In 1970, June maximum temperatures at the Plateau and Lowland stations d i f f e r e d l i t t l e . At Cheticamp and Ingonish Beach these 38 averaged 20.4°C and 21.5°C respectively (Table 5 ), less than three degrees higher than means for Plateau stations. Mean minimums for this month at the Lowland Stations, however, were 1° to 3° higher than those on the Plateau. Similarly, in July and August averages of both minimum and maximum temperatures at both Cheticamp and Ingonish Beach were 2° to 3° higher than those for Plateau stations. When the frequency of occurrence of various maximum and minimum temperatures of the entire period at the Lowland stations is examined (Figs. 8,9 ), i t i s seen that maximum temperatures were below 19°C for about 20% of the days under consideration. In contrast, this temperature group had a frequency of about 30% on the Plateau. At Cheticamp and Ingonish 35% and 40% of the total number of days had maximum temperatures above 25°C, whereas at station 01 on the Plateau these occurred with a frequency of 22%. Plateau station 02 was more similar to the Lowland stations in this respect, having a frequency of 31%. Differences in minimum temperatures between the two areas appear to be greater. On the Plateau minimums were below 10°C on 29% and 36% of the days measured, while at Cheticamp and Ingonish Beach only 19% and 14% of these days had temperatures below this level. In addition, minimums above 15°C occurred with frequencies of 50% and 44% at the two Lowland stations, compared with frequencies of 29% and 26% at Plateau stations 01 and 02. At Buchans, Newfoundland, maximum temperatures in June, 1970 averaged 20.0°C (Table 5 ), varying l i t t l e from those for the Plateau. Minimum temperatures for this month at Buchans, however, averaged 7.7°C, and were 1° to 3° lower than mean minimums on the Plateau. July and Ton-jxvature Classei i i i III iv v vi vii VIII ix x x: xn 35 -I Figure 8. % Frequency of Daily Max/jaum and Ilinimun: Temperatures at Cheticamp, N.'S. i n Various Classes Temperature Classes I II Dl IV V VI VII VIII IX. X XI XII Figure 9. Z Frequency of Daily Maximum and Minimum Temperatures at Ingonish Beach,N.S. i n Various Classes August means of both maximum and minimum temperatures at Buchans a l l d i f f e r e d l e s s than 2° from means at Plateau st a t i o n s . Graphs of the frequencies with which temperatures Occurred at Buchans (Fig. IO ) show that maximum temperatures were below 19°C on 26% of the days considered, about 5% fewer than on the Plateau. Maximum temperatures above 25°C occurred with about the same frequency i n the two areas. In Newfoundland minimum temperatures were not below 10°C more often than at Plateau s t a t i o n 01, but minimums were above 15°C only 14% of the time, compared with 29% and 26% at Plateau st a t i o n s . Mean temperature ranges for June at Cheticamp and Ingonish Beach (Table 6 ) are s l i g h t l y lower than those of the Plateau st a t i o n s . July and August means for Cheticamp are also lower than those of the Plateau, but means for Ingonish Beach during these months are equal to or higher than those of the Plateau areas. Mean ranges for a l l three months at Buchans are s l i g h t l y higher than those of the Plateau. P r e c i p i t a t i o n at Ingonish Beach for the three-month period resembled that of the Plateau i n both t o t a l amount received (Table 7 ) and i n d i s t r i b u t i o n (Fig. II ). R a i n f a l l at Cheticamp was s i m i l a r l y d i s t r i b u t e d but t o t a l r a i n f a l l was 12 cm le s s than that of Ingonish Beach, owing to the fact that during the week of August 6 to 13 Cheti-camp received much l e s s than did the other Cape Breton areas. Total p r e c i p i t a t i o n at Buchans, Newfoundland was s i m i l a r to that of Cape Breton, but Figure II shows that the d i s t r i b u t i o n was much more uniform, with more r a i n f a l l i n g i n July at Buchans than at other areas. Wind and r e l a t i v e humidity comparisons among the three areas are not possible, since these are not measured at the D.O.T. stat i o n s . 4 1 30 H 25 A 20-15-10-u c » N ° 5 H 10 15-2 0 -2 5 -30-Temperature Classes I II III IV V VI VII VIII IX X XI XII Maximum V j -M inimum F i g u r e 10. I, % F r e q u e n c y - o f D a i l y Maximum and Minimum Temperatures a t Buchans, Newfoundland i n V a r i o u s C l a s s e s . i F i g u r e II. Weekly P r e c i p i t a t i o n T o t a l s a t D.O.T. S t a t i o n s i n Newfoundland and Labrador. 43 In summary, the c l i m a t e of t h e P l a t e a u d u r i n g June, J u l y and August was g e n e r a l l y s e v e r a l degrees warmer than t h a t o f c o a s t a l l o w l a n d a r e a s a t Cheticamp and I n g o n i s h Beach. Temperature d i f f e r e n c e s were s m a l l , and d i f f e r e n c e s f o r any one day might have been caused by the d i f f e r e n c e s i n i n s t r u m e n t l o c a t i o n mentioned p r e v i o u s l y . I t seems u n l i k e l y , however, t h a t a c o n t i n u o u s t r e n d of h i g h e r temperatures i n the Lowlands c o u l d be thus accounted f o r , s i n c e the e f f e c t o f h e i g h t above ground l e v e l i s not c o n s i s t e n t ( G e i g e r , 1965). D a i l y temperature ranges i n June were h i g h e r on t h e P l a t e a u than i n the Lowlands, but f o r the remainder of the summer, P l a t e a u ranges were h i g h e r than those a t Cheticamp o n l y . P r e c i p i t a t i o n t o t a l s were g e n e r a l l y t h e same on the P l a t e a u as those r e c o r d e d a t the Lowland s t a t i o n s . At Buchans, Newfoundland, June temperatures were s l i g h t l y lower than t h o s e on the P l a t e a u , w h i l e those f o r J u l y and August a t the two a r e a s were s i m i l a r . D a i l y temperature ranges were g e n e r a l l y h i g h e r i n Newfoundland, p a r t i c u l a r l y d u r i n g June. . P r e c i p i t a t i o n i n the two a r e a s d i f f e r e d o n l y by s m a l l amounts. A l t h o u g h the summer c l i m a t e of the P l a t e a u tends to be s l i g h t l y c o o l e r than t h a t o f the Lowlands, i t i s d i f f i c u l t to suggest t h a t the d i f f e r e n c e s between the two a r e a s a r e g r e a t enough to a f f e c t v e g e t a t i o n . The r e s u l t s do s u g g e s t , however, t h a t c l i m a t i c c o n d i t i o n s on the P l a t e a u f o r the f i r s t few weeks of summer a r e p o o r e r f o r v e g e t a t i o n than a r e t h o s e i n the Lowlands. In o t h e r words, the onset of the growing season i s s e v e r a l weeks l a t e r on the P l a t e a u . 44 IV. DESCRIPTIONS OF FOREST ASSOCIATIONS 1. The Upland Fir (Abies balsamea - Dryopteris spinulosa - Hylocomium umbratum)  Association (Table I , Appendix I ) This is the most common of the three associations, forming the major part of the forest vegetation on the Plateau. It i s found on well-drained soils of low ridges. Maximum slope gradients in these areas are 4°, exposures are variable, and ground surfaces are characteristically hummocky, due to an abundance of decayed wood (Fig. t r ). The overstory vegetation of this association varies somewhat in density. The uppermost (A^) layer ranges in coverage from 25% to 65% and is predominantly composed of Abies balsamea, which has an average coverage of 40.8%. The only other species found in this layer i s Picea glauca, which occurred in 30% of the stands studied, with an average cover of only 4.3%. The low tree layer (A^) varies in coverage from 2% to 52% and averages 34.6%. Only two species form this layer: Abies balsamea, again dominant, covering an average of 32.3%, and Betula papyrifera, with an average coverage of 6.1%. I. Shrub layers are sparsely developed in the upland f i r association, in many stands probably because of poor light conditions. The high shrub layer (B ), composed of Abies balsamea transgressives, .i occurred in only 70% of the stands, and has an average coverage of 2.5%. 45 a F i g u r e 1 Z . The u p l a n d f i r a s s o c i a t i o n showing t h e hummocky m i c r o r e l i e f c r e a t e d by abundant f a l l e n l o g s . The s t a k e i s 1 m. i n h e i g h t . (Photo by Roy) 45b 46 The low shrub layer (B^) was present i n a l l stands and averaged 6%. t o t a l coverage. Abies balsamea dominates the layer with an average cover of 3.3%. Betula payrifera, Amelanchiev bartramiana, Sorbus decora, and Picea glauca also occur i n t h i s l a y e r , but with lower constancy and abundance. The herb and dwarf shrub (C) i s the best developed vegetation layer, having an average cover of 81.2%. Development of t h i s layer i s often very i r r e g u l a r and appears to be determined i n part by l i g h t conditions. Figures 13 and 14 demonstrate these differences i n development between two areas adjacent to each other, one shaded and the other unshaded. Dryopteris spinulosa i s the dominant species of the C layer (Fig. 15 ), and has an average coverage of 26.5%. Cornus canadensis i s an important subdominant, occurring i n a l l stands studied with an average coverage of 19.8%. This species i s p a r t i c u l a r l y abundant i n unshaded areas, and may cover as much as 40% of the t o t a l stand area. Abies balsamea seedlings and Oxalis montana are also c h a r a c t e r i s t i c members of the C layer, having average coverages of 12.5% and 17.8% re s p e c t i v e l y . Seventeen other species which have constancy values of 70% or more are found i n t h i s layer; of these, Coptis trifolia, Aster acuminatus, Clintonia borealis and Trientalis borealis have average coverages of 5% or more. ), Bryophytes and lichens growing on humus (Dh layer) are common in the upland f i r a s s o c i ation. T o t a l coverage of the layer averages 55%, and varies from 20% to 90%. Development of the layer i s probably co n t r o l l e d mostly by both l i g h t and dense shading, i n some stands 47a Figure 13. The understory vegetation beneath an unshaded area i n an upland f i r stand, showing the r e l a t i v e abundance of Dryovier-is spinulosa, Cornus canadensis, and SoZidago ma.crovkyZ^. (Photo by Roy) Figure 1^  . A shaded area of the same stand as above, showing the r e l a t i v e sparseness of the understory vegetation. EyZocomiviTi virbvatvm i s the major bryophyte species here. (Photo by Roy) 47b 48a Figure 1 5 . An upland f i r stand showing the abundance of Dryopteris spinulosa. Shrub layers are nearly absent i n these stands. (Photo by Roy) 48b hindering bryophyte growth. The most common species of the Dh layer are Hylocomium umbratum and Pleurozium schreberi; these intermingle to form large discontinuous mats on humus hummocks. H. umbratum is the more abundant of the two, having an average coverage of 29.0%, compared with 11.9% for P. shreberi. In shallow depressions between the hummocks, where runoff water may accumulate, small patches of Sphagnum capillacewn often occur. This species was present in 90% of the stands, and has an average coverage of 12%. Four additional, but less abundant species occurring in this layer with high constancy are Dicranum majus, Rhytidiadelphus loreus, P t i l i u m c r i s t a - c a s t r e n s i s , and Polytrichum commune. Abundant windthrown and standing dead trees provide suitable microhabitats for a number of bryophytes and lichens (Ddw layer), whose total coverage varies from 4% to 20% and averages 10.5%. Constant species of this layer are: Dicranum fuscescens, Bazzania t r i l o b a t a , Brachythecium s t a r k e i , Hypnum pallescens, Plagiothecium laetum, A l e c t o r i a americana, and several species of Cladonia. 2. The Black Spruce (Picea mariana -Pleurozium schreberi) Association  (Table II , Appendix I ) The black spruce association most commonly occurs on the plateau as a band of vegetation in low-lying and poorly-drained areas surrounding raised bogs. The association may also be found in erosion trenches of peat bogs (Comeau, 1970) (Figure I ) and, occasionally, on 50a Figure 16 . Open peat bogs on the Plateau around which the black spruce association commonly develops. (Photo by B e i l ) Figure 17 . A black spruce stand showing wind-trimmed appearance of Picea mariana stems that grow above approximately 2.5 m. The t a l l e s t trees here are l i t t l e more than 3 m. (Photo by Forwood) 50b the t h i n r o c k y s o i l s of low r i d g e s . The s o i l s i n l o w - l y i n g a r e a s a r e c h a r a c t e r i z e d by t h i c k upper l a y e r s o f mixed peat u n d e r l a i n by a r e d d i s h c o l o u r e d B h o r i z o n . Ground water i s u s u a l l y p r e s e n t a t depths of one meter or l e s s . The topography o f t h e s e a r e a s i s l e v e l , and m i c r o r e l i e f i s f l a t . Picea mariana i s the dominant s p e c i e s i n a l l the v a s c u l a r p l a n t l a y e r s of t h i s a s s o c i a t i o n . I t s development i s g r e a t e s t i n the shrub l a y e r s , where i t forms dense clumps t h a t have an average coverage of 55.2% i n the B^ and 41.4% i n the B^ l a y e r . A l t h o u g h d e n s i t i e s a r e h i g h , P. mariana shows poor growth, seldom e x c e e d i n g 3 m i n h e i g h t . T r e e s were c l a s s e d as p a r t o f the l a y e r i n o n l y two s t a n d s ; t hose t h a t do r e a c h t h i s h e i g h t a r e s e v e r e l y pruned by snow and i c e b l a s t i n g ( F i g . 17 ). Most t r e e s , r e g a r d l e s s o f h e i g h t , have a p e c u l i a r growth form i n which the b a s a l p o r t i o n o f t h e stems extend h o r i z o n t a l l y f o r up to a metre. T h i s d e f o r m i t y may be produced by l a y e r i n g , a v e g e t a t i v e form o f r e p r o d u c t i o n t h a t i s common among P. mariana i n t h i s a s s o c i a t i o n . In t h i s a s s o c i a t i o n a number of shrub s p e c i e s o c c u r i n openings between the P. mariana t h i c k e t s ( F i g . 18 ). Nemopanthus muoronata and Rhododendron canadense a r e the most abundant of t h e s e , o c c u r r i n g w i t h average coverages of 13.1% and 8.5% r e s p e c t i v e l y . Other c o n s t a n t s p e c i e s i n c l u d e d Viburnum cassinoides, Amelanchier bartramiana, Abies balsamea, and Kalmia angustifolia. T o t a l coverage of the herb and dwarf shrub l a y e r (C) i s low, p r o b a b l y because of dense s h a d i n g by P. mariana and shrub s p e c i e s . The l a y e r v a r i e s i n coverage from 20% to 68%, and averages 48.4%. P. mariana r e p r o d u c t i o n i s dominant, w i t h an average coverage o f 9.1%, 52a Figure \Z . A black, spruce stand showing the abundance of low shrubs in openings between dense growths of Picea mariana. Shrub species seen here are Viburnum cassinoides. Ledum groenlandicum, and Rhodendron canadense. . (Photo by Roy) 52b followed by Rhododendron canadense with an average of 8.3%. Cornus canadensis, Vaccinium angustifolium, C\intonia b o r e a l i s , Coptis t r i f o l i a , Gaultheria h i s p i d u l a , and Nemopanthus mucronata are constant species with average coverages of 3.0% or greater. Kalmia a n g u s t i f o l i a , Taxus canadensis, and Ledum groenlandicum have s i m i l a r coverages but occur l e s s frequently. Bryophytes and lichens of the Dh layer are abundant here ranging i n t o t a l coverage from 65% to 95%, and averaging 76.3%. Pleurozium schreberi and Sphagnum capillaceum are the dominant species, occurring with average coverages of 27.8% and 25.3% res p e c t i v e l y , and are accompanied by l e s s abundant species such as Bazzania t r i l o b a t a , Dicranum majus, Hylocomium splendens, and several Cladonia species. Only two constant species are found i n the Ddw layer of t h i s a s s o c iation. These are P t i l i d i u m c i l i a r e and Dicranum fuscescens; each has an average coverage of about 2%. The poor development of the layer may be due to a lack of both l i g h t and decayed wood i n the dense stands. 3. The Swamp F i r (Abies balsamea -Osmunda cinnamomea - Sphagnum capillaceum)  Association (Table HI , Appendix ] ) The swamp f i r ass o c i a t i o n i s rare on the Cape Breton Plateau; stands are small and are found only on c e r t a i n low-lying s i t e s at the bases of seepage slopes and along streams, where ground water i s abundant and near the surface for most of the year. The topography of these areas i s l e v e l , and the m i c r o r e l i e f i s f l a t . These s i t e s are more protected than are those of the black spruce association. 54 The s o i l s i n these areas have t h i c k organic layers underlain by Ae and B horizons. The t a l l tree layer i s not as we l l developed i n the swamp f i r a s s o c i a t i o n as i n the upland f i r a s s o c i a t i o n ; i n the swamp f i r a s s o c i a t i o n the A^ only averages 17.4% i n coverage. The A^ ,, however, averages 38.9% and i s s i m i l a r to that of the upland f i r a s s o c i a t i o n . Abies balsamea i s the,dominant species i n both layers of swamp f i r stands, with an average coverage of 19.2% i n the A^ layer, and 34% i n the A^. Frequently Picea glauca i s present as wel l ; i t was found i n the A^ layer i n 57% of the stands examined but has an average coverage of only 3%. I t occurs i n the A^ with a constancy of 71%, and an average coverage of 8%. The poorer development of the A^ l a y e r . i n swamp f i r stands r e s u l t s i n better l i g h t conditions at understory l e v e l s than i n upland f i r stands. This, together with the higher s o i l moisture, allows a greater development of the shrub layers 'in the swamp f i r a s s o c i a t i o n . The high shrub layer (B^), composed mainly of Abies balsamea, has an average coverage of 13%. In 43% of the stands, Picea mariana and Alnus rugosa were also present i n t h i s l a y e r , but were not abundant. The low shrub layer i s better developed and has an average coverage of 40.4%. It i s composed of seven species with constancy values of 70% or more. The most abundant of these i s Abies balsamea, occurring with an average coverage of 19.6%, followed by Alnus rugosa, an i n d i c a t o r of wet s o i l conditions, with an average of 19.0%. Other constant'species i n decreasing order of abundance are Amelanchier ba/rtrajniano,, Serous decora, Picea glauca, Nemopanthus mucronata, and Betula papyrifera. 55 The high l i g h t and moisture conditions also favour the development of a dense herb and dwarf shrub layer, which i n t h i s a ssociation averages 92% i n coverage. The most abundant species i n t h i s layer i s Osmunda cinnamomea (Fig. 19 ). The coverage of t h i s species averages 42.5%, but on favourable s i t e s may reach 85%. Dryopteris spinulosa often grows together with t h i s species, covering an average of 11.5%. Beneath these Cornus canadensis and Coptis trifolia often form large patches, with mean coverages of 14.0% and 12.5% res p e c t i v e l y . Abies balsamea seedlings are also common, covering an average of 11.8%. Seventeen a d d i t i o n a l species with constancy of 70% or more compose the C layer of t h i s a s s o ciation. Of these, Solidago macrophylla, Aster acuminatus, Aralia nudicaulis, Oxalis montana and Sorbus decora were found i n a l l pl o t s and have average coverages greater than 4%. Bryophytes and lichens of the Dh layer form an average coverage of 43.6% i n t h i s a s s o ciation. Sphagnum capillaceum i s usually dominant, and has an average coverage of 27.9%. Pleurozium schreberi and Hyloco-mium umbratum, with average coverages of 7.5% and 5.5% re s p e c t i v e l y , are common, p a r t i c u l a r l y on d r i e r s i t e s such as humus hummocks. Bazzania trilobata, Dicranum majus, and Ptilium crista-castrensis are also constant but are less abundant. The Ddw layer averages 13.6% i n coverage, and i s composed of nine species with constancy vjalues greater than 70%. These are, i n decreasing order of abundance: Rhytidiadelphus loreus, Bazzania trilobata, Ptilidium ciliare, Dicranum fuscescens, Plagiothecium laeturn, Hypnum pallescens, Tetraphis geniculata, Alectoria americana, and several Cladonia species. 56a Figure 19 . A stand of the swamp f i r association showing the abundance of Osmunda cinnamonea. The tree strata of these stands are relatively open, allowing understory species to grow in abundance. (Photo by Roy) 56b 57 4. Successional Communities (Table [V , Appendix I ) In a number of areas on the Plateau successional communities have developed following the disturbance of upland f i r stands. These 2 areas are relatively small, usually covering less than about 1000 m . In the areas examined, windfalls were not more abundant than those usually found in undisturbed stands, and most of the trees present were standing dead. This suggests that tree mortality was perhaps a result of insect infestation or partial wind damage that in turn led to decay or infestation. Although serious outbreaks of spruce budworm on the Plateau have been reported (Recks, 1953), i t i s not known that these would result in small, isolated areas of extensive damage as found in the study area. No evidence of f i r e was found anywhere in the study area. Three of these areas were examined. The tree layers, where present, were very reduced and were composed of Abies balsamea. In plots 12 and 14 only A^ layers were present, with coverages of 7.5% and 25%, and plot 13, a l l that remained was an A^ layer with a coverage of 15%. Shrub layers were well developed in a l l three areas, being composed of saplings that were released from the suppression of over-story shading after disturbance. In stands 12 and 13 the layer was composed solely of Abies balsamea (Fig. 2,0), whereas in stand 14 Betula papyrifera was the dominant species and few A., balsamea individuals were present (Fig. 11 ). The B^  layer of the three stands had an average coverage of F i g u r e 2.0. A s u c c e s s i o n a l community i n s a p l i n g s a r e dominant. The d e s t r o y e d and some mature A. by Forwood) 58a which Abies balsamea o v e r s t o r y i s n o t c o m p l e t e l y balsamea remain. (Photo F i g u r e 2,1 A s u c c e s s i o n a l community i n which Betula papvyvifeva i s dominant. Most of the mature t r e e s seen h e r e a r e dead. (Photo by Forwood) 58b 59 61.6%. In stands 12 and 13 Betula papyrifera and Abies balsamea were equally abundant in this layer, while in stand 14, Betula payrifera was dominant. Rubus idaeus was also present in the B^ ; i t occurred with a coverage of 7.5% in stand 13 and 15% in stands 12 and 14. Sorbus decora, Prunus pennsylvanica,and Ribes glandulosum were also present but less abundant in two of the three stands. The C layer of the three stands was similar in coverage to that of the upland f i r association, averaging 78.3%. Although in the disturbed areas species diversities of the C layer were lower than those of the upland f i r stands, most of the species present in the successional communities were also present in upland f i r stands. The most abundant of these species in the disturbed stands were Cornus canadensis, Dryopteris spinulosa, and Abies balsamea', a l l had average coverages of about 11%. Other less abundant but constant species included Oxalis montana, Aster acuminatus, Carex trisperma, and Trientalis borealis. Rubus idaeus and Ribes glandulosum were common in the disturbed areas, with average coverages of 8.3% and 7.5% respectively, but are not usually found in undisturbed upland f i r stands. These species appear to be suited to growing under the exposed conditions of the disturbed areas, and successfully compete with the dense sapling growths. Other species, such as Athyrium Filix - femina, Dryopteris Phegopteris, and Spreptopus roseus, may prefer the more shaded conditions of undisturbed stands, where competition with saplings is less intense. 