Science, Faculty of
Botany, Department of
DSpace
UBCV
Kesting, Stephan Fritz
Master of Science - MSc
University of British Columbia
The Lower Anderson River Valley was chosen as a study area to investigate the effects of slope, aspect, and insolation on plant community composition and distribution through the treeline ecotone. Seventy-one plant communities were surveyed; abiotic measurements included soil temperature and depth to frozen soil. Soil samples were taken and later analyzed for pH, conductivity, and particle size distribution. TWINSPAN, a divisive clustering algorithm, defined 4 basic community-types for study area: Tundra, Forest, Steppe, and Sparse. Except for Sparse these community-types have quite discrete distributions along a potential insolation gradient. Sparse communitytypes are associated with acidic, high conductivity soils near smoking bituminous shale deposits. Equivalent latitude, a variable expressing potential insolation relative to flat surfaces at given latitudes, explained about 7 times more of the variance in Detrended Correspondence Analysis axis 1 scores than latitude alone. N Canonical Correlation Analysis was employed to further investigate the relationship of plant community composition to the measured environmental variables. The most important trend underlying plant community composition was found to be a potential insolation-soil temperature gradient. Anderson River Steppe is the eastern-most example described to date of so-called 'arctic steppe', which is thought to have been much more extensive in Beringia during the Wisconsin glacial maximum. Steppe communities occurred primarily on southfacing slopes and occupied at least 560 hectares/kilometer along the Lower Anderson River. Three major northward range extensions were associated with species found in south-facing Steppe.
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POTENTIAL INSOLATION AND PLANT COMMUNITIES THROUGH TREELINE IN THE LOWER ANDERSON RIVER VALLEY, N.W.T., CANADA. S T E P H A N FRITZ RESTING B . S c , M c G i l l University, 1993 A THESIS S U B M I T T E D IN P A R T I A L F U L F I L L M E N T OF T H E REQUIREMENTS FOR T H E D E G R E E OF M A S T E R OF SCIENCE i n T H E F A C U L T Y OF G R A D U A T E STUDIES DEPARTMENT OF B O T A N Y We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA January 1996 © Stephan Fritz Resting, 1996 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department The University of British Columbia Vancouver, Canada DE-6 (2/88) A B S T R A C T The Lower Anderson River Va l l ey was chosen as a study area to investigate the effects of slope, aspect, and insolation on plant community composit ion and distribution through the treeline ecotone. Seventy-one plant communities were surveyed; abiotic measurements included soi l temperature and depth to frozen soi l . So i l samples were taken and later analyzed for p H , conductivity, and particle size distribution. T W I N S P A N , a divis ive clustering algorithm, defined 4 basic community-types for study area: Tundra, Forest, Steppe, and Sparse. Except for Sparse these community-types have quite discrete distributions along a potential insolation gradient. Sparse community-types are associated with acidic, high conductivity soils near smoking bituminous shale deposits. Equivalent latitude, a variable expressing potential insolation relative to flat surfaces at given latitudes, explained about 7 times more of the variance in Detrended Correspondence Analys is axis 1 scores than latitude alone. N Canonical Correlat ion Analys i s was employed to further investigate the relationship of plant community composit ion to the measured environmental variables. The most important trend underlying plant community composit ion was found to be a potential insolat ion-soil temperature gradient. Anderson River Steppe is the eastern-most example described to date of so-called 'arctic steppe', which is thought to have been much more extensive in Ber ingia during the Wiscons in glacial maximum. Steppe communities occurred primari ly on south-facing slopes and occupied at least 560 hectares/kilometer along the Lower Anderson River . Three major northward range extensions were associated with species found in south-facing Steppe. i i i T A B L E O F C O N T E N T S Abstract i i Table of Contents i i i List of Tables i v List of Figures v Acknowledgements vii Dedication vii i INTRODUCTION 1 METHODS Study Area 5 Community Description 8 Statistical Analyses 10 Grassland Area 12 RESULTS Plant Community-types 13 Correspondence to Potential Insolation 23 , Vegetation-Environment Relationship 30 Species Range Extensions 30 Steppe Area 35 DISCUSSION 37 LITERATURE CITED 44 A P P E N D I X 1: Comparison of two percent cover estimation methods for 36 species occurences in five quadrats 50 A P P E N D I X 2: Vascular plant species cover for 71 plant communities on the Lower Anderson River valley, NWT 52 A P P E N D I X 3:' Abiotic data gathered from 71 plant communities in the Lower Anderson River valley, NWT 64 IV LIST OF TABLES T a b l e Page 1 Mean values of abiotic variables for the four T W I N S P A N -defined plant community-types i n the Lower Anderson River valley..... 15 2 Tukey H S D test showing probabilities of significant differences in environmental variable means between the four T W I N S P A N - d e f i n e d community-types i n the Lower Anderson River valley, N W T . . . , 16 3 Environmental variable correlation matrix 31 4 Inter-set correlations of environmental variables with Canonical Correspondence Analysis 32 5 Northward range extensions for three species found in the Lower Anderson River valley 34 6 Vascular plant species occuring in Steppe communities on the Lower Anderson River that have been reported from other arctic steppe communities 40 • • s~ • LIST OF FIGURES F i g u r e Page 1 M a p of the s tudy area showing camp locations on the Lower Anderson River, N W T 6 2 Dendrogram of plant community-types produced by T W I N S P A N using al l 71 plant communities surveyed in the Lower Anderson River valley 14 3 Typ ica l Tundra community along the Lower Anderson River 17 4 Typ ica l Forest community along the Lower Anderson River 19 5 Typ ica l Stable Steppe community along the Lower Anderson River 21 6 T y p i c a l Disturbance Steppe community along the Lower Anderson River 22 7 Typ ica l Sparse community along the lower Anderson River . . . 24 r 8 Distributions of the four T W I N S P A N - d e f i n e d plant community-types in the Lower Anderson Rive r valley along an equivalent latitude gradient 25 LIST OF FIGURES (continued) 9 Detrended Correspondence Analysis of a l l 71 plant communities surveyed along the Lower Anderson River 27 10 D C A axis 1 scores plotted against equivalent latitude of surveyed communities along the Lower Anderson River .... 28 11 D C A axis 1 scores plotted against actual latitude of surveyed plant communities along the Lower Anderson River 29 12 C C A biplot of 71 plant communities along the Lower Anderson River including abiotic variable vectors 33 A C K N O W L E D G M E N T S I would first l ike to thank my supervisors Gary Bradfield (Botany) and Greg Henry (Geography) for their support throughout the planning, execution, analysis, and writ ing phases of this thesis. Commit tee member Roy Turkington provided many useful critiques and insights during the planning and analysis stages of my work. I cannot thank Ksenia O. Barton enough for her invaluable and exemplary assistance with the f ield work. Logis t ic support was provided by the Continental Polar Shelf Project, Tuktoyaktuk, and its incredibly helpful staff. J . Ross Mackay provided useful information about the Lower Anderson Region. Thanks to B i l l Cody and Peter B a l l for their help with plant identification. M i k e Church was very helpful with the analyses of soil samples. This work was supported by an N S E R C special collaborations grant (Henry) and the Northern Scientif ic Training Project. DEDICATION This thesis is dedicated to my partner Ksenia O. Barton without whom the quantity and quality of this work would have been considerably lessened. Our summer of f ieldwork together remains one of the highlights of my life. INTRODUCTION Isolated grassland communities in Siberia, Alaska, and the Yukon have been studied both as relicts of the Beringia steppe and from the perspective of what they can tell us about plant community distributions in the arctic today today (Hibbert 1982; Lloyd et al. 1994; Murray et al. 1983; Walker et al. 1991). The area known as "Beringia" connected and included "the entire region between the Kolyma River in eastern Siberia and the Mackenzie River in the Canadian Northwest Territories, including intervening continental shelf areas shallower than approximately 200 m" (Mathews 1982). The drop in sea level was associated with periods of extensive glaciation during the Wisconsin cold cycle (120,000 to 8000 BP: Hopkins 1982). Beringia was not glaciated and probably had a dry continental climate (Barry 1981). The Anderson River area, east of the MacKenzie Delta, was close to the ice-sheet margins during most of the Wisconsin glacial period (Dyke and Prest 1987). Beringia almost certainly lacked extensive forests although tree species may have persisted as shrubs or in isolated groves (Mathews 1982). Dated pollen spectra from sediment cores typically show that grasses and Artemisia spp. contributed very strongly to the pollen present until about 10,000 B.P. (e.g. Ager 1982; Anderson 1985; and Rampton 1971). This pollen spectra may indictate either a cold, dry steppe vegetation (Mathews 1982) or an open herb-tundra now restricted to higher altitude alpine areas (Ritchie 1977; Ritchie and Cwynar 1982). In Siberia, Alaska,: and the Yukon xeric steppe-like grasslands have been identified as possible relict Beringia steppe communities, and most often occur oh steep south facing bluffs or slopes (Douglas 1974; Edwards and Armbruster 1989; Howenstein el al. 1985; Juday et al, 1985; Kassler 1985; Lloyd et al. 1994; Walker et al, 1991; Yurtsev 1982). This community-type has, been called steppe, steppe-tundra and/or arctic-steppe by various researchers, and is typically dominated by grass and sedge taxa (e.g. species of Festuca, Cdlamagrostis, Poa, Agropyroh and Carex), Artemisia species,, and other taxa such as Selaginella,Potentilla and Oxytropis (Howenstein et al. 1985; Juday. et al, 1985; Kassler 1985; Murray et al. 1983; Walker et al. 1991; Yurtsev 1982). Many of these, species are not common in the nearby tundra communities, but are more, representative of prairie; grassland communities far to the south. > Slope and aspect (orientation) are fundamental in calculating net radiative input to a surface because they determine the, solar 'angle of incidence' (the angle between the sun and a line perpendicular to the slope) at any given time (Oke 1992). South facing slopes in the northern hemisphere are often drier than the surrounding landscape, receiving the greater radiative input (Oke 1992) and experience large fluctuations in daily temperature (Howenstein et al. 1985; Murray et al. 1983). Much research, largely qualitative, has described the biotic and abiotic characteristics of-various sites,, ascribing differences between sites to differences in slope orientation (Cooper 1986; Drew and Shanks 1965; Gensac 