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UBC Theses and Dissertations

Studies of the effects of logging on stream cutbanks and of the occurrence of cutbanks as related to… Toews, David Andrew Alan 1975

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STUDIES OF THE EFFECTS OF LOGGING ON STREAM CUTBANKS AND OF THE OCCURRENCE OF CUTBANKS AS RELATED TO LAND CHARACTERISTICS by DAVID ANDREW ALAN TOEWS B.Sc, University of British Columbia, 1968 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF vMASTER OF SCIENCE in the Faculty of Forestry (Forest Hydrology) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA Ap r i l , 1975 In present ing th is thes is in p a 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 sha l l make it f r ee 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 representa t ives . It is understood that copying or p u b l i c a t i o n of th is thes is fo r f i n a n c i a l gain sha l l not be allowed without my wri t ten permission. Department of The Un ivers i ty of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date *foU^ / . I?7.S~ f J i ABSTRACT A study was undertaken to determine the effect of streambank logging practices on salmonid cover in four streams in north central British Columbia. Undercut streambanks were chosen for measurement since they constitute a component of cover that is easily disturbed by logging activity. Sections of streams flowing through winter and summer logged regions were classified as either heavily or moderately disturbed and compared to adjacent unlogged sections with regard to stream widths and cutbank areas. Logging resulted in increased stream widths and de-creased cutbank areas particularly in the heavily disturbed sections. Results indicate that skidder operators should avoid activity in and immediately adjacent to streams. For winter logging, this can be fac-i l i t a t e d by marking streams prior to snowfall. A second study was undertaken in an attempt to develop a model for stream surveys which would permit prediction of cutbank formation by identifying associated land and stream characteristics on a i r photos. With the use of 1:63,000 air photographs, several streams in the Robert-son River Watershed on Vancouver Island were divided into homogeneous units on the basis of the landform adjacent to the stream, valley shape, and stream pattern. Nine sections were compared with regard to cutbank area. No simple relationships between land and stream characteristics were found, making i t impossible to develop a reliable model for pre-dicting potential bank cover with the use of a i r photos alone. However, i t was concluded that i t is valid to use the survey techniques described i i t o d i v i d e streams i n t o r e l a t i v e l y homogeneous u n i t s and determine l o c a t i o n s w a r r a n t i n g ground c h e c k s . i i i TABLE OF CONTENTS ABSTRACT ACKNOWLEDGEMENTS LIST OF TABLES LIST OF FIGURES PREFACE Chapter I INTRODUCTION THE STUDY AREA A. Criteria for the Study Site B. Description of the Area 1. Location 2. Geology 3. Vegetation 4. Flow characteristics of streams C. Logging Techniques MATERIALS AND METHODS RESULTS AND DISCUSSION A. Extent of Disturbance of Streambanks B. Width and Bankful Width Measurements 1. Karolyn Creek 2. Rosanne Creek 3. Pseudohah Creek 4. Hah Creek C. Cutbank Areas i v TABLE OF CONTENTS CONT'D Page 1. Karolyn Creek 29 2. Rosanne Creek 31 3. Pseudohah Creek 32 4. Hah Creek 32 5. Comparison with results in the literature 33 D. Composition of the Cutbanks 34 MANAGEMENT IMPLICATIONS 36 A. Winter Logging 36 B. Summer Logging 36 Chapter II INTRODUCTION 38 DESCRIPTION OF THE STUDY AREA 42 A. Location 42 B. Geology 42 C. Vegetation 42 MATERIALS AND METHODS 45 RESULTS AND DISCUSSION 49 A. Section 1 49 B. Section 2 54 C. Section 3 54 D. Section 4 59 E. Section 5 59 F. Section 6 62 G. Section 7 67 V TABLE OF CONTENTS CONT'D Page H. Section 8 67 I. Section 9 72 J. General Discussion 74 SUMMARY 78 REFERENCES