5. Discussion The forest associations described above may be compared by considering the d i s t r i b u t i o n of constant species (occurring i n 70% or more of the stands studied) among them. These species are l i s t e d by layer and arranged such that groups by ass o c i a t i o n form (Table 9 ) . Total numbers of constant species are highest i n the swamp f i r association, which has a t o t a l of 40, are s l i g h t l y lower i n the upland f i r stands, t o t a l l i n g 34, and are lowest i n black spruce stands, t o t a l l i n g only 28. The explanation f o r the r e l a t i v e l y high number of constant species i n swamp f i r stands i s perhaps that s i t e conditions here allow the establishment of species c h a r a c t e r i s t i c of black spruce stands as well as species constant i n upland f i r stands. In f a c t , most species constant i n the swamp f i r ass o c i a t i o n are also constant members of at le a s t one of the other two associations. The swamp f i r s i t e s must then share physical c h a r a c t e r i s t i c s with those of black spruce stands and upland f i r stands. Fewer species are constant i n the black spruce as s o c i a t i o n . A comparison of constant species by layer f or the three associations i n d i c a t e s that although low shrub species are more numerous i n black spruce stands, herb, dwarf shrub, and bryophyte species are fewer i n the black spruce a s s o c i a t i o n than i n the others. whereas a t o t a l of 31 and 33 constant C( and D layer species are found i n the upland f i r and swamp f i r associations, the black spruce a s s o c i a t i o n has only 20. The establishment and growth of herb and bryophyte species i s perhaps l i m i t e d i n black spruce stands because of competition for l i g h t and space with dense growths of shrubs and black spruce. Table 9 . . Distribution of Constant Species among Forest Associations Upland F i r Swamp Fi r Black Spruce Association Association Association A^ layer Abies balsamea 100 (40.8) a 86 (19.2) A„ layer Abies balsamea 100 (32.3) 100 (34.2) •k Betula papyrifera 70 ( 6.1) Picea glauca 71 (8.5) layer Abies balsamea 70 (2.5) 100 (13.2)* 71 (3.5) Picea mariana 100 (52.8) B£ layer Kalmia angustifolia .86 (4.0) Picea mariana • 100 (41.4)* Viburnum cassinoides 100 (6.6) * Rhododendron canadense 100 (8.5) k Nemopanthus mucronata 86 (2.8) 100 (13.1) * Amelanchier bartramiana 100 (7.4) 100 (5.6) Abies balsamea 95 (3.4) 100 (19.6) 100 (4.5) Betula papyrifera 70 (4.0) 71 (2.0) Sorbus decora 100 (3.6) •k Alnus rugosa 71 (14.0) ON Picea glauca C layer Dryopteris Phegopteris 100 * (3.8) Athyrium Filix-femina 95 (4.2)*. Osmunda claytoniana 85 A (2.6) Moneses uniflora 80 A (1.6) Acer spicatum 70 A (2.1) Betula papyrifera 95 A (4.4) A (1.9) Streptopus roseus 95 Trientalis borealis 100 (5.1)* Solidago macrophylla 90 (5.3) . Sorbus decora 90 (2.1) Aster acuminatus 85 (9.2) Aralia nudicaulis 85 (4.7) Dryopteris spinulosa 100 (26.5)* Oxalis montana 100 (17.8)* Cornus canadensis 100 (19.8)* Abies balsamea 100 A (12.5) Coptis t r i f o l i a 100 (8.0) Clintonia borealis 100 A (5.8) Maianthemum canadense 100 (4.3)* Amelanchier bartramiana 95 (2.0) Picea glauca Osmunda cinnamomea Gaultheria hispidula . Vaccinium angustifolium 71 (2.9) 71 (1.9) 100 (2.4) 100 A (7.9) 100 A (4.8) 86 A (8.7) 100 (5.4) 100 (11.5) 100 (4.6) 100 (14.6) 100 (6.4) 100 (11.8) 86 (2.0) 100 A (12.5) 100 (3.9) 100 (3.9) 100 (4.5) 100 (3.6) 71 (2.1) 100 (2.0) 100 A (2.6) 100 (2.1) 100 A (42.5) 100 (2.3) 100 A (3.1) 86 (1.8) 100 A (6.4) Viburnum cassinoides Taxus canadensis Carex trisperma Linnaea borealis Ledum groenlandicum Rhododendron canadense Rub us Chamaemorus Picea mariana Kalmia angustifolia Epigaea repens D layer Tetraphis geniculata Sphagnum magellanicum A Rhytidiadelphus loreus 90 (1.8) Bazzania trilobata 80 (2.4) A Hypnum palbescens 75 (2.0) A Hylocomium umbratum 100 (29.0) Alectoria americana 85 (1.8) Ptilium crista-castrensis 80 (1.8) Pleurozium schreberi 100 (11.9) Dicranum majus 95 (5.0) Sphagnum capillaceum 90 (12.1) Cladonia spp. 95 (1.3) Dicranum fuscescens 70 (2.1) 71 (2.9) 71 ((1.1) 86 100 (4.5) (4.9)' 100 71 71 (2.6) (4.1)! (2.9) 71 100 71 100 86 86 (3.0) ' (8.3): (2.2)' (9.1) ; (7.9)1 (2.7)' 71 71 86 100 71 100 100 100 100 100 100 100 100 (1.6)" (2.1)* (2.0) * (1.9) (1.6) (4.9) (1.4) A (1.8) (7.5) (2.4) (27.9); (1.4) (1.7) 100 (10.3) 86 (4.1) 100 100 100 100 100 (27.8) (3.9)* (25.3) (1.7)* (2.0)* Plagiothecium laetum 70 (2.0) Polytrichum commune 75 (2.1) Brachythecium curtum 75 (1.9) Ptilidium c i l i a r e Alectoria orchroleuca Polytrichum juniperinum " ' > Hylocomium splendens The f i r s t value is Constancy (%) and the second is Values marked with an * denote associations in 86 (1.7)" ' 100 (1.9) 100 (2.1)* 100 (5.9)* Average Coverage (%) which a species is most constant and abundant 65 A number of the s p e c i e s i n T a b l e 9 a r e widespread i n d i s t r i b u t i o n , b e i n g c o n s t a n t i n a l l v e g e t a t i o n t y p e s s t u d i e d . These i n c l u d e the f o l l o w i n g : Abies balsamea Ptilium crista-castrensis Amelanchier bartramiana Pleurozium schreberi Coptis trifolia Dicranum majus Maianthemum canadense Dicranum fuscescens Clintonia borealis Cornus canadensis Sphagnum capillaceum These s p e c i e s may be c o n s t a n t i n a l l t h r e e a s s o c i a t i o n s f o r s e v e r a l r e a s o n s . They may be more t o l e r a n t than some of the o t h e r c o n s t a n t s p e c i e s , b e i n g a b l e t o occupy a w i d e r d i v e r s i t y o f m i c r o -h a b i t a t s and s u c c e s s f u l l y compete w i t h o t h e r s p e c i e s . On the o t h e r hand, they may have r a t h e r narrow t o l e r a n c e ranges but demand c o n d i t i o n s which a r e f a i r l y common i n a l l t h r e e of the s i t e s on which t h e a s s o c i a t i o n s d e v e l o p . Other s p e c i e s a r e c o n s t a n t i n o n l y one a s s o c i a t i o n , or a r e much more abundant i n one p a r t i c u l a r a s s o c i a t i o n than i n o t h e r s . These a r e u s e f u l as d i s t i n g u i s h i n g s p e c i e s f o r an a s s o c i a t i o n , and i n some i n s t a n c e s may i n d i c a t e the e x i s t e n c e o f c e r t a i n s i t e c o n d i t i o n s found i n n e i t h e r o f the o t h e r two a s s o c i a t i o n s . F i v e s p e c i e s a r e l i m i t e d as c o n s t a n t s p e c i e s t o t h e upland f i r a s s o c i a t i o n ; t h e s e i n c l u d e Dryopteris Phegopteris, Athyrium Pilix-femina, Osmunda claytoniana, Moneses uniflora and Acer spicatum. These s p e c i e s a p p a r e n t l y ' g r o w w e l l on the P l a t e a u o n l y on the c e r t a i n s i t e s o c c u p i e d by upland f i r s t a n d s , and a r e unable to t o l e r a t e c e r t a i n c o n d i t i o n s i n 66 o t h e r v e g e t a t i o n t y p e s . Without a knowledge o f the i n d i v i d u a l s p e c i e s ' r e q u i r e m e n t s , however, i t i s d i f f i c u l t to p i n p o i n t which c o n d i t i o n s a r e u n f a v o u r a b l e . F i v e o t h e r s p e c i e s a r e f r e q u e n t l y found i n o t h e r a s s o c i a t i o n s , but a r e more abundant i n upland f i r s t a n d s . These a r e : Dryopteris spinulosa, Oxalis montana, Cornus canadensis and Hylocomium umbratum. S e v e r a l s p e c i e s a r e c o n s t a n t o n l y i n the swamp f i r a s s o c i a t i o n . These i n c l u d e Alnus rugosa, Picea glauca, Osmunda cinnamomea, Sphagnum magellanicum, and Tetraphis geniculata. Some of t h e s e s p e c i e s may r e q u i r e the c o m b i n a t i o n of an abundance o f m o i s t u r e c h a r a c t e r i s t i c o f the swamp f i r s o i l s combined w i t h r e l a t i v e l y f a v o u r a b l e l i g h t c o n d i t i o n s . A l t h o u g h b l a c k s p r u c e s i t e s a l s o have t h e s e c h a r a c t e r i s t i c s , o t h e r f a c t o r s such as c o m p e t i t i o n may d i s c o u r a g e the s p e c i e s ' growth t h e r e . O t h e r s , such as Picea glauca, may a c t u a l l y p r e f e r t h e b e t t e r -d r a i n e d s i t e s o f u p l a n d f i r s t a n d s , but a r e p r e v e n t e d from o c c u p y i n g t h e s e i n abundance because o f poor l i g h t c o n d i t i o n s . The b l a c k s p r u c e a s s o c i a t i o n i s d i s t i n g u i s h e d from the o t h e r a s s o c i a t i o n s by the c o n s t a n c y o f s e v e r a l s p e c i e s , most of which a r e a l s o common i n r a i s e d bog communities (Comeau, 1971) which the b l a c k s p r u c e s t a n d s t y p i c a l l y s u r r o u n d . These s p e c i e s a r e Picea mariana, Rhododendron canadense, Ledum groenlandicum, Rubus chamaemorus, Kalmia angustifolia, Hylocomium splendens, and Epigaea repens. Pleurozium schreberi commonly o c c u r s i n o t h e r a s s o c i a t i o n s , but i s much more abundant i n b l a c k s p r u c e s t a n d s . A d d i t i o n a l groups a r e formed by s p e c i e s which a r e c o n s t a n t i n o n l y two of the t h r e e a s s o c i a t i o n s , o r a r e c o n s t a n t i n a l l but a r e 67 p a r t i c u l a r l y abundant i n two ty p e s o n l y . These s p e c i e s i n d i c a t e a f f i n i t i e s between the p a i r s of a s s o c i a t i o n s which share them i n t h i s way. Ten o f t h e s e a r e share d by the upland f i r and swamp f i r a s s o c i a t i o n s . These a r e : Streptopus roseus, Trientalis borealis, Solidago macrophylla, Sorbus decora, Aster acuminatus, Aralia nudicaulis, Dryopteris spiriulosa, Oxalis montana, Rhytidiadelphus loreus, and Hypnum pallescens. S e v e r a l o t h e r s p e c i e s a r e c o n s t a n t o n l y i n the b l a c k s p r u c e and swamp f i r a s s o c i a t i o n s . These i n c l u d e Nemopanthus mucvonata, Gaultheria hispidula, Vaccinium angustifolium, Viburnum cassinoides, and Taxus canadensis. No b r y o p h y t e or l i c h e n s p e c i e s f a l l i n t o t h i s c a t e g o r y . i The p r e v i o u s d i s c u s s i o n s u g g e s t s t h a t a l t h o u g h t h e swamp f i r a s s o c i a t i o n s h a r e s c o n s t a n t s p e c i e s w i t h b o t h the upland f i r and b l a c k s p r u c e a s s o c i a t i o n s , f l o r i s t i c a l l y i t i s more c l o s e l y r e l a t e d to the upl a n d f i r a s s o c i a t i o n . T h i s may i n p a r t be r e l a t e d t o physiognomic s i m i l a r i t i e s between t h e upland f i r and swamp f i r a s s o c i a t i o n s . Both of t h e s e have d e f i n i t e t r e e l a y e r s and p o o r l y d e v e l o p e d shrub l a y e r s , whereas the r e v e r s e i s t r u e f o r b l a c k s p r u c e s t a n d s . The b l a c k s p r u c e a s s o c i a t i o n s h a r e s a number o f c o n s t a n t s p e c i e s w i t h swamp f i r s t a n d s , but i s much^less s i m i l a r t o the up l a n d f i r a s s o c i a t i o n . R e l a t i v e l y few s p e c i e s a r e c o n s t a n t i n bo t h o f t h e s e t y p e s ; those t h a t a r e shared a r e a l s o c o n s t a n t i n the swamp f i r a s s o c i a t i o n and may have wide t o l e r a n c e ranges.- ' 68 6. Comparison of the Plateau Associations  with Boreal Forests i n Eastern Canada As previously mentioned i n the introduction, some controversy e x i s t s over the question of whether or not the Plateau forests are boreal, and a comparison of r e s u l t s from t h i s study with those of neighbouring boreal regions would be valuable. The following, then, i s an examination of forest vegetation studies i n c e n t r a l Newfoundland (Damman, 1964), southeastern Quebec (Linteau, 1955) and Labrador (Wilton, 1964), and a comparison of these with the Plateau associations. Newfoundland Central Newfoundland forests dominated by Abies balsamea were grouped by Damman (1964) into the balsam f i r - w h i t e b i r c h a s s ociation. Five subassociations were recognized i n t h i s a s s o ciation. Of these the Dryopteris - Lycopodium balsam f i r i s selected as being more s i m i l a r to the upland f i r association of Cape Breton than are the other sub-associations, since i t occurs on apparently s i m i l a r s o i l s and has a herb layer dominated by Dryopteris spinulosa. The tree layers of the upland f i r as s o c i a t i o n and the Dryopteris - Lycopodium - balsam f i r forest are s i m i l a r i n species composition. In both types, Abies balsamea i s dominant, while Betula papyrifera and Picea glauca occur i n small numbers. Tree layer I: coverages are also s i m i l a r in, the two types, although the Newfoundland trees tend to be several metres t a l l e r than those on the Plateau. Both Newfoundland and Cape Breton stands have poorly developed shrub laye r s , although A. balsamea and B. papyrifera saplings are more frequent i n 69 the Cape Breton association. The herb layer of the Newfoundland forest type i s more poorly developed than that of the upland f i r association, having a maximum coverage of 65%, compared with an average of 81.2% in the Cape Breton association, while moss layer coverages are similar in both areas. Both the herb and moss layers of the Newfoundland subassociation are f l o r i s t i c a l l y poorer than those of the upland f i r association. The upland f i r association has a total of 34 constant species. Damman did not calculate constancy, thus those species occurring in two of the three stands of his subassociation are here considered of equal value to the constant species of Cape Breton associations for the purposes of type characterization. These total 18 in number, of which 12 are also constant in the upland f i r association. They are as follows: Abies balsamea Hylocomium umbratum Acer spicatum Maianthemum canadense Betula papyrifera Moneses uniflora Cornus canadensis Pleurozium schreberi Dryopteris spinulosa Ptilium crista-castrensis Several others are constant in the Newfoundland type, but are uncommon or absent in the Cape Breton association. These are Brachythecium salebrosun, Hylocomium splendens, Lycopodium annotinum, Picea glauca, Streptopus amplexifolius, and/, Viola incognita. Five of the remaining 26 species constant in Cape Breton commonly occur in other subassociations of the Newfoundland balsam f i r white birch association. These are: Bazzania trilobata, Coptis groenlandica (C. trifolia)3 Clintonia borealis, Dicranum majus, and 70 Polytrichum commune. In a d d i t i o n ten other species are present, although non-constant, i n the balsam f i r white b i r c h a s s o c i a t i o n . They i n c l u d e : Amelanchier bartramiana Dryopteris phegopteris Aralia nudicaulis Rhytidiadelphus toreus Athyrium. Filix-femina Solidago macrophylla Cladonia spp. Sphagnum capillacewn Dicranum fuscescens Streptopus roseus Thus, of the 34 species constant i n the Cape Breton upland f i r a s s o c i a t i o n , 27 are present i n the Newfoundland balsam f i r white b i r t h a s s o c i a t i o n . Only 17 of these, however, are common i n any of the sub-a s s o c i a t i o n s , and only 12 are common i n the s u b a s s o c i a t i o n which most resembles the upland f i r type. Although Damman may have defined h i s a s s o c i a t i o n s and subassociations more narrowly than those of t h i s study, the Cape Breton a s s o c i a t i o n g e n e r a l l y appears to be r i c h e r i n both number of species and spec i e s ' abundance than the Newfoundland a s s o c i a t i o n . Many of the Cape Breton species which are present but uncommon i n Newfoundland, may i n Newfoundland be at or near the northern l i m i t of t h e i r geographic range. Black spruce f o r e s t s i n Newfoundland were grouped i n t o two a s s o c i a t i o n s , the Kalmia - C o n i f e r F o r e s t s , and the Black Spruce Moss Fo r e s t s . The Kalmia - Conifer Forests occur on poor s o i l s , some of which are poo r l y - d r a i n e d , and l i k e the b l a c k spruce f o r e s t s i n Cape Breton, have a well-developed shrub l a y e r i n which Kalmia angustifolia i s abundant. The Black Spruce-Moss F o r e s t s , on the other hand, are mostly of f i r e o r i g i n , occur on upland s i t e s o r i g i n a l l y occupied by 71 Abies balsamea f o r e s t s , and have very sparse shrub layers. For these reasons the Kalmia - Conifer Forests are considered more s i m i l a r to the Cape Breton black spruce association, and the following comparisons are made with that type. The Kalmia - Conifer type was further subdivided into three subassociations. Of these, the Sphagnum - Kalmia subassociation appears to be most s i m i l a r to the Cape Breton association, and i s selected f o r comparison. The stands of the Newfoundland forest type d i f f e r s t r u c t u r a l l y from those on the Plateau. While the trees of the Plateau stands are very dense and shrub-like i n nature, with few exceeding 3.5 m i n height, those i n Newfoundland form a d e f i n i t e tree layer that appears to be l e s s dense and ranges i n height from 25 f t (7.5 m) to 33 f t (9.9 m). This suggests that habitat conditions on the Newfoundland s i t e s are generally more favourable for tree growth. r i c h e r than the Sphagnum-Kalmia-black spruce forests i n Newfoundland. 