1990; Price 1971; Walker et al. 1991). An alternative, quantitative approach involves the calculation of an insolation index that.may be used to analyze the distr ibut ion and compos i t ion o f plant communi t i es . E x a m p l e s of synthetic variables used to quanti fy the effect o f slope and aspect on co ld cl imate plant communi t ies inc lude heat /ar idi ty index (Armbruster and M c G u i r e 1985), s lope x aspect interact ion (Edwards and Armbruster 1989; and L l o y d et al. 1994), heat index (He ikk inen 1991), and potential insolat ion ( D i n g m a n and K o u t z 1974). Recent general c i rculat ion models suggest that in the next 50-100 years the A r c t i c , especia l ly the western A r c t i c , w i l l exper ience a w a r m i n g trend, that arctic soi l moisture w i l l decrease, and that winter precipi tat ion w i l l increase (Etk in 1990; M a x w e l l 1992). T h e plant communi t i es present on the warmer and drier south - fac ing slopes may be analogs of post -g lobal warming plant communi t ies . It is poss ib le that the range and extent of currently l imi ted arct ic-steppe vegetat ion may expand into low arctic tundra and the . borea l forest g iven a warmer and drier cl imate. These unusual species assemblages on south- fac ing bluffs c o u l d also serve as ini t ia l centers of co lon iza t ion of new species into the tundra itself, fo l low ing c l imat ic change. A n understanding of arct ic-steppe communi t ies c o u l d therefore be very usefu l in attempting to predict b i o m e - w i d e eco log ica l changes in the A r c t i c . v W o r k on possib le rel ict steppe communi t ies has been conducted pr imar i ly in S iber ia and A l a s k a , and to a lesser extent i n . the Y u k o n . Pre l iminary work indicated that south- fac ing grasslands existed on the A n d e r s o n R i v e r , al though their extent, c o m p o s i t i o n , and distr ibut ion was u n k n o w n . T h e first objective of the present research was the descr ipt ion and character izat ion of the eastern-most example of arctic-steppe communities reported to date. The second objective was the quantitative invest igat ion. of the interactions between slope, aspect, latitude, and plant community composit ion through the western ^ arctic treeline. Here I examined the hypothesis that slope and aspect systematically underly plant community composit ion and distribution. Predictions stemming from this hypothesis include: a) that a strong correlation w i l l exist between slope orientation and some measure of community species composit ion; and b) that species or communities representative of more southerly latitudes w i l l tend to occur on south-facing exposures, and that 'northern' species w i l l tend to occur on north-facing exposures. The Lower Anderson River is an ideal area to investigate the above issues. A wide diversity of northern plant community types (low arctic tundra, boreal forest, steppe, and disturbance communities) form a mosaic along this section, yet most community boundaries are fairly distinct s impl i fy ing sampling protocols. The winding river valley also provides a wide range of slopes and aspects in which to work. This section of river flows northward through, and perpendicular to, the boreal treeline (Timoney et al . 1993), diversifying the variety of plant communities along the river. Anthropogenic influence on the Anderson is minimal , and the region is accessible only by air (from Inuvik or Tuktoyaktuk) , boat, or snowmobile. METHODS STUDY AREA The.study area was the Lower. Anderson River valley, N.W.T. (from 68° 26'N to 69° 30'N and between 128°10'W to 128° 51' W), the first large river to the east of the Mackenzie River. The -Anderson is at least 670 km long and has a drainage basin of about 56,300 sq km (Mackay 1958). The Lower Anderson refers to the 240 km section from the . confluence of the Anderson and the Carnwath River (known as "The Forks") to its mouth at Wood Bay on the Beaufort Sea (Figure 1). The final 50 km section of the the river was not used in this study as the extensive flat floodplain made it difficult to find appropriate study sites. The settlement of Fort Anderson, about 50 km north of the Forks, was abandoned in 1866 (Stager 1967); Stanton, a small village at the mouth of the river, is abandoned and currently only one Inuvialuit family hunts. and traps on this section of the river. A meteorological station on Nicholson Peninsula (now "Nicholson Island"), 20 km north of the mouth of the Anderson, t reports a mean January temperature (30 year normal from 1961 to 1991) of -29.1°C and mean July temperature of +8.3°C. Precipitation is 111.9 mm anually, and mean annual windspeed is 21.-5. km/hr (Anonymous 1993). Mackay (1958) reports that, in the Lower Anderson valley itself, mean annual precipitation is about 30 cm, peaking in the summer, and about half falling as snow. The Lower Anderson cuts through the Anderson Plain, a gently rolling upland. The river valley is between 70 and 200+ m deep, and 6 FIGURE 1. Map of study area showing camp locations (letters A-F) and the number of study sites on the Lower Anderson River, NWT. Dashed lines indicate contours of percent cover of trees (according to Timoney et al. 1993), and are a measure of distance through treeline. Inset shows location of study area in north-western North America. is rich in gray shales and associated sediments (Mackay 1958). Towards the northern end of the Lower Anderson, the river and some of its tributaries occasionally expose bituminous Cretaceous shale deposits similiar to those of the nearby Smoking Hills Upland on the Lower Horton River described by Mathews et al. (1989). Heat, sulphurous smoke, and brilliant soil coloration are locally present. The vegetation of the Lower Anderson undergoes a transition from subarctic boreal forest to arctic low-shrub tundra. The 1 0 ° C mean July isotherm, traditionally used to delineate the tundra-forest boundary (Bliss, et al. 1973), crosses the Anderson approximately at Windy Bend ( 6 9 ° , 10' N). The transition from boreal forest to arctic tundra along the Anderson River is actually relatively gradual, with tree cover falling off from more than 80% at the southern end of the research area to less than 5% at the northern end (Fig. 1; Timoney et dl. 1993). -Research began in late June, 1994, at the junction of the Anderson and Carnwath Rivers (known as "The Forks" (Mackay 1958)). A t 7 to 10 day intervals a new base camp was established approximately 25 km downriver (Figure 1); grassland (steppe-like) areas observed during camp moves were marked on 1:50,000 topographic maps to determine the area covered by this anomalous community-type (see below). The south-to-north direction of travel was used so as to maximize the time spent working during the flowering season and aid in the identification of plant species. At each base camp a preliminary reconnaisance was conducted to assess the main plant communities in the vicinity. In this study a community is defined as "a visually homogeneous area in terms of its dominant vascular vegetation and habitat characteristics": in practice this translated into an area of vegetation with reasonably distinct borders, visually distinguishable at a distance (i.e. from river level). C O M M U N I T Y DESCRIPTION Eight to 16 plant communities were surveyed in the vicinity of each camp (iFigure 1) attempting to maximize community diversity and the range of ^aspects at which they were found. At the scale of interest (100+ m 2 ) community boundaries were typically easily distinguishable by a change in dominant species and plant life-forms. A random walk algorithm using random number tables was used to locate 1 m 2 quadrats within each community, starting in the centre the community being sampled. The number of quadrats per community varied with species diversity but typically was between 15 and 18. Percent cover for each species was visually estimated within each quadrat. Vascular plant nomenclature followed Pbrsild and Cody (1980), except for the genus Steliaria where Chinnappa and Morton (1991) was used. Species not occurring in any quadrats but still present in the community were collected and identified, but not included in any subsequent analyses. Mean cover values for , each species were calculated by averaging cover for all the quadrats within that community. Visually estimated percent cover was checked and calibrated with a quadrat strung to allow point-hit cover estimation. The coefficient of determination (r 2 ) between visually estimated percent cover and cover estimated using point hits for 36 species-incidents was 0.88 (Appendix 1). Slope and aspect were determined with compass and clinometer at each community. The position of each community on the slope was subjectively assigned a value between 1 to 3, 1 being low on the valley side and close to the river or floodplain, and, 3 being close to the r im of the valley. If a community spanned more than one position, or occupied intermediate positions, then values of 1.5 and 2.5 were also used to describe position. A t three locations within each community an area of representative slope and vegetation was chosen for investigation of soils. A Y S I soil temperature probe was used to determine temperature at a depth of 30 cm and the depth to 0° C . The temperature at 10 cm was also measured but later discarded as this measurement was probably subject to greater short-term variat ion than the deeper soil temperatures. A t each of the three sites a soi l pit was dug in order to measure the thickness of. the organic layer ( including surface litter) and maximum rooting depth. S o i l samples were taken from the non-organic layer, usually a clay and silt r ich inorganic sediment. It was felt that the mineral soi l layer would provide insight into the edaphic effects on community distribution. Quantitative measurement Of soi l moisture was precluded by the amount of equiptment that could be transported for such a lengthy time in the field. Subjective assessments of soi l moisture were made for each community based on the depth at which moisture was first noticeable to the touch. S o i l samples were air-dried and combined to form one sample per community. In later laboratory analyses a portion of every combined soi l sample was rehydrated with dist i l led water to create a slurry and soi l conductivity (measured in x>mhos/cm) and p H were measured. S o i l sub-samples for texture analysis were also ground with mortar and pestle and wet sieved through 2, 0.5, and 0.063 mm screens. The resulting fractions were dried and weighed to determine the proportions of gravel (>2 mm), coarse sand (<2 mm and > 0.5 mm), fine sand (<0.5 mm and >0.063 mm), and clay/silt (<0.063 mm). STATISTICAL ANALYSES The use of both soil temperature at 30 cm, and depth to 0° C is complicated by the. fact that both variables were measured over a span of 2 months. To circumvent the confounding effect of time, the two soil temperature variables were ranked, relative to the other communities studied at that camp and then converted to a scale of 1 to 3 (1 = colder soil or shallower depth to 0°; 3 = warmer soil or deep 0° isotherm). Soil temperature (at a depth of 30 cm) is thus compared over approximately a 1 week period, during which only small changes might be expected. To summarize the interaction of slope, aspect, and latitude, equivalent latitude was calculated for each community. Equivalent latitude (Eq 0 ) is an expression of potential insolation and is calculated as: Eq 8 = arcsin (sin S cos A cos 0 + cos S sind ) (1) where S is the slope in degrees, A is aspect in degrees clockwise from north, and 9 is the actual latitude of the community in degrees (Lee 1964). To illustrate the calculation of equivalent latitude, consider 2 different surfaces, one oriented south-west and the other facing north (aspects of 225° and 0°, respectively). To make these surfaces typical of Anderson River communities, assume that they both have latitudes of 69° N and slopes of 25°. Substituting into Equation 1, the potential insolation regime of these slopes, both at latitudes of 6 9 ° N , corresponds to that of horizontal planes at latitudes of 4 7 . 