CITED 79 APPENDIX I 82 APPENDIX II 84 ACKNOWLEDGEMENTS I would l i k e to thank my a d v i s o r , Dr. R.P. W i l l i n g t o n , f o r h i s d i r e c t i o n and encouragement; Dr. J.P. Kimmins, Dr. T.G. N o r t h c o t e , and Dr. P.G. Haddock f o r r e v i e w i n g the m a n u s c r i p t ; Mr. B a r r y Lam f o r a s s i s t i n g d u r i n g the f i e l d work; Dr. W.B. S c h o f i e l d f o r i d e n t i f y i n g the mosses; Mr. Tom See and Dr. J u l e s Demaerschalk f o r h e l p i n g w i t h the s t a t i s t i c a l a n a l y s i s ; Mr. Dennis A r a k i o f Northwood Pulp and Timber L t d . f o r a s s i s t a n c e i n l o c a t i n g s t u d y s i t e s ; Mr. Rod B o e n i s c h f o r d r a f t i n g the diagrams; and Mrs. L e s l i e Biddlecombe f o r the t y p i n g . The s t u d y was s u p p o r t e d by the Committee on R e s e a r c h , U n i v e r s i t y o f B r i t i s h Columbia. Northwood Pulp and Timber p r o v i d e d room and board d u r i n g the f i e l d work p e r i o d i n n o r t h c e n t r a l B.C. I would l i k e t o thank my w i f e , Judy, f o r a s s i s t a n c e d u r i n g p r e p a r a t i o n o f the f i n a l m a n u s c r i p t . v i i LIST OF TABLES Table Page 1 Length of stream sections surveyed in the study (metres) 22 2 Percentage of the streambanks (by length) within the logged areas which are disturbed by logging activity (classified as heavily disturbed) in summer and winter logged sections. 22 3 Mean widths and bankful widths of Karolyn Creek in winter and summer logged study sections and adjacent forested sections 24 4 Mean widths and bankful widths of Rosanne Creek in summer and winter logged sections and adjacent forested areas 26 5 Mean widths and bankful widths of Pseudohah Creek 27 6 Mean widths and bankful widths of Hah Creek 29 7 Mean cutbank area per 25 metres section of Karolyn Creek (metres /25 metre section of stream) 31 8 Mean cutbank area per 25 metres section of Rosanne Creek (metres /25 metre section of stream) 31 9 Mean cutbank area per 25 metre section of Pseudohah Creek (metres2/25 metre section of stream) 32 10 Mean cutbank area per 25 metre section of Hah Creek (metres^/25 metre section of stream) 33 11 Description of landform units 46 12 Land and stream characteristics of the study 50 reaches 13 Measurements of stream characteristics of the study reaches 51 14 Duncan's Multiple Range Test of cutbank areas 74 v i i i LIST OF TABLES CONT'D. Table Page 15 Summary of section characteristics 75 ix LIST OF FIGURES Figure Page 1 Map showing the location of study streams with respect to nearby rivers with an inset showing the location of the study area in B.C. 10 2 Map of the stream study sections on Rosanne and Karolyn Creeks and the adjacent cutting units 11 3 Map of the stream study sections on Hah and Pseudohah Creeks and the adjacent cutting units 12 4 Examples of heavily disturbed sections of Rosanne Creek including: A. the site of a skidder crossing; and 17 B. heavy debris accumulations 17 5 A cutbank in the upstream control section of Pseudohah Creek 19 6 A typical section of overhanging cutbank in the control section of Pseudohah Creek 20 7 A. A heavily disturbed section of Karolyn Creek flowing through coarse, bouldery material 25 B. An area of Kenneth Creek flowing through s i l t y lacustrine material with extensive streambank erosion 25 8 Stream diversions caused by debris accumulations in the winter logged section of Rosanne Creek 28 9 Heavy accumulations of debris above Pseudohah Creek 30 10 Map of the Robertson River watershed showing the study sections 43 11 Section 1 - Robertson River. 52 A. Location of section 1 in the watershed. B. Landformmap. The reach z-z 1 was sampled for cutbanks. C. Valley cross section at x-x' . The ratio of vertical to horizontal axis is 1:2. X LIST OF FIGURES CONT'D. Figure Page 12 Section 1 - Robertson River. 