27 species are constant i n the Cape Breton forest type, while only 15 are constant i n the Newfoundland type. Most of the species constant i n Newfoundland however, are also constant i n Cape Breton. These include: F l o r i s t i c a l l y , the black spruce as s o c i a t i o n i n Cape Breton i s Abies balsamea\.. Kalmia angustifolia Bazzania trilobata Picea mariana Cladonia spp. Pleurozium schreberi Cornus canadensis Sphagnum capillaceum Gaultheria hispidula Vaccinium angustifolium Hylocomium umbratum Ptilium crista-castrensis 72 The r e m a i n i n g t h r e e s p e c i e s c o n s t a n t i n Newfoundland, Vacciniwn vitis-idaea, dicranum scopavium, and Dicranum undulatum , a r e i n f r e q u e n t o r absent i n Cape B r e t o n ; -S e v e r a l Cape B r e t o n P l a t e a u s p e c i e s a r e uncommon i n the Sphagnum-Kalmia s u b a s s o c i a t i o n i n Newfoundland., b u t a r e more f r e q u e n t l y -found i n o t h e r s u b a s s o c i a t i o n s . In t h e b l a c k s p r u c e f o r e s t s , t h e s e a r e Rhododendron canadense, Ledum groenlandicum and Ptilidium ciliare. Other Cape B r e t o n s p e c i e s a r e c o n s t a n t i n none o f t h e Newfoundland sub-a s s o c i a t i o n s , but a r e p r e s e n t i n the Kalmia - C o n i f e r F o r e s t a s s o c i a t i o n as a whole. These i n c l u d e : Amelanchier bartramiana Epigaea repens ' . Carex trisperma Maianthemum canadense Clintonia borealis Nemopanthus mu.cronata Coptis groenlandica (C. trifolia). Dicranum fuscescens Viburnum cassinoides In summary, a l t h o u g h o n l y about h a l f o f t h e s p e c i e s c o n s t a n t i n t h e Cape B r e t o n b l a c k s p r u c e a s s o c i a t i o n a r e common i n t h e Newfoundland Kalmia - C o n i f e r F o r e s t , a l l but t h r e e a r e p r e s e n t i n Newfoundland, and i n t u r n most o f t h e s p e c i e s c o n s t a n t i n Newfoundland a r e a l s o c o n s t a n t i n Cape B r e t o n . The f o r e s t t y p e s o f t h e two a r e a s a r e , t h e n , f a i r l y s i m i l a r f l o r i s t i c a l l y . Damman d e s c r i b e d o n l y one f o r e s t t y p e i n Newfoundland t h a t i s dominated by Abies balsamea and o c c u r s on- s i t e s s i m i l a r t o t h o s e o f the. • swamp- f i r - " a s s o c i a t i o n " i n Cape-Breton. Th±s~±s-• the-Garex' - balsam f i r ' • f o r e s t s u b a s s o c i a t i o n o f t h e balsam f i r - w h i t e b i r c h a s s o c i a t i o n . A l t h o u g h the two t y p e s do d e v e l o p under a p p a r e n t l y . s i m i l a r h a b i t a t conditions, only a few of the species which i n Cape Breton d i s t i n g u i s h the swamp f i r a s s o c i a t i o n from the upland f i r type were present i n the Newfoundland type. These are Carex trisperma, Gaultheria hisvidula, Linnaea borealis, and Taxus canadensis. On the other hand, Osmunda cinnamomea, the most abundant herb species of the swamp f i r a s s o c i a t i o n , i s absent i n the Newfoundland f o r e s t s . Quebec Linteau (1955) recognized a number of broad f o r e s t groups i n southeastern Quebec dominated by Abies balsamea. Of these, only the Herb and Fern Forests group has a well-developed herb l a y e r . I t i s thus the most s i m i l a r of these to the upland f i r a s s o c i a t i o n on the Cape Breton Plateau. This group i s composed of three cover types, based on the species composition of the understory vegetation. Of these, the Dryopteris-Oxalis type i s the most s i m i l a r to the upland f i r a s s o c i a t i o n on the Plateau, having a herb layer i n which dryopteris spinulosa. i s r e l a t i v e l y abundant. . The Dryopteris-Oxalis cover type, l i k e the upland f i r a s s o c i a t i o n , occurs on well-drained s o i l s developed from g l a c i a l t i l l . As i n the upland f i r a s s o c i a t i o n , tree layers of the Dryopteris-Oxalis type, are composed l a r g e l y of Abies balsamea with low d e n s i t i e s of Betula papyrifera and Picea glauca, and shrub layers are poorly developed. The herb and bryophyte l a y e r s , however, are much more poorly developed than those of the Cape Breton a s s o c i a t i o n . . Only 11 species occur i n t h e Quebec type with a presence o f 20%.or more. Of these, eight are also constant i n the upland f i r association... These are Abies balsamea, Clintonia borealis, Calliergon schreberi (Pleurozium schreberi), Cornus canadensis, Dryopteris spinulosa, Maianthemum canadense, Oxalis montana, and Solidago macrophylla. The remaining three, Dicranum scoparium, Plagiothecium denticulatum, and Thuidium delicatulum were not found i n upland f i r stands. Eleven other constant species of the upland f i r association are present but les s common i n the Dryopteris-Oxalis type than are those above. They are: Amelanchier bartramiana Ptilium crista-castrensis Aralia nudicaulis Moneses uniflova Aster acuminatus Sorbus decora Coptis groenlandica Sphagnum capillaceum (C. trifolia) Streptopus roseus Dryopteris phegoptoris Trientalis borealis Thus, a t o t a l of 14 constant species of the upland f i r asso c i a t i o n i n Cape Breton, are absent from the Quebec Dryopteris-Oxalis type, i n d i c a t i n g that generally the Quebec forests are f l o r i s t i c a l l y l e s s s i m i l a r to the Cape Breton forests than are those i n Newfoundland. The black spruce ass o c i a t i o n i n Cape Breton appears to be most s i m i l a r to the Peat Moss and Dwarf Shrub Forest group i n Quebec. Both occur on poorly-drained s o i l s ( and have a well developed shrub layer. Two cover types are recognized i n Quebec for t h i s group, of which the Sphagnum-Rubus type most resembles the Cape Breton a s s o c i a t i o n . The s o i l s of the Sphagnum-Rubus type are water-saturated for part of the year, and have thick humus layers , as do most of those beneath black spruce stands i n Cape Breton. Unlike the Cape Breton stands, however, the Quebec forests have a f a i r l y w e ll developed tree l a y e r . The Sphagnum-Rubus type, l i k e a l l of the boreal forest types described above, i s f l o r i s t i c a l l y poorer than the Cape Breton as s o c i a t i o n . Most of the species common i n black spruce stands i n Quebec are also common i n Cape Breton, but a large number of the con-stant Cape Breton species are r e s t r i c t e d i n occurrence or absent i n the Quebec f o r e s t s . Only 16 species are found i n 20% or more of the Sphagnum-Rubus stands, t h i r t e e n of which are constant i n the Cape Breton as s o c i a t i o n as well. These are: Abies balsamea Ledum groenlandicum Carex trisperma Picea mariana Calliergon schreberi Ptilium crista-castrensis (Pleurozium schreberi) Chiogenes hispidula (Gaultheria hispidula) Vacciniwn pennsylvanicum Rubus chamaemorus \ um pen syli (V. angustifolium) Clintonia borealis Coptis groenlandica (C. trifolia) Cornus canadensis Kalmia angustifolia The remaining three species common i n Quebec are: Vaccinium canadense (V. myrtilloides), Smilacina prifolia, and Sphagnum palustre. Two other Cape Breton species, Eylocomium splendens and Amelanchier bartramiana are present but uncommon i n the Sphagnum-Rubus forests of Quebec. ! The above 15 species which are present i n both Cape Breton and Quebec make up only about 55% of the t o t a l constant i n the black spruce a s s o c i a t i o n i n Cape B r e t o n . S e v e r a l o f those which a r e not found i n Quebec, a r e p a r t i c u l a r l y f r e q u e n t i n Cape B r e t o n . These a r e : Nemopanthus mucronatus, Viburnum cassinoides, Rhododendron canadense, Sphagnum capillaceum, and Ptilidium ailiare. None o f the cover t y p e s d e s c r i b e d f o r s o u t h e a s t e r n Quebec c o r r e s p o n d t o the swamp f i r a s s o c i a t i o n on the P l a t e a u . In Quebec, low-l y i n g wet s i t e s appear to be o c c u p i e d by Picea mariana f o r e s t s , and i n L i n t e a u ' s study Abies balsamea i s r e s t r i c t e d as a dominant t o more w e l l - d r a i n e d s i t e s . I t i s p o s s i b l e t h a t A. balsamea o c c u p i e s a wider range of s i t e s i n Cape B r e t o n than i n Quebec. L a b r a d o r W i l t o n (1964) d e s c r i b e d f i v e F o r e s t t y p e s f o r L a b r a d o r o f which o n l y one, the F i r - S p r u c e - B i r c h / R i c h Herb t y p e , has Abies balsamea as the dominant t r e e s p e c i e s . I t i s one of the most p r o d u c t i v e f o r e s t t y p e s i n L a b r a d o r , and i s r e s t r i c t e d i n d i s t r i b u t i o n to c e r t a i n a r e a s , many of which a r e f e r t i l e r i v e r v a l l e y s . As i n the Cape B r e t o n u p l a n d f i r a s s o c i a t i o n , the t r e e l a y e r of the Labrad o r type i s composed m o s t l y o f Abies balsamea, accompanied by low d e n s i t i e s o f Picea glauca and Betula papyrifera. The shrub l a y e r i n b o t h f o r e s t types i s p o o r l y d e v e l o p e d , and i s composed o f few s p e c i e s . In L a b r a d o r these a r e Sorbus decora, Acer spicatum, Alnus I, crispa, Alnus rugosa, and Viburnum edule, of which o n l y the f i r s t two a r e a l s o common i n t h e upland f i r a s s o c i a t i o n . Herb and br y o p h y t e l a y e r s i n t h e La b r a d o r f o r e s t s a r e a p p a r e n t l y l e s s w e l l d e v e l o p e d than a r e those i n Cape B r e t o n . In 77 Labrador, these layers are composed of only 13 c h a r a c t e r i s t i c species, whereas a t o t a l of 31 are constant i n the upland f i r a s s o c i a t i o n of Cape Breton. Eight of the species mentioned for Labrador are also common i n the Cape Breton association. These are: Clintonia borealis Oxalis montana Cornus canadensis Pleurozium schreberi Dryopteris spinulosa Ptilium crista-oastrensis Maianthemum canadense Other Labrador species, Goody era repens, Listera cordata, and Hylocomium splendens were occasionally found i n the Cape Breton f o r e s t s , while Climacium dendroides and Mnium ciliare were absent. Of the Labrador forest types dominated by Picea mariana, the Spruce/Sphagnum type i s most s i m i l a r to the black spruce a s s o c i a t i o n i n Cape Breton. Both forest groups occur i n poorly drained areas, often along the edges of open bogs, and tree species compositions are s i m i l a r . Trees i n the Labrador type, however, are larger and more widely spaced than those on the Plateau. Wilton's d e s c r i p t i o n of the understory vegetation i n black spruce forests i s b r i e f , but generally suggests that i n the Labrador fo r e s t s understory species are fewer than those i n Cape Breton. Only seven species are mentioned f o r Labrador, whereas 20 are constant i n the Cape Breton black spruce /association. Four of the Labrador species, Ledum groenlandicum, Pleurozium schreberi, Rubus chamaemorus, and Sphagnum spp. are also common i n Cape Breton. The remaining species, Chamaedaphhe calyculata, Kalmia polifolia, and Equisetum arvense do not frequently occur i n the Cape Breton a s s o c i a t i o n . 78 The above d i s c u s s i o n i n d i c a t e s t h a t most of the common s p e c i e s of the s e l e c t e d L a b r a d o r f o r e s t t y p e s a r e a l s o common i n t h o s e o f the Cape B r e t o n P l a t e a u . S i n c e t hese r e p r e s e n t a s m a l l p e r c e n t a g e of the t o t a l number o f c o n s t a n t s p e c i e s i n the Cape B r e t o n P l a t e a u a s s o c i a t i o n s , the P l a t e a u f o r e s t s a r e perhaps much r i c h e r f l o r i s t i c a l l y . T h i s i s i n d i c a t e d by W i l t o n ' s d e s c r i p t i o n s , y e t because h i s stu d y was de s i g n e d as a broad survey o f f o r e s t types i n L a b r a d o r , a number of f a i r l y common s p e c i e s may have been i g n o r e d . The above comparisons between f o r e s t a s s o c i a t i o n s on t h e P l a t e a u and s e l e c t e d b o r e a l f o r e s t t y p e s i n Quebec, Newfoundland, and Lab r a d o r i n d i c a t e a number of s i m i l a r i t i e s . A l t h o u g h growth o f Abies balsamea and Pieea mariana appears to be po o r e r i n Cape B r e t o n than on s i m i l a r s i t e s i n the o t h e r t h r e e a r e a s , the t r e e s p e c i e s c o m p o s i t i o n o f stan d s compared a r e v e r y s i m i l a r . The herb and b r y o p h y t e l a y e r s o f the Cape B r e t o n f o r e s t a s s o c i a t i o n s c o n t a i n most o f the s p e c i e s d e s c r i b e d as common i n the o t h e r f o r e s t t y p e s , but g e n e r a l l y have an a d d i t i o n a l number o f s p e c i e s t h a t a r e uncommon o r absent i n Quebec, Newfoundland, and L a b r a d o r . These i n c l u d e : Amelanchier bartramiana Dryopteris phegopteris Aralia nudicaulis Nemopanthus mucronata Aster acuminatus Osmunda claytoniana Athyrium Filix-ffemina Osmunda cinnamomea Brachythecium curtum Rhytidiadelphus loreus Dicranum majus Sphagnum capillaceum ' Dryopteris phegopteris Streptopus roseus H u l t e n (1964) i n d i c a t e d t h a t Athyrium-Filix-femina, Osmunda cinnamomea, and Osmunda claytoniana have only scattered d i s t r i b u t i o n i n northern Canada, and LaRoi (1967) found them i n only a few boreal forest stands. Streptopus roseus and Aralia, nudicaulis, however, are f a i r l y widespread i n boreal f o r e s t s , (LaRoi, 1967) i n s p i t e of the fact that they were infrequent i n Newfoundland (Damman, 1964) and Quebec (Linteau, 1955). It appears, then, that boreal forest types s t r u c t u r a l l y , resembling the two most common Plateau forest associations are found i n cen t r a l Newfoundland, southeastern Quebec, and parts of Labrador. The majority of species c h a r a c t e r i s t i c of these types are also common on the Plateau. For these reasons, the forests of the Cape Breton Plateau should be considered part of the Boreal Forest Region described by Rowe (1959, 1972). The comparative richness of the understory vegetation of the Cape Breton f o r e s t s , both i n numbers of species and i n species' abundance, however, suggests that they be classed as a d i s t i n c t section within t h i s Region. I, 80 V. FOREST SOILS General c h a r a c t e r i s t i c s of s o i l p r o f i l e s examined on the Plateau suggest the existence of four s o i l types. These are: w e l l -drained s o i l s beneath upland f i r stands, poorly drained s o i l s under swamp f i r stands, poorly drained s o i l s below black spruce stands i n low-lying areas, and s o i l s of black spruce stands on ridges. These groups are broad, and a f a i r amount of v a r i a b i l i t y , p a r t i c u l a r l y i n terms of chemical c h a r a c t e r i s t i c s , i s found i n each. Nevertheless, these are considered v a l i d f o r the purposes of generally describing the forest s o i l s of the Plateau and r e l a t i n g them to vegetation. 1. Morphological C h a r a c t e r i s t i c s S o i l s beneath upland f i r stands have p r o f i l e s c o n s i s t i n g of three horizons above the parent material or C horizon: an organic L-F-H horizon, a leached Ae horizon, and an i l l u v i a t e d B horizon (Fig. 2 2 ) . A composite d e s c r i p t i o n of these p r o f i l e s i s as follows: Horizons Mean Depth Description (cm) L-F-H 10.3 - 0 c o n i f e r needles and herbaceous l i t t e r underlain by very dark brown (10YR2/2, I; dry and wet) fibrous mor humus; white 1 fungal hyphae present;^abundant coarse, medium, and f i n e roots ; boundary smooth and abrupt; horizon thickness 6.3 cm to 15.2 cm; pH 3.4-4.6. Size and abundance classes for roots are as described i n Table I , Appendix II . 0 81a Figure 22. A s o i l profile i n an upland f i r stand. The Ae horizon here is very thin and gravel sized fragments are common in the lower horizons. Few roots are found below the upper B horizon. ( Photo by Roy ) 82 Horizons Ae (Aej) Mean Depth (cm) 0 - 10.6 10.6-37.9 37.9 + Description gray (10YR 5/1, dry) to very dark gray (10YR 3/1, moist) s i l t y loam to sandy loam; p l e n t i f u l medium and f i n e roots; granular structure; abrupt and smooth to wavy boundary; horizon thickness 1.3 cm to 25.4 cm; pH 4.2 to 5.2. yellowish red (5YR 4/6, dry) to dark reddish brown (5YR 3/2, m o i s t ) ^ s i l t y loam to sandy loam; 5 to 25% gravel ; compacted; few to very few medium and f i n e roots; average maximum rooting depth 34.2 cm; granular structure; compacted; boundary gradual and i r r e g u l a r ; horizon thickness 6.8 cm to 12.8 cm; pH 4.5 to 5.7. l i g h t yellowish brown (10YR 6/4, dry) to dark brown (7.5 YR 4/4, moist) loam to sandy loam; 5% to 25% gravel and cobbles; compacted; granular structure; roots absent; pH 5.0 to 5.9. Swamp f i r stands are developed on s o i l s characterized by the presence of a very thick, water-saturated L-F-H horizon. Beneath t h i s are well developed Ae and B horizons (Fig. 2 3 ) . Groundwater seepage i s common i n these s o i l s , p a r t i c u l a r l y at the boundary between the L-F-H and Ae horizons. P r o f i l e c h a r a c t e r i s t i c s are summarized as follows: Horizons L-F-H Ae Mean Depth (cm) 35.9-0 0-14.2 Description black mixed peat; abundant coarse, medium and f i n e roots; boundary abrupt and smooth; Ihorizon thickness 18.0 cm to 60.9 cm; i'pH 4.0 to 4.7. gray (10YR 6/1 dry, 10YR 5/1, moist) s i l t y loam to sandy loam; granular structure; p l e n t i f u l medium and f i n e roots; abrupt, way boundary; horizon thickness 7.6 cm to 23.0 cm; pH 4.2 to 4.9. 1 C l a s s e s used for rock fragments are outlined i n Table II, Appendix II . 83a Figure 23. A s o i l p r o f i l e i n a swamp f i r stand. The L-F-H layer i s relatively thick and composed of fibrous moss peat. The upper B horizon i s dark, showing i l l u v i a t i o n of organic matter leached from above. ( Photo by Roy ) 83b 84 H o r i z o n s Mean Depth (cm) 14.2-25.3 25.3 D e s c r i p t i o n y e l l o w i s h r e d (5YR 4/6, d r y ) to dark r e d d i s h brown (2.5YR 3/4, m o i s t ) s i l t y loam to loam; 0% to 5% g r a v e l and c o b b l e s ; g r a n u l a r s t r u c t u r e ; compacted; few to v e r y few medium and f i n e r o o t s ; average maximum r o o t i n g d e p th, 29.2 cm; c l e a r , wavy boundary; h o r i z o n t h i c k n e s s 8.0 cm to 15.0 cm; pH 4.8 to 5.1. y e l l o w i s h r e d (5YR 5/2 d r y , 5YR 4/8, mo i s t ) s i l t y loam to loamy sand; 5% to 25% g r a v e l and 0% to 5% c o b b l e s ; g r a n u l a r s t r u c t u r e ; compacted; r o o t s a b s e n t ; pH 5.0 to 5.7. Most b l a c k s p r u c e s t a n d s a r e found i n d e p r e s s i o n s , on p o o r l y d r a i n e d s o i l s t h a t appear s a t u r a t e d f o r a t l e a s t p a r t o f the y e a r . These s o i l s , l i k e t h o s e beneath swamp f i r s t a n d s , have a t h i c k L-F-H h o r i z o n composed o f mixed peat, beneath which seepage i s u s u a l l y e ncountered. Below t h i s h o r i z o n B and C h o r i z o n s a r e d e v e l o p e d . M o r p h o l o g i c a l f e a t u r e s of th e s e s o i l p r o f i l e s may be summarized as f o l l o w s : H o r i z o n L-F-H Mean Depth (cm) 55.8 - 0 0 - 19.7 D e s c r i p t i o n d a r k r e d d i s h brown (5YR 2/2, d r y , m o i s t ) mixed peat; commonly water s a t u r a t e d ; abundant c o a r s e , medium and f i n e r o o t s ; a b r u p t , smooth boundary; h o r i z o n t h i c k n e s s 20 cm t o 104 cm; pH 3.2 to 4.5. y e l l o w i s h r e d (5YR 5/6, d r y ) to r e d d i s h brown (5YR 4/4, m o i s t ) s i l t y loam t o sandy loam; 0% to 5% g r a v e l ; g r a n u l a r s t r u c t u r e ; compacted; v e r y few f i n e r o o t s ; average maximum r o o t i n g d e p th, 47.1 cm; c l e a r , wavy boundary; h o r i z o n t h i c k n e s s 10.4 cm to 35.6 cm; pH 4.4 to 4.9. 85 Horizon Mean Depth (cm) 19.7 + Description pale brown (10YR 6/3, dry) to dark brown (10YR 4/3, moist) s i l t y loam to sandy loam; 5% to 25% gravel and cobbles; granular structure; compacted, roots absent; pH 4.9 to 5.6. Some of the black spruce stands studied are located on low ridges; the s o i l s here are d i f f e r e n t from those i n low-lying areas and are described separately. The s o i l s on ridges have a thinner L-F-H horizon, and unlike the wetter black spruce s o i l s , have an Ae horizon. The B and C horizons of the s o i l s on ridges are very stony, and seepage i s not usually encountered. The p r o f i l e of these may be summarized as follows: Horizon L-F-H Ae Mean Depth (cm) 14.2 - 0 0 - 5.0 5.0 - 24.1 24.1 + Description l i t t e r of coniferous needles and herbaceous material, underlain by very dark brown fibrous mor humus; white fungal hyphare present; abundant roots of a l l s i z e s ; boundary smooth and abrupt; horizon thickness 12.7 cm to 15.2.cm; pH 4.5 to 4.7. gray to very dark gray s i l t y loam to sandy loam; p l e n t i f u l medium and f i n e roots; granular structure; boundary abrupt and smooth; thickness 2.5 cm to 7.6 cm, pH 4.6. dark reddish brown sandy loam; very f i n e roots; mean rooting depth 23.3 cm; 5% to 25% gravel and cobbles; granular structure; compacted; boundary gradual and i r r e g u l a r ; horizon thickness 17.8 cm to 20.3 cm; pH 5.3. dark brown sandy loam; roots absent; 25% to 50% gravel, 5% to 25% cobbles; granular structure; compacted; pH 5.05 to 5.50. 2. Physical and Chemical C h a r a c t e r i s t i c s The texture of mineral s o i l s beneath upland f i r stands varies with depth. The uppermost mineral horizon, the Ae, has the lowest sand content, averaging 44.50% (Table 10 ), and the highest clay content, averaging 11.70% of a l l three horizons. B horizon s o i l s have more sand (avg. 48.59%) and l e s s clay (avg. 5.66%), and the C horizon has the most sand (avg. 60.03%) of the three. Textural v a r i a t i o n with depth i s not as great i n swamp f i r s o i l s . The average sand content here varies from 51.67% i n the B horizon to 54.50% i n the C horizon (Table 11 ) and clay ranges from an average of 8.03% i n the B to 5.00% i n the C horizon. The mineral s o i l s beneath black spruce stands i n depressions are more f i n e l y textured than the other s o i l groups. Sand content averages only 29.90% i n the B horizon s o i l s and 32.0% i n the C horizon, while s i l t forms an average of about 60% i n both (Table 1 2 . ) . These s o i l s may thus be more poorly drained than those beneath the other vegetation types. S o i l texture data for s o i l s of black spruce stands on ridges are not a v a i l a b l e . Available water, a measure of a s o i l s ' a b i l i t y to r e t a i n water i n a form that can be extracted by plants, i s d i r e c t l y correlated with contents of s i l t , clay, and organic matter. In a l l of the s o i l s analyzed, a v a i l a b l e water i s highest i n the organic L-F-H horizon. In upland f i r s o i l s , t h i s horizon has an average a v a i l a b l e water percentage of 23.36%.' Mineral s o i l s have much lower a v a i l a b l e water, the B horizon of these s o i l s having an average of 10.03%. Available water percentages for the L-F-H peat of swamp f i r s o i l s are s l i g h t l y lower, averaging 15.51%, while those for the B and C horizons, averaging 13.11% and 12.22% re s p e c t i v e l y , are s i m i l a r to those of the upland f i r s o i l s . Black spruce s o i l s i n depressions have higher A v a i l a b l e Water percentages than the other Plateau forest s o i l s . The L-F-H averages 37.89%, and the mineral B and C horizons have f a i r l y high percentages, averaging 31.58 and 16.73 re s p e c t i v e l y . The high Available Water percentages of these horizons r e l a t i v e to those of the other s o i l s i s perhaps related to the fact that the black spruce s o i l s have high s i l t contents. A v a i l a b l e Water percentages determined for black spruce s o i l s on ridges are lower than the black spruce s o i l s i n depressions, but the data are too few to be considered i n d i c a t i v e of a poorer a b i l i t y to r e t a i n water (Tablel3). Organic matter i n the L-F-H horizon of upland f i r s o i l s v a r i e s from 30.19% to 89.92%, and averages 64.75%. Some of the lower values may be a r e s u l t of p a r t i a l intermixing of mineral and organic matter by s o i l organisms. In the mineral horizons, organic matter content i s lowest i n the leached Ae, averaging 4.19%, and highest i n the B horizon, averaging 5.90%, probably a r e s u l t of i l l u v i a t i o n . The L-F-H of swamp fjir s o i l s has a higher organic matter content than that of upland f i r s o i l s , averaging 73.51%, perhaps because of l e s s organic and mineral s o i l mixing i n the thicker L-F-H of swamp f i r s o i l s . ' Organic matter contents i n the mineral horizons of these s o i l s are comparable to those of the upland f i r s o i l s . Again, the B Table 10 . Physical and Chemical C h a r a c t e r i s t i c s of Upland F i r S o i l s Horizon Av a i l a b l e Water (%) Sand (%) S i l t (%) Clay (%) Organic Matter (%) Total Nitrogen (%) C - N Ratio L-F-H 4 - - - 4 - -A b 23.36 - - - 64.75 - -R C 13.41 -30.41 - - -30.19 -89.92 -Ae N 2 2 2 2 9 8 8 A' 12.87 44.50 .43.80 11.70 4.19 0.12 31.37 R 5.31 37.60 37.40 11.20 1.30 0.06 18.00 -20.45 -51.40 -50.20 -12.20 -8.21 -0.32 -90.00 B N 3 3 3 3 10 8 8 A 10.03 48.59 45.73 5.66 5.90 0.10 43.87 R 6.88 43.00 33.80 3.00 3.27 0.07 32.00 -12.89 -57.40 -59.00 -8.80 -12.58 -0.17 -62.00 C N 3 3 3 3 4 2 2 A 15.65 60.03 31.63 8.33 4.44 0.05 59.00 R 12.30 51.30 23.00 4.20 1.82 0.04 30.00 -21.40 -67.40 -44.50 -11.20 -8.80 -0.06 -88.00 oo oo Horizon C.E.C.d L-F-H N 2 A 97.24 R 80.22 -114.27 Ae N 2 A- 18.65 R 15.50 -21.80 B N 3 A 36.53 R 27.10 -44.02 C N 2 A 12.14 R 11.82 -12.47 Number of samples. Table 10 . (Continued) p (ppm) Na (meq/lOOg) Ca (meq/lOOg) Mg (meq/lOOg) K (meq/lOOg) pH 19 19 19 19 12 _ 0.70 0.81 1.24 0.68 4.24 0.22 0.20 0.23 0.18 3.40 - -1.61 -2.02 -2.26 -1.52 -4.60 8 12 12 12 12 9 349 0.22 0.13 0.24 0.06 4.66 125 0.08 0.02 0.06 0.03 4.20 -950 -0.33 -0.29 -0.55 .