6 ° and 86° , respectively. T W I N S P A N (Hill 1979) is a divisive clustering algorithm based on Correspondence Analysis (CA) and was used to objectively define the main community-types present in the Lower Anderson River valley. This program also identifies indicator species of these communities and produces site by species tables. T W I N S P A N was run using all 71 plant communities and the default pseudospecies cut levels (used to weight the importance of a species relative to its abundance in a community; here set at 0, 2, 5, 10, 20%). The data were dichotomized two consecutive times dividing the 71 plant communities into four groups, or community-types. One of these groups (Steppe) was bifurcated an additional time to further investigate the structure of this, unique community-type. Differences among abiotic variables, of community types were determined using A N O V A and Tukey H S D post-hoc tests. The C A N O C O statistical package (ter Braak 1987) was used for further multivariate analyses. Unimodal, as opposed to linear, ordination techniques were used after a preliminary , Detrended Canonical Analysis ( D C A ) indicated that the first 2 axes were 7.1 and 6.2 standard deviation units long (Jongman et al. 1987). Canonical Correspondence Analysis ( C C A ) was used to examine the vegetation-environment relationship using the species data and 13 variables for each community. G R A S S L A N D A R E A Steppe and Sparse (see below) vegetation coverage in the Lower Anderson Rive r V a l l e y was estimated by marking al l observed areas on a 1:50,000 topographic map throughout the field season and subsequently cutting and weighing the pieces of mapsheet. This estimate of Steppe and Sparse area i s ' probably conservative because r iver- level observation l ike ly did not allow notation of every patch of these community-types i n the val ley. R E S U L T S P L A N T C O M M U N I T Y - T Y P E S T W I N S P A N divided the 71 plant communities into 4 major community-types (Figure 2), here called Tundra, Forest, Steppe, and Sparse (capitalized to differentiate these community-types from the common usages and definitions). Steppe was bifurcated an additional time because the, 2 Steppe subdivisions have particuliar ecological relevance (see below). Mos t abiotic variable means differed widely between the 4 main community-types (Tables 1 and 2). However, no significant differences between community-types were found for the variables associated with soil texture (i.e. % gravel, % coarse sand, % fine sand, and % clay/silt) , or for position on slope. Biot ic data are presented in Appendix 2, abiotic data in Appendix 3. ' " . . 1) Tundra: dominated by woody shrubs and lacking trees (F igure 3), Tundra typically has close to 100% ground cover. Dominant species include Betula glandulosa, Vaccinium vitis-idea, Ledum decumbens, and Empetrum nigrum. L o c a l l y , thickets are dominated by Salix glauca, Salix arbusculoides, and Alnus crispa. Moss , and to a lesser extent,. l ichen, are common components of the Tundra understory. Smaller herbs include Pyrola grandiflora, Pyrola secunda, Cardamine digitata, Carex vaginata, Arctagrostis latifolia, and Petasites frigidus. Tundra soils are characterized by a thick organic layer, low p H , and relatively low temperatures. 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CD C/J O ^ 2 h-« 1"^ o 3 co CL CD Go H n a GO ^ • P ^ 2 > CD T 3 O C/3 o" 3 O 13 O CD H o C/3 •H-•a C/3 C/3 < CD CL 3* CD < ' PS 1-1 ' P3 cr • on ?R CTQ I-I P3 < CD O o P2 i-l m P3 13 CL 13 CD 2 o CD 13 < - h-» I-I o 13 •z s 13 CD Fr o CD n CL CD 3 ^ 3 3 2 . 3 ^3 1 = 3 CD N| < X P3 II H CD c! ^ 3 CL • O 50 II o C/3 I-I •CTQ cn 3 r * • P3 H 3 h3 rt II 00 n-CD CD £ ' cr ^ i ± CD CD 00 P D 3 CD PT ^ i-h C/3 i - i O > l Z CTQ O NJ > cr P cr C/3 h-. CD rj-1—^ C/3 I s . CD H—^ Op' w 3 cT ? " p CD CD CL CD 3" 1 - 1 s § c ? ^ 1-1 M. 3 F I G U R E 3. Typ ica l Tundra community along the Lower Anderson River (site 61, camp F) . This community was dominated by Betula glandulosa and Calamagrostis inexpansa, these species having average covers of 21% and 12% respectively. Note brightly coloured sediment to the left side of the background: such colouration was associated with the combusted bituminous shales present i n the northern half of the Lower Anderson River . rare and mosses were usually abundant in this generally moist c o m m u n i t y - t y p e . 2) Forest: Recognizable by an abundance of Picea glauca, the understory of this community-type is dominated by Vaccinium vitis-idea, Empetrum nigrum, Arctostaphylos rubra, and Salix glauca (Figure 4). Very little bare soil is exposed in Forest, and plant litter, especially spruce needles, is abundant. Dryas integrifolia is loca l ly abundant, forming small matted areas. Other herbs and shrubs i n this diverse community-type include Ledum groenlandicum, Arctagrostis latifolia, Carex vaginata, Cassiope tetragona, Anemone multifida, Elymus innovatus, Conioselium cniidifolium, Epilobium, angustifolium and Hedysarum alpinum . Forest was similar to Tundra with regard to the measured phys ica l parameters: only equivalent latitude, deviation from north (aspect), and soil p H differed significantly (Table 2). Forest communities were found on al l slopes and aspects in the southern end of the study area, but tended to be found on south or west-facing slopes at higher latitudes. Forest did not differ significantly from Tundra in depth to 0° C and temperature at 30 cm; both community-types had a thick insulating organic layer near the 0 surface of their soi l profiles. 3) Steppe: This community-type had much more bare soil than either Tundra or Forest, with grasses and sages making a very strong contribution to the species composition. Many of the ubiquitous understory species along the Lower Anderson River , Vaccinium vitis-idea, Arctastaphylos rubra and Empetrum nigrum for example, were completely absent from this community-type. Common F I G U R E 4. Typ ica l Forest community along the Lower Anderson River (site 22, camp F) . This community was dominated by Vaccinium vitis-idea and Picea glauca, with average covers of 26% a n d l 4 % respectively. dominants in Steppe include Calamagrostis purpurascens, Elymus innovatus, Poa glauca, Linum lewisii, and Artemisia species. Steppe communties had the warmest soil and the deepest unfrozen layer of all community-types. Steppe was divided into two community sub-types, here called "Stable Steppe" (Figure 5), and "Disturbance Steppe" (Figure 6). Stable Steppe communities were diverse and often with a strong presence of woody plant species such as Juniperus communis, Shepherdia canadensis, Rosa ascicularis, and Picea glauca. Other common species include Anemone multifida, Poientilla nived, and Solidago multiradiata. Artemisia frigida is common in this community sub-type and often comprises a major component of the community understory, while Artemisia tilesii is relatively infrequent. Calamagrostis purpurascens commonly occured and was often abundant in this community-type. Although bare soil was abundant and signs of erosion present, there was nO evidence of recent major disturbances such as slumping. Disturbance Steppe was associated with slumping or other disturbances. Slump scars were often visible along the edges of these communities. Isolated spruce saplings were occasionally found growing in these communities and coring revealed that their maximum age was about 15 to 20 years. This suggests a fairly young age for this community sub-type and the possibility of succession from Disturbance Steppes to Forest over time. Almost every Disturbance Steppe community included Artemisia tilesii which was often quite abundant. Grasses included Bromus pumpellianus, 2 1 FIGURE 5 . Closeup of a typical Stable Steppe community along the Lower Anderson River (site 17, camp B ) . Dominant species included Artemisia frigida and Calamagrostis purpurascens, both at the forefront of the photo, with average covers of 7% and 4.3% r e s p e c t i v e l y . 22 F I G U R E 6. Typ ica l Disturbed Steppe community along the Lower Anderson Rive r (site 23, camp B) . This community was dominated by Artemisia Tilesii which had an average cover of 31%. The grasses Festuca rubra, Bromus pumpellianus, and Boa glauca were the next most abundant species with average covers of 5.2%, 2.4%, and 2% r e s p e c t i v e l y . Festuca rubra and Elymus innovatus. Poa glauca, in particuliar, was often fair ly abundant i n this community-type. 4) Sparse: Situated on highly eroded slopes and very species poor (Figure 7), Sparse communities are dominated by Calamagrostis inexpansa and Artemisia .tilesii: Epilobium angustifolium, Poa glauca, and Elymus innovatus were the only, other species that commonly occurred. One unusual Sparse community was dominated by Betula papyrifera but the absence .of Steppe, Forest, or Tundra indicator species placed it in the Sparse community-type. It appeared as i f this anomalous community was / undergoing fairly recent heavy erosion and thus probably represented an unusual, t rans i t ional communi ty - type . These communities are mostly located close to brightly colored mineral deposits associated with bituminous shale deposits that occurred towards the northern l imit of the study area. Mean soi l conductivity was 2.6 to 9 times that of other, community-types, almost certainly a reflection of the unique, underlying geology. S o i l p H was very low (3.8), in contrast to Tundra, Forest and Steppe (pH of 4.7, 6.1, and 6.8, respectively). C O R R E S P O N D E N C E T O P O T E N T I A L INSOLATION Steppe, Forest, and Tundra community-types are sharply differentiated according to their equivalent latitudes (Figure 8). W i t h one exception, Steppe communities a l l occurred at equivalent latitudes of 60° or less, the mean being 43 .1° . Forest communities occurred at a mean equivalent latitude of 58 .7° , and Tundra had a mean equivalent latitude of 70 .7° . Sparse equivalent latitude "(55.9°) F I G U R E 7. Typ ica l Sparse community along the Lower Anderson River (site 4 9 A , camp E) . M u c h of this community was not vegetated with bare soil occupying about 87% of the community. Artemisia tilesii was the most abundant plant species (10% cover) and Elymus innovatus, the next most abundant species, had a cover of only 1.3%. • 25 o U J 3 o 111 u . n STEPPE A A A mean = 43.4 se=2.67 20 S5 FOREST mean = 57.5 se=3.10 ^ 0 TUNDRA . mean = 70.7 se=2.26 SPARSE mean = 55.9 se=5.65 10 55 SO EQUIVALENT LATITUDE Figure 8. Distributions of the four^ TWINSPAN-defined piant community-types in the Lower Anderson River Valley along an equivalent latitude gradient. The differences between Steppe, Forest, and Tundra equivalent latitudes are highly significant (ANOVA, p<0.001); Sparse differs only from Tundra (p<0.05). Mean equivalent latitude and standard error are shown for each community-type. was significantly different only from Tundra (p=0.026). Along the Lower Anderson River the greatest diversity of community-types occurs on south-facing (including south-east or south-west-facing) slopes;. Between equivalent latitudes 4 5 ° and 6 0 ° one may find all of the 4 main community-types; at higher equivalent latitudes Steppe becomes rare, and Tundra was not observed at equivalent latitudes less than 4 5 ° . . . . During 2-months of field work more than 100 distinct Steppe communities were observed; only two of which faced northward. One of these north-facing Steppe communities was surveyed (equivalent latitude of 8 5 . 