53 A. Schematic representation of the channel cross section at y-y' of the landform map. (Fig. 11.B). B. Photograph taken near y-y' of the landform map (Fig. 11.A). A large quantity of coarse bedload has been deposited in this section. 13 Section 2 - Robertson River. 55 A. Location of section 2 in the watershed. B. Landform map. The reach z-z 1 was sampled for cutbanks. C. Valley cross section at x-x!. 14 Section 2 - Robertson River. 56 A. Schematic representation of the channel cross section at y-y' of the landform map. (Fig. 13.B). The forest floor is too high above the channel to form cutbanks. B. Photograph looking, downstream near y-y' (Fig. 13.B). 15. Section 3 - Robertson River. 57 A. Location of section 1 in the watershed. B. Landform map. The reach z-z' was sampled for cutbanks. C. Valley cross section at x-x'. 16. Section 3 - Robertson River. Schematic representation of the channel cross section at y-y' of the landform map (Fig.15.B). 58 xi LIST OF FIGURES CONT'D. Figure Page 17 Section 4 - Robertson River. 60 A. Location of section 4 in the watershed. B. Landform map. The reach y-y' was sampled for cutbanks. The channel pattern of the upstream part of section 4 is under bedrock control. C. Valley cross section at x-x'. 18 Section 4 - Robertson River. 61 Schematic representation of the channel cross section at z-z' of the landform map (Fig. 17.B). 19 Section 5 - Robertson River. 63 A. Location of section 5. B. Landform map. The reach z-z' was sampled for cutbanks. C. Valley cross section at x-x'. 20 Section 5 - Robertson River. 64 Schematic representation of the channel cross -section at y-y' of the landform map (Fig. 19.B). Although the valley bottom is extremely narrow, small pockets of alluvium have been deposited adjacent to the channel. 21 Section 6 - Unnamed Creek. 65 A. Location of section 6 in the watershed. B. Landform map. The reach z-z' was sampled for cutbanks. C. Valley cross section at x-x'. 22 Section 6 - Unnamed Creek. 66 Schematic representation of the channel cross section at z-z' of the landform map (Fig.21.B). Cutbanks are found on both sides of the channel for most of this section. Dense shrub vegetation borders the stream. x i i LIST OF FIGURES COOT^D. Section 7 - Nineteen Creek. A. Location of section 7 in the watershed. B. Landform map. The reach z-z' was sampled for cutbanks. C. Valley cross section at x-x 1. Section 7 - Nineteen Creek. A. Schematic representation of the channel cross section at y-y' (Fig. 23.B). The valley f l a t consists of coarse rubble. The few cutbanks in the study reach are formed under roots or logs embedded in the streambank. B. Photograph looking upstream at y-y' (Fig.23.B) Sections 8 and 9 - Swamp Creek and Sixteen Creek. A. Locations of sections 8 and 9 in the watershed B. Landform map. Section 8 is located between 1 and 2. Section 9 is located between 3 and 4. Reaches v-v' and z-z 1 were sampled for cutbanks. C. Valley cross section at x-x 1. Section 8 - Swamp Creek. Schematic representation of the channel cross section at t - t ' of the landform map.(Fig.25.B). Section 9 - Sixteen Creek. A. Schematic representation of the channel cross section at y-y' of the landform map (Fig.25.B) B. Photograph looking upstream at y-y' (Fig.25.B) Cutbanks have formed under the roots of the alder trees adjacent to the channel. 1 PREFACE Whenever logging adjacent to streams occurs, the streambanks are in danger of being physically damaged and, because physical changes in streams affect salmonid habitat, such logging is potentially hazard-ous to fi s h (Chapman, 1962; Hall and Lantz, 1969; Burns, 1972). A number of studies have found that population size of sal-monids is positively correlated with the amount of cover available (Boussu, 1954; Gunderson, 1969; Lewis, 1969; Chapman and Bjorrn, 1969; Hunt, 1971). This relationship of salmonid populations to suitable habitat is not simple, since a number of variables besides cover are important in determining fish populations (Allen, 1969). Further, cover requirements may vary with species of salmonid (Hartman, 1965; Allen, 1