> -0.17 -5.20 8 20 20 20 20 12.-540 0.22 0.10 0.12 0.07 5.12 270 0.03 0.01 0.10 0.03 4.50 -920 -1.04 -0.32 -0.26 -0.37 -5.75 2 20 20 20 20 12 385 0.12 0.07 0.05 0.05 5.34 375 0.03 0.01 0.02 0.02 5.00 -395 -0.40 -0.28 -0.10 -0.18 -5.85 'Average. CRange. Nation Exchange Capacity expressed i n meq/lOOg. 00 VD Table 11 . Physical and Chemical C h a r a c t e r i s t i c s of Swamp F i r S o i l s Available Organic Total C - N Horizon Water Sand S i l t Clay Matter Nitrogen Ratio (%) . (%) (%) (%) (%) (%) L-F-H N a 4 - - ' . - 5 3 3 A b 15.51 - ,73.51 1.72 25.00 R° 7.12 - - 56.46 1.39 18.00 -27.64 - - - . -93.67 -1.91 -29.00 Ae N _ 4 4 4 4 5 2 2 A 12.93 53.25 39.20 7.39 3.69 0.08 34.00 R 4.44 45.00 34.20 4.00 1.50 , 0.05 33.00 -21.12 -58.80 -51.00 -10.40 -7.50 -0.12 -35.00 B N 5 5 5 5 5 -A 13.11 51.67 40.27 8.03 4.87 R 2.05 34.00 20.40 2.80 0.64 -22.92 -76.80 -62.00 -15.00 -11.10 C N • 2 2 2 2 . 3 A 12.22 54.50 40.50 5.00 2.95 R 7.51 33.00 20.00 4.00 1.75 -16.94 -76.00 -61.00 -6.00 -4.17 Table 11 . (Continued) P Na Ca Mg K Horizon C.E.C. (ppm) (meq/lOOg) (meq/lOOg) (meq/lOOg) (meq/lOOg) pH L-F-H N 1 3 6 6 6 6 3 A 99.3 380 0.91 1.47 1.44 0.28 4.22 R - 320 0.75 0.30 0.20 0.04 4.00 -480 -1.15 -2.70 -2.20 -0.82 -4.70 Ae N 3 2 5 5 5 5 3 A 20.52 232 0.18 0.29 0.25 0.04 4.63 R ~ 8.02 140 0.05 0.04 0.07 0.03 4.20 -44.88 -325 -0.33 -0.74 -0.68 -0.05 -4.90 B N 3 1 5 5 5 5 3 A 10.94 140 0.13 0.25 0.07 0.05 5.00 R 9.32 - 0.03 0.01 0.03 0.02 4.80 -13.22 - -0.31 -0.86 -0.20 -0.09 -5.10 C N 2 1 3 3 3 3 3 A 11.97 545 0.21 0.05 0.10 0.09 5.36 R 9.76 - 0.10 0.02 0.03 0.06 5.00 -14.20 - -0.30 .-0.09 -0.25 -0.15 -5.70 Number of samples. Range. Average. ^Cation Exchange Capacity (meq/lOOg). Table 12 . Physical and Chemical Characteristics of Black Spruce Soils i n Depressions Available Organic Total C - N Horizon Water Sand S i l t Clay Matter Nitrogen Ratio (%) (%) (%) (%) (%) (%) L-F-H N a 2 - - - 2 - -A b 37.89 - - - 94.31 - -R C 33.19 - - - 91.97 - --42.59 - - - -96.65 - -B N 2 2 2 2 2 1 1 A 31.58 29.90 61.20 11.60 9.46 1.91 32.00 R 28.19 27.80 50.80 6.00 9.02 s, - --34.97 -32.00 -71.60 -17.20 -9.90 - -C N 1 1 1 1 1 - -A 16.73 32.00 62.80 5.20 4.23 - -R - - - - — — — vO Table U . (Continued) P Na Ca Mg K Horizon C. E. C. (ppm) (meq/lOOg) (meq/lOOg) (meq/lOOg) (meq/lOOg) pH L-F-H N 2 - 5 5 5 5 5 A 104.40 - 0.86 1.21 3.58 0.14 4.00 R 91.72 - 0.60 0.47 0.98 0.04 3.20 -117.09 - -1.27 -1.87 -6.25 -0.42 -4.50 B N 1 1 5 5 5 5 5 A~.=- 24.28 145 0.18 0.43 0.56 0.07 4.73 R - - 0.05 0.09 0.11 0.03 4.92 - - -0.33 -0.95 -1.87 - -0.10 -4.90 C N 1 - 5 5 5 5 5" A 13.66 - 0.22 0.11 0.13 0.11 5.22 R - - 0.05 0.05 0.03 0.04 4.90 - - -0.38 -0.15 -0.34 -0.23 -5.63 'Number of samples. Range. 'Average. ^Cation Exchange Capacity (meq/lOOg). Table 13 Physical and Chemical Characteristics of Black Spruce Soils on Ridges Horizon Available Water (%) Sand (%) S i l t Clay (%) (%) Organic Matter (%) Total Nitrogen (%) C - N Ratio L-F-H N a 1 - - 1 1 1 A b 25.41 - - 63.4 0.09 41 R C - - - - - -Ae N - - - 1 1 1 A... _ R - - - - 0.90 0.04 22 B N 1 _ _ ' 1 ' 1 1 A 20.23 - - 6.54 0.09 45 -R - - _ - - -C N - - - - - -A - - - - - -R - - - - - — — VO •c-Table 13 . (Continued) P Na Ca Mg K Horizon C.E.C.d (ppm) (meq/lOOg) (meq/lOOg) (meq/lOOg) .(meq/100g) pH L-F-H N 1 1 2 2 2 2 2 A 13.44 225 . 0.27 0.28 0.26 0.13 4.65 R - - 0.19 0.19 0.10 0.05 4.55 ' - - -0.36 -0.37 -0.42 -0.21 -4.75 Ae N - 1 1 1 1 1 1 A - - 40 0.20 0.10 0.12 0.02 4.60 R - - - - - - -B N 1 1 2 • 2 2 2 2 . A 13.88 420 0.20 0.15 0.27 0.04 5.32 R - - - 0.14 0.03 - 5.30 - - - -0.17 -0.51 - -5.35 C N - - 2 2 2 2 2 A - - 0.12 0.15 0.06 0.04 5.27 R - - 0.06 - - 0.03 5.05 - - -0.18 - - -0.05 -5.50 'Number of samples. Range. Average. dCation Exchange Capacity (meq/lOOg). h o r i z o n s o i l s have the h i g h e s t o r g a n i c matter c o n t e n t , a v e r a g i n g 4.87%, w h i l e the Ae and C h o r i z o n s have l e s s , w i t h means of 3.69% and 2.95% r e s p e c t i v e l y . O r g a n i c matter c o n t e n t s a r e h i g h e s t i n the peat o f spruce s o i l s i n d e p r e s s i o n s , a v e r a g i n g 94.31%. The B h o r i z o n o f t h i s group a l s o has a h i g h e r o r g a n i c matter c o n t e n t than the B of o t h e r s o i l s , w i t h an average of 9.46%, w h i l e the C i s s i m i l a r to t h a t o f the o t h e r s . A n a l y s i s o f b l a c k s p r u c e s o i l s on r i d g e s f o r o r g a n i c m a t t e r i n d i c a t e d the L-F-H has l e s s o r g a n i c matter than the b l a c k s p r u c e s o i l s i n d e p r e s s i o n s , a v e r a g i n g 63.4% ( T a b l e 1 3 ) . The Ae h o r i z o n of t h e s e s o i l s on r i d g e s has v e r y l i t t l e o r g a n i c matter (0.90%) w h i l e the B h o r i z o n i s s i m i l a r i n t h i s r e s p e c t t o t h e B of upland f i r s o i l s . T o t a l n i t r o g e n l e v e l s a r e low i n the f o r e s t s o i l s o f the P l a t e a u , perhaps because of slow d e c o m p o s i t i o n r a t e s and l e a c h i n g l o s s e s . In a d d i t i o n , the a v a i l a b i l i t y of n i t r o g e n may be low, s i n c e c a r b o n -n i t r o g e n r a t i o s a r e o f t e n f a i r l y h i g h . T o t a l n i t r o g e n o f the m i n e r a l h o r i z o n s o f upland f i r s o i l s ranges from an average o f 0.05% i n t h e C h o r i z o n , t o an average o f 0.12% i n t h e Ae. C a r b o n - n i t r o g e n r a t i o s f o r t h e s e s o i l s a r e f a i r l y h i g h , means r a n g i n g from 31.37 i n the Ae to 59.00 i n the C. T o t a l n i t r o g e n of the L-F-H of swamp f i r s o i l s i s h i g h e r than t h a t of the m i n e r a l s o i l s above, a v e r a g i n g 1.72%, w h i l e c a r b o n - n i t r o g e n r a t i o s , a v e r a g i n g 25.00, a r e lower. The Ae of these s o i l s i s s i m i l a r i n t h e s e r e s p e c t s to t h a t of upland f i r s o i l s . Ohly one n i t r o g e n d e t e r m i n a t i o n was made from b l a c k s p r u c e s o i l s i n d e p r e s s i o n s ; the B h o r i z o n had a t o t a l n i t r o g e n c o n t e n t o f 1.91%, and a carbon-nitrogen ratio of 32.00. Total nitrogen in one of the black spruce soils on ridges was measured at 0.09% in the L-F-H and B horizons, and 0.04% in the Ae. Carbon-nitrogen ratios for these three horizons are 41.00, 45.00, and 22.00 respectively. The Plateau soils have low concentrations of exchangeable calcium, magnesium, potassium and sodium, perhaps because of low concentrations in the parent material as well as leaching losses. In the L-F-H horizon of upland f i r s o i l s , exchangeable calcium and magnesium are the most abundant, with averages of 1.47 meq/100 g and 1.44 meq/100 g, respectively. Exchangeable sodium is slightly less abundant in this horizon (avg. 0.91 meq/100 g) and potassium i s the least abundant, averaging 0.28 meq/100 g. In the Ae horizon, cation concentrations are lower, ranging from an average of 0.06 meq/100 g for potassium, to an average of 0.24 meq/100 g for magnesium. Concentrations are similar in the B horizon with the exception of magnesium, which has a lower average concentration of 0.12 meq/100 g. Cation levels are lowest in the C horizon; here averages range from 0.05 meq/100 g for potassium and magnesium to 0.12 meq/100 g for sodium. In the L-F-H of swamp f i r so i l s , calcium and magnesium are the most abundant, averaging 1.47 meq/100 g and 1.44 meq/100 g respectively, followed by sodium, with an average of 0.91 meq/100 g, and potassium with an average of 0.28 meq/100 g. As in upland f i r s o i l s , the Ae i s poorer in a l l four cations; average concentrations range from 0.04 meq/100 g for potassium to 0.29 meq/100 g for calcium. The B horizon of these soils i s similar to the Ae in levels of a l l except 98 magnesium, which is lower here, averaging only 0.07 meq/100 g. Unlike upland f i r s o i l s , magnesium and potassium levels are slightly higher in the C horizon than in the B horizon, averaging 0.10 meq/100 g and 0.09 meq/100 g, respectively, while sodium and calcium are lower in the C, having averages of 0.21 meq/100 g and 0.05 meq/100 g respectively. Exchangeable sodium and calcium are slightly more concentrated in the L-F-H of black spruce soils in depressions than in swamp f i r and upland f i r soils. Potassium levels, however, are lower in black spruce soils. In the black spruce so i l s , sodium averages 0.86 meq/100 g, calcium has a mean of 1.21 meq/100 g, and potassium averages 0.14 meq/100 g. Magnesium, however, has a very high average of 3.58 meq/100 g in this horizon. The B horizon of these soils is also high in magnesium, which averages 56 meq/100 g. Whereas average concentrations of potassium and sodium in this horizon at 0.07 meq/100 g and 0.18 meq/100 g, are similar to those of the B of swamp f i r s o i l s , calcium is more abundant here, averaging 0.43 meq/100 g. In the C horizon, levels of a l l measured cations except calcium are similar to those of the C of swamp f i r s o i l s . Calcium i s more abundant in the black spruce so i l s , averaging 0.11 meq/100 g. Although only two examples of black spruce soils on ridges were examined, cation levels appear to be lower in the L-F-H of these than in other forest soils of/, the Plateau. Averages in the black spruce soils range from 0.13 meq/100 g for potassium, to 0.28 meq/100 g for calcium. Single determinations for each cation in the Ae indicate lower cation concentrations here. These range from 0.02 meq/100 g for potassium to 0.20 meq/100 g for sodium. Average levels are higher in 99 the Ae of other s o i l groups, but are based on more determinations. The B horizon has similar average concentrations of potassium and sodium to those of the B of most other s o i l groups, while calcium levels, averaging 0.15 meq/100 g are most similar to that of upland f i r soils. Magnesium has an average of 0.27 meq/100 g, higher than that of upland f i r and swamp f i r s o i l s , but lower than black spruce soils in depressions. In the C layer of black spruce soils on ridges, average concentrations of sodium, magnesium, and potassium are similar to those of upland f i r soils while the average for calcium is slightly higher in the black spruce soils. Cation Exchange Capacities (C.E.C.) of the Plateau soils are generally highest in the L-F-H where organic matter contents are high, and lowest in the C horizons where organic matter contents are low. In upland f i r soils, the L-F-H has an average C.E.C. of 97.24 meq/100 g,. the B averages 36.53 meq/100 g, and the Ae and C have means of 18.65 meq/100 g and 12.14 meq/100 g respectively (Table 10 ). The L-F-H, Ae, and C horizons of swamp f i r soils have average Cation Exchange Capacities (Table 11 ) similar to those of upland f i r s o i l s , while the B horizon of swamp f i r soils has a lower average C.E.C. (10.94 meq/100 g) than the upland f i r soils. The L-F-H of black spruce soils in depressions has an average Cation Exchange Capacity of 3,04.40 meq/100 g, higher than the L-F-H of a l l other forest s o i l s , while the B and C horizons have averages similar to those of swamp f i r soils (Table 12. ). Only two determinations of C.E.C. were made for black spruce soils on ridges (Table 13 ); these are both much lower than those above. 100 Average c o n c e n t r a t i o n s of phosphorus i n the m i n e r a l h o r i z o n s of u p l and f i r s o i l s a r e h i g h e s t i n t h e B, a v e r a g i n g 540 ppm, and l o w e s t i n the Ae, a v e r a g i n g 349 ppm. No d a t a i s a v a i l a b l e f o r phosphorous l e v e l s i n the L-F-H of these s o i l s . I n swamp f i r s o i l s , phosphorus i s most abundant i n the L-F-H, a v e r a g i n g 380 ppm, and i s l e s s abundant i n the Ae, w i t h a mean of 232 ppm. S i n g l e d e t e r m i n a t i o n s i n t h e B and C h o r i z o n s o f these s o i l s a r e 140 ppm and 545 ppm r e s p e c t i v e l y ( T a b l e II ). The few d e t e r m i n a t i o n s made f o r b l a c k s p r u c e s o i l s ( T a b l e s 12 ,13 ) suggest t h a t phosphorus l e v e l s i n t h e s e a r e s i m i l a r to those of s o i l s beneath o t h e r v e g e t a t i o n t y p e s . A l l of the P l a t e a u f o r e s t s o i l s a n a l y z e d a r e a c i d , a r e s u l t o f an a c c u m u l a t i o n of c o n i f e r o u s o r g a n i c m a t e r i a l , l e a c h i n g , and an a c i d p a r e n t m a t e r i a l . PH v a l u e s a r e lowest i n the L-F-H h o r i z o n s , where o r g a n i c matter c o n c e n t r a t i o n s a r e h i g h e s t and g e n e r a l l y i n c r e a s e s l i g h t l y w i t h depth. In upland f i r s o i l s , the L-F-H has an average pH of 4.24, the Ae averages 4.66, and the B and C h o r i z o n pH r e a d i n g s average 5.12 and 5.34 r e s p e c t i v e l y . Swamp f i r s o i l s a r e s i m i l a r l y a c i d , the L-F-H h a v i n g an average of 4.52, the Ae an average of 4.63, the B an average of 5.00, and the C an average of 5.36. B l a c k s p r u c e s o i l s i n d e p r e s s i o n s a r e more a c i d than the o t h e r s o i l s s t u d i e d , p r o b a b l y because of h i g h c o n c e n t r a t i o n s of a c i d o r g a n i c m a t e r i a l i n the t h i c k peat o f ( t h e L-F-H. The L-F-H pH averages o n l y 4.00, t h a t of the B averages 4.73, and the C h o r i z o n has an average pH s i m i l a r to those of o t h e r s o i l s . The L-F-H h o r i z o n of b l a c k s p r u c e s o i l s on r i d g e s has an average pH of 4.65, s l i g h t l y h i g h e r than t h a t of the u p l a n d f i r s o i l s , 101 but the mineral horizons of the two s o i l groups have similar pH readings. 3. Discussion The p r o f i l e descriptions and a n a l y t i c a l results presented above indicate a number of differences among the s o i l groups; many of these are s i g n i f i c a n t with respect to vegetation. One of the more obvious differences l i e s i n the accumulation of organic matter i n the L-F-H horizons. Whereas the upland f i r and black spruce s o i l s on ridges have r e l a t i v e l y thin L-F-H horizons, those beneath swamp f i r stands and black spruce stands i n depressions have very thick organic horizons. These s o i l s are located i n areas where seepage i s abundant, and are water-saturated for much of the year. Lutz and Chandler (1946) reported that such conditions depress s o i l temperatures and create anaerobic conditions, resulting i n low decomposition rates and an accumulation of r e l a t i v e l y undecomposed peat. The thickness of the organic horizon, except as a potential seedbed, i s i n i t s e l f less important to vegetation, than are characteristics such as nutrient content and a v a i l a b i l i t y , water content, and s o i l aeration. In the thick organic horizons of the swamp f i r s o i l s and black spruce s o i l s i n depressions concentrations of most of the exchangeable cations are equal to or higher than those of upland f i r s o i l s . Exchangeable magnesium, calcium, and sodium are more concentrated i n the peat soils!, while i n these potassium i s generally less concentrated. High s o i l water content as observed i n the swamp f i r and black spruce s o i l s i s usually accompanied by poor s o i l aeration, which i n turn 102 i s p a r t i a l l y responsible for the accumulation of organic matter. Poorly aerated s o i l s are unfavourable for many plants, low oxygen and high CO^ levels resulting i n poor root growth, a decreased absorption of both water and nutrients and often the accumulation of toxic compounds, (Buckman and Brady, 1960), Since species d i f f e r widely i n terms of tolerance of oxygen deficiencies (Lutz and Chandler, 1946), judgments concerning the s u i t a b i l i t y of s o i l s to part i c u l a r species on th i s basis must be made with due consideration of the species' requirements. Although oxygen concentrations were not measured i n t h i s study, the abundant seepage observed i n the low-lying areas on the Plateau suggests the s o i l s there are poorly aerated and i n t h i s respect less favourable for vegetation than those i n higher areas of better drainage. The combination of poor aeration and high a c i d i t y that may exist i n swamp f i r and black spruce s o i l s i n depressions often i n h i b i t s ammonification and n i t r i f i c a t i o n . Available nitrogen l e v e l s may also be lowered by d e n i t r i f i c a t i o n , the reduction of nit r a t e s to gaseous nitrogen, (Lutz and Chandler, 1946). Consequently, although t o t a l nitrogen concentrations obtained i n t h i s study for the poorly drained s o i l s are comparable to those for upland f i r s o i l s , available nitrogen levels may be low i n the wet areas. A l l of the Plateau s o i l s examined, with the exception of those beneath black spruce stands ih depressions, have Ae horizons, a feature of podzol s o i l s . Podzol s o i l s are formed by a process i n which organic acids are transported downward through the s o i l p r o f i l e by seepage, removing bases from the uppermost mineral s o i l . These are replaced by hydrogen, and s o i l a c i d i t y here increases, leading to an 103 i n s t a b i l i t y of iron and aluminum, which, together with colloidal organic matter, tend to settle in the lower levels of the profile, (Lutz and Chandler, 1946). Podzol soils are usually recognized, then, by an accumulation of iron and aluminum complexes in the B horizons. Since neither of these have been measured in this study, no definite classification of the Plateau soils has been made. The presence of an Ae horizon and the reddish colour of the B horizon in many of the soils does suggest, however, that leaching of the upper s o i l and i l l u v i a t i o n of the lower horizons i s taking place. The expected lower cation concentrations in the Ae compared to those of the B horizon are not always found in the Plateau soils. In swamp f i r and upland f i r soils, the reverse is sometimes found, indicating that they may generally be juvenile. Although the black spruce soils on ridges and the black spruce soils in depressions support the same vegetation type, the two differ in many respects. Whereas the soils in depressions are very wet and have thick organic horizons, those on ridges appear to have better drainage and have much thinner organic horizons. Unlike those of low-lying areas, the L-F-H of soils on ridges have lower organic matter contents and cation concentrations than any of the other soils studied. Few trends are apparent among the results of analyses for exchangeable cations, beyond /those mentioned above. In the soils of humid regions, the four cations measured usually occur in decreasing order of abundance as follows: calcium, magnesium, potassium, and sodium, determined by the relative strengths by which each cation i s absorbed to the s o i l micelles, (Lutz and Chandler, 1946). In the L-F-H 104 of a l l except the b l a c k spruce s o i l s on r i d g e s , c a l c i u m and magnesium a r e the most abundant. T h i s i s a l s o t r u e i n the Ae of swamp f i r s o i l s , w h i l e i n the Ae of upland f i r s o i l s , sodium, r a t h e r than c a l c i u m , i s the most c o n c e n t r a t e d , a g a i n s u g g e s t i n g some o f the s o i l s a r e j u v e n i l e . In the t h r e e uppermost h o r i z o n s of a l l s o i l s , p o t a s s i u m i s the l e a s t abundant, p a r t i c u l a r l y i n the Ae h o r i z o n s , where i t has markedly lower c o n c e n t r a t i o n s than the o t h e r c a t i o n s . Maximum r o o t i n g depths a r e s h a l l o w i n a l l of the P l a t e a u s o i l s . Roots a r e most abundant i n the L-F-H h o r i z o n s and, i n many s o i l s , p e n e t r a t e no deeper than the upper p a r t o f the B h o r i z o n . Root systems a r e p a r t i c u l a r l y s h a l l o w i n b l a c k s p r u c e s o i l s on r i d g e s . I n a l l s o i l s the B and C h o r i z o n s appear t o be compacted. That t h e s e may be impermeable i s suggested by the f r e q u e n t o b s e r v a t i o n o f l a t e r a l seepage f l o w i n g through the s o i l a t the upper B h o r i z o n , whereas t h e s o i l s b eneath a r e d r y . Root p e n e t r a t i o n i s a l s o h i n d e r e d by v e r y s t o n y s o i l c o n d i t i o n s , found i n a number of u p l a n d f i r s o i l s and a l l b l a c k s p r u c e s o i l s on r i d g e s . In summary, c o n c e n t r a t i o n s o f exchangeable c a t i o n s , t o t a l n i t r o g e n , and carbon n i t r o g e n r a t i o s i n d i c a t e the f o r e s t s o i l s of the Cape B r e t o n P l a t e a u a r e n u t r i t i o n a l l y poor. Among t h e s e , t h e s o i l s b eneath b l a c k s p r u c e s t a n d s or r i d g e s a r e the l e a s t f a v o u r a b l e , b e i n g b o t h poor i n c a t i o n s and n i t r p g e n , and v e r y s t o n y . The o r g a n i c s o i l s oi the l o w - l y i n g b l a c k s p r u c e and swamp f i r a s s o c i a t i o n a r e p o s s i b l y l e s s f e r t i l e than those o f the upland f i r a s s o c i a t i o n ; the former have c a t i o n c o n c e n t r a t i o n s e q u a l t o t h o s e o f the up l a n d f i r s o i l s , but a r e l i k e l y to be p o o r l y a e r a t e d and perhaps n i t r o g e n poor. 105 Although the well-drained s o i l s have acid, greyish A horizons, indicative of podzolization, results suggest that the s o i l s are generally immature. In an e a r l i e r section, results of vegetation analyses from thi s study are compared with descriptions of boreal forests i n south-eastern Quebec (Linteau, 1955) and central Newfoundland (Damman, 1964). These studies and an additional paper for Newfoundland (Damman, 1971) include descriptions of s o i l s beneath the various forest types, and i t seems appropriate to b r i e f l y compare these with the results obtained for the Plateau. So i l s beneath Abies balsamea forests i n Quebec have thinner L-H and Ae horizons than those on the Plateau. In addition, the L-H of the Quebec s o i l s i s less acid, and has higher concentrations of exchangeable magnesium, potassium, and calcium than that of s o i l s beneath upland f i r s o i l s on the Plateau. Phosphorus l e v e l s , on the other hand, are much lower i n the Quebec s o i l s . Poorly-drained s o i l s beneath Picea mariana i n Quebec s i m i l a r l y have thinner and less acid organic horizons than those of the Plateau, and have much higher concentrations of exchangeable calcium. Exchange-able potassium l e v e l s , however, are similar i n the two s o i l types, and both magnesium and phosphorus levels are lower i n the Quebec s o i l s . Although no nitrogen), determinations are available for the humus of upland f i r and poorly-drained black spruce s o i l s on the Plateau, levels i n the Quebec s o i l s are similar to the average L-F-H of swamp f i r s o i l s . Forest s o i l s on the Plateau beneath upland f i r stands 106 morphologically resemble well-drained s o i l s i n Newfoundland classed as Iron Podzols (Damman, 1964). These are found beneath balsam f i r forests, and l i k e the s o i l s of the Plateau, have a f a i r l y thick, acid L-F-H horizon (11.5 cm.) underlain by Ae and B horizons, extending to a depth of 38 cm. As i n the Plateau s o i l s , a c i d i t y increases s l i g h t l y with depth. The F and H horizons of A. balsamea forest s o i l s i n Newfound-land (Damman, 1971) have much higher concentrations of potassium and calcium than do those of the Plateau s o i l s , whereas the mineral horizons of the Newfoundland s o i l s , have lower levels of both of these cations than the Plateau s o i l s . In the Newfoundland s o i l s , organic matter contents (% loss on ignition) are lower i n the Ae horizon and higher i n the B horizon than i n the Plateau s o i l s , suggesting the Plateau s o i l s are more juvenile. Phosphorus concentrations are much lower i n a l l horizons i n the Newfoundland s o i l s than i n the Plateau s o i l s . The Plateau s o i l s beneath black spruce stands on poorly-drained sit e s are most similar to those s o i l s i n Newfoundland classed as Peat Bog s o i l s (Damman, 1964). In these, the peat layer i s over 12 i n (30.5 cm) i n thickness, has low pH values of 4.0 or lower, and i s underlain by gleyed mineral s o i l having poor horizon development. The organic horizons^of similar s o i l s beneath Kalmia heath i n Newfoundland (Damman, 1971) have higher concentrations of potassium and calcium than those of the black spruce s o i l s i n poorly-drained areas on the Plateau, whereas the B and C horizons of the Newfoundland are poorer in these cations than those of the Plateau s o i l s . 