6 ° ) , and its inclusion in the study probably resulted in an overestimation of the mean Steppe community equivalent latitude. Mean Steppe equivalent latitude dropped from 4 3 . 4 ° to 4 1 . 3 ° when the north-facing community W a s excluded. Like most Disturbance Steppes this north-facing grassland had undergone recent slumping. Ordination with D C A resulted in good separation among the four main community-types (Figure 9). There was a strong correlation between the D C A axis 1 site scores and the equivalent latitude at each site (Figure 10). Equivalent latitude, a theoretical, variable, explained 47% of the variation in D C A axis 1, whereas latitude alone, which in this case is^ directly analagous to distance through treeline, explains only 6.8% of D C A . axisl variance (Figure 11). In this study area, equivalent latitude, which synthesizes slope, aspect, and latitude, was almost seven times more powerful a predictor of plant community composition than latitude alone. 2 7 CM (/> ">< (0 < O Q 7 .6 5 4 3 2 1 0 • Tundra • Forest A Steppe • Sparse • • A A • • A A 0 3 4 5 DCA axis 1 7 8 FIGURE 9. Detrended Correspondence Analysis of all 71 plant communities surveyed along the Lower Anderson River, NWT. Eigenvalues were 0.868 (Axis 1) and 0.669 (Axis 2) respectively. 28 • Tundra ° Forest A Steppe • Sparse 10 20 30 40 50 60 70 80 90 Equivalent Latitude FIGURE 1 0 . DCA axis 1 scores plotted against equivalent latitude, a potential insolation index, of surveyed communities (n=71) along the Lower Anderson River. Steppe communities have low DCA . scores and low equivalent latitudes, Tundra communities have high DCA scores and equivalent latitudes, Forest communities have intermediate scores, and Sparse communities, generally with low DCA scores are found over a range of equivalent latitudes. 2 9 o o o CO < < o Q 8 7 6 5 4 3 2 1 0 • T u n d r a • F o r e s t A S t e p p e • S p a r s e A A A* i 6 8 . 4 D C A = -110.7 + 1.66 (Latitude) R A 2 = 0.068, p < 0.02 A A A A A A 6 8 . 6 6 8 . 8 6 9 Latitude 6 9 . 2 6 9 . 4 6 9 . 6 FIGURE 1 1 . D C A ax i s 1 s c o r e s plot ted aga ins t ac tua l lat i tude of s u r v e y e d plant c o m m u n i t i e s (n=71) a l o n g the L o w e r A n d e r s o n R i v e r . E a c h c o m m u n i t y - t y p e is f ound ove r a w ide range of a c t u a l l a t i t u d e s . V E G E T A T I O N - E N V I R O N M E N T R E L A T I O N S H I P S C C A revealed two important environmental gradients underlying the vegetation-environment relationship (Tables 3 & 4, Figure 12). The first C C A axis represents a solar radiation-heat gradient in which equivalent latitude is strongly correlated to soi l temperature at 30 cm and depth to 0° C (Table 3). So i l moisture was not measured quantitatively but observations in the f ie ld clearly showed that sites towards the right side of the ordination diagram in Figure 12, where soi l temperatures were the highest, had the driest soils. Monte Carlo permutation revealed that axis one was significant (F-ratio= 5.21, p=0.01). The second C C A axis corresponds to a soil chemistry gradient that seems to be an important influence on the species composit ion of the outlier communities (Sparse community-type) towards the top of the ordination diagram. M a n y environmental variables had short vector lengths including a l l the soil texture variables, latitude, slope steepness, and position on slope. It is l ikely that the ranges of many of these variables were too small to influence community species composit ion; the soil texture variables in particuliar (% gravel, % fine sand, % coarse sand, and % silt and clay) were remarkably uniform across communities and along the length of the Lower Anderson Rive r (Table 1). SPECIES R A N G E EXTENSIONS Three major range extensions were documented: Arabis holboellii, Carex stenophylla ssp. eleocharis, and Schoenocrambe linifolia represented northward range extensions of 630, 600, and . 1700 kilometers respectively (Table 5). 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CD p cr w > <D. * I 8 CD 2 ^ i-S CD h-. CL 3 on CT O CD P ^ n, O CD 3 3 O § . 0 c ^ O w S. 3 U J p.; ^ o' •3- 3 . CTQ cr on O 2 . 3 P3 CD <pa o P c 3 C CD w CD C L C L CD era i-t CD CD T3 O on < CT S X CD " H CD • CL C fa CD o o on O CD1 P P era «• 3 O CL CL P 3- K P CD T3 CD O O O O O T A B L E 4. Inter-set correlations of environmental variables with Canonical Correspondence Analysis axes. Scores are x 1000. The most important values are i n bold. V a r i a b l e A x i s 1 A x i s 2 E i g e n v a l u e 7 7 0. Species-environment Cor re la t ion 94 9 600 915 L a t i t u d e - 2 6 6 . 334 Slope 393 -120 Aspect 6 5 4 -182 Posit ion on Slope 295 95 Equiva len t Lat i tude -710 321 S o i l Conduct ivi ty 508 7 8 7 Soi l p H 512 -483 Temperature at 30 cm 9 3 1 89 Depth to 0° C 9 03 7 % Gravel 361 - 3 3 9 % Coarse Sand 41 ' - 2 6 5 . % Fine Sand o -3 34 % Clav and Sil t -223 ' 398 '3 3 • Tundra A Steppe D Forest • Sparse CCA Axis 1 FIGURE 12. CCA biplot of 71 plant communities along the Lower Anderson River. Also shown are the vectors of the 13 abiotic variables included in the analysis (vector lengths are halved for ease of presentation). Axis 1 is primarily a thermal gradient, with communities to the right of the diagram receiving greater insolation and having the deepest active layers and warmest soil temperatures of the communities studied. Axis 2 largely reflects a soil chemistry gradient, with Sparse communities occurring towards the top of the diagram where soil conductivity is high and soil pH is low. Co <"J ar-cs, re a -I a 3 re U H U J ON oo to t o 0 0 o co O 3 CTQ 00 C? CT> \s re • s o re %d ^ a s-a ON ON NO to U J to oo to U J Go O CTQ GO ci>' C5 a <5-o o re ON ON ON 0 0 0 0 U J VO VO to to 0 0 0 0 to to ON ON U J U J U J I-* un ON NO - 0 CO 00 f . >•+> i-ti P3 to o o 3 3 CTQ OQ CO CO n> CD X) • a • o • a Ct> CD 00 CD o ?0 3^ "> t - 1 -2 ta p ^ o pv < I-I . <-» » a . c O- CO w O > O 3 O C L CD . I-I O 3 r 2" O =* 3 S3 C &: •CD 2 3 n o 3 pr i-h O ev 3 o P 3 C/3 o" 3 3 O lOSt >-b lOSt »—f 3* 3 CD O i-t 3 cr CD CD ' i-l C/3 >-» •CD C/3 I— • 3 C L CD >-l CD >T3 O i-i <—*-CD C L o o o i-t C L 3 P CD C/3 cn 3" CD £ L1 ii ° 3-3 * CD i-l P i-l C L i-l P 3 > 3 CL cn CD O 3 CD X 50 g k-. 3 < CD i-l < P i—> CD o 3 C/3 !-+> o co < P C/3 o 3 P * |-t cn 173 P .cr 1— 3 o £> ° * I . ~ Cj CTQ *T3 cr CD XV ^ 0 P ET CD rt tl m question oeccurred exclusively on south or south-west facing slopes. Other species growing in the largely south-facing steppe communities that were at, or close to, the northern limits of their reported ranges included Anemone multifida, Arabis divaricarpa, Epilobium angustifolium, Galium boreale, Hordeum jubatum, Juniperus communis, Populus balsamifera and Solidago decumbens. Species for which minor range extensions were recorded included Carex concinna, Cerastium arvense, Crepis nana, Draba palanderiana, Draba pilosa, and Elymus innovatus. These are primarily range extensions from the Mackenzie Delta area to the Anderson River area. Still under investigation by Dr. Cl i f f Crompton (Agriculture Canada, Ottawa) is the possibility of an Atriplex species specimen, collected on a south-facing Steppe community ( 6 9 ° 7 ' , 1 2 8 ° 1 9 ' ) , representing an altogether new species. This investigation is outside the scope of my thesis work and may be presented in a later publication. \ S T E P P E A R E A During this study 112 distinct patches of steppe vegetation were observed along the Lower Anderson River. Estimated minimum cover of Steppe is 107,000 ha (10.7 sq km) spread fairly evenly between the Forks and the Husky Bend, and resulting in approximately 560 ha per kilometer of river. 'Sparse' communities covered an estimated 20,000 ha (2 sq km), mostly in the Yellow Cliffs and Red Cliffs/Husky Bend Area (Figure 1). These estimates are conservative since no attempt was made to extrapolate Steppe or Sparse cover for areas not visible from river level. Also no correction was made to account for the fact that these communities 3 6 occur on a slanted surface and their area on a flat map is under-represented. The remainder of the valley was almost exclusively dominated by boreal forest or tundra communities. D I S C U S S I O N Soil temperature and depth to frozen soil were found to be strongly correlated to equivalent latitude. This gradient was the most important trend underlying the vegetation-environment relationship. Slope, aspect, and their interaction have been found to strongly affect soil temperature, soil moisture, the occurrence of permafrost and the depth of the active layer in a variety of northern studies (Dingman and Koutz 1974; Lloyd et al. 1994; Price 1971; Will iams and Smith 1989). Temperature has profound effects on northern vegetation at a variety of scales (Chapin 1983; Edlund and Alt 1989; Gross et al. 1990; Price 1971; and Tryon and Chapin 1983). The importance of slope and aspect in the occurrence, distribution, and composition of steppe communities has been addressed in several studies, although typically over much smaller areas than the one. dealt with here (i.e. a 150 km transect through treeline). In this study potential insolation explained 46.7% of the variance in D C A scores, a remarkable amount of predictive power for an essentially theoretical variable. At least two other studies of steppe and tundra vegetation in interior Alaska have used a similiar approach: Armbruster and McGuire (1985) found a 30% correlation between their slope-aspect interaction term and D C A scores. Similarly, in a path analysis, Lloyd et al. (1994) found that 73.4% of the D C A axis 1 variation was explained by seven variables including slope x aspect interaction and soil temperature. Working on esker vegetation in Finland, Heikkinen (1991) found that insolation terms dominated' axis 1 of a canonical correlation analysis. In rather more qualitative work, Hoefs et al. (1975), Howenstein et al. (1985), Juday et al. (1985), Kassler (1985), Walker el al. (1991), and Yurtsev (1982) stressed the importance of south-facing slopes in controlling the occurrence of steppe-like vegetation. The use of potential insolation and equivalent latitude is superior to many other slope-aspect interaction terms for three reasons. Firstly, it acknowledges the interaction of latitude, with slope and aspect and allows comparison of