107 In addition, Damman (1971) noted that root systems i n the Newfoundland s o i l s , as i n the Plateau s o i l s , are f a i r l y shallow. In the f i r forest s o i l s of Newfoundland nearly a l l of the larger roots were found within 20 cm of the s o i l surface, few extending beyond the upper B horizons, and most of the small roots were concentrated i n the organic horizons. These comparisons indicate, then, that the p r o f i l e s of s o i l s beneath upland f i r stands and those below black spruce stands i n depressions resemble those beneath similar vegetation types i n Quebec and Newfoundland. The Plateau s o i l s are generally more acid than those of Quebec, and have less calcium and magnesium i n the L-H layers than s o i l s i n both Quebec and Newfoundland. .i 108 VI. AUTECOLOGY OF MAJOR TREE SPECIES The performance of major tree species is an important feature of forest communities. Factors such as reproductive success, growth rates, and productivity, often reflect site conditions as well as characteristics of the stands themselves. The following i s an examination of some of these factors, displayed by four major tree species in the three forest associations on the Plateau. 1. Abies balsamea (balsam f i r ) Abies balsamea seedlings occur in a l l three forest associations, but are most abundant in the upland f i r association. In these stands, seedbeds composed of several moss species and decaying wood appear to be favourable for seedling establishment, and densities of A. balsamea average 16,162 stems/ha (Table 14 ) . Seedlings are much less abundant in the swamp f i r association, where densities average 5,950 stems/ha. In these stands, seedbeds consist largely of sphagnum mosses, whose thick-ness, moisture-retaining capacity, and high growth rate may hinder seed germination and seedling establishment. In black spruce stands, competition for light with low shrubs and Picea mariana reproduction i s probably severe, and A. balsamea seedlings are uncommon, averaging only 1,160 stems/ha. Although in upland f i r stands densities of young seedlings are high, very'low sapling numbers (avg. 187 stems/ha) indicate high seedling mortality. This may be a result of poor light conditions at Table H. Summary of Mensurational Data for Major Cape Breton Plateau Tree Species Species Association Densities (stems/ha) Seedlings Saplings Live Trees Basal Area (m2/ha) Age (yrs) Height (m) upland f i r R 16,162 7,550 -24,425 187 0 -450 1,390 925 -1,750 41.1 31.7 -52.2 56.0 26.0 -134.0 9.6 3.3 -13.8 Abies balsamea swamp f i r A R 5,950 1,400 -12,325 1,212 425 -2,275 842 550 -1,650 22.9 16.7 -49.7 93.2 54.0 -139.0 8.0 3.9 •12.0 black spruce A R 1,160 700 -5,100 400 0 1,400 100 0 -400 0.4 0 -1.4 Picea mariana black spruce A R 2,400 100 -7,400 4,200 2,500 -5,900 6,827" 4,700 •11,100 13.8 8.6 -17.8 44.2 24-80 2.7 1.8-3.7 Picea  glauca upland f i r A R 105 0-300 7 0-50 11 0-75 0.6 0-4.9 swamp f i r A 337 77 R 100-675 0-175 75 0^175 2.6 0-6.1 Betula  papyrifera upland f i r A R 1,360 0-3,250 355 0-2,475 33 0-125 1.2 0-18.9 swamp f i r A R 702 0-3,325 260 0-1,325 5 0-5 0.1 0-0.1 Average Range These data represent individuals in the B 1 stratum rather than in the A strata. o 110 ground levels, since A. balsamea saplings are common only in areas where windfalls have created openings in the tree strata. Swamp f i r stands have more open tree strata, and conditions appear to be much more favourable for the growth of young trees. Although A. balsamea seedlings are less abundant here than in upland f i r stands, seedling survival i s probably greater, since sapling densities are higher, averaging 1,212 stems/ha. In black spruce stands A. balsamea seedlings are very few, but favourable light conditions probably compensate for other factors and saplings of this species average 400 stems/ha in density, more than twice that of upland f i r stands. In the tree strata, Abies balsamea is most successful in the upland f i r association where liv e trees have an average density of 2 1,390 stems/ha and an average total basal area of 41.1 m /ha. In the swamp f i r association, both densities and stand basal areas are lower, 2 averaging 842 stems/ha and 22.9 m /ha, respectively. In the black spruce association, exposure to adverse weather prevents most tree species from reaching tree height (3.5m), and densities of Abies balsamea in the tree layer average only 100 stems/ha. 2 The total basal area of this species averages only 0.4 m /ha in these stands. Graphs of the distribution of liv e A. balsamea trees among diameter classes in the upland f i r and swamp f i r associations (Fig.24 ) are in some respects similar. The curves have a similar shape, and both indicate that in both associations, the stem diameters of most A. balsamea trees are f a i r l y similar. Few trees with very small or very 45 -40 -5 10 15 20 25 30 Stem Diameter (cm) I F i g u r e 2<t. The D i s t r i b u t i o n o f Mature A b i e s balsamea among Stem Diameter C l a s s e s i n the Swamp F i r and Upland i F i r A s s o c i a t i o n s . 112 l a r g e d i a m e t e r s a r e found i n e i t h e r a s s o c i a t i o n . T h i s g e n e r a l l y s u g g e s t s t h a t the m a j o r i t y of t r e e s c o m p r i s i n g the sta n d s b e l o n g to a p a r t i c u l a r age group. In b o t h a s s o c i a t i o n s , t r e e s 15 cm t o 20 cm i n d i a m e t e r a r e most abundant, but i n swamp f i r s t a n d s , s m a l l e r t r e e s a r e more abundant, and l a r g e r t r e e s a r e l e s s abundant than i n upland f i r s t a n d s , s u g g e s t i n g t h a t t h e up l a n d f i r s i t e s a r e more p r o d u c t i v e . Age d e t e r m i n a t i o n s f o r s e l e c t e d A. balsamea i n the upland f i r a s s o c i a t i o n v a r y from 26 t o 134 y e a r s , and average 56.0 y e a r s . A graph of t h e s e a g a i n s t D.B.H. (Fig."2.5) i n d i c a t e s t h a t i n c r e a s e s i n age a r e not always accompanied by c o r r e s p o n d i n g i n c r e a s e s i n d i a m e t e r . In a number o f ca s e s d i a m e t e r growth appears t o have been s u p p r e s s e d , p r o b a b l y through c o m p e t i t i o n f o r l i g h t . Ages o f A. balsamea t r e e s measured i n swamp f i r s t a n d s v a r y from 54 y e a r s to 139 y e a r s and average 93.2 y e a r s . These d a t a suggest the t r e e s i n swamp f i r stands a r e o l d e r than those i n up l a n d f i r s t a n d s , but a r e based on few d e t e r m i n a t i o n s . A l a r g e r sample might resemble t h a t o f the upland f i r a s s o c i a t i o n more c l o s e l y . I n u p l a n d f i r s t a n d s , A. balsamea t r e e s tend to be s l i g h t l y t a l l e r than those i n swamp f i r s t a n d s . H e i g h t s of t r e e s s e l e c t e d by diameter c l a s s i n t h i s a s s o c i a t i o n range from 3.3 m to 13.8 m and average 9.6 m. In the swamp f i r a s s o c i a t i o n , s i m i l a r l y s e l e c t e d h e i g h t s v a r y from 3.9 m to 12.0 m and have an average o f 8.0 m (T a b l e 14 ). T h i s comparison i s f u r t h e r i l l u s t r a t e d by l i n e a r r e g r e s s i o n s of h e i g h t and'diameter d a t a f o r A. balsamea i n up l a n d f i r and swamp f i r s t a n d s ( F i g s . 26, 27 ). These show t h a t r e l a t i o n s h i p s between h e i g h t and 113 UPFR 140*4-iao... no... 100... 90... BO... X X X X x* X X X XX ^ X X x ^ x * \ x x x x * x x x x X * X X x x X X X X x x x 1 1 1 1 1 1 1 1 h 0. 5» 10. 15. i:. SO. S5- 30. 35. 40* 45. • • B - H . (CM 3 F i g u r e 25 Graph of Age v s . D.B.H. of Mature A b i e s balsamea i n the Upland F i r A s s o c i a t i o n . 114 UPFR 15.+ 1E.1 9-4-6.1 3-1 0« X X X X X / X ) K $ H h 10« 15. SO* E5« 30* 35« 40* 45-•»B'H« (CM) F i g u r e 26. L i n e a r R e g r e s s i o n o f H e i g h t v s . D.B.H. Data f o r A b i e s balsamea i n the Upland F i r A s s o c i a t i o n . 115 SWFR 15.+ 1 S . 1 _ 9 « 2 H !±f G. 3-1 xx X X X x x > X X XX XX X X i 1 1 1 1 1 1 1 1 b 0 . 5 . 10. 15 . 20 . E5. 30. 35 . 40. 45. •'•B'H* (CM) F i g u r e 2.7. L i n e a r R e g r e s s i o n o f H e i g h t v s . D.B.H. Data f o r A b i e s balsamea i n the Swamp F i r A s s o c i a t i o n 116 diameter growth are the same in both associations, but in upland f i r stands conditions are more favourable for height growth, and trees of a particular diameter are t a l l e r in upland f i r stands than in swamp f i r stands. Mortality among A. balsamea trees in the upland f i r and swamp f i r associations may be generally compared by considering the relative abundance of standing dead tress in each. Although common in both associations, standing dead are more abundant in swamp f i r stands. In these they form an average of 38.5% of the total stand density, compared with an average of 29.6% in upland f i r stands. Standing dead trees in swamp f i r stands also have a larger basal area, averaging 2 12.0 m /ha, than those in upland f i r stands, whose basal area averages 2 10.0 m /ha. A graph of the percentages of total stand densities formed by standing dead trees by diameter class (Fig. 1% ) indicates that in upland f i r stands 80% or more of a l l stems under 10 cm in diameter are standing dead, whereas in swamp f i r stands these diameter classes have relatively low percentages of standing dead. Trees greater than 15 cm in diameter, however, are composed of more standing dead in swamp f i r stands than in upland f i r stands. Mortality, then, is high among small trees in upland f i r stands, probably because of competition with ta l l e r trees for light. Since tree densities are less dense in swamp f i r stands, competition would not be as severe, and mortality among small trees is lower. More mature trees, however, are thinned out to a greater extent in swamp f i r stands possibly because edaphic conditions here do not support volumes as great as those on upland f i r sites. In upland f i r stands, therefore, trees which survive competition to reach 117 90 0 .1 — — 5 10 15 20 25 30 35 Stem Diameter (cm) Figure 28 Distribution of Standing Dead Abies balsamea among Stem Diameter Classes in the Upland F i r and Swamp Fir Associations. i 118 canopy height seem to have better chances of survival than those in swamp f i r stands. The above results indicate that habitat conditions in upland f i r stands are generally more favourable for A. balsamea trees than are those of swamp f i r stands. Upland f i r sites support a greater tree volume, indicated by higher densities, higher basal area and lower mortality, than the swamp f i r stands. Trees in swamp f i r stands also tend to be smaller in height and D.B.H. than-those in upland f i r stands. These differences in productivity between the two associations are probably controlled by edaphic factors. The organic soils of swamp f i r stands are typically very wet and thus probably are poorly aerated. This may be unfavourable for the growth of A. balsamea, although definite statements to this effect would have to be preceded by an analysis of both species' tolerance limits and the actual oxygen content of the soils. 2. Picea mariana (black spruce) Picea mariana trees occasionally are found in the swamp f i r association, but are common only in the black spruce association, where they are dominant. Seedlings of this species vary in density here from 100 to 7,400 stems/ha in these stands, and average 2,400 stems/ha. Actual regeneration of P. mariana i s probably greater, however, since vegetative reproduction by layering i s very common. Densities of P. mariana in the shrub layers are very high. Individuals of low shrub height (.3 m to 1.8 m) have an average density of 4,200 stems/ha and those of high shrub height (1.8 m - 3.5 m) average 119 6,827 stems/ha (Table 1* ). Very few trees exceed 3.5 m to be classed in the tree strata, because exposure to strong winds and winter storms has a pruning effect on leader growth. The high densities of this species may be related to the prevalence of layering as a means of reproduction. Individuals arising in this way might, as a result of attachment to the present, be able to survive crowded conditions better than seedlings. Although densities of P. mariana are high in these stands, volumes are low. The average height i s 2.7 m, and because stem 2 diameters are very small, total basal area averages only 13.8 m /ha, in spite of high densities. Although stem diameters of P. mariana are consistently small, a wide range of ages are found, suggesting growth in a number of cases is poor. Ages of selected trees average 44.2 years, but range from 24 years to 80 years. 3. Piaea glauca (white spruce) Picea glauca occurs in both upland f i r and swamp f i r stands, but is not abundant in either. Seedlings are scarce, possibly because of poor seed sources as well as poor light conditions. In upland f i r stands seedlings average only 105 stems/ha, and in swamp f i r stands 337 stems/ha. Densities may be higher in swamp f i r stands because mature l, trees are more abundant and form a larger seed source than in upland f i r stands. Similarly, and perhaps for the same reasons as above, P. glauca saplings are rather few in upland f i r stands. Densities here average 120 only 7 stems/ha compared with an average of 77 stems/ha in swamp f i r stands. As previously noted, mature P. glauca trees are more abundant in swamp f i r stands, having an average density of 75 stems/ha and an 2 average basal area of 2.6 m /ha. In upland f i r stands, P. glauca may be unable to compete with A. balsamea as young trees; consequently 2 mature trees average only 11 stems/ha in density and 0.6 m /ha in basal area. Because so few P. glauca trees were found in the associations, few age data are available for this species. 4. Betula papyrifera (white birch) Betula papyrifera is usually dominant in successional forest communities on the Plateau, but is a relatively minor component of mature forests. As a mature tree, the species is most abundant in upland f i r forests, scarce in swamp f i r forests, and very rare on black spruce sites. Seedlings are most common in upland f i r stands, where densities average 1,360 stems/ha. Since B. papyrifera i s generally considered intolerant of shade, (Oosting and Reid, 1944), the more open stands of the swamp f i r association would seem to be more favourable for seedling establishment. They are less abundant here than in upland f i r stands, however, averaging 702 stems/lia. This may be a result of a scarcity of mature B. papyrifera in swamp f i r stands, or unfavourable seedbed conditions, as suggested above for Abies balsamea seedlings. Although densities of B. papyrifera seedlings are lower than those of A. balsamea, B. papyrifera saplings are more abundant. In upland f i r stands these average 355 stems/ha, and in swamp f i r stands average 260 stems/ha. These saplings are usually found beneath canopy openings created by a windfall or other localized disturbance. A. balsamea outnumber B. papyrifeva as seedlings in these areas, but the more rapid growth of B. papyrifeva allows them to be classed as saplings soon after the opening has been created. In the tree layers of upland f i r stands, B. papyvifeva has an 2 average density of 33 stems/ha and an average basal area of 1.2 m /ha. Trees of this species are much less abundant in swamp f i r stands, averaging only 5 stems/ha, with an average basal area of only 2 0.1 m /ha, indicating swamp f i r sites are less favourable for mature B. papyrifeva than are upland f i r sites. Swamp f i r sites are probably less favourable because of periodic flooding of the soil s , although the certainty of this could not be established without further study. Standing dead B. papyrifera trees are more than twice as abundant as live trees of this species, averaging 67.5 stems/ha in upland f i r stands. A number of these were perhaps k i l l e d by disease in the past, while others were possibly individuals that developed in windfall areas unt i l overtopped by A. balsamea. The frequent occurrence of windfalls in upland f i r stands may explain why B. papyrifera is able to maintain i t s e l f here. 5. Discussion Advance growth as produced by Abies balsamea in the upland f i r i and swamp f i r associations is common in forests throughout the species' . 1 2 2 range (Bakuzis, 1965). C o l l i n s (1953) reported an abundance of A. balsamea seedlings i n forests on the Plateau, and Candy (1951) gave an average" density of 2,970/acre (7,335/ha) for'seedlings i n Cape Breton, which i s within the range of those noted i n t h i s study. Oosting and B i l l i n g s (1951) reported that A. balsamea seedlings i n forests of the 2 northern Appalachians s i m i l a r l y average 2.7/100 m (13,750/ha). The high mortality among these seedlings suggested e a r l i e r for upland f i r stands i s also found i n other areas. Oosting and Reid (1944) reported that i n northwestern Maine Forests, 60% to 90% of a l l A., balsamea seedlings die within the f i r s t two years of l i f e . Other authors i n d i r e c t l y indicate s i m i l a r conditions, noting higher seedlings but very low densities of i n shrub layers (Buell & Niering, 1957). Opinions vary as to what the major causes of these high mortality rates. Zon (1914) believed A. balsamea could grow i n dense shade as a young seedling, but i n l a t e r years required more l i g h t . Others (Cooper, 1913; Hutchinson, 1918; Oosting and Reid, 1944) Believed A. balsamea to be generally shade intolerant. This may explain ppor seedling survival i n upland f i r stands, since most of these have closed canopies and consequently low l i g h t i n t e n s i t i e s at ground l e v e l s . Place (1955) suggested that on wet s i t e s , A.. balsamea seedlings are often smothered by rapidly-growing species of sphagnum mosses. Smothering and shading by dense growths of ferns and low shrubs were also implicated as causes of poor seedling growth (Place, 1952). These factors may account for low seedling densities i n swamp f i r stands on the Plateau. Sphagnum mosses are abundant here, and densities of the fern Osmunda einnamomea are usually high. Place (1965) believed that 123 on well-drained sites, drought is the major cause of seedling mortality in the f i r s t season, and additional losses may occur during winter from smothering by heavy accumulations of ice and snow. On the Plateau, drought may be an additional cause of seedling deaths. The distribution of summer precipitation on the Plateau in both 1970 and 1971 was unevenly distributed, and during periods of July, l i t t l e rain was received. During these periods, seedlings whose roots had not extended below the l i t t e r and upper humus layers to more moist s o i l may have been k i l l e d . Mature A. balsamea trees in boreal forests of southeastern Quebec vary from 565/acre to 625/acre (1395/ha - 1544/ha) (Linteau, 1955), which i s similar to the average in the upland f i r association on the Plateau (Table 14). However, tree heights in the Quebec stands (56 ft/16.8 m) are greater than those in Plateau stands. Similarly, in western Newfoundland stands dominated by A. balsamea, with total basal 2 areas averaging 42.5 m /ha (Damman, 1971), are similar to the average for upland f i r stands on the Plateau, but again the Newfoundland stands are generally t a l l e r , averaging 10;8 m in height. Thus, although total basal areas and densities in Quebec and Newfoundland stands are similar to those on the Plateau, timber volumes are probably lower in the Cape Breton stands. The maximum age of Abies balsamea reported in the present study (139 yrs.) is similar to those of other areas. Linteau (1955) gave a maximum age of 140 years for A. balsamea stands in southeastern Quebec, and Wilton (1964), reported that mature A. balsamea in the boreal forests of Labrador average 125 years in age and have a maximum 124 age of 220 years. Oosting and B i l l i n g s (1951) stated that the l i f e expectancy of A. balsamea i n the northern Appalachians i s about 148 years, and Bakuzis (1965) reported that i n even the more favourable parts of i t s range, A. balsamea seldom exceeds 200 years i n age. Abies balsamea i s commercially important, i n many areas, and damage to stands has received much attention. Zon (1914) and Wilton (1964) believed the species i s characterized by a shallow rooting habit making large trees highly vulnerable to windthrow. Zon (1914), Cooper (1913) and Nichols (1918) stated that A. balsamea stems are often b r i t t l e , r esulting i n extensive damage by breakage. Both types of damage were commonly found on the Cape Breton Plateau i n the present study. Windfalls are common, and stem decay was frequently found, p a r t i c u l a r l y among larger trees. According to Bakuzis (1965), fungal decay or "heart rot" i s common among mature A. balsamea, frequency of infection increasing with age such that most trees 100 years of age and over are damaged. Insect infestations, p a r t i c u l a r l y those of the spruce budworm (Choristoneura fumiferans) are an additional cause of damage i n A. balsamea stands. Although no recent spruce budworm damage was found i n t h i s study, i n f e s t a t i o n i n the past has been reported. Reeks (1953) and Cuming (1966) reported that large areas of forest i n the Cape Breton Highlands National Pau.k and adjacent areas suffered severe spruce budworm de f o l i a t i o n . Damage was apparently most extensive on the Plateau. Spruce budworm populations remained large for about three years u n t i l a sharp decline was reported i n 1956 (Forbes, et al. , 1956). Although no d e f o l i a t i o n has been reported since that time, according to 125 Baskerville (1950), Abies balsamea stands damaged by spruce budworm are more susceptible to the fungal infections that produce "heart r o t " and "top rot". This might account for the high frequency of t h i s type of damage among A. balsamea on the Plateau. Reproduction of Betula papyrifera i n forests dominated by A. balsamea i s described as poor by many authors (Cooper, 1913; C o l l i n s , 1951; Oosting and Reid, 1944; Nichols, 1918; Wilton, 1964). The major reason given i s that the species requires an abundance of l i g h t for seedling success. This may explain low seedling densities for B. papyrifera on the Plateau. As noted e a r l i e r , mature B. papyrifera trees are frequently encountered on the Plateau, but densities are low. Fernow (1912) estimated that i n northern Cape Breton B. papyrifera formed only 3% of the forest volume, and C o l l i n s noted that about 14% of the Plateau forests were made up of a combination of B. papyrifera, Picea glauca, and Sorbus americana. According to McDonald (1958), these low densities of B. papyrifera on the Plateau are a result of severe depletions by a disease known as 'birch dieback'. In other regions, however, B. papyrifera i s s i m i l a r l y a frequent, but minor component of forests dominated by A. balsamea. In Newfoundland B. papyrifera has a high frequency but low coverage i n balsam f i r - white birch forests (Damman, 1964), and i n Labrador, the species forms no more than 1% of the t o t a l tree coverage i n similar forest types (Wilton, 1964). Linteau (1955) found B. papyrifera was f a i r l y common i n young f i r stands, but reduced to scattered individuals i n many older stands. Si m i l a r l y , LaRoi (1967) reported that B. papyrifera was present i n every boreal white-spruce balsam f i r stand examined southeast of Great 126 Slave Lake, but indicated that t o t a l basal areas for the species were generally low. I t appears, then, that the frequent but low-density presence of B. papyrifera among upland f i r stands on the Plateau i s not unusual for A. balsamea-dominated forests. Poor reproduction of Piaea glauca i n Abies balsamea forests, as noted i n the present study, has been reported by several writers. Cooper (1913) suggested that P. glauca seedlings are shade intolerant, and on I s l e Royale were thus largely confined to canopy openings created by windfalls. Nichols (1918) reported a similar s i t u a t i o n for P. glauca seedlings i n the Cape Breton Plateau forests, and i n Labrador forests, although seed sources for Picea glauca seem to be adequate, germination i s poor and seedlings of t h i s species form less than 1% of a l l advance growth (Wilton, 1964). In comparing of seedling growth on various types of seedbeds i n New Brunswick, Place (1955) found that P. glauca seedlings i n i t i a l l y had a slower rate of root growth than did A. balsamea seedlings. P. glauca seedlings would thus have more d i f f i c u l t y establishing themselves on thick l i t t e r layers before they were k i l l e d by drought. Fernow (1912) and Nichols (1918) both considered mature P. glauca trees to be common i n Cape Breton Plateau forests, Fernow estimating the volume of species formed from 15% to 25% of northern Cape Breton forests. C o l l i n s (1951), however, indicated P. glauca trees are less abundant on the Plateau. In Labrador, P. glauca trees form less than 5% of the forest volume (Wilton, 1964), and i n the balsam fi r - w h i t e birch forests of Central Newfoundland (Damman, 1964), P. glauca trees have both low coverage and frequency. In addition, LaRoi 1s (1967) 127 survey of boreal forests indicated that except for southeastern Newfoundland, Picea glauca occurred i n . a l l stands, but in stands east of Gaspe, had low basal areas resembling those of B. papyrifera. Low densities of this species in upland f i r forests on the Plateau, there-fore, is not unusual for boreal forests in eastern Canada. As noted above, Picea mariana on the Cape Breton Plateau reproduces mostly by layering. Several writers (Damman, 1964; Wilton, 1964, Vincent, 1965) contend that this type of vegetative reproduction, is prevalent among P. mariana growing in wet habitats. In comparing trees formed by layering with those developed from seedlings, Wilton noted that those of vegetative origin usually have curved trunks, sometimes described as "butt sweep". This may explain the peculiar growth form that i s characteristic of most P. mariana trees growing in depressions. On the Cape Breton Plateau, P. mariana trees were rarely found on sites dominated by Abies balsamea. Although Nichols (1918) commented that P. mariana was locally an important component of A. balsamea forests on the Plateau, Collins (1951) spoke of the species only as a dominant of a separate community type. In Newfoundland P. mariana i s a frequent although minor component of balsam-fir-white birch forests (Damman, 1964), and in Labrador, P. mariana i s as abundant as A. balsamea on poor sites, sdldom occurs in mesic. Productivity among forests on the Plateau is lowest in black spruce stands. Although edaphic factors may partially account for this, growth of P. mariana trees, particularly in exposed low-lying stands near bogs, is also discouraged by ice and snow blasting in winter (Nichols, 1918). 128a The s i t e s on which b l a c k s p r u c e stands d e v e l o p on the P l a t e a u appear to be p o o r e r f o r growth than a p p a r e n t l y s i m i l a r h a b i t a t s i n Newfoundland and L a b r a d o r , whereas few t r e e s i n the Cape B r e t o n stands r e a c h 3.5 m, b l a c k s p r u c e s t a n d s a l o n g the edges o f bogs i n Newfoundland average 38 f t (11.4 m) (Damman, 1964), and W i l t o n ' s (1964) photographs of s i m i l a r communities i n Labrado r i n d i c a t e stand h e i g h t s a r e g r e a t e r than those i n Cape B r e t o n . Comparisons made i n an e a r l i e r s e c t i o n between peat s o i l s beneath b l a c k s p r u c e stands on the P l a t e a u and m o r p h o l o g i c a l l y s i m i l a r s o i l s i n Newfoundland i n d i c a t e d the Cape B r e t o n s o i l s were p o o r e r i n exchangeable p o t a s s i u m and c a l c i u m . T h i s might p a r t i a l l y account f o r d i f f e r e n c e s i n growth i n the two a r e a s . In a d d i t i o n , Newfoundland and Labrado r s t a n d s may not be s u b j e c t e d to wind and i c e storms as s e v e r e as those on the P l a t e a u . 128b V I I . FINAL DISCUSSION P r e v i o u s c h a p t e r s have p r e s e n t e d d e s c r i p t i o n s o f f o r e s t a s s o c i a t i o n s , f o r e s t s o i l s , and t r e e s p e c i e s performances on the P l a t e a u , as w e l l as a p a r t i a l c h a r a c t e r i z a t i o n o f the c l i m a t e o f the a r e a . The f o l l o w i n g u t i l i z e s some of the r e s u l t s from each of these c h a p t e r s i n a d i s c u s s i o n o f e c o l o g i c a l r e l a t i o n s h i p s among the t h r e e P l a t e a u f o r e s t a s s o c i a t i o n s , s u c c e s s i o n a l s t a t u s of the a s s o c i a t i o n s , and r e l a t i o n s h i p s between f o r e s t s on the P l a t e a u and those i n Lowland a r e a s of Cape B r e t o n . The t h r e e f o r e s t a s s o c i a t i o n s on the P l a t e a u a r e d e v e l o p e d on s i t e s which a r e t o p o g r a p h i c a l l y and e d a p h i c a l l y d i s t i n c t . The upland f i r a s s o c i a t i o n , the most widespread of the t h r e e , o c c u r s on the f a i r l y w e l l - d r a i n e d s o i l s o f low r i d g e s . B l a c k s p r u c e s t a n d s may a l s o d e v e l o p on r i d g e s , but have s o i l s which a r e more s t o n y and n u t r i t i o n a l l y p o o r e r than those beneath upland f i r s t a n d s . L o w - l y i n g a r e a s on the P l a t e a u o f t e n have p o o r e r d r a i n a g e , and s o i l s h e r e have t h i c k peat h o r i z o n s . On t h e s e s i t e s , the swamp f i r and b l a c k s p r u c e a s s o c i a t i o n s d e v e l o p . The b l a c k s p r u c e a s s o c i a t i o n i s f a i r l y common, and o f t e n o c c u r s i n exposed a r e a s such as t h o s e b o r d e r i n g peat bogs. The o r g a n i c l a y e r s o f s o i l s found beneath t h i s t y p e a r e v e r y t h i c k , and u n d e r l y i n g m i n e r a l h o r i z o n s a r e p o o r l y d e v e l o p e d . Swamp f i r s t a n d s a r e l e s s common, and a r e found f o r poor t r e e growth i n swamp f i r and b l a c k s p r u c e s t a n d s compared w i t h u p l a n d f i r s t a n d s . S o i l 129 chemical analyses made i n the present studies indicated that aside from L.F.H. horizons beneath black spruce stands being poorer i n exchangeable cations and t o t a l nitrogen, s o i l s beneath the three associations are, on the average, similar i n terms of exchangeable sodium, calcium, magnesium, and potassium, t o t a l nitrogen, phosphorus, and pH. Nevertheless, the swamp f i r and black spruce s o i l s i n depressions have thick organic horizons that appear to be poorly-drained and consequently water-saturated for most of the growing season. Poorly-drained organic s o i l s such as these are often poor i n available nitrogen and are l i k e l y to be poorly aerated, a condition which i n h i b i t s root metabolism (Lutz and Chandler, 1946; Wilde, 1946). The swamp f i r and black spruce s o i l s are, i n these respects, l i k e l y to be less favourable for growth than those beneath upland f i r stands. Although s o i l s beneath swamp f i r stands are similar i n many respects to those of black spruce stands i n low-lying areas, swamp f i r stands are s t r u c t u r a l l y more similar to upland f i r stands. Both have d e f i n i t e tree layers dominated by Abies balsamea, and i n both types, shrub layers are more poorly developed while herb layers are better developed only i n more sheltered areas. Soils here again are poorly drained and have thick organic horizons, but usually have well developed Ae and B horizons as w e l l , indicating the occurrence of v e r t i c a l seepage. I, The s i t e s on which the black spruce association develops are the least favourable, as indicated by stand productivity. Picea mariana i s ' the only tree species which can grow i n abundance i n the poorly drained areas surrounding bogs and on n u t r i t i o n a l l y poor s o i l s 130 on ridges. Growth i s very poor on these s i t e s ; stands averaging 44 years of age have a mean height of l e s s than three metres. Although stem d e n s i t i e s of trees i n these stands are high (Avg. 6,827/ha), stem diameters r a r e l y exceed 10 cm., and t o t a l basal areas are low (13.8 m 2/ha). Swamp f i r s i t e s are more favourable than those of black spruce stands, but are l e s s productive than upland f i r s i t e s . Trees of Abies balsamea, the dominant species i n both associations, have a lower average density, t o t a l basal area, and height i n swamp f i r stands than those i n upland f i r stands. In addition, standing dead trees i n swamp f i r stands are, on the average, more numerous and form higher t o t a l basal areas than those i n upland f i r stands. Thus, the s i t e s on which the upland f i r association develops are the most favourable. Although the exposure of black spruce stands to severe wind storms probably accounts i n part f or the poor growth there, edaphic conditions are considered to be p a r t l y responsible. In the upland f i r a s s o c i a t i o n , the abundance of Abies balsamea seedlings and the wide age range among trees indicates that these forests are i n a stable climax state. Very l o c a l i z e d disturbances, r e s u l t i n g i n the removal of only a few trees, release the abundant A. balsamea seedlings from suppression by shading, and t h i s species i s predominant i n the new growth'. Nichols (1918) believed that A. balsamea on the Plateau was p a r t i c u l a r l y susceptible to w i n d f a l l , owing to i t s shallow rooting habit, and small disturbed areas such as t h i s were considered common. He also noted the presence of larger areas, however, such as the successional stands examined i n t h i s study. In 131 t h e s e , l i g h t c o n d i t i o n s a r e markedly improved to the e x t e n t t h a t e s t a b l i s h m e n t and growth of Betula papyrifera s e e d l i n g s i s more s u c c e s s f u l . B. papyrifera s a p l i n g s grow w e l l under t h e s e c o n d i t i o n s , and o f t e n dominate the new v e g e t a t i o n . E v e n t u a l l y , however, A. balsamea w i l l o v e r t o p B. papyrifera., and i n the r e s u l t i n g c o m p e t i t i o n f o r l i g h t , B. papyrifera t r e e s a r e reduced i n number to a few i n d i v i d u a l s . The r e p e a t e d o c c u r r e n c e o f t h e s e d i s t u r b a n c e s , p o s s i b l y c r e a t e d by l o c a l i z e d wind storms, may e x p l a i n the f r e q u e n t p r e s e n c e of B. papyrifera t r e e s i n o l d e r s t a n d s . S i n c e the upland f i r a s s o c i a t i o n o c c u p i e s the most f a v o u r a b l e s i t e s on the P l a t e a u , i t i s c o n s i d e r e d the c l i m a t i c c l i m a x of the r e g i o n . V e g e t a t i o n c h a r a c t e r i s t i c s d i s t i n g u i s h i n g the swamp f i r and b l a c k s p r u c e a s s o c i a t i o n s appear to be d i r e c t l y r e l a t e d t o e d a p h i c f a c t o r s , and t h e s e f o r e s t s a r e e d a p h i c c l i m a x e s . Both of t h e s e a r e c o n s i d e r e d to be i n s t a b l e s t a t e s , a g a i n because of the wide age ranges and the p r o d u c t i o n of advance growth by the dominant t r e e s p e c i e s . In the Lowland a r e a s of Cape B r e t o n , second growth f o r e s t s a r e found which, i n some r e s p e c t s resemble the c l i m a t i c c l i m a x f o r e s t s on the P l a t e a u ( N i c h o l s , 1918). These l o w l a n d f o r e s t s r e p o r t e d l y a r e dominated by Abies balsamea, have s c a t t e r e d Picea glauca and Betula papyrifera t r e e s , and have u n d e r s t o r y s t r a t a t h a t a r e f l o r i s t i c a l l y s i m i l a r t o those i n the Plate'au f o r e s t s . The two t y p e s d i f f e r , however, by the p r e s e n c e o f Pinus strobus and Acer rubrum t r e e s i n the Lowland f o r e s t s , n e i t h e r o f which o c c u r s . a s t r e e s on the P l a t e a u . A c c o r d i n g to N i c h o l s , i n the Lowlands t h i s f o r e s t type i s a s u c c e s s i o n a l s t a g e on f a v o u r a b l e s o i l s , w h i l e on poor s o i l s , i t forms an e d a p h i c c l i m a x . On 1 3 2 r i c h e r s o i l s , succession proceeds to a predominantly deciduous forest climax, i n which Abies balsamea trees occupy a r e l a t i v e l y minor p o s i t i o n , and trees of species such as Fagus grandifolia, Acer saccharum, Betula lutea (B. alleghaniensis), and Acer rubrum are dominant. A l l of these species are absent on the Plateau, except for Acer rubrum, which occurs there as a low shrub. Nichols believed the complete absence of these species among Plateau could be a t t r i b u t e d to differences i n climate between the two areas, suggesting that on the Plateau, minimum temperatures are lower, maximums are higher, and p r e c i p i t a t i o n i s greater than i n Lowland areas. While c l i m a t i c measurements of the present study made i n the summers of 1970 and 1971 do not i n d i c a t e differences i n p r e c i p i t a t i o n between the two areas, they do suggest that temperatures are generally several degrees lower on the Plateau, e s p e c i a l l y i n early summer. General observations made during t h i s time also coincide with Nichol's opinion that low fogs are much more frequent on the Plateau than i n the Lowlands. Results of the present study, then, support Nichol's conclusion that differences between climax forests on the Plateau and Lowlands are determined by climate. 133 VIII. SUMMARY Phytosociological methods were used in the present study to sample and describe major forest communities on the Cape Breton Plateau. These forests were grouped into three associations, a l l of which are f l o r i s t i c a l l y , topographically, and edaphically distinct. The most common of these forest types is the upland f i r or Abies balsamea -Dryopteris spinulosa - Hylooomium umbratum association. This type occurs on the most favourable sites found on the Plateau, on low ridges, and is considered to be the climatic climax of the region. In poorly-drained sheltered areas, a f a i r l y uncommon association, the swamp f i r or Abies balsamea - Osmunda cinnamomea - Sphagnum capillaceum association develops. Soils beneath these stands have thick organic horizons, and the forest type is an edaphic climax. The third association, the black spruce or Picea mariana - Pleurozium schreberi association, occurs primarily on wet organic soils as well, but usually in more exposed areas, such as those near open peat bogs. This association is also found, although less frequently, on thin,^rocky soils on low ridges. Upland f i r stands usually have closed tree canopies, in which Abies balsamea is dominant, with average coverages of 41% for the A^ layer, and 32% for the A^  layer. Trees of Betula papyrifera are usually present as well, but with much lower coverages and densities. Shrub layers are poorly developed in these stands, total averages averaging only about 5%. Although several shrub species are f a i r l y common, these 134 layers are comprised primarily of saplings of Abies balsamea and Betula papyrifera. Poor development of the shrub layers is probably due to the fact that understory levels are usually shaded. Windfalls are common in these stands, and where these create openings in the canopy, shrubs and saplings of tree species are more abundant. The herb and dwarf shrub layer of the upland f i r association is much better developed, and has an average coverage of 81%. Dryopteris spinulosa, with an average coverage of 26%, is the most abundant species of the layer. Cornus canadensis, Oxalis montana, Abies balsamea seedlings, Coptis trifolia, Aster acuminatus, Clintonia borealis, and Trientalis borealis are also abundant. In addition to these, a number of species distinguish the upland association from the other two types, by being common in this type only. These are: Dryopteris Phegopteris, Athyrium Filix-femina, Osmunda claytoniana, and Moneses uniflora. Bryophytes are f a i r l y abundant in upland f i r stands, where ground surfaces are not heavily shaded. The Dh layer averages 55% in coverage, and is largely composed of Hylocomium umbratum and Pleurozium schreberi. Other less abundant but frequently occurring species are Sphagnum capillaceum, Dicranum magus, Rhytidiadelphus loreus, Ptilium cristacastrensis, and Polytrichum commune. Bryophytes common on decayed wood include Bazzania\, trilobata and Dicranum fuscescens. Swamp f i r stands have more open tree canopies, again dominated by A. balsamea. Picea glauca trees are also frequently found, but have low coverages. Unlike upland f i r stands, the swamp f i r stands have poorly developed Aq layers. These average only 17% in coverage, and as 135 a result, shrub layers below are only partially shaded. These are thus better developed than those of upland f i r stands, with respective coverages of 13% and 40% for the and B^  layers. In both of these layers Abies balsamea saplings are the most abundant, although Amelanchier bartramiana, Sorbus decora, and Nemopanthus mucronata are also common. Favourable light conditions in swamp f i r stands also allow the C layer to be f a i r l y well developed. This layer has an average coverage of 92%, and is dominated by Osmunda cinnamomea, covering an average of 42%. 