sites occurring over a range of different latitudes. Secondly, most other slope-aspect Interaction terms assume linearity and are not calculated using trigometric functions which more closely model the physical processes involved. Thirdly, despite the simplifying assumptions involved, it is much easier to relate to a 'real world' number such as latitude than, say, an interaction term ranging from -1 to +1. The interaction of slope and aspect is a fundamental factor underlying the distribution of steppe in areas where it coexists with tundra and/or boreal forest. Arctic plant communities are thought to be less affected by 'competitive and other biotic interactions than are more temperate ecosystems. Consequently, abiotic factors are ; relatively more important in structuring these northern communities (Bliss and Peterson 1992; Svoboda and Henry 1987), and this may contribute to the power of equivalent latitude in predicting plant community distribution and composition in cold climate regions In my opinion the Steppe communities in the Lower Anderson River area, particularly Stable Steppe, deserve the arctic .steppe denomination. Steppe along the Lower Anderson is quite similiar to the arctic-steppe communities described by Edwards and Armbruster (1989); Howenstein et al (1985), Walker et al. (1991), and Yurtsev (1982), and others for areas in Yukon, Alaska, and Siberia. At least 27 species occurring in Steppe communities occur in so-called arctic steppe communities described by other authors (Table 6). In addition, Agropyron violaceum, Anemone multifida, Artemisia tillesii, and Festuca rubra are examples of species in Anderson Steppe communities that are represented by closely related species in Alaskan and Siberian arctic-steppe communities. The conventional view that all of Beringia was covered in a monotonous steppe similar to todays steppe remnants has been challenged on palynological grounds (Ritchie and Cynwar 1982), making it difficult to say whether or not the communities described in this paper are representative of Beringia's vegetation 10,000' years ago. Nevertheless, the botanical and ecological uniqueness of these communities has been sufficient to warrant the continued interest of many northern researchers. Arctic-steppe vegetation has been reported in Siberia, Alaska, and the Yukon (see Introduction). Previously, the only known report of steppe-like vegetation in the Northwest Territories are some Artemisia /n'gz'da-dominated grasslands on the east bank of the Mackenzie River (Corns 1974). The Anderson River Steppe communities are thus the eastern-most representatives of arctic-steppe in North America described to date. South-facing Steppe along the Lower Anderson River provides habitat for many plant species that are not found in Forest or Tundra communities. Three major range extensions were associated with south-facing slopes (Table 4). The occurrence, of Schoenocrambe T A B L E 6 . Vascular plant species occuring in Steppe communities on the Lower Anderson River that have been reported from other arctic steppe communities (including the territory or state of previous studies: Ala=Alaska, Sib=Siberia, Yuk=Yukon). Both Yukon studies (Douglas 1974, Hoefs et al. 1975) do not refer to the communities as 'arctic steppe' per se, but have been cited as examples of this community type in later studies. Author key: l=Douglas 1974; 2=Edwards & Armbruster 1989; 3=Hoefs et al. 1975; 4=Howenstein et al. 1985; 5=Juday et al. 1985; 6=Lloyd et al. 1994; 7=Murray et al. 1983; 8=Walker et al. 1991; 9=Yurtsev 1982. Species A r e a References Anemone multifida Y u k 3 Androsace septentrionalis. Ala , Sib 6, 8, 9 Arabis holboelli A l a 2, 6, 7 Artemisia frigida Ala, Sib, Yuk 1, 2, 3, 4, 5, 6, 7, 9 Arenaria capitlaris A l a 6 Bromus pumpellianus A l a 3, 5, 6, 8 Calamagrostis purpurascens Ala , Sib 2, 3, 4, 5, 6, 9 Carex obtusata Ala , Sib 5, 6, 8, 9 Cerastium arvense Sib 9 Conioselium cniidifolium Ala 5 Elymus innovatus Ala 5 Epilobium angustifolium A l a 6 Erigeron compositus Ala, Sib 6, 7, 9 Galium boreale A l a 6 Hedysarum alpinum A l a 6, 8 Hordeum jubatum Sib 9 Juniperus communis A l a 6, 7 Linum lewisii Ala 7 Oxytropis maydelliana A l a 8 <> Plantago canescens A l a 7 Poa glauca Ala Sib Yuk 1, 3, 5, 8, 9 Potentilla nivea A l a 6 Rosa asicularis Sib 6, 9 Saxifraga reflexa A l a 5, 6 Solidago decumbens Ala Yuk 3,. 6 Solidago multiradiata Ala Yuk 3, 6 Zygadenus elegans A l a 6 linifolia, in particuliar, represents a range extension of about 1700 km, and is the first report of this species in the Northwest Territories. In a biogeographical analysis of steppe communities on Alaskan pingos, Walker et al. (1991) found that pingo-specific plant species were significantly more 'southerly' (using a classification system based on northern range limits) than species in the surrounding tundra. It appears that the warmer and drier conditions in south-facing steppe communities result in species assemblages drawn from a more southerly species pool. Assuming that a plant species has an optimal climatic regime it follows that this optimum is found on cool northern aspects at its southern geographical limit and on warm south-facing aspects at its northern limit. In the Anderson River valley Artemisia frigida and Linum lewisii are near the northern limit of their ranges and occur almost exclusively on south-facing slopes. In the coulees of the Oldman River in southern Alberta, where both species are close to the southern limit of their distributions (Porsild and Cody 1980), Artemisia frigida is found over all aspects and Linum lewisii is found only on north-facing aspects (Lieffers and Larkin-Lieffers 1986). Other factors are important as well: for example, Linum lewisii is probably sensitive to competitive shading (Wesser and Armbruster 1991; Wesser 1991) so biotic, as well as abiotic, factors wi l l influence its local distribution. The Sparse community-type on the Lower Anderson is similar to vegetation in the Smoking Hills area along the Horton River, NWT (approximately 50 km east of the Anderson River)! Along the Horton River long-term exposure to sulphur dioxide and acidic aerosols produced by the combustion of bituminous shales has created unique pollution-resistant communities described by Freedman et al. (1990). Anderson Sparse communities and Horton 'severly fumigated' communities both exhibit low species diversity, comparable mean cover of Artemisia tilesii (4.8% on the Horton, 5.7%, on the Anderson), low soil p H (3.5 on the Horton, 3.8 on the Anderson), the presence of grasses, and high levels of bare soil (90% on the Horton, 75% on the Anderson). Bituminous shale geology is locally common on the Anderson, but actual fumigation events are definitely much rarer than on the Horton. It is therefore likely that edaphic, rather than airborne, factors are important in controlling the occurrence and distribution of Sparse communities in the Anderson area. A river valley such as the one in this study is important in maintaining the species diversity of the area for at least two reasons. Firstly, the valley provides a variety of slopes and aspects that are -not available on the relatively flat uplands. The resultant diversity of insolation regimes affects habitat characteristics such as soil moisture and temperature allowing a variety of plant communities t o n exist in close proximity. Secondly, the valley slopes are prone to mass-wasting events such as slumping and erosion. These disturbances create breaks in the tundra and forest communities and expose mineral soil, creating potential colonization sites for weak competitors. This mechanism, whereby some intermediate level of slumping and erosion will facilitate maximum species diversity, is consistent with the intermediate disturbance hypothesis (Connell 1978; Huston 1979; Sousa 1979). Species diversity in the Steppe community-type is lower than either that of Tundra or Forest, but, because of the presence of many unique species, Steppe contributed strongly to the overall species diversity of the Lower Anderson River Valley. This contribution is especially relevant when one considers how little of the valley is actually covered by Steppe relative to Tundra and Forest. Global circulation models generally suggest that global warming wi l l result in lower summer soil moisture, as well as higher summer and winter air temperatures in the Arctic (reviewed in Maxwell 1992). In a warmer and drier Arctic it is. possible that the steppe-like communities throughout Alaska, Yukon, and Northwest Territories may expand in size and distribution. Slumping events may be important in the establishment of grassland communities in areas formerly dominated by tundra and forest. Another, although not necesarily exclusive, possibility is the invasion of tundra and boreal forest communities by species currently restricted to steppe-like communities. 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C A N O C O - a F O R T R A N program for canonical community ordination by [partial] [detrended] [canonical] correspondence analysis arid redundancy analysis (version 2.1). 2.1 ed., V o l . Wageningen: TNO Institute of Applied Computer Science, Statistics Department. Timoney, K.P. , G.H. La Roi, and M.R.T. Dale. 1993. Subarctic forest-tundra vegetation gradients: ^the sigmoid wave hypothesis. Journal of Vegetation Science 4: 387-394. , Tryon, P.R. and F.S. Chapin III. 1983. Temperature control over root growth and root biomass in taiga forest trees. Canadian Journal of Forest Research 13: 827-833. Walker, M.D . , D.D. Walker, K.R. Everett, and S.K. Short. 1991. Steppe Vegetation on south-facing slopes of pingos, central arctic coastal plain, Alaska, U.S .A. Arctic and Alpine Research 23: 170-188. Wesser, S.D. 1991. The effects of light and. moisture on two species from contiguous communities of south-facing bluffs in interior Alaska. Arctic and Alpine Research 23 (\Y. 99-103. Wesser, S.D. and W.S. Armbruster. 1991. Species distribution controls across a forest-steppe transition: a causal model and experimental test. Ecological Monographs 61 (3): 323-342. Williams, P.J. and M.W. Smith. 1989. The Frozen Earth. Fundamentals of Geocryology. Cambridge: Cambridge University Press. Yurtsev, B . A . 1982. Relicts of the xerophyte vegetation of. Beringia. In Paleoecology of Beringia. ed. D . M . Hopkins, J.V. Mathews Jr., C.E. Schweger, and S.B. Young. 157-178. New York: Academic Press. A P P E N D I X 1. Comparison of two percent cover estimation methods for 36 species-occurrences in five quadrats wi thin a Steppe community. V i sua l % cover ( Y axis) was estimated using a plain 1 m 2 quadrat. Point hit % cover was then estimated in the same location using a 1 m 2 quadrat divided into 100 equal squares with thin string. A needle was then dropped'at the 121 corners and intersections of the strung quadrat and each contact with a plant part recorded. This was converted to a cover value for each species by dividing the number of contacts with that species by 121 and mul t ip lying by 100%. A strong correlation (r 2=0.88) exists which seemed to indicate that v isual estimates were sufficient to characterize community composit ion, especially given that visual estimation was at least five times as fast as the point hit method. 