0. cinnamomea an important distinguishing species for the association, being common in none of the other forest types. Other species abundant in the C layer of this association are: Dryopteris spinulosa, Cornus canadensis, and Coptis trifolia. Among bryophytes of the Dh layer in this association, Sphagnum capillaceum is the most abundant, with an average coverage of 28%. Other common species include Pleurozium schreberi, Hylocomium umbratum, and Bazzania trilobata. Common bryophytes growing on decayed wood in this type include Rhytidiadelphus loreus, Ptilidium ciliare, and Dicranum fuscescens. The black spruce association structurally differs from the two other Plateau forest types by lacking a definite tree canopy. Picea mariana individuals, the most); abundant species in a l l except the bryophyte strata, instead form dense thickets of about three metres in height. Coverages are high, averaging 55% in the B^  layer, and 41% in the B^  lay'er. A number of shrub species are abundant in spaces between the P. mariana thickets; these include Nemopanthus mucronata, 136 Rhododendron canadense, Viburnum cassinoides, Amelanchier bartramiana, and Kalmia a u g u s t i f o l i a . Abies balsamea s a p l i n g s are f r e q u e n t l y found i n these stands, but are never abundant here. . The dense development of these shrub l a y e r s discourages the growth of herb and dwarf shrub species below. The C l a y e r has an average coverage of 48%, and i s predominantly composed of shrub seedlings and P. mariana advance growth. Constant herb and dwarf shrub species i n c l u d e Cornus canadensis, C l i n t o n i a b o r e a l i s , Coptis t r i f o l i a , and Gaultheria h i s p i d u l a . Bryophytes i n these stands are not as s e r i o u s l y a f f e c t e d by shading, and those growing on humus have an average coverage of 77%. The most abundant of these species are Pleurozium schreberi and Sphagnum capillaceum. These are u s u a l l y accompanied by Bazzania t r i l o b a t a , Dicranum majus, Hylocomium splendens, and s e v e r a l Cladonia species. Two constant species form the D dw l a y e r of t h i s a s s o c i a t i o n ; they are P t i l i d i u m c i l i a r e and Dicranum fuscescens. In a d d i t i o n to sampling stands of the three f o r e s t a s s o c i a t i o n s , three s u c c e s s i o n a l stands on upland f i r s i t e s were examined. In a l l three of these stands, the t r e e canopies have been e s s e n t i a l l y destroyed, p o s s i b l y by l o c a l i z e d wind storms. The dominant v e g e t a t i o n i n these areas i s composed of young s a p l i n g s . In two of the stands examined, Abies balsamea and B e t u l a p a p y r i f e r a s a p l i n g s were both abundant, w h i l e i n the t h i r d , few A. balsamea were present, and the shrub l a y e r s c o n s i s t e d mostly of B. papyrifera. I t appears, then, that although B\ p a p y r i f e r a t r e e s are only s c a t t e r e d i n mature stands, the species i s f a r more abundant i n s u c c e s s i o n a l stages. Often i t i s 137 dominant i n d i s t u r b e d a r e a s , u n t i l o v e r t o p p e d by A. balsamea. A l t h o u g h many a u t h o r s have c l a s s e d the P l a t e a u f o r e s t s as b o r e a l , i n the f o r e s t c l a s s i f i c a t i o n s o f H a l l i d a y (1937) and Rowe (1956, 1972), the f o r e s t s of the a r e a a r e c o n s i d e r e d p a r t o f the t r a n s i t i o n a l A c a d i a n F o r e s t Region. In an attempt t o answer the q u e s t i o n o f whether or not the P l a t e a u f o r e s t s a r e b o r e a l , comparisons were made between t h e s e and b o r e a l f o r e s t s i n Newfoundland d e s c r i b e d by Damman (1964) i n Quebec ( L i n t e a u , 1955) and i n La b r a d o r ( W i l t o n , 1964). These comparisons g e n e r a l l y i n d i c a t e d t h a t i n each a r e a , f o r e s t t y p e s e x i s t which a r e s i m i l a r to t h e Cape B r e t o n b l a c k s p r u c e and up l a n d f i r a s s o c i a t i o n s , i n terms o f physiognomy and t r e e s p e c i e s c o m p o s i t i o n . A l t h o u g h the P l a t e a u a s s o c i a t i o n s a r e f l o r i s t i c a l l y r i c h e r , e s p e c i a l l y i n terms o f herbaceous s p e c i e s , a l l b u t a few o f the s p e c i e s l i s t e d as common i n the more n o r t h e r n f o r e s t t y p e s a r e a l s o common on the P l a t e a u . The s i m i l a r i t i e s between the P l a t e a u f o r e s t s and those i n t h e B o r e a l F o r e s t Region i n d i c a t e t h a t a l t h o u g h t h e P l a t e a u f o r e s t s c o n t a i n a number o f s p e c i e s c h a r a c t e r i s t i c o f s o u t h e r n r e g i o n s , they s h o u l d be c o n s i d e r e d b o r e a l . The f o r e s t s o i l s o f the P l a t e a u were sampled by a s s o c i a t i o n , and m o r p h o l o g i c a l f e a t u r e s of p r o f i l e s suggest f o u r b road g r o u p i n g s . S o i l s beneath upland f i r stands a r e m o d e r a t e l y w e l l d r a i n e d , and have a t h i n L-F-H (10 cm) u n d e r l a i n by Ae and B h o r i z o n s . The m i n e r a l s o i l s a r e sandy loam, and a r e o f t e n f a i r l y s t o n y . Roots extend i n t o the upper B h o r i z o n , but a r e c o n c e n t r a t e d i n the L-F-H h o r i z o n . S o i l s below swamp f i r s o i l s a l s o have Ae and B h o r i z o n s , but the s e a r e o v e r l a i n by t h i c k peat l a y e r s , a v e r a g i n g 35 cm. i n t h i c k n e s s . 138 Again most of the roots are found i n the organic horizon. This peat layer i s usually wet, and seepage i s often found at the Ae horizon. Black spruce stands are developed on two s o i l types. Those i n low ly i n g areas have s o i l s characterized by thick peat horizons averaging 56 cm i n thickness, underlain by a poorly developed B horizon. Roots are rarely found below the organic horizon i n these s o i l s . S oils beneath black spruce stands on ridges have thinner organic horizons, developed over Ae and B horizons. The mineral s o i l s here are stony, and very few roots are found i n the B horizon. Chemical analysis indicate the forest s o i l s on the Plateau are n u t r i t i o n a l l y poor. Few differences e x i s t , however, among results obtained for the s o i l s beneath the three types. Total nitrogen i n organic horizons has a concentration of about 2%, but i n mineral horizons i s generally less than 0.1%. Carbon-nitrogen r a t i o s are f a i r l y high, averages ranging from about 25 to nearly 60, suggesting that nitrogen a v a i l a b i l i t y i s low. The L-F-H of black spruce s o i l s on ridges i s especially poor i n th i s respect, having a t o t a l nitrogen concentration of only 0.09%, and a carbon-nitrogen r a t i o of 41. Concentrations of exchangeable cations are generally low i n a l l of the Plateau forest s o i l s . These are highest i n the L-F-H horizons, where concentrations of calcium and magnesium are about 1.5 meq/100 g. Sodium levels here are about 0.1 meq/100 g, and potassium concentrations are about 0.2 meq/100 g. Again black spruce s o i l s on ridges are generally poorer, levels of a l l exchangeable cations i n the L-F-H horizon being only about 0.1 meq/100 g. In addition, the organic s o i l of black spruce s o i l s i n depressions have high concentrations of 139 exchangeable magnesium, averaging 3.58 meq/100 g. Otherwise, exchange-able cation concentrations, are similar,beneath the various associations. In the mineral horizons of these s o i l s , exchangeable cation levels are very low, averages ranging from 0.05 to 0.10 meq/100 g. Cation exchange capacities are highest i n the L-F-H horizons, at about 100 meq/100 g, averages i n the mineral horizons varying from 10 meq/100 g to 30 meq/100 g. A l l of the Plateau forest s o i l s are acid, pH values being lowest i n the L-F-H horizon, at about 4.5, and increasing s l i g h t l y with depth, to about 5.0 i n the B and C horizons. The high a c i d i t y of these s o i l s i s probably due to the acid nature of the coniferous organic material, as well as leaching a c t i v i t y . Although analyses indicated the organic s o i l s below swamp f i r and black spruce stands generally have similar concentrations of exchangeable cations as those beneath upland f i r stands, the organic s o i l s are poorly drained, and hence may be poorly aerated. If this i s true, the organic s o i l s might be poor for vegetation development. The forest s o i l s of the Plateau were b r i e f l y compared with s o i l s beneath similar vegetation types i n Quebec described by Linteau (1955) and i n Newfoundland (Damman, 1964, 1971). Comparisons indicated that Plateau s o i l p r o f i l e s are generally similar to those i n the other regions, with the exception that the Cape Breton s o i l s generally have thicker and more acid L-F-H horizons than those i n Quebec. In addition, exchangeable calcium and magnesium levels are generally higher i n Quebec and Newfoundland s o i l s . General characteristics of major tree species on the Plateau 140 were described for each of the three associations. Abies balsamea, the dominant species of both upland f i r and swamp f i r associations, produces advance growth in both associations, indicating both types are in f a i r l y stable climax states. Seedlings are more abundant in upland f i r stands, where seedbed conditions are more favourable. On swamp f i r sites, thick sphagnum moss layers probably smother young seedlings. However, light conditions in swamp f i r stands are more favourable for survival of seedlings that do establish themselves, and A. balsamea saplings are much more abundant here than in upland f i r stands. In upland f i r stands, seedling mortality is high, probably because of shading and occasional periods of drought. Upland f i r stands are much more favourable for growth of A. balsamea trees. Densities here average 1,390 stems/ha, and total basal areas average 41.1 m /ha. On the other hand, swamp f i r stands have an average tree density of only 842 stems/ha, and an average total basal 2 area of 22.9 m /ha. In addition, trees in swamp f i r stands are smaller in diameter and height. Standing dead trees are more abundant in swamp f i r stands, further indicating conditions are less favourable here for growth of A. balsamea trees than are those in upland f i r stands. Picea mariana is common only in the black spruce association, where i t i s dominant. Reproduction on these sites i s f a i r l y successful, and i s mostly vegetative, by /layering. This type of regeneration produces a low, sweeping growth habit. Densities in the shrub layers are high, averaging from 4,000 to 6,000 stems/ha., and the thickets formed by this species are very dense. Growth is very poor, and although the trees have an average age of about 45 years, few individuals grow 141 more than 3 m in height or 5 cm in diameter. Piaea glauoa is most abundant in swamp f i r stands, whereas in upland f i r stands, few seedlings or trees of this species are found. The species may prefer the swamp f i r sites because of more favourable light and moisture conditions. P. glauca was rarely found in black spruce stands. 'Betula papyrifeva is often dominant in successional stages, but is a minor component of mature stands. Seedlings are most abundant in upland f i r stands, where seed sources are usually present. In swamp f i r stands, few B. papyrifera trees are found, and seedling densities of this species are lower than in upland f i r stands. Although B. papyrifera saplings are also f a i r l y abundant in upland f i r stands, trees of this species are only scattered, and standing dead are twice as abundant as live trees. Although many of these probably died in competition for light with A. balsamea, others were possibly k i l l e d by the birch dieback disease. Nichols (1918) compared the forests of the Plateau with those of the Lowlands of Cape Breton, and noted that although forests dominated by A. balsamea are found in Lowland areas, they are successional stages, or edaphic climaxes. The climatic climax of the Lowlands is predominantly deciduous, and i s composed of a number tree species absent on the Plateauj. Nichols (1918) believed this situation is attributable to climatic differences between the two areas. Weather stations were established on the Plateau as part of the present study during the'periods from June to September in 1970 and 1971. Temperatures measured during this period on the Plateau ranged from 0°C to 31°C in 142 1970 and from 3°C to 28°C i n 1971. June was the coldest month i n both years, maximum temperatures averaging about 20°C and minimum temperatures averaging from 8°C to 10°C. In July and August, mean maximums were about the same, but minimums were generally higher, averaging about 12°C. During this period, maximum and minimum temperatures at Cheticamp and Ingonish Beach i n the Lowlands were generally two or three degrees lower. Daily temperature ranges on the Plateau were highest i n June, averaging 10°C to 12°C. Average ranges at the Lowland stations during this month were about 9°C. Wind speeds on the Plateau were s l i g h t l y higher i n June, averaging 13 km/hr i n 1970, with a maximum reading of 28.7 km/hr. Average wind speeds for July and August were less than 1 km/hr lower, however. Pr e c i p i t a t i o n on the Plateau during the 77-day period i n 1970 to t a l l e d from 30 cm to 40 cm, and i n 1971, t o t a l l e d from 28 cm to 31 cm over a 44-day period. P r e c i p i t a t i o n at Cheticamp i n 1970 was lower than that of the Plateau, but was similar at Ingonish Beach. These r e s u l t s , then, support Nichols' b e l i e f that the Plateau i s s l i g h t l y colder than the Lowland areas, although p r e c i p i t a t i o n does not appear to be dif f e r e n t i n the two regions. Climate at Buchans, Newfoundland i n 1970 appeared to be generally similar to that of the Plateau, although minimum temperatures were s l i g h t l y lower i n June, suggesting that the onset of the growing season i n Newfoundland might be l a t e r than on the Plateau. 143 IX. CONCLUSIONS From the present study of climate, and forest vegetation and s o i l s on the Cape Breton Plateau, the following conclusions are formed: 1. Three major associations can be recognized among undisturbed f o r e s t s . These are the upland f i r or Abies balsamea - Dryopteris spinulosa - Hylocomium umbratum a s s o c i a t i o n , the Abies balsamea -Osmunda cinnamomea - Sphagnum capillaceum or swamp f i r as s o c i a t i o n , and the black spruce or Picea mariana - Pleurozium schreberi association. 2. The swamp f i r as s o c i a t i o n , while being a d i s t i n c t type, i s f l o r i s t i c a l l y s i m i l a r to both the upland f i r and black spruce associations, whereas these two associations have fewer species i n common. 3. The upland f i r association i s i n a stable climax state, and i s considered to be the c l i m a t i c climax of the Plateau. The swamp f i r and black spruce associations are also stable, and are edaphic climaxes. 4. The upland f i r and black spruce f o r e s t s are s i m i l a r i n many respects to c e r t a i n boreal f o r e s t types i n southeastern Quebec, c e n t r a l I, Newfoundland, and Labrador, and should be classed as part of the Boreal Forest Region. The Cape Breton forests are f l o r i s t i c a l l y r i c h e r than those i n the neighbouring boreal f o r e s t s , and should be classed as a d i s t i n c t section within the boreal region. 144 5. F o r e s t s o i l s on the P l a t e a u a r e a c i d , and poor i n t o t a l n i t r o g e n , and exchangeable potassium, c a l c i u m , magnesium and sodium. A l t h o u g h s o i l s beneath b l a c k s p r u c e s t a n d s on r i d g e s a r e n u t r i t i o n a l l y p o o r e r than o t h e r s o i l s , c h e m i c a l c h a r a c t e r i s t i c s examined a r e g e n e r a l l y s i m i l a r among the f o r e s t s o i l s on o t h e r s i t e s . A v a i l a b i l i t y o f n u t r i e n t s may be p o o r e r i n the p o o r l y - d r a i n e d o r g a n i c s o i l s beneath b l a c k s p r u c e and swamp f i r s t a n d s because of poor s o i l a e r a t i o n . 6. S i t e s on which the upland f i r a s s o c i a t i o n i s d e v e l o p e d a r e more f a v o u r a b l e f o r growth o f Abies balsamea t r e e s than those o f the swamp f i r a s s o c i a t i o n . P r o d u c t i v i t y i s h i g h e r and t r e e m o r t a l i t y r a t e s a r e lower i n upland f i r s t a n d s . T r e e growth on b l a c k s p r u c e s i t e s , on the o t h e r hand, i s v e r y poor. 7. D i f f e r e n c e s between c l i m a t i c c l i m a x v e g e t a t i o n on the P l a t e a u and t h a t of the Lowlands of Cape B r e t o n a r e p r o b a b l y r e l a t e d t o c l i m a t i c d i f f e r e n c e s . Summer temperatures on the P l a t e a u a r e s l i g h t l y lower than those a t c o a s t a l Lowland a r e a s , and i n June, d a i l y temperature ranges a r e h i g h e r on the P l a t e a u . The b e g i n n i n g o f t h e growing season i s p r o b a b l y s e v e r a l weeks l a t e r on the P l a t e a u than i n the Lowlands. A l t h o u g h low f o g s a r e more common on the P l a t e a u , summer p r e c i p i t a t i o n f o r the a r e a i s s i m i l a r t o t h a t r e c e i v e d i n Lowland a r e a s j, 8. 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Soil chemical analysis. Prentis-Hall Inc. 498 pp. Killam, I. C. 1951. Paleoecological studies of postglacial forest succession in Cape Breton I. B.Sc. (honours) Thesis. Acadia Univ., Wolfville, N.S. (unpublished). La Roi, G. H. 1967. Ecological studies in the boreal spruce-fir forest of the North American taiga. I. analysis of the vascular flora. Ecol. Monog. 37: 229-253. Linteau, A. 1955. Forest site classification of the northeastern coniferous section boreal forest region, Quebec. For. Br. Canada. Bull. 118 85 pp. Loucks, 0. L. 1962. A forest classification for the Maritime Provinces. Proc. N.S. Inst, of Sci. 25: 85-167. Lutz, H. J. and R. F. Chandler, Jr. 1946. Forest soils. John Wiley and Sons, N.Y. 514 pp. McDonald, A. C. 1958. A study of the transition zone in northern Cape Breton Island. B.Sc. (honours) Thesis. Acadia Univ., Wolfville, N.S. (unpublished). Macoun, J. 1899. Report on natural history. Summ. Rep. Geol. Surv. Canada. 1898. pp. 194A-200A. I: Neale, E. W. 1963. 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Association for the Upland F i r Association (Abies balsamea - Dryopteris splnulosa - Hylocomium umbratum) Number of Plots 1 2 3 4 5 6 7 8 9 10 11 12 •13 14 15 16 17 18 19 20 Plot No. 2 Plot size (m ) Landform Relief Exposure 1 3 4 8 10 17 18 19 22 23 25 26 27 28 ! 29 30 31 32 34 35 upper slope ridge top ridge base lower slope upper slope ridge bsse ridge top lower slope ridge base upper slope upper slope upper slope upper slope lower i. slope lower Blope upper slope lower slope lower slope upper slope lower slope E neutral neutral S N neutral neutral S neutral E S SW u W N NW W SE NW S Slope Gradient 3° 0 0 3° 2° 0 0 2° .0 2° 2° 4° 3° 4° 2° 2° 3° 2° 2° 1° Average Coverage Total Layer Coverage (Z) i A^ layer 62 40 25 40 47 40 49 40 43 65 40 45 33 30 25 45 28 25 60 40 41.1 layer 2 48 40 40 40 40 45 40 15 28 25 25 30 28 40 45 52 30 40 40 34.4' B^ layer 1 3 0 0 0 2 15 2 0 0 1 1 3 i ; 2 1 0 1 2 2 2.5 Bj layer 5 12 25 8 10 20 12 18 5 7 2 2 2 2 5 2 3 2 1 0.5 7.2 C layer 90 90 95 95 90 95 90 90 65 85 58 45 92 83 85 75 93 63 88 53 81.2 Dh layer 25 60 90 80 50 70 30 55 60 65 75 90 30 70 50 75 20 35 40 40 55.5 Ddv layer 15 15 15 20 15 15 18 10 12 15 10 15 6 10 15 5 5 5 5 10 11.8 Ground Surface Coverage (X) Humus 73 65 85 85 84 85 83 68 81 83 92 81 90 86 93 92 93 87 87 89 84.1 Mineral Soil ~~ 0 0 0 0 0 0 2 2 1 1 0 2 2 '2 0 0 2 0 1 1 0.2 Exposed Rock 2 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0.8 Decayed Wood 25 35 15 15 15 15 15 30 18 15 8 16 8 12 7 8 5 13 12 10 14.8 F l o r i s t i c Composition and Species Coverage (X) Constancy (» layer Abies balsamea 62.5 40.0 25.0 40.0 40.0 40.0 40.0 40.0 40.0 62.5 62.5 40.0 40.0 25.0 25.0 40.0 25.0 25.0 62.5 40.0 100 Picea glauca - - - - 7.5 - 7.5 - 2.5 ~ — — 7.5 0.5 0.5 — — — — 30 Aj layer Abies balsamea 2.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 15.0 25.0 25.0 25.0 25.0 . 25.0 40.0 40.0 40.0 25.0 40.0 40.0 100 Betula papyrifera - 7.5 - - - 15.0 15.0 - - 2.0 0.5 0.5 2.5 7.5 0.5 7.5 15.0 7.5 2.5 2.5 70 B^ layer Abies balsamea 0.5 2.5 _ 2.5' 15.0 2.5 — 0.5 0.5 2.5 0.5 2.5 i 0.5 - 0.5 2.5 2.5 70 &2 layer Abies balsamea 1.0 2.5 7.5 2.0 7.5 7.5 7.5 7.5 2.5 2.5 2.5 2.5 2.0 0.5 2.5 Betula papyrifera 2.0 7.5 ' 15.0 2.0 2.5 15.0 2.5 2.5 2.0 2.5 — 2.5 j 2.5 Amelanchier bartramiMa 2.0 7.5 7.5 2.0 2.5 7.5 2.5 7.5 2.5 2.0 — — — 1 2.0 Sorbus decora 1.0 2.0 1.0 2.0 - - - - 1.0 1.0 — 0.5 1 2.0 Picea glauca 0.5 - - - - - 2.0 2.0 -— — — ~ ! 2.0 2.0 1.0 C Layer Eh layer Ddv layer Cladonla spp. Alectorla amerlcana Bazzania trilobata Hypnum pallescens Brachythecium curturn Dicranum fuscescens Plaglothecium laetum Tetraphia geniculata Alectorla orchrolouca Ptilidiura c i l i a r e Hypnum imponena Sporadic species (occurrence limited to 1 plot) B^ Amelanchier bartramiana (0.5%) &2 Acer spicatum (0.5%) C Layer Acer rub rum (2.0Z) Coverage values represent midpoints of the Domin-Krajlna scale of cover-abundance (Becking, 1957) (Table 6 ) kAverage coverages were computed using only plots In which species occurred. 95 70 60 40 15 1.0 — 2.0 2.0 1.0 1.0 2.0 1.0 1.0 1.0 2 0 1.0 1.0 1.0 2.0 1.0 2.0 1.0 1.0 1.0 95 2.0 - 2.0 2.0 2.0 2.0 2.0 - 2.0 2 0 2.0 1.0 2.0 2.0 2.0 1.0 2.0 1.0 1.0 85 - 1.0 2.0 2.0 - 2.0 - 2.0 2.0 2.0 2 0' 2.5 — 2.0 2.0 1.0 1.0 1.0 2.0 2.0 80 2.0 2.0 - 2.0 2.0 2.0 2.0 2.0 2.0 2.0 - 2.0 — 2.0 2.0 2.0 - 2.0 - " 75 2.0 2.0 2.0 2.0 - 2.0 2.0 2.0 2.0 2.0 1 o- 2.0 2.0 — 2.0 - 2.0 - - 2.0 75 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2 5 2.5 2.5 2.0 - - - - - -70 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 - 2.0 2.0 ~ 2.0 70 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 - - 1.0 — 2.0 - - - - - 55 2.0 2.0 - 2.0 2.0 2.0 2.0 - 2.0 2.0 1 0 2.0 — — - - - - - 50 2.0 2.0 2.0 2.0 2.0 - 2.0 — — 2.0 - — — — 2.0 1.0 - - - 45 — — _ — 1.0 1.0 — — 2.0 15 Epicjaea repens (0.5%) Habenarla obtusata (1.0Z) Llnnaea borealis (2.5%) Pyrola e l l i p t l c a (I.OX) Viburnum cassinoides'(1.1%) Viburnum edule (0.5Z) Dh Peltigera apthosa (0.5Z) Pogonatum alplnum (1.0Z) Sphagnum mage Hani cum (1.0Z) Sphagnum palustre (1.0Z) Total number of apeciee including sporadics: Total number of species with Constancy 70Z or more: 34 Average _ Coverage (X) 40.8 4.3 32.3 6.1 3.4 4.0 3.9 1.3 1.5 Dryopteris splnulosa 40.0 40.0 15.0 40.0 25.0 25.0 25.0 15.0 15.0 15.0 25.0 25.0 40.0 25.0 40.0 25.0 40.0 25.0 15.0 15.0 100 26.5 Comus canadenals 7.5 15.0 15.0 40.0 15.0 25.0 40.0 25.0 15.0 15.0 15.0 7.5 25.0 , 5 25.0 40.0 25.0 7.5 15.0 15.0 100 19.8 totalis montana 15.0 15.0 15.0 15.0 25.0 25.0 25.0 25.0 15.0 7.5 25.0 15.0 15.0 7.5 15.0 15.0 15.0 25.0 15.0 25.0 100 17.8 Abies balsamea 7.5 7.5 25.0 7.5 15.0 25.0 15.0 15.0 7.5 15.0 7.5 2.5 7.5 7.5 7.5 7.5 15.0 25.0 15.0 15.0 100 12.5 Coptls t r i f o l l a 2.0 7.5 25.0 2.5 2.5 7.5 15.0 15.0 2.5 2.5 2.5 7.5 2.5 2.5 15.0 25.0 2.5 15.0 2.5 2.5 100 8.0 Cllntonia borealis 2.5 15.0 2.5 2.5 2.5 15.0 7.5 7.5 2.5 2.5 7.5 2.5 7.5 7.5 2.5 7.5 7.5 2.5 7.5 2.5 100 5.8 Trlentalls borealis 7.5 7.5 7.5 2.5 7.5 15.0 7.5 2.5 7.5 2.5 2.5 7.5 7.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 100 5.1 Malanthemum canadense 2.5 7.5 2.5 7.5 2.5 2.0 2.5 2.5 2.5 2.0 2.5 2.5 15.0 2.5 7.5 7.5 2.5 2.5 7.5 2.5 100 4.3 Dryopteris Phegopteris 2.0 7.5 1.0 * 7.5 1.0 7.5 2.0 7.5 2.5 2.0 2.5 2.5 2.5 2.5 2.5 7.5 7.5 2.5 2.5 . 2.5 100 3.8 Betula papyrifera 7.5 2.5 7.5 2.5 7.5 15.0 2.5 2.5 - 2.5 1 15.0 2.0 2.5 2.5 2.5 2.5 2.5 2.0 1.0 1.0 95 4.4 Athyrium Filix-femina — 2.0 2.5 7.5 2.5 15.0' 2.0 2.5 2.5 1 2.0 15.0 2.5 2.0 2.5 2.5 7.5 2.5 2.5 2.5 2.5 95 4.2 Amelanchier bartramiana 2.0 2.0 2.5 2.5 2.5 2.5 2.0 2.5 2.5 2.5 2.0 2.0 1.0 1.0 2.5 2.0 2.0 — 0.5 1.0 95 2.0 Streptopus roseus - 2.5 2.0 2.0 1.0 2.5 1.0 2.5 2.5 2.0 2.0 2.0 2.0 1.0 2.0 2.5 -- 2.0 2.0 1.0 2.0 95 1.9 Solldago macrophylla — — 2.5 15.0 2.0 15.0 7.5 7.5 2.5 2.5 2.5 2.5 7.5 2.5 7.5 2.5 7.5 2.5 2.5 2.5 90 5.3 Sorbus decora 2.0 2.0 2.5 2.5 — 2.5 2.0 2.0 2.5 2.0 2.0 2.0 1.0 2.5 2.5 2.5 2.5 2.0 — 1.0 90 2.1 Aster acumlnatus 15.0 15.0 2.0 — 2.5 - - 15.0 2.5 2.5 7.5 2.5 2.5 15.0 15.0 15.0 15.0 7.5 15.0 7.5 85 9.2 Aralla nudicaulis 7.5 2.5 2.0 — 2.5 - 2.5 • 2.5 - 2.5 7.5 2.5 7.5 7.5 2.5 7.5 15.0 2.5 2.5 2.5 85 4.7 Osmunda Claytoniana 2.5 — 2.5 2.5 2.5 2.5 7.5 2.0 2.0 2.0 7.5 2.0 - 2.5 1.0 1.0 — 1.0 2.0 1.0 85 2.6 Moneses uniflora — 1.0 0.5 1.0 2.0 1.0 - 2.0 2.5 2.0 2.0 1.0 2.0 1.0 2.0 2.0 1.0 — — 80 1.6 Acer spicatum — 2.0 1.0 - 1.0 2.5 - _ - - 1.0 2.0 2.5 2.0 ! 2 ' ° 2.0 2.5 1.0 1.0 2.0 70 2.1 Picea glauca 1.0 - 25.0 7.5 2.5 25.0 2.5 15.0 7.5 2.5 — — 1.0 - _-— r 1.0 — — 1.0 1.0 65 7.1 Dryopteris noveboracensis 2.0 7.5 7.5 - - - 2.0 2.5 1.0 2.5 7.5 2.0 1.0 i - 2.5 2.5 - -2.0 65 3.3 Viola pallens 1.0 - - 1.0 2.0 1.0 - - 2.0 - -2.0 2.0 - 2.0 2.0 - -2.0 50 1.7 Carex trisperma - - 1.0 1.0 2.0 1.0 - - 1.0 - — — 1.0 - — 1.0 0.5 1.0 2.0 50 1.2 Gaultheria hispidula 1.0 - 2.0 2.0 2.0 2.0 -2.0 — 1.0 — — — 1.0 — 1.0 — — — 45 1.6 Ribes glandulosum - - - 2.0 2.5 2.0 - 1.0 0.5 — — — 1.0 — 1.0 2.0 — 1.0 — 45 1.4 Rubus ldaeus 0.5 0.5 1.0 2.0 3.5 2.0 0.5 - - — — 0.5 1.0 — — — — — — 45 1.2 Osmunda cinnamomea — - - - - - - - -0.5 1.0 1.0 -2.5 1.0 2.5 1.0 40 1.3 Monotropa uniflora 2.0 - - - 2.0 - - 2.0 2.0 1.0 • — — — 0.5 — 0.5 -1.0 40 1.2 Calamagrostis canadensis - - 1.0 2.5 1.0 2.5 - 2.0 2.0 - — — — — — — — — — 2.0 35 1.9 Lycopodium clavatum - - -- - - - - - - -1.0 0.5 — 1.0 2.0 — — — — — 20 1.1 Rubus pubescens - - - 1.0 - 1.0 - - -' 0.5 — — — — 1.0 — — — — 20 0.9 Lycopodium lucldulum - - - - - - 0.5 - - — — — — — — 2.1 — — — 10 1.2 Luzula acuminata — - - . - - 1.0 - -1.0 — — — — — — — — — 10 1.0 Pcerldlum aquillnum - - - - - — — — — — — 1.0 1.0 ~ — 10 1.0 Listera cordata - - 1.0 - - - - - - — — — — 0.5 10 0.8 Monotropa Hypopythya — — — — - 1.0 - - - - - - - — 2.0 — — - 10 0.8 Hylocmlum umbratum 7.5 40.0 25.0 25.0 40.0 25.0 25.0 15.0 15.0 40.0 40.0 62.5 25.0 25.0 40 0 40.0 15.0 25.0 25.0 25.0 100 29.0 Pleurozium schreberi 7.5 25.0 25.0 7.5 7.5 7.5 7.5 2^5 15.0 15.0 25.0 25.0 7.5 7.5 , 7 1 5 15.0 2.5 7.5 7.5 7.5 100 11.9 Dicranum majus 2.0 - 2.0 7.5 2.0 7.5 2.0 2.5 2.5 7.5 15.0 7.5 2.5 7.5 1 2 5 7.5 2.5 2.5 7.5 2.5 95 5.0 Sphagnum capillaceum 1.0 1.0 40.0 25.0 2.0 25.0 2.0 40.0 25.0 — 2.0 1.0 1.0 _25.n 1 0 15.0 - 2.0 2.5 7.5 90 12.1 Rhytldladelphus loreus 2.0 "2.0 1.0 2.6 2.0 — ~ 2.6~' — 1.0 2.0 1.0 2.0 2.0 2.0 2 ! 0 2.5 2.0 2.0 2.0 1.0 90 1.8 Ptilium crista-castrensls - 2.0 2.5 2.0 2.5 2.0 — — 2.0 2.0 2.0 1.0 2.0 2.0 1 0 2.0 - 1.4 2.0 1.0 80 1.8 Polytrichum commune 2.0. 2.5 - 2.5 - 2.5 — 2.0 — — 2.5 2.0 1.0 2.0 i 2 0 2.0 2.0 2.0 •2.5 2.0 75 2.1 Dicranum montanum 2.0 — 2.0 — 2.0 __ 1 — — — — — 15 2.0 1.3 1.8 2.4 2.0 1.9 2.1 2.0 1.9 1.9 1.9 1.3 , ' V . j i t W o 'mi L i,: i.. ( j i •o Table II., Association Table for the Black Spruce Association (Picea mariana-Pleurozium sherberi) Number of Plots 1 2 3 4 5 6 7 Plot No. 5 6 7 11 15 24 33 Plot size (m2) Landform low lower low upper area slope '.r area slope Relief . . f l a t . . . Total Layer Coverage (%) Average Coverage (%) A2 layer 0 0 0 0 0 0.5 40 22.5 B^ layer 62.5 87 42 48 42 43 62 55.2 %2 layer 85 90 70 60 75 43 20 63.3 C layer 55 45 50 63 68 38 20 48.4 Dh layer 85 95 80 .70 65 65 78 76.8 Ddw layer 5 5 8 2 8 5 5 "4.6 Ground Coverage (%) Humus 95 98 98 95 87 95 98 95.1 Exposed Mineral S o i l Exposed Rock Decayed Wood 0... 5 2 2 5 13 5 2 4.8 F l o r i s t i c Composition and Species Coverage (%) a A2 layer Picea mariana B 1 layer Picea mariana Abies balsamea B, layer Constancy Average C layer Osmunda cinnamomea Sorbus decora Linnaea borealis T r i e n t a l i s borealis Solidago macrophylla A r a l i a nudicaulis Dh layer Ddw layer P t i l i d i u m c i l i a r e Dicranum fuscescens Hypnum pallescens Brachythecium curtum (%) 0.5 40.0 29 Coverage (%) 22.5 62.5 85.0 2.5 40.0 2.5 40.0 7.5 40.0 2.5 40.0 2.5 62.5 Picea mariana 2.0 15.0 15.0 15.0 15.0 1.0 1.0 Rhododendron canadense 15.0 15.0 2.5 15.0 7.5 1.0 2.0 Cornus canadensis 7.5 2.5 7.5 7.5 15.0 2.5 2.5 Vaccinium angustifolium 2.5 7.5 7.5 15.0 2.5 7.5 2.5 C l i n t o n i a borealis 7.5 2.0 2.5 7.5 7.5 2.5 2.0 Coptis t r i f o l i a 2.5 2.5 7.5 2.5 2.5 7.5 2.5 Gaultheria hispidula 2.5 2.5 7.5 2.5 2.0 2.5 2.0 Nemopanthus mucronata 2.0 2.0 2.5 2.0 7.5 2.5 2.0 Amelanchier bartramiana 2.5 2.5 7.5 2.0 1.0 1.0 2.0 Viburnum cassinoides 2.5 •1.0 2.0 7.5 2.5 1.0 2.0 Kalmia angustifolia 7.5 7.5 7.5 — 15.0 7.5 2.5 Epigaea repens 2.5 2.0 2.0 7.5 2.5 1.0 — Abies balsamea 2.0 2.0 2.5 '2.5 2.5 — 1.0 Taxus canadensis 7.5 — 2.0 — 7.5. 2.5 1.0 Carex trisperma 7.5 — 2.0 — 2.0 1.0 2.0 Ledum groenlandicum 2.5 — 2.0 — 2.0 7.5 1.0 Rubus Chamaemorus 2.5 — 2.0 — 2.0 2.5 2.0 Maianthemum canadense — 2.0 2.5 2.0 2.0 2.0 — 1.0 2.0 2.5 2.0 2.0 2.0 1.0 2.0 2.0 2.0 1.0 2.0 0.5 1.0 2.0 2.0 2.0 1.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.5 2.0 2.5 2.0 2.5 100 71 100 100 100 100 100 100 100 100 100 100 86 86 86 71 71 71 71 71 57 57 43 43 29 29 100 100 57 29 52.8 3.5 Picea mariana 62.5 65.0 40.0 40.0 40.0 15.0 7.5 100 41.4 Nemopanthus mucronata 15.0 15.0 2.5 2.0 25.0 25.0 7.5 100 13.1 Rhododendron canadense 15.0 15.0 2.5 15.0 7.5 2.0 2.5 100 8.5 Viburnum cassinoides 7.5 2.0 2.0 15.0 15.0 2.5 2.5 100 6.6 Amelanchier bartramiana 15.0 7.5 7.5 2.0 2.5 2.0 2.5 100 5.6 Abies balsamea 7.5 2.5 15.0 2.5 2.5 1.0 0.5 100 4.5 Kalmia an g u s t i f o l i a 2.5 7.5 2.5 — 7.5 2.0 2.0 86 4.0 Viburnum edule 1.0 1.0 — — — ' i — — 29 1.0 9.1 8.3 6.4 6.4 4.5 3.9 3.1 3.0 2.6 2.6 7.9 2.7 2.0 4.1 2.9 3.0 2.2 2.1 1.8 1.3 2.2 1.7 2.0 1.0 Pleurozium schreberi 15.0 40.0 25.0 40.0 25.0 25.0 25.0 100 27.8 Sphagnum capillaceum 40.0 40.0 40.0 2.5 7.5 7.5 40.0 100 25.3 Bazzania t r i l o b a t a 15.0 15.0 7.5 2.5 15.0 15.0 2.5 100 10.3 Dicranum majus 2.5 2.5 2.5 2.5 2.5 7.5 7.5 100 3.9 Hylocomium splendens 2.5 2.5 2.0 15.0 15.0 2.5 2.5 100 5.9 Cladonia spp. 2.0 1.0 1.0 1.0 2.0 2.5 2.5 100 1.7 Ptili um crista-castrettsis 7.5 2.0 2.5 7.5 2.5 — 2.5 86 4.1 Sphagnum subsecundum 2.0 1.0 — — — 7.5 — 43 3.5 Spgagnum magellanicum 2.5 — 2.5 — — — 2.5 43 2.5 2.1 2.0 2.1 2.0 Sporadic Species (occurrence limited to 1 plot) Ledum groenlandicum (2.OX) Sorbus decora (1.0%) C layer Cinna l a t i f o l i a (0.5%) Drosera rotu n d i f o l i a (1.0%) Picea glauca (2.5%) Streptopus roseus (o'.5%) Ddw layer , -Alectoria orchroleuca (2.0%) Plagiothecium laetum (2.0%) Total number of..species' including sporadics: 43 Total number of species with constancy 70% or more: 27 Species coverage values represent midpoints of the Domin-Krajina scale o i Cover-Abundance (Becking, 1957) (Table 6 ). ''Average coverages were computed using only plots where species occurred. O l rO Table I I I . Association Table for the Swamp F i r Association (Abies balsamea - Osmunda clnnamonea. - Sphagnum capillaceum) Number of Plots 1 2 3 4 5 6 7 Plot. No. 2 9 16 20 21 36 37 Plot size (m2) Land form ridge base lake shore depression ridge base R e l i e f t o t a l Layer Coverage (%) Average Coverage (%) A^ layer 25 40 5 0 10 17 25 17.4 Aj layer 50 40 55 42 45 15 25 38.9 B^ layer 15 15 15 20 15 2 15 13.8 layer 50 55 45 50 58 10 15 40.4 C layer 95 90 90 95 - 90 96 88 92.0 Dh layer 35 50 60 65 35 20 40 43.6 Ddw layer 10 15 15 10 15 15 15 13.6 Ground Coverage (%) Humus 90 90 92 95 84 90 90 90.6 Mineral S o i l 0 0 0 0 1 2 0 0.4 Exposed Rock Decayed Wood 0.0 10 10 15 10 15 8 10 11.1 F l o r i s t i c Composition and Species Coverage (Z) A. layer Average Constancy (Z) Coverage (Z) Abies balsamea Picea glauca Aj layer Abies balsamea Picea glauca layer Abies balsamea Picea mariana Alnus rugosa layer C layer 25.0 40.0 15.0 40.0 40.0 2.5 2.5 2.5 40.0 15.0 15.0 15.0 15.0 2.5 2.5 2.5 40.0 2.5 15.0 2.5 2.0 7.5 15 25 7.5 2.5 0.5 40.0 15.0 25.0 7.5 15.0 2.5 2.5 15.0 86 57 100 71 100 43 43 «2 layer Betula papyrifera (0.5Z) layer Acer spicatum (1.0Z) Picea glauca (2.0Z) Bj layer Acer rubrum (0.5%) Kalmia angustifolia (2.0Z) C layer Total number of species of Constancy 70Z or more: C layer Prenanthes t r i f o l i o l a t a (0.5Z) Pteridium aquilinum (1%) Viburnum edule (1Z) Viola pallens (2Z) Dh Dicranum montanum (1Z) Sphagnum squarrosum (1.0Z) 19.2 3.3 34.2 8.5 13.2 2.5 2.3 Abies balsamea 15.0 40.0 25.0 25.0 15.0 2.5 15.0 100 19.6 Amelanchier bartramiana 7.5 2.5 7.5 15.0 15.0 2.0 2.0 100 7.4 Sorbus decora 7.5 2.5 2.5 7.5 2.5 2.0 0.5 100 3.6 Nemopanthus mucronata 1.0 - 2.0 7.5 1.0 2.5 2.5 86 2.8 Picea glauca - 2.0 2.5 - 7.5 2.0 0.5 71 2.9 Alnus rugosa 15.0 7.5 15.0 7.5 25.0 - - 71 14.0 Betula papyrifera 2.0 - - 2.0 1.0 2.0 2.5 71 2.0 Picea mariana 15.0 7.5 2.5 2.5 - - - 57 6.9 Viburnum cassinoides 0.5 - 2.5 - - 2.0 1.0 57 1.5 Osmunda cinnamomea 85.0 40.0 40.0 40.0 15.0 62.5 15.0 100 42.5 Cornus canadensis 15.-0 15.0 25.0 15.0 15.0 2.5 15.0 100 14.6 Coptis t r i f o l i a 7.5 15.0 25.0 15.0 15.0 2.5 7.5 100 12.5 Abies balsamea 7.5 15.0 25.0 15.0 15.0 2.5 2.5 100 11.8 Dryopteris spinulosa 40.0 15.0 7.5 2.0 7.5 7.5 1.0 100 11.5 Solidago macrophylla 2.0 25.0 2.5 7.5 15.0 1.0 2.0 100 7.9 A r a l i a nudicaulis 7.5 2.5 7.5 2.5 7.5 2.5 7.5 100 5.4 Linnaea borealis 2.5 2.0 2.5 2.5 2.5 15.0 7.5 100 4.9 Sorbus decora 2.0 2.5 15.0 7.5 2.5 2.0 2.0 100 4.8 Oxalis montana 2.5 7.5 7.5 7.5 7.5 2.0 2.5 100 4.6 Clintonia borealis 2.5 2.5 7.5 2.5 2.5 2.0 7.5' 100 3.9 Maianthemum canadense 1.0 2.5 7.5 2.5 2.0 2.0 7.5 100 3.6 T r i e n t a l i s borealis 2.5 2.5 2.5 2.5 2.5 2.0 2.5 100 2.4 Gaultheria hispidula 2.0 2.5 2.5 2.5 2.0 2.5 2.0 100 2.3 Picea glauca 2.5 2.5 2.5 2.5 2.5 1.0 1.0 100 2.1 Amelanchier bartramiana 2.0 2.5 2.5 2.5 2.5 1.0 1.0 100 2.0 Aster acuminatus 7.5 - 7.5 2.5 25.0 7.5 2.5 86 8.7 Carex trisperma 15.0 2.5 2.5 2.5 2.0 2.5 - 86 4.5 Vaccinium angustifolium 1.0 2.0 2.0 2.0 - 2.0 2.0 86 1.8 Nemopanthus mucronata - - 15.0 2.5 1.0 2.0 2.0 71 4.5 Viburnum cassinoides - 2.0 7.5 2.0 - 1.0 2.0 71 2.9 Streptopus roseus 1.0 2.0 2.0 2.0 2.5 - 71 1.9 Taxus canadensis 2.0 0.5 - 1.0 1.0 - 1.0 71 1.1 Alnus rugosa - 2.5 1.0 2.5 1.0 - - 57 1.7 Calamagrostis canadensis - 1.0 2.5 2.0 1.0 - - 57 1.6 Rubus Chamaemorus - 2.0 2.5 - 2.0 - - 43 2.2 Epiqaea repens 1.0 2.0 - 2.0 - - - 43 1.7 Dryopteris novaboracensis - - - - - 15.0 15.0 29 15.0 Picea mariana - 2.5 - 2.5 - - - 29 2.5 P y r o l l a e l l i p t i c a - - - - - 2.0 2.5 29 2.3 Habenaria obtusata 2.0 2.0 - - - - 29 2.0 I r i s v e r s i c o l o r - 2.0 2.0 - - - - 29 2.0 Rubus idaeus - - - - - 2.0 0.5 29 1.3 Betula papyrifera 1.0 1.0 - - - - - 29 1.1 layer Sphagnum capillaceum 25.0 25.0 40.0 40.0 25.0 15.0 25.0 100 27.9 Pleurozium schreberi 2.5 7.5 15.0 15.0 2.5 2.5 7.5 100 7.5 Hylocomium umbratum 2.5 7.5 2.5 15.0 7.5 1.0 2.5 100 4.9 Dicranum majus 2.0 2.5 2.5 2.5 2.5 2.0 2.5 100 2.4 Ptili u m crista-castrensls 2.0 2.5 2.0 2.0 '1.0 1.0 2.0 100 1.8 Sphagnum mage H a n i cum 2.5 2.0 2.0 2.0 2.0 - - 71 2.1 Hylocomium splendens 2.0 - - 2.0 - 2.0 2.0 57 2.0 Polytrichum commune - - - - - 2.0 2.0 29 2.0 Sphagnum palustre - - - - - 2.0 2.0 29 2.0 layer Bazzanla t r i l o b t a 2.0 2.5 2.0 2.0 1.0 2.0 2.0 100 1.9 P t i l i d i u m c i l i a r e 2.0 2.0 2.0 2.0 1.0 2.0 2.0 100 1.9 Dicranum fuseescens 2.0 2.0 1.0 2.0 2.0 2.0 1.0 100 1.7 Alectoria americana 1.0 2.0 2.0 1.0 2.0 1.0 1.0 100 1.4 Cladonia spp. 2.0 1.0 1.0 1.0 2.0 1.0 2.0 100 1.4 Rhytidiadelphus loreus 2.0 - 2.0 2.0 2.0 2.0 2.0 86 2.0 Plagiothecium laetum - 2.0 2.0 2.0 2.0 2.0 1.0 86 1.7 Hypnum pallescens - 2.0 2.0 - 2.0 1.0 1.0 71 1.6 Tetraphis geniculate - 2.0 2.0 1.0 2.0 - 1.0 71 1.6 A l e c t o r i a orchroleuca 2.0 - 2.0 - - 1.0 1.0 57 1.5 Hypnum imponens - - - - - 1.0 1.0 - -radic Species (occurrence l i m i t e d to 1 plot) T o t a l number of Species including Sporadics: 68 40 Acer rubrum (2.0%) Aster radula (2.0%) Dryopteris Phegopteris (1.0Z) Equisetum sylvaticum (3.0Z) Kalmia angustifolia (2.0%) Lycopodium clavatum (0.5%) Mitchella repens (7.5%) Monotropa uniflorus (1%) Osmunda Claytoniana (25%) aSpecies Coverage values represent midpoints of the Domin-Krajlna Scale of Cover-Abundance (Becking, 1957) (Table 6 ) 'Average Coverages were computed using only plots where species occurred. Table IV. Association Table for Success ional Stages of the Upland Fir Associati on. Number of Plots Plot No. Plot size m Landform Relief Layer Coverage (%) A^ layer A2 layer layer B2 layer C layer Dh layer Ddw layer Ground Coverage (%) Humus Mineral S o i l Exposed Rock Decayed Wood F l o r i s t i c Composition and Species Coverage (%) a A^ layer Abies balsamea A 2 layer Abies balsamea B^ layer Abies balsamea Betula papyrifera B 2 layer ( Betula papyrifera Abies balsamea Rubus idaeus Sorbus decora Prunus pennsylvanica Ribes glandulosum C layer Cornus canadensis Dryopteris spinulosa Abies balsamea Oxalis montana Rubus idaeus Ribes glandulosum Aster acuminatus Carex trisperma Trientalis borealis 1 . 2 3 12 13 14 100 .... ridge-top ....Hummocky Average Coverage (%) 25 0 7.5 16.2 0 15 0 15.0 10 25 27 20.7 50 55 80 61.6 85 80 70 78.3 45 10 30 28.3 8 10 10 7.3 83 92 80 85.0 2 3 10 5.0 15 10 10 11.7 25.0 7.5" Constancy (%) 66 16.2 15.0 — 33 15.0 10.0 25.0 2.5 100 12.5 — — 25.0 33 25.0 15.0 25.0 40.0 100 26.7 15.0 25.0 25.0 100 21.7 15.0 7.5 15.0 100 12.5 1.0 15.0 66 8.0 2.0 — 7.5 66 4.8 2.5 2.5 — 66 2.5 15.0 2.5 15.0 100 10.8 15.0 2.5 15.0 100 10.8 15.0 2.0 15.0 100 . 10.7 7.5 2.5 15.0 100 8.3 15.0 7.5 2.5 100 8.3 7.5 7.5 • 7.5 • 100 7.5 2.5 7.5 7.5 100 5.8 7.5 2.0 7.5 100 5.7 2.0 1.0 7.5 100 3.5 Coptis t r i f o l i a 2.5 2.5 2.0 100 2.3 Maianthemum canadense 2.5 2.0 2.0 100 2.2 Monotropa uniflora 1.0 2.0 1.0 100 1.3 Calamagrostis canadensis 2.0 40.0 — 66 21.0 Linnaea borealis 7.5 2.5 — 66 5.0 Aralia nudicaulis 7.5 — 2.0 66 4.8 Solidago macrophylla 2.0 7.5 — 66 4.8 Clintonia borealis 2.1 , — 2.0 66 2.0 Viola pallens 2.0 2.0 — 66 2.0 Sorbus decora 1.0 2.5 — 66 1.8 Amelanchier bartramiana 2.0 — 0.5 66 1.3 layer Hylocomium umbratum 15.0 2.5 15.0 100 10.8 Pleurozium schreberi 15.0 2.5 2.5 100 6.7 Sphagnum capillaceum 7.5 1.0 7.5 100 5.3 Polytrichum commune 2.0 2.0 2.5 100 2.2 Dicranum majus 2.0 2.0 2.0 100 2.0 Polytrichum juniperinum 2.0 — 2.0 66 2.0 •Ptilium crista-castrensis 2.0 2.0 — 66 2.0 w layer Dicranum fuseescens 2.0 2.0 2.5 100 2.2 Alectoria americana 2.0 2.0 2.0 100 2.0 Alectoria orchroleuca 2.0 2.0 2.0 100 2.0 Brachythecium curtum — 2.0 2.0 66 2.0 Plagiothecium laetum — 2.0 2.0 66 2.0 Ptilidium c i l i a r e 2.0 — 2.0 66 2.0 oradic species (occurrence limited to 1 pi ot) layer Viburnum cassinoides (2.0%] Total number of species including sporadics: 47 Total number of species with constancy of 66% or more: 36 C layer Acer rubrum (0.5%) Athyrium Filix-femina (2.0%) Betula papyrifera (1.0%) Dryopteris Phegopteris (2.0%) Gaultheria hispidula (7.5%) Picea glauca (0.5%) Prunus pennsylvanica (0.5%) Pyrolla e l l i p t i c a (2.0%) Sphagnum subsecundum (1.0%) D Layer Rhytidiadelphus loreus (0.5%) Ddw layer Dicranum montanum (2.0%) Tetraphis geniculata (2.0%) Coverage values represent midpoints of the Domin-Krajina scale of Cover Abundance (Becking, 1957) (Table 6 ).. Average coverages were computed using only plots in which species occured. APPENDIX I I TERMINOLOGY USED IN SOIL DESCRIPTIONS 157 Table I. Terminology Used For Root Descriptions. ( Canada Department of Agriculture, 1970 ) Abundance Classes very few few plen t i f u l abundant Number Per Unit Area of Surface less than 1 1 to 3 4 to 14 more than 14 Diameter Classes very fine fine medium coarse : 0.075 to 1 mm. : 1 to 2 mm. : 2 to 5 mm. : more than 5 mm. 158 Tablell. Terminology Used for Rock Fragments in Soils. ( Canada Dept. Agriculture, 1970 ) Size up to 3 inches in diameter. 3 to 10 inches in diameter. 10+ inches in diameter. Abundance Classes Name gravel cobbles boulders Class 1 2 3 4 5 Area Coverage (% 0-5 5-25 25-50 50-75 75-100 APPENDIX I I I CLIMATE DATA FOR THE CAPE BRETON PLATEAU 160 Table I. Maximum and Minimum Temperatures ! Recorded on the Cape Breton Plateau Daily Temperatures 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 12 13 21 22 23 23 21 25 17 16 21 23 21 18 14 14 21 18 -1 -1 6 12 13 14 18 17 9 7 7 10 12 6 8. 8 4 9 23 22 23 25 23 21 26 26 17 16 21 24 22 19 14 13 19 17 6 17 13 ; 13 17 16 15 11 9 7 9 11 6 8 9 6 8 12 15 23 24 26 24 21 26 18 15 21 26 24 20 1* . 20 1 -1 4 12 i 13 1 15 17 16 11 10 6 9 11 4 8 10 3 21 21 19 18, 26 24 . 26 18 11 17 19 21 20 1 23 26 21 23 24 18 16 24 27 29 26 28 27 26 27 9 14 13 10 . 8 15 15 17 9 6 6 11 14 17 17 11 7 14 14 9 9 10 16 18 19 • 20 11 12 22 22 19 20 27 25 27 18 11 18 18 22 22 23 26 22 22 23 18 16 25 27 31 26 28 28 27 27 9 13 13 io 8 15 16 16 9 6 5 10 15 16 17 16 10 14 13 10 9 10 17 17 18 19 14 14 21 21 .20 27 26 27 21 17 17 19 22 21 24 26 22 23 23 19 16 24 26 29 26 28 . 13 10 7 14 16 17 9 6 5 14 17 17 15 8 13 16 13 8 15 17 18 20 20 2i 23 22 23 24 20 20 18 27 27 28 28 20 14 21 18 17 17 19 18 19 16 12 11 16 12 7 18 17 16 9 15 13 16 14 18 18 • 19 15 5 2 11 10 9 12 12 12 11 4 4 17 21 21 27 24 19 18 17 26 28 29 27 21 16 20 18 17 16 18 17 18 16 12 10 10 14 14 16 14 16 15 18 18 18 15 12 6 14 9 9 12 12 12 9 23 23 19 20 18 24 27 28 27 21 15 19 18 16 17 19 17 18 16 12 12 12 16 10 16 13 16 17 16 17 : 1 8 15 11 2 9 14 8 12 12 11 14 10 . 9 6 1 21 13 14 8 17 19 13 10 8 4 ,3 11 June 1970 Station Max. 01 Min. Station Max. 02 Min. Station Max. 03 Min. July 1970 Station Max. 11 01 Min. 9 Station Max. 11 02 Min. 10 Station Max. . 03 Min. August 1970 Station Max. 28 01 Min. 16 Station Max. 29 02 Min. 15 Station Max. 03 Min. June 1971 Station Max. 11 Min. i Table I (Continued) 161 8 10 11 12 13 14 15 161 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 July 1971 Station Max. 19 18 9 16 21 23 24 16 22 11 Min. 16 9 7 6 2 15 18 12 11 25 21 18 18 20 19 23? 24 27 24 21 18 21 24 26 21 24 24 21 25 24 24 17 11 9 11 12 13 141 15 13 15 14 13 12 14 17 8 6 16 11 6 18 19 August 1971 Station Max. 22 26 22 21 17 17 22 24 23 28 28 26 22 22 15 18 11 18 12 19 20 11 12 8 13 16 17 21 16 14 14 13 16 14 Table II 1970 Precipitation Totals for the Cape Breton Plateau Location Precipitation (cm) June 13 June 19 June 27 July 6 July 13 Aug 6 Aug 13 Aug 19 to to to to to to to to June 19 June 27 July 6 July 13 Aug 6 Aug 13 Aug 19 Aug 30 Station 0.7 0.4 4.3 2.9 4.0 15.0 3.6 12. 9 01 Station 0.4 4.2 0.8 .8.8 3.1 13. 2 02 Table III 1971 Precipitation Totals for the Cape Breton Plateau Precipitation (cm) Location June 25 July 4 July 11 July 17 July 24 Aug 3 Aug 8 to to to to to to to July 4 July 11 July 17 July 24 Aug 3 Aug 8 Aug 17 Station 9.1 1.0 0.2 3.0 0.5 4.1 13.3 11 Station 3.0 2.3 0.2 2.0 0.8 3.0 16.7 12 Station 7.4 0.8 0.2 3.3 1.5 4.6 10.9 13 Table IV 1970 Wind Measurements for Plateau Station 01 June 14 June 20 June 27 July 6 July 11 July 25 July 28 Aug 6 Aug 13 Aug 19 to to to to to to to to to to . June 20 June 27 July 6 July 11 July 25 July 28 Aug 6 Aug 13 Aug 19 Aug 30 Total Wind 2469.7 1931.2 2488.1 1443.8 4597.7 419.7 2338.5 1594.4 1632.5 3361.1 (Km) Mean Wind 445.6 270.0 284.0 . 310.6 328.4 261.2 259.8 283.9 285.2 330.6 Km/day Km/hr 18.9 11.2 12.0 13.0 13.7 10.8 10.8 11.9 11.9 13.3 Table V 1971 Wind Measurements for Plateau Station 11 June 25 July 4 July 11 July 17 July 23 Aug 3 Aug 8 Aug 14 to to to to to to to to July 4 July 11 July 17 July 23 Aug 3 Aug 8 Aug 14 Aug 17 Total Wind 2126.2 1730.6 1375.7 1281.2 2351.7 1156.1 1528.7 998.8 (Km ) Mean Wind Km/day 233.6 249.7 233.9 214.9 210.6 228.9 263.6 319.6 Km/hr 9.7 10.5 9.7 9.0 8.7 9.5 10.9 13.4 

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