5 1 Point Hit % Cover A P P E N D I X 2 . Vascular plant species cover for 71 plant communities on the Lower Anderson River valley, N W T . Cover for each species was assessed visually in a number of randomly located 1 m 2 quadrats, and then averaged across a l l quadrats in the community. Communities are arranged by T W I N S P A N defined community-types which are Tundra, Forest, Stable Steppe, Disturbance Steppe, and Sparse. These data are available in spreadsheet format by contacting Dr . Greg Henry, Department of Geography, Universi ty of Br i t i sh Columbia . Mean Vascular Plant Species Cover for Tundra Communities Stand # 12 1 3 20 26 27 31 35 37 39 # of quadrats 15 1 5 1 5 1 5 1 5 1 0 1 6 1 5 15 Alnus crispa 7.67 2.33 3.87 7.77 13.5 0 2 0 4.7 Anemone multifida 0 0 0 0 0 0 0 0 0 Arctagrostis latifolia 0.03 0.37 0.27 0.73 0.73 3.6 5.19 0.87 1.77 Arctostaphylos rubra 1.93 0 0 1.4 1.33 5.9 1.25 3.53 5.5 Artemesia Tilesii 0 0 0 0 0 0 0 0 0 Betula glandulosa 7,4 1.87 1.4 40.2 0 41.5 17.9 62.3 4.43 Betula papyrilera 9 12.1 12.4 0 0 0 0 0 0 Calamagrostis inexpansa 0 0 0 0 0 0 0 •, o 0 Calamagrostis lapponica 0 0 1.4 . 0.83 2.47 0.2 0 0 0 Calamagrostis purpurascens 0 0 0 0 0 0 0 2.9 0 Carex concinna 0.27 0 0 0 0 0 0. 0 0 Cardamine digitata 0 0 0 0.03 0.1 0.05 0.16 0 0.07 Carex lugens 0 0 0 0 0 0 0 0 0 Carex scirpoidea 0.8 0.03 0 0.5 0.13 0 0.06 0 0.07 Carex vaginata 0.13 0 0 0.13 6.27 0 1.38 0 0.73 Cassiope tetragona 0 0 0 0 0 0 0 0 5.87 Dryas integrilolia 1.73 0 0 0.73 0 1.5 0 0 5.73 Elymus innovatus 0 0 0 0 0 0 0 0 0 Empetrum nigrum 4.53 0 11.8 0.93 14.3 21.2 9.63 7.33 11.4 Epilobium angustifolium 0 0 0 0 0 0 0 0.23 0 Equisetum arvense 0 0 0 0.3 0 0 0.22 0 0.67 Equisetum scirpoides 0 0 0 0 0.03 0 0 0 0.1 Eriophorum vaginatum 0 0 0 0 0 0 2.69 0 0.2 Hierochloe alpina 0 0 0 0 0 0 0 0 0 Ledum decumbens 29.5 1.87 45.7 6.67 3.13 11.2 8.97 13.6 1 1.2 Ledum groenlandicum 0.47 1.53 0.57 12.9 6.8 0 0.06 0 0.23 Linnaea borealis 0 0 0 0 0 0 0 0 0 Lupinus arcticus 0 0 0 0.03 0 1.95 0.13 0 0 Luzula mulillora 0 0 0 0 0 0 0.59 0 0.07 Pedicularis labradorica 0 0 0 0 0 0 0.06 0 0.27 Petasites trigidus 0 0 0 0.13 0 0.7 2.22 0 0.13 Picea glauca 0.67 0 3.27 0.2 0 0.3 o 0.67 1.43 Poa arctica 0 0 0 0 0 0 0 0 0 Poa glauca 0.27 0 0 0 0 0 0 0 0 Poa pratensis 0 0 0 0 0 0 0.09 0 0 Potentilla fruticosa 0 0 0 0.03 0 0 0 0 0 Purola granditlora 0 0 0.47 0.23 26 1.75 1.47 0.57 0.07 Pyrola secunda 0.03 0 0 0.2 0.2 0.85 0.03 0 0.13 Ribes triste 0 0 0 0 0.13 0 0 0 0 Rhododendron lapponicum 0.03 0 0 0 0 0 0 0 0 Rubus Chamaemorus 0 0 0 0 0 0.5 0 0 0.5 Rumex Acetosa . 0 0 0 0.27 0 0 0 0 0 Salix arbusculoides 0.33 0 0 0 11.5 1.8 0 0 0 Salix glauca 1.53 0 5.3 3.13 0.07 5.3 2.44 9.27 2 Saussurea angustitolia 0 0 0 1.03 .2.07 0 0.31 0 0 Senecio atropurpureus 0 0 0 0 0 0 0.09 0 0.23 Senecio lugens 0 0 0 0.03 0 0 0 0 0 Spirea Beauverdiana 0 0 0 0 0 0 0 0 0 Stellaria calycantha 0 0 0 0 0.1 0 0 0 0 Stellaria longipes 0 0 0 0 0 0 0 0 0 Taraxacum lacerum 12.3 0 0.13 4.77 0.57 0 5.94 0 9 Vaccinium vitis-idea 22.5 19.9 21.6 5.4 10.3 14.9 13.3 21.6 18.3 Mean Vascular Plant Species Cover for Tundra Communities Stand # 41 A 47 4 8 A 48B 51 52 5 3 A 53B 56 # of quadrats 1 0 1 5 9 1 0 1 5 1 5 8 8 1 5 Alnus crispa 0 7.57 1.72 58.8 3.13 5.33 0 0 0 Anemone multifida 0 0 0 0 0 0 0 0 0 Arctagrostis latifolia 3.05 0 0 0 2.07 0.2 0 0 0 Arctostaphylos rubra 2.3 0.07 1.11 0.2 0 0 0 0 0 Artemesia Tilesii 0 0 0 0 0 0 0 0 0 Betula glandulosa 19.3 9.47 24.4 2.6 29.5 46 25.8 41.9 22.8 Betula papyrifera 0 0 0 0 0 0 0 0 0 Calamagrostis inexpansa 0 1.87 0 0 0 0 0 0 1.1 Calamagrostis lapponica 0 0 1.33 1.4 2.77 3.37 5.38 2.19 3.7 Calamagrostis purpurascens 0 0 0 0 0 0 0 0 0 Carex concinna 0 0 0 0 0 0 0 0 0 Cardamine digitata 0.45 0 0 0 0 0 0 0 0 Carex lugens 0 0 0 0 0 0 0 0 0 Carex scirpoidea 0 0 0 0 0 0 0 0 0 Carex vaginata 0.4 0 0 0 0 0 0 0 0 Cassiope tetragona 0 0 0 0 0 0 0 0 0 Dryas integrifolia 0.7 0 0 0 0 0 0 .0 0 Elymus innovatus 0 0 0 0 0 0 0 0 1 Empetrum nigrum 12.2 3.13 6.22 0.7 4.6 1.27 0 0 0 Epilobium angustifolium 0 0 0 0 0 0 0 0 0 Equisetum arvense 0 0 0 0 0 0 0 0 0 Equisetum scirpoides 0.5 0 0 0 0 0 0 0 0 Eriophorum vaginatum 1.2 0 0 0 0 0 0 0 0 Hierochloe alpina 0 0 0 0 0.07 0 0 0 0 Ledum decumbens 9.75 34.1 38.9 7.5 7.13 6.33 2.88 0.56 1.67 Ledum groenlandicum 0 0 0 0 0 0 0 0 0 Linnaea borealis 0 2.13 0 0 0 4.67 0 0 0 Lupinus arcticus 0.1. 0 0 0 2.2 0 0 0 0 Luzula muliflora 0.1 0 0.11 0 0 0 0 0 0 Pedicularis labradorica 0 0 0 0 0.07 0 0 0 0.5 Petasites frigidus 0.3 .0 0 0 0.27 0.53 0 0 0 Picea glauca 4 12.3 0 0 0 0 1 0 7.13 13.4 Poa arctica 0 0 0 0 0.07 0 0 0 0 Poa glauca 0 0 0 0 0 0 0 0 0 Poa pratensis 0 0 0 0 0 0 0 0 0 Potentilla fruticosa 0.1 0 0 0 0 0 0 0 0 Purola grandiflora 0.25 0 0 0 0.33 0 0 0 0 Pyrola secunda 0.5 0 0 0 0.03 0 0 0 0 Ribes triste 0 0 0 0 0 0 0 0 0 Rhododendron lapponicum 0 0 0 0 0 0 0 0 0 Rubus Chamaemorus 0 0 0 0 0 0 0 0 0 Rumex Acetosa 0 0 0 0 0 0 0 0 0 Salix arbusculoides 0.05 0 0 0 0.13 0 0 0 0 Salix glauca 9.65 0 0 0 3.87 0.8 0 0 0 Saussurea angustifolia 0.7 0 0 0 0 0 0 0 0 Senecio atropurpureus 0.2 0 0 0 0.2 0 0 0 0 Senecio lugens 0 0 0 0 0.1 0 0 0 0 Spirea Beauverdiana 0 8.4 2.33 18.4 0 0 0 0 0 Stellaria calycantha 0 0 0.11 0.2 0 0 0 0 0 Stellaria longipes 0.05 0 0 0 0.23 0.13 0 0 0 Taraxacum lacerum 0.7 0 0 0 0 0 0 0 0 Vaccinium vitis-idea 18.5 29.7 10.2 5 8.93 10.5 5.44 0.19 8.03 Mean Vascular Plant Species Cover for Tundra Communities Stand # 58 59 60 61 # of quadrats 1 2 1 5 1 5 1 5 Alnus crispa 67.2 0 0 0 Anemone multifida 0 0 0.2 0 Arctagrostis latifolia 2.08 2.63 0.53 0 Arctostaphylos rubra 0 1 0 0 Artemesia Tilesii - 1.83 0 0 0 Betula glandulosa 0 13.6 30.9 20.9 Betula papyrifera 0 0 0 ; 0 Calamagrostis inexpansa 0 0 0 12.4 Calamagrostis lapponica 1.88 3.23 2.73 0.73 Calamagrostis purpurascens 0 0 0.13 0 Carex concinna 0 0 0 0 Cardamine digitata 0 0.4 0 0 Carex lugens 0 4.33 0 0 Carex scirpoidea 0 0 0.6 0 Carex vaginata ' 0 0.07 0 0 Cassiope tetragona 0 0 , 0 0 Dryas integrifolia 0 0 0 0 Elymus innovatus 0 0 0 0 Empetrum nigrum 0 8.07 2.33 0.27 Epilobium angustifolium 0 0 0.43 0 Equisetum arvense 0 0.07 0 0 Equisetum scirpoides 0 0 0 0 Eriophorum vaginatum 0 20.9 0 0 Hierochloe alpina 0 0 0 0 Ledum decumbens 0 0.47 2.87 2.27 Ledum groenlandicum 0 0 0 0 Linnaea borealis 0.92 0 0 0 Lupinus arcticus 0 0 0.07 0 Luzula muliflora 0 0 0 0 Pedicularis labradorica 0 0 0 0 Petasites frigidus 5.25 0.13 0 0 Picea glauca 0 0.47 0 0 Poa arctica 0 0 0 0 Poa glauca 0 0 0 0 Poa pratensis 0 0 0.03 0 Potentilla fruticosa 0 0 0 0 Purola grandiflora 0 0.33 0.5 0 Pyrola secunda 0 0.23 0 0 Ribes triste 0 0 0 0 Rhododendron lapponicum 0 0 0 0 Rubus Chamaemorus 0 0 0 0 Rumex Acetosa 0 0 0 0 Salix arbusculoides 18.3 15.5 0 0 Salix glauca 0 0.2 20.3 0 Saussurea angustifolia 0 0 0 0 Senecio atropurpureus 0 0.67 0 0 Senecio lugens 0 0 0 0 Spirea Beauverdiana 0.17 0 0 0.4 Stellaria calycantha 7.17 0 0 0 Stellaria longipes 0 0 0 0 Taraxacum lacerum 0 1.93 0 0 Vaccinium vitis-idea 0 2.63 5.2 2.67 Mean Vascular Plant Cover for Forest Communities Stand # 2 5 1 6 18B 1 9 22 25 29 3 2 A 34 # of quadrats 16 1 6 15 9 1 6 1 6 1 5 1 9 1 2 1 5 Achillea nigrescens 0 0 0 0 0 0 0 0 3 0 Agoseris glauca 0 0.06 0 0 0 0 0 0 1.33 0 Alnus crispa 0 0 0 0 1.88 0 0 0 0 1.67 Androsace septentrionalis 0 0 0 0 0 0 0 0.03 0 0 Anemone multifida 2.13 3.34 0.33 0 0.09 0 0.03 0 2.13 0 Anemone parvitlora 0.47 0 0 0 0.06 0 0 0 0 0.03 Arctagrostis latilolia 0 0 0 0 0.47 4.31 1.53 2.74 0.83 1.33 Arctostaphylos rubra 11.3 1.16 0.73 0 6.81 1.5 6.03 2.32 .1 7.53 Arctostaphylos uva-ursi 0.03 0 0.03 0 0 0 0 0 0 0.03 Artemesia Tilesii 0 0 0 0 0 0 0 0 0.17 0 Aster sibiricus 0 0 0 0 0 0 0 0 0 0 Astragalus alpinus 0 0 0 0 0 0 0 0 0 0 Betula glandulosa 0 0 0 0 0 0 0.07 0 0 3.67 Betula papyrifera 0 0 0 14.1 0 0 0 0 0 0 Boschniakia rossica 0 0 0 0 0.13 0 0 0 0 0 Bromus Pumpellianus 0 0 0 0 0 0 0 0 2 0 Calamagrostis inexpansa 0 0 0 0 0 0 0 0 0 0 Calamagrostis lapponica 0 0.78 0 0 0 1.09 0.07 3.37 1.92 0 Calamagrostis purpurascens 1.13 0 1.07 0 0.56 0 0 0 0 0 Carex consimilis 0 0 0 0 0 0 0 0 0 0 Carex concinna 3.59 0.47 0 0 1.34 0 0.17 0 0 0 Cardamine digitata 0 0 0 0 0 0 0 0 0 0 Carex scirpoidea 0 0 0 0 0 0 0 0 0 4 Carex vaginata 0 0 0 0 0 0 0 0.71 0 2.17 Castilleja raupii 0 0 0 0 0 0 0 0 0 0 Cassiope tetragona 0 0 0 0 0.5 0 3.2 0 0 5.4 Conioselium cnidiitolium 0.06 0 0.07 0 0 0 0 0 1.08 0 Draba glabella 0 0 0 0 0 0 0 0 0.04 0 Draba pilosa 0 0 0 0 0 0 0 0 0 0 Draba Palanderiana 0 0 0 0 0 0 0 0 0 0 Dryas integrifolia 0 0 0 0 12.3 0 1.17 2.89 0 25.3 Elymus innovatus 0 0 0 6.28 0 0 0 0 0.17 0 Empetrum nigrum 1 0.16 3 0.11 7.06 24.9 13.5 20 0.42 4.6 Epilobium angustilolium 0.03 0.06 0 0 0 0 0 0.11 1.5 0 Equisetum arvense 0 0 0 0 0 0 0 0 0 0 Equisetum scirpoides 0.09 0 0 0 0.06 0 0.37 0.5 0 1.47 Eriophorum triste 0 0 0 0 0 0 0 0 0 0 Eriophorum vaginatum 0 0 0 0 0 0 0 0 0 0 Erysimum inconspicuum 0 - 0 0 0 0 0 0 0 0.04 0 Festuca rubra 0 0 0 0 0 0 0 0 1.42 0 Gentiana propinqua 0 0 0 0 0 0 0 0.11 0 0 Habenaria obtusata 0.09 0 0 0 0 0 0 0 0 0 Hedysarum alpinum 1.38 0.72 4.23 0 0 0 0 0 0 0 Hedysarum Mackenzii 1.44 0.72 0 0 0 0 0 0 0 0 Hierochloe alpina 0 0 0 0 0 0 0 0 0 0 Juniperus communis 0.25 0.22 0.37 0 0.03 0 0 0 0 0 Ledum decumbens 0 0.09 0 3.78 0 5.97 4.2 3.45 0 0.43 Ledum groenlandicum 0 0 0 0 4.31 1.03 1.6 1.05 0 1.87 Mean Vascular Plant Cover for Forest Communities CONTINUED.... Stand # 2 5 1 6 18B 1 9 22 25 29 3 2 A 34 Linnaea borealis 9.91 0 0 0 0 0 0 0.79 1.25 0 Linum Lewisii 0 0 0 0 0 0 0 0 0.04 0 Lupinus arcticus 0.5 0 0.3 0 2.63 0.63 0.77 0.84 7.25 0.2 Luzula muliflora 0 0 0 0 0 0 0 0 0 0 Minuartia rubella 0 0 0 0 0 0 0 0 ' 0 0 Oxytropis deflexa 0 0 0 0 0 0 0 0 0 0 Oxytropis glutinosa 0.03 0.09 0 0 0 0 0 0 0 0 Oxytropis hyperborea 0 0 0 0 0 0 0 0 0 0 Pedicularis labradorica 0 0 0 0 0 0 0 0 0 0.83 Petasites frigidus 0 0 0 0 0 1.25 0.4 0.47 0.42 0 Picea glauca 21.2 30.3 29 8.56 17.5 13.8 9.33 10.6 0 8.73 Plantago canescens 0 0 0 0 0 0 0 0 0 0 Poa arctica 0 0 0 0 0 0 0 0 0 0 Poa glauca 0 0 0.03 0.28 0 0.81 0.03 0.05 1.08 0 Populus balsamifera 0 0 0 0 0 0 0 0 0 0 Potentilla fruticosa 0 0 0 0 0 0 0 0.26 0 0.8 Potentilla nivea 0 0 0 0 0 0 0 0 0.5 0 Purola grandiflora 0.06 0 0.07 0 0.28 1.28 0.27 0.13 1.42 0.07 Pyrola secunda 0.09 0 0 0 0 1.69 0.33 0.11 0 0 Ribes triste 0 0 0 0 0 0.06 0 0 0 0 Rhododendron lapponicum 0 0 0 0 0.13 0 0 0 0 2.33 Rosa acicularis 0 0.44 0 0 0 0 0 . 0.11 0 0 Rumex Acetosa 0 0 0 0 0 0 0 0 0 0 Salix arbusculoides 0 4.38 4 0.56 1.28 4.25 3.47 1.05 18.8 0 Salix glauca 1.06 0 0.2 0 1 1 0.13 6.9 10.7 29 4.87 Salix myrtillifolia 1.03 0 0 0 0 0 0 0 0 0 Salix niphoclada 0 0 0 0.78 0 0 0 0 0 0 Saussurea angustifolia 0.19 0 0 0 0.06 0.06 0.1 0 0 0 Saxifraga reflexa 0 0 0 0 0 0 0 0 0.04 0 Senecio atropurpureus 0.16 0 0 0 0 0 0 0.34 0 0.07 Senecio hyperborealis 0.06 0 0 0.44 0 0 0 0 0 0 Senecio lugens 0.06 0 0.83 0 0 0 0.03 0 2.13 0 Shepherdia canadensis 0 2.69 0.37 3.89 0 0 0 0 2.08 0 Solidago multiradiata 0 0.16 0.63 0 0 0 0 0 0.67 0 Stellaria longipes 0 0 0 0 0 0 0 0 0 0 taraxacum lacerum 0.03 0.06 0 0 1.19 0.03 6.13 3.5 0 5.57 Vaccinium vitis-idea 0 0.56 0.33 3.72 9 26.3 22 20.5 4.5 0.93 Zygadenus elegans 0 0 0 0 0.13 0 0 0 0 0.07 Mean Vascular Plant Cover for Forest Communities Stand # 38B 40 41 B 43 45 50 54 # of quadrats 9 1 5 7 1 5 1 5 1 5 15 Achillea nigrescens 0 0 0 1.17 0 0 0.33 Agoseris glauca 0 0 0 0.77 0 0 0 Alnus crispa 0 0 0 0 21.9 0 0 Androsace septentrionalis 0 0 0 0 0 0 0 Anemone multitida 0 0.2 0 0 0 0 1.1 Anemone parvitlora 0 0.27 0.07 0 0 0 2,17 Arctagrostis latilolia 0 0.77 2.71 3.43 1.83 8.83 0 Arctostaphylos rubra 0 2.47 2.64 0 3.93 17.2 2 Arctostaphylos uva-ursi 0 0 0 0 0 0 0 Artemesia Tilesii 5.67 0 0 0.87 0 0 0 Aster sibiricus 0 0 0 0 0 0 0.63 Astragalus alpinus 0 0 0 0 0 0 0.2 Betula glandulosa 14.4 2.2 4.14 . 0.53 0 9.67 0 Betula papyritera 0 0 0 0 0 0 0 Boschniakia rossica 0 0 0 0 0 0 0 Bromus Pumpellianus 0 0 0 0 0 0 0.53 Calamagrostis inexpansa 1.44 0 o 0 0 0 0 Calamagrostis lapponica 0 0 0 0 0 0 0 Calamagrostis purpurascens 0 0.27 0 0 0 0 3.03 Carex consimilis 0 0 2.14 0 0 0 0 Carex concinna 0 0 0 0 0 0 P Cardamine digitata 0 0 0.43 0 0 0 0 Carex scirpoidea 0 0.5 0 0 0 1.27 0.17 Carex vaginata 0 0.6 0.43 0 0 0 0 Castilleja raupii 0 0 0 1.2 0 0 0.07 Cassiope tetragona 0 0 0 0 0 0 0 Conioselium cnidiitolium 0 0.17 0 0.67 0.03 0 0.17 Draba glabella 0 0 0 0.13 0 0 0 Draba pilosa 0 0 0 0 0 0.2 0 Draba Palanderiana 0 0 0 0 0 0.17 0.1 Dryas integritolia 0 25 6.86 0 0 0 0 Elymus innovatus 1.28 0 0 0.23 0 0 0 Empetrum nigrum 0 5.7 6.57 0.07 6.73 0 3.7 Epilobium angustitolium 0.39 0 0 1.07 0.07 0 0.23 Equisetum arvense 0 0 0 2 0.67 0 0.33 Equisetum scirpoides 0 3.2 3.86 0 2.13 0 0.63 Eriophorum triste 0 o 0.29 0 0 0 0 Eriophorum vaginatum 0 0 3.29 0 0 0 0 Erysimum inconspicuum 0 0 0 0 0 0 0 Festuca rubra 0.22 0 0 0 0.27 0 0 Gentiana propinqua 0 0.07 0 0 0 0 0 Habenaria obtusata 0 0 0 0 0 0 0 Hedysarum alpinum 0 0 0 0 0.27 0.67 2 Hedysarum Mackenzii 0 0 0 0 0 0 0 Hierochloe alpina 0 0 0 0 0 1.23 0 Juniperus communis 0 0 0 0 0 0 2.63 Ledum decumbens 0 0 1 0 0 0 0 Ledum groenlandicum 0 1.8 0 0 0 0 0 Mean Vascular Plant Cover for Forest Communities CONTINUED.... Stand # 38B 40 41B 43 45 50 54 Linnaea borealis 0 0 0 0 0 0 0 Linum Lewisii 0 0 0 0 0 0 0 Lupinus arcticus 0 0.67 0.21 9.73 0.8 0 0 Luzula muliflora 0 0 • 0.79 0 0 0 0 Minuartia rubella 0 0 0 0 0 0.17 0 Oxytropis deflexa 0 0 0 0 0 0 0.07 Oxytropis glutinosa 0 0 0 0 0 2.77 0 Oxytropis hyperborea 0 0 0 0 0 0 0.4 Pedicularis labradorica 0 0 0 0 0 0 . 0 Petasites frigidus 0 0 0.57 0 0 0 0 Picea glauca 12.3 16.7 3.57 0 9.13 0 8.7 Plantago canescens 0 0 0 0 0 0.03 0 Poa arctica 0 0 0 0 0.3 0 0 Poa glauca 0.83 0 0 0.6 0 1.4 0.27 Populus balsamifera 0 0 0 0 0 0 10.2 Potentilla fruticosa 0 0.27 0.07 0 0 0 0 Potentilla nivea 0 0 0 0.07 0 0 0 Purola grandiflora 0 0.03 0.64 5.13 0.3 0 0.07 Pyrola secunda 0 0.1 0.5 0.53 0.13 0 0 Ribes triste - 0 0 0 0 0 0 0 Rhododendron lapponicum 0 1.93 0.07 0 0 0 0 Rosa acicularis 0 0 0 0 0 0 0 Rumex Acetosa 0 0 0.14 0 0 0 0 Salix arbusculoides 0 0.17 0 20.1 18.7 1.8 - 0.37 Salix glauca 0 5.53 10.6 10.3 6.27 9.8 15.4 Salix myrtillifolia 0 0 0 0 0 0 0 Salix niphoclada 0 0 0 0 0 0 0 Saussurea angustifolia 0 0 0.29 0 0 0 0 Saxifraga reflexa 0 0 0 0 0 0 0.17 Senecio atropurpureus 0 0 0.43 0 0 0 0 Senecio hyperboreans 0.06 0 0 0.2 0 0.03 0 Senecio lugens 0 0.33 0 2.77 0.07 0 1.1 Shepherdia canadensis 0 0 0 0 0.6 0 0.37 Solidago multiradiata 0 0.23 0 0 0 0 0.23 Stellaria longipes 0 0 0.07 0.33 0.13 1.07 0.03 taraxacum lacerum 0 3.2 11.6 0 0.73 0 0.53 Vaccinium vitis-idea 6.67 1.93 8.14 0.47 2.3 1.27 1 Zygadenus elegans 0 0 0 0 0 0 0.13 Mean Vascular Plant Cover for Stable Steppe Communities Stand # 3 6 8 9 1 4 1 5 1 7 33 44A 44B 55 # of quadrats 15 1 5 12 1 5 1 2 1 5 1 5 1 5 5 1 0 1 5 Achillea nigrescens 0 0 0 0 0 0 0 0 0 0.4 0.03 Agoseris glauca 0 0 0.08 0 0 0 0 0 0 0 0 Agropyron violaceum 1.37 0 0 0.1 0 0 3 0 0 0 0 Androsace septentrionalis 0 0 0 0 0 0 0 0.13 0.8 0.4 0.5 Anemone multifida 0 0 6.67 0.13 0.13 0.97 0.53 4 1 3.7 2.97 Arabis divaricarpa 0.23 0 0 0 0 0 0 0 0.1 0.1 0 Arabis Holboellii 0 0 0 0 0 0.13 0.23 0 0 0 0 Arctostaphylos uva-ursi 0 0 0 0 0 3.13 0.1 0 0 0 0 Arenaria capillaris 0 0 0 0 0 0 0 0 0 0 0.5 Artemesia frigida 0 0 0 0 27.4 0.27 7 12.5 25.2 3.05 16.6 Artemesia Tilesii 1.5 0.39 0 0.07 0 0 1.3 0 0 1.2 0 Aster sibiricus 0 0 0 0 0 0 0 0 0 0 0.33 Bromus Pumpellianus 1.33 4.75 0 0 0 0.03 1.8 0 0 0 0.13 Calamagrostis purpurascens 0.33 0.29 0.54 0.4 0.58 6.7 4.37 15.1 3 4.6 9 Carex obtusata 0 0 0 0 0 0 0 1.67 1 8.1 0 Carex stenophylla 0 0 0 0 0 0 0 0 0 0 1.3 Cerastium arvense 0 0 0 0 0 0 0 0 0 0.9 0 Conioselium cnidiifolium 0 0 0.04 0 0 0 0 0 0 0 0 Elymus innovatus 0 0 0 0 0 0 0.23 0 3 0.8 0 Epilobium angustifolium 4.97 2.54 0 0.53 0 0 0 0.43 0 2.05 0.33 Erigeron compositus 0 0 0 0 2.92 0.07 0 0 2.2 .0.7 0 Erysimum inconspicuum 0 0 0 0.03 0 0 0 0 0 0 0 Festuca rubra 0 0 0 0 0 0 0 0 0 0.2 0 Galium boreale 0 0 0 0 0 0.27 0 0 0 0 2.17 Hedysarum alpinum 0 0 0 0 0 0 0 0 0 0.8 0 Hedysarum Mackenzii 0.5 0.5 3 0.57 0 0 0 0 0 0 0 Juniperus communis 22.3 13.9 1.88 12.6 0 5.47 0.43 0 0 0 14.3 Linnaea borealis . 0 0 0.13 0 0 0 0 0 0 0 0 Linum Lewisii 0.43 0 0 0 0.29 0.03 0.73 0 0 0 0.63 Oxytropis hyperborea 0 0 0 0 0 0 0 0 0 0 0.07 Oxytropis Maydelliana 0 0 0 0 S o 0 0 0 0 0.3 0.27 Picea glauca 0 4.43 25.9 0.33 0 0 2 0 0 0 0 Plantago canescens 0 0 0 0 0 0 0 0 0.3 0.6 0.2 Poa glauca 0.53 0.14 0.13 0.07 0 0.4 0.2 0.13 0.3 2.3 0.27 Populus balsamifera 0 0 0 31.4 0 13.3 0 0 0 0 0 Potentilla nivea 0 0 0 0 0.75 1.67 0.03 2.53 0.3 1.55 0.73 Rosa acicularis 0 0 0 3.9 0 20 0.03 0 0.6 0.7 0.13 Salix arbusculoides 0 2.14 0.67 0 0 0 0 0 0 0 0 Salix glauca 0 24.9 0 0 0 0 0 0 0 0 0 Salix niphoclada 0 0 0 0 0 0 0.23 0 0 0 0 Saxifraga reflexa 0 0 0 0 0 0 0 0.23 0 0.45 0 Senecio hyperboreans 3.3 0.07 0.08 0.43 0 0 0.83 0 0.4 0.3 0 Senecio lugens 0 0 0.29 0 0 0 0 0 0 -0.05 0 Shepherdia canadensis 12.5 29.5 8.25 26.3 0 1 1 5 0 0 6.5 1.67 Solidago decumbens 0 0 0 0 0 0.8 0.17 0 0 0 0 Solidago multiradiata 0.5 0.82 0 0.03 0 0 0 0 0 0.65 0.47 Stellaria longipes 0 0 0 0 0 0 0 0 0 0.05 0 Zygadenus elegans 0 0 0 0 0 0.27 0 0 0 0 0 Mean Vascular Plant Cover for Disturbance Steppe Communities Stand # 1 4 7 1 0 1 1 21 2 3 2 4 2 8 # of quadrats 2 0 1 5 1 5 1 5 1 6 1 2 1 6 1 4 1 8 Achillea nigrescens 0 0 0 0 0 0 0.97 0.71 0.33 Agoseris glauca 0 0 0 0 0 0 0 0 0 Agropyron violaceum 12 4.23 0 2.77 0.13 0 0.09 11.4 0 Androsace septentrionalis 0.05 0 0 0 0 0 0 0 0 Anemone multifida 0 0 0 0 0 0 0 0 0 Arabis divaricarpa 0 0 0 0 0 0 0 0.14 0 Arenaria capillaris 0 0 0 0 0 0 0 0 0 Artemesia frigida 0 0 0 0 0 9.25 0 3.32 1.97 Artemesia Tilesii 8.71 2.3 0.07 3.03 19.1 0 31 6.21 7.31 Aster sibiricus 0 0 0 0 .' o 0 0.22 0 0 Bromus Pumpellianus 0.21 0 0 0 0 0 2.44 0.5 0 Calamagrostis purpurascens 0 .11 0 0 0 0 . 0 0 0 0 Castilleja raupii 0 0 0 0 0 0 0 0 0 Chenopodium capitatum 0 0 0 0 0.06 0 0 0 0 Conioselium cnidiifolium 0 0 0 0 0 0 0 0 0 Crepis nana 0 0 0.33 0 0 0 0 0 . 0 Elymus Calderi 0 0 0 0 0 0 0 0 1.11 Elymus innovatus 0 0 0 0 0 1 0 0 3.03 Epilobium angustifolium 2.79 0.03 0 0 3 0 0.28 0 0 Equisetum arvense 0 0 0 0 0.06 0 0 0 0 Festuca rubra 0 0 0 0 0 0 5.16 0.07 1.42 Hedysarum alpinum 0 .0 0 0 0 0 0.38 0 0 Hedysarum Mackenzii 0.26 0.1. 0.6 0.4 0.16 0.08 0.63 4.71 3.22 Juniperus communis 0 0.2 0 2 0 0 0 0 0 Linum Lewisii 2.37 0.67 0 0.27 0 0.04 0 2.43 0 Lupinus arcticus 0 0 0 0 0 0 0.06 0 0 Picea glauca 0 0 0 0 0.63 0 0 0 0 Plantago canescens 0 0 0 0 0 0 0 0 0 Poa arctica 0 0 0 0 0 0 0 0 8.08 Poa glauca 0.21 1.83 0 0 0.28 0.17 2 0.18 7.83 Potentilla nivea 0 0 0 0 0 0 0 0.43 0 Puccinnellia borealis 0 0 0 0 0.13 0 0 0 •0 Rosa acicularis 0 0 0 0 0.31 0 0 0 0 Salix alaxensis 0 0 0 0 0.16 0 0 0 0 Salix arbusculoides 0 0 0 0 0 0 0.13 0 0 Salix niphoclada 0 0 0 0 0.03 0 0 0 0 Senecio hyperboreans 2.34 0.9 0.33 2.17 0.06 0.04 0.03 0.43 2.03 Senecio lugens 0 0 0 0 0 0 0 0 0 Shepherdia canadensis 8.79 0 0 0 0 0 0 0 0 Solidago decumbens 0 0 0 0 0 0 0 0.14 0 Solidago multiradiata 0.32 0 0 0 0 0 0 0 0 Stellaria longipes 0 0 0 0 0 0 0 0 0 Mean Vascular Plant Cover for Disturbance Steppe Communities Stand # 30 32B 36 42 # of quadrats 1 5 4 1 5 1 5 Achillea nigrescens 0 . 4 3 1 3 2 . 6 7 0 . 0 3 Agoseris glauca 0 . 0 3 8 .75 0 0 Agropyron violaceum 0 0 4 . 8 3 0 . 0 3 Androsace septentrionalis 0 0 0 . 0 7 0 Anemone multifida 0 . .1 0 0 Arabis divaricarpa 0 0 0 0 Arenaria capillaris 0 0 0 . 1 3 0 Artemesia frigida 0 0 0 2 . 2 7 Artemesia Tilesii 5 . 6 7 2 .5 15.1 1 4 . 4 Aster sibiricus 0 0 0 0 Bromus Pumpellianus 0 5 .5 0 0 Calamagrostis purpurascens 0 0 0 0 Castilleja raupii 0 . 0 7 0 0 0 Chenopodium capitatum 0 0 0 0 Conioselium cnidiifolium 0 . 1 3 0 .5 , 0 0 Crepis nana 0 0 0 0 Elymus Calderi 0 4 . 7 5 0 0 Elymus innovatus 2 . 3 3 0 9 . 5 3 0 Epilobium angustifolium 0 0 . 7 5 0 . 0 7 0 Equisetum arvense 0 0 0 0 Festuca rubra 8 . 9 3 1.5 3 .2 0 Hedysarum alpinum 1 0 . 7 1.5 1.67 0 Hedysarum Mackenzii 0 .8 0 0 2 .3 Juniperus communis 0 0 0 0 Linum Lewisii 0 3 . 2 5 1.7 0 Lupinus arcticus 0 1 1 . 8 0 0 Picea glauca 0 0 0 0 Plantago canescens 1.53 1 0 . 1 7 0 .5 Poa arctica 0 0 1.03 0 Poa glauca 5 . 6 7 2 4 . 9 3 6 . 0 3 Potentilla nivea 0 8 .75 0 0 Puccinnellia borealis 0 0 0 0 Rosa acicularis 0 0 0 0 Salix alaxensis 0 0 0 0 Salix arbusculoides 0 0 0 0 Salix niphoclada 0 0 0 0 Senecio hyperborealis 2 . 8 2 . 7 5 3 . 2 7 0 . 8 3 Senecio lugens 0 . 8 7 0 0 0 Shepherdia canadensis 0 0 . 1 3 0 0 Solidago decumbens 0 0 0 0 Solidago multiradiata 0 0 . 1 3 0 0 Stellaria longipes 0 0 .5 0 0 Mean Vascular Plant Cover for Sparse Communities Stand # 18A 3 8 A 4 6 A 46B 46C 4 9 A 49B 5 7 # of quadrats 9 1 6 7 7 8 1 0 1 0 1 5 Artemesia Tilesii 0 . 6 1 9 . 3 1 2 . 6 4 7 . 4 3 0 . 6 3 10 .1 1 3 . 2 1 . 1 3 Betula glandulosa 1.11 0 0 0 0 0 0 0 Betula papyrifera 2 5 0 0 0 0 0 0 0 Calamagrostis inexpansa 0 6 . 9 4 10 .1 6 . 9 3 3 0 . 6 0 0 1 6 . 3 Elymus innovatus 1 . 7 8 6 . 6 6 0 0 . 2 9 0 1 . 2 5 2.1 1 .4 Epilobium angustifolium 0 . 1 7 1.5 2 . 1 4 1 . 4 3 0 .81 1 0 0 . 6 3 Festuca rubra 0 1 . 4 4 0 0 0 0 0 0 Picea glauca 1 . 7 2 0 . 0 6 0 0 0 0 0 0 Poa glauca 0 0 . 3 1 0 . 1 4 0 0 0 0 0 Salix glauca 0 . 2 2 0 0 0 0 0 0 0 Salix niphoclada 5 . 5 6 0 0 0 0 0 0 0 Senecio hyperboreans 0 0 . 1 3 0 0 0 0 0 0 Stellaria longipes 0 0 0 0 0 0.1 0 0 A P P E N D I X 3. Abio t ic data gathered from 71 plant communities at 6 camps (see Figure 1) in the Lower Anderson River valley, N W T . The % cover of bare soil and dead plant material were estimated by averaging estimates made in a number of randomly located 1 m 2 quadrats in the community. The position on slope of each community was subjectively assigned a value between 1 to 3, 1 being low on the valley side and close to the river or floodplain, and 3 being close to the r im of the valley. Equivalent latitude is calculated from slope, aspect, and latitude and is an expression of potential insolation. S o i l conductivity (-omhos/cm) and soil p H were measured i n the laboratory using rehydrated soi l samples. Relative soil temperature at 30 cm and relative depth to 0° C both vary between 1 and 3, 1 representing cold soils or greater distance to frozen soi l , and 3 being warmer soils. Communities are arranged by T W I N S P A N defined community types which are Tundra, Forest, Stable Steppe, Disturbance Steppe, and Sparse. This information is avail ible in spreadsheet form by contacting Dr . Greg Henry, Department of Geography, Universi ty of Br i t i sh Columbia . Environmental Data for Tundra Communities Community # 1 2 1 3 20 26 27 31 35 37 Camp A A B B B C C D Julian Day of Survey 187 187 193 196 196 203 206 209 Latitude 68.46 68.46 68.65 68.68 68.69 68.98 68.95 69.13 Longitude 128.71 128.72 128.43 128.52 128.51 128.40 128.40 128.43 Bare soil % cover 0.0 41.9 0.0 0.7 0.0 0.0 0.3 6.7 Dead material % cover 9.7 22.1 12.1 5.0 11.0 13.6 9.1 26.3 Slope (degrees) 38 40 29 1 7 1 8 0 14 1 8 Aspect (degrees) 325 340 330 65 25 n/a 345 135 Position on Slope 2.0 2.0 2.0 2.0 2.0 flat 2.0 2.0 Equivalent Latitude 66.7 69.1 75.3 69.4 81.0 69.0 81.7 54.2 Soil Conductivity 190 130 290 300 390 1400 250 250 Soil pH 4.7 4.1 4.2 6.0 5.4 7.0 6.0 5.1 Temp, at 30cm (Celcius) .0.0 9.0 2.0 0.3 1.0 2.6 2.3 1.3 Temp, at 30cm (relative) 1 2 1 1 1 1 1 1 Depth to 0 C (cm) 27.0 78.3 14.3 29.3 30.7 55.3 36.3 34.3 Depth to 0 C (relative) 1 2 1 1 1 2 1 1 Rooting Depth (cm) 12.0 13.3 20.0 11.3 15.3 18.0 15.0 22.0 Organic Layer depth (cm) 21.0 8.7 11.0 12.0 15.3 15.3 11.6 22.0 % Gravel (>2mm) 0.4 48.3 0.0 0.0 0.0 5.2 0.0 5.1 % Coarse Sand (>0.5mm) 1.3 3.6 0.2 0.7 0.5 3.2 '0.8 2.1 % Fine Sand (>0.068mm) • 8.4 10.6 0.2 3.6 3.1 17.9 1.1 2.1 % Clay & Silt (<0.068mm 89.9 37.5 99.7 95.8 96.4 73.8 98.1 90.8 Environmental Data for Tundra Communities Communi ty # 39 41 A 47 48A 48B 51 52 53A Camp D D E E E E E E Julian Day of Survey 211 213 219 220 220 222 222 228 Latitude 69.15 69.11 69.26 69.25 69.25 69.28 69.28 69.26 Longitude 128.25 128.30 128.23 128.23 128.23 128.48 128.48 128.23 Bare soil % cover 0.0 0.0 14.4 8.8 0.0 8.5 1.9 31.4 Dead material % cover 16.0 3.7 1.3 25.6 43.5 15.9 23.0 24.4 Slope (degrees) 1 5 0 26 30 35 1 9 20 1 7 Aspect (degrees) 335 n/a 315 345 345 344 135 40 Position on Slope 2.0 flat 2.0 2.0 3.0 1.5 1.5 1.5 Equivalent Latitude '80.5 69.1 71.9 78.8 74.2 84.3 52:5 76.8 Soil Conductivity 180 200 250 190 200 330 200 180 Soil pH 6.2 5.4 3.8 4.0 3.9 4.4 4.4 3.6 Temp, at 30cm (Celcius) 1.6 2.0 1.3 3.5 2.0 5.0 6.0 5.5 Temp, at 30cm (relative) 1 1 . 1 1 1 1 1 1 Depth to 0 C (cm) 50.0 38.0 33.6 38.5 29.5 52.3 62.7 50.5 Depth to 0 C (relative) 1 1 1 1 1 2 2 1 Rooting Depth (cm) 15.6 12.5 17.7 6.0 14.0 15.7 9.0 15.5 Organic Layer depth (cm) 21.0 9.5 8.7 6.0 10.5 6.7 4.0 0.0 % Gravel (>2mm) 26.6 0.4 0.0 0.0 0.0 9.2 24.3 0.0 % Coarse Sand (>0.5mm) 18.6 4.9 . 0.4 0.5 0.0 1.3 10.0 0.7 % Fine Sand (>0.068mm) 30.7 16.3 0.8 1.9 1.3 1.9 11.8 1.8 % Clay & Silt (<0.068mm) 24.2 78.4 • 98.8 97.6 98.7 87.6 53.9 97.5 Environmental Data for Tundra Communities Community # 53B 56 58 59 60 61 Camp E F F F F F Julian Day of Survey 228 227 227 227 228 229 Latitude 69.26 69.39 69.39 69.38 69.39 69.41 Longitude 128.23 128.14 128.14 128.13 128.13 128.26 Bare soil % cover 38.4 30.1 4.6 0.0 2.7 28.3 Dead material % cover 25.0 35.1 70.4 11.1 42.3 19.7 Slope (degrees) 1 7 29 30 0 24 23 Aspect (degrees) 330 268 35 n/a 180 28 Position on Slope 1.5 2.0 2.0 flat 2.0 1.5 Equivalent Latitude 79.7 54.4 72.7 69.4 45.4 79.4 Soil Conductivity 180 1300 235 220 200 500 Soil pH 3.6 3.6 4.3 5.2 4.4 3.4 Temp, at 30cm (Celcius) 7.5 9.0 4.0 2.0 4.7 6.0 Temp, at 30cm (relative) 2 2 1 1 1 1 Depth to 0 C (cm) 49.5 65.3 36.0 39.7 55.3 51.0 Depth to 0 C (relative) 1 2 1 1 2 2 Rooting Depth (cm) 21.0 20.0 23.3 18.0 23.0 18.3 Organic Layer depth (cm) 0.0 1.0 8.3 8.7 9.7 2.0 % Gravel (>2mm) ' 0.0 0.3 0.0 2.9 1.1 0.3 % Coarse Sand (>0.5mm) 0.4 1.0 0.4 5.9 2.6 1.4 % Fine Sand (>0.068mm) 1.5 3.0 1.8 45.4 4.7 1.9 % Clay & Silt (<0.068mm) 98.2 95.6 97.9 45.8 91.6 96.3 V Environmental Data for Forest Communities Community # 2 5 1 6 18B 1 9 22 25 Camp A A B B B B B Julian Day of Survey 187 186 193 193 193 194 196 Latitude 68.43 68.47 68.65 68.65 68.65 68.70 68.68 Longitude 128.84 128.85 128.43 128.43 128.43 128.50 128.51 Bare soil % cover 1.4 8.5 12.6 58.3 0.0 0.0 0.3 Dead material % cover 27.2 33.9 37.0 9.7 26.3 25.1 11.7 Slope (degrees) 25 35 25 42 25 1 6 0 Aspect (degrees) 288 160 240 310 335 145 n/a Position on Slope 2 1 1.5 2.5 2 2 flat Equivalent Latitude 63.0 34.3 50.1 58.1 79.6 54.4 68.7 Soil Conductivity 405 450 580 770 185 340 300 Soil pH 6.9 7.3 7.1 4.5 4.4 5.2 7.2 Temp, at 30cm (Celcius) 5.3 9 3.3 10.6 1.7 1.6 1.6 Temp, at 30cm (relative) 1 2 1 2 1 1 1 Depth to 0 C (cm) 67 63 75 120 32 36.3 34.7 Depth to 0 C (relative) 2 2 2 3 1 1 1 Rooting Depth (cm) 7.7 4.3 1 3 9.3 16.7 9.7 1 6 Organic Layer depth (cm) 7 6 5.7 0 20 15.7 19.3 % Gravel (>2mm) 0.2 0.5 40.1 0.2 4.1 0.0 10.3 % Coarse Sand (>0.5mm) 0.8 0.2 15.9 0.4 3.9 0.2 4.2 % Fine Sand (>0.068mm) 9.2 13.3 19.2 6.4 31.3 0.2 15.8 % Clay & Silt (<0.068mm) 89.8 86.0 24.8 93.1 60.7 99.6 69.7 Environmental Data for Forest Communities Community # 29 32A 34 38B 40 41B 43 Camp C C C D D D D Julian Day of Survey 199 204 206 210 211 213 214 Latitude 68.93 68.93 68.95 69.17 69.15 69.11 69.12 Longitude 128.40 128.40 128.40 128.25 128.25 128.30 128.29, Bare soil % cover 2.6 1.8 2.7 53.3 0.0 0.0 4.7 Dead material % cover 18.7 20.4 28.6 16.7 33.0 5.7 20.5 Slope (degrees) 1 5 1 6 1 8 21 25 0 1 5 Aspect (degrees) 230 230 270 170 290 n/a 320 Position on Slope 2 1.5 2 1.5 2.5 flat 2 Equivalent Latitude 57.3 56.4 62.6 48.3 63.9 69.1 76.7 Soil Conductivity 450 610 320 300 300 200 450 Soil pH 6.8 6.2 6.6 4.5 6.8 5.4 4.6 Temp, at 30cm (Celcius) 1.6 6 5 6.5 3.6 2 5.7 Temp, at 30cm (relative) 1 2 1 2 1 1 2 Depth to 0 C (cm) 36.7 61.5 59.3 77 40 53 66.3 Depth to 0 C (relative) 1 2 2 2 1 1 2 Rooting Depth (cm) 19.3 33 22.3 1 0 16.7 20 18.3 Organic Layer depth (cm) 21 2 . 8.7 1 1 7 20 8 % Gravel (>2mm) 0.0 0.7 0.0 0.0 48.4 0.4 0.0 % Coarse Sand (>0.5mm) 0.9 1.0 2.9 1.2 22.2 4.9 0.5 % Fine Sand (>0.068mm) 0.9 1.0 16.3 2.7 20.8 16.3 1.4 % Clay & Silt (<0.068mm) 98.2 97.4 80.8 96.1 8.5 78.4 98.1 Environmental Data for Forest Communities Community # 50 54 45 Camp E F E Julian Day of Survey 221 224 218 Latitude 69.26 69.38 69.26 Longitude 128.22 128.25 128.43 Bare soil % cover 7.3 3.3 0.0 Dead material % cover 22.3 58.0 42.3 Slope (degrees) 0 30 23 Aspect (degrees) n/a 179 165 Position on Slope flat 1 1.5 Equivalent Latitude 69.3 39.4 46.7 Soil Conductivity 520 190 250 Soil pH 5.7 6.7 6 Temp, at 30cm (Celcius) 5.6 1 0 3 Temp, at 30cm (relative) 1 2 1 Depth to 0 C (cm) 62.3 46.7 Depth to 0 C (relative) 2 3 1 Rooting Depth (cm) 16.7 23 1 8 Organic Layer depth (cm) 2.3 0.7 8 % Gravel (>2mm) 5.4 4.3 2.6 % Coarse Sand (>0.5mm) 2.3 4.3 7.0 % Fine Sand (>0.068mm) 5.8 62.7 17.3 % Clay & Silt (<0.068mm) 86.5 28.7 73.2 Environmental Data for Stable Steppe Communities Community # 3 6 8 9 14 1 5 17 33 Camp A A A A B B B C Julian Day of Survey 186 186 186 186 193 193 193 205 Latitude 68.47 68.47 68.48 68.48 68.65 68.65 68.65 68.99 Longitude 128.85 128.85 128.78 128.78 128.43 128.43 128.43 128.40 Bare soil % cover 22.0 2.3 22.4 38.7 67.0 12.8 43.3 42.3 Dead material % cover 25.8 45.0 19.7 22.3 0.4 29.7 31.8 20.7 Slope (degrees) 36 26 21 45 31 36 38 33 Aspect (degrees) 128 135 168 190 220 220 223 190 Position on Slope 2 2 2 2 3 2 2 2 Equivalent Latitude 38.3 46.2 47.7 23.7 40.9 36.1 34.8 36.2 Soil Conductivity 580 600 660 300 240 380 2900 320 SoilpH 7.5 6.5 6.8 7.3 7.3 7 6.7 7.2 Temp, at 30cm (Celcius) 14.3 5.6 4.6 8.6 21 13.7 17.3 16.3 Temp, at 30cm (relative) 3 1 1 2 3 2 3 3 Depth to 0 C (cm) 77 35 Depth to 0 C (relative) 3 2 1 3 3 3 3 3 Rooting Depth (cm) 15.8 20.3 1 0 1 8 24.3 19.3 25 19.3 Organic Layer depth (cm) 0 4 1 8 3.2 0 4.3 0 0.3 % Gravel (>2mm) 1.0 0.6 5.2 0.0 61.1 ,53.9 0.0 55.9 % Coarse Sand (>0.5mm) 2.0 2.0 0.9 0.2 6.9 7.7 1.1 11.8 % Fine Sand (>0.068mm) 8.5 8.1 4.3 2.2 11.7 11.1 7.5 15.8 % Clay & Silt (<0.068mm) 88.5 89.3 89.6 97.6 20.3 27.3 91.4 16.6 Environmental Data for Stable Steppe Communities Community # 44A 44B 55 Camp E E F Julian Day of Survey 216 216 224 Latitude 69.26 69.26 69.38 Longitude 128.43 128.43 128.25 Bare soil % cover 3.0 19.7 33.5 Dead material % cover 49.0 25.0 11.3 Slope (degrees) 23 23 34 Aspect (degrees) 165 165 186 Position on Slope 3 1 1 Equivalent Latitude 46.7 46.7 35.5 Soil Conductivity 250 250 290 Soil pH 6 6 7 Temp, at 30cm (Celcius) 1 5 1 5 19.7 Temp, at 30cm (relative) 3 3 3 Depth to 0 C (cm) Depth to 0 C (relative) 3 3 3 Rooting Depth (cm) 14.3 14.3 30 Organic Layer depth (cm) 6 6 0.7 % Gravel (>2mm) 61.2 61.2 29.3 % Coarse Sand (>0.5mm) 9.2 9.2 11.3 % Fine Sand (>0.068mm) 17.2 17.2 37.9 % Clay & Silt (<0.068mm) 12.4 12.4 21.5 Environmental Data for Disturbance Steppe Communities Community # 1 4 7 1 0 1 1 21 23 24 Camp A A A A A B B B Julian Day of Survey 186 186 186 186 186 194 194 194 Latitude 68.47 68.47 68.47 68.48 68.48 68.70 68.70 68.70 Longitude 128.85 128.85 128.85 128.78 128.78 128.50 128.50 128.50 Bare soil % cover 38.9 80.4 99.0 89.2 61.6 75.7 40.9 53.6 Dead material % cover 26.4 10.4 0.0 2.4 17.1 7.8 23.1 12.8 Slope (degrees) 28 42 50 40 28 1 5 22 27 Aspect (degrees) 140 120 180 180 195 190 145 190 Position on Slope 2 3 1.5 3 2 3 2.5 2.5 Equivalent Latitude 43.6 34.6 18.5 28.5 40.9 53.8 48.8 41.9 Soil Conductivity 2300 1000 440 2000 2200 2500 1300 1200 Soil pH 5.4 6.3 7.6 6.5 6.5 7.1 7.5 7.7 Temp, at 30cm (Celcius) 15 15 15.3 14.3 1 4 16.3 14.3 18.3 Temp, at 30cm (relative) 3 3 3 3 3 3 2 3 Depth to 0 C (cm) Depth to 0 C (relative) 3 3 3 3 3 3 3 3 Rooting Depth (cm) 17.7 18.2 0 3.3 3.3 1 6 1 4 -7 Organic Layer depth (cm) 0 0 0 0.08 0 0 0 0 % Gravel (>2mm) 0.1 0.1 5.0 0.0 6.9 0.0 0.0 0.0 % Coarse Sand (>0.5mm) 0.6 0.4 0.5 0.1 1.6 0.2 0.3 0.2 % Fine Sand (>0.068mm) 11.8 4.0 6.7 1.9 6.3 0.2 0.3 0.2 % Clay & Silt (<0.068mm) 87.4 95.4 87.8 98.0 85.2 99.6 99.5 99.5 Environmental Data for Disturbance Steppe Communities Community # 28 32B 30 36 42 Camp C C C D D Julian Day of Survey 199 204 203 209 214 Latitude 68.93 68.93 68.98 69.13 69.13 Longitude 128.40 128.40 128.40 128.43 128.41 Bare soil % cover 54.2 23.0 50.2 35.2 63.7 Dead material % cover 10.1 3.3 6.5 18.7 10.8 siope (degrees) 16 1 6 23 24 20 Aspect (degrees) 217 230 340 210 210 Position on Slope 3 1.5 2 2 2 Equivalent Latitude 54.9 56.4 82.3 46.7 50.6 Soil Conductivity 2250 610 1000 2400 2000 Soil pH . 6.9 6.2 7.1 7.2 7.1 Temp, at 30cm (Celcius) 1 3 1 6 9.6 15.6 1 5 Temp, at 30cm (relative) 3 3 2 3 3 Depth to 0 C (cm) 90.3 Depth to 0 C (relative) 3 3 3 3 3 Rooting Depth (cm) 14 1 0 18.7 4 0 Organic Layer depth (cm) 0 0 0 0 6.3 % Gravel (>2mm) 0.5 0.7 0.3 19.9 0.2 % Coarse Sand (>0.5mm) 0.3 1.0 0.3 2.7 0.2 % Fine Sand (>0.068mm) 0.8 •1.0 1.0 4.7 1.3 % Clay & Silt (<0.068mm) 98.5 97.4 98.5 72.6 98.3 ) Environmental Data for Sparse Communities Community # 18A 38A 46A 46B 46C 49A 49B 57 Camp B D E E E E E F Julian Day of Survey 193 210 218 218 218 221 221 227 Latitude 68.65 69.17 69.26 69.26 69.26 69.26 69.26 69.39 Longitude 128.43 128.25 128.43 128.43 128.23 128.22 128.22 128.14 Bare soil % cover 72.4 57.3 87.9 86.6 51.9 87.6 83.4 72.5 Dead material % cover 22.3 12.4 3.1 2.7 17.5 2.7 2.4 15.4 Slope (degrees) 34 21 20 24 23 40 40 28 Aspect (degrees) 270 170 300 220 1 0 45 225 248 Position on Slope 2 2 1.5 1.5 2 3 3 2 Equivalent Latitude 50.5 48.3 69.9 48.1 85.7 61.3 33.7 49.9 Soil Conductivity 770 2800 4000 4000 4000 2300 2000 5000 Soil pH 4.5 4.2 3.5 3.5 3.5 4.2 3.6 3.7 Temp, at 30cm (Celcius) 10.6 1 1 9 9 7 8 9.5 12.3 Temp, at 30cm (relative) 2 3 2 2 2 2 2 2 Depth to 0 C (cm) 120 92.5 69 81 62 62.5 56 90 Depth to 0 C (relative) 3 3 2 2 2 2 2 3 Rooting Depth (cm) 9.3 19.3 23 22 21 11.5 1 5 23 Organic Layer depth (cm) 0 0 0 0 0 0 0 0 % Gravel (>2mm) 0.2 13.4 0.7 0.7 0.7 0.3 0.3 0.2 % Coarse Sand (>0.5mm) 0.4 7.1 1.1 1.1 1.1 0.6 0.6 0.8 % Fine Sand (>0.068mm) 6.4 12.2 1.4 1.4 1.4 1.2 1.2 2.9 % Clay & Silt (<0.068mm) 93.1 67.3 96.7 96.7 96.7 97.8 97.8 96.0
Thesis/Dissertation
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Botany
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Graduate
Potential insolation and plant communities through treeline in the Lower Anderson River valley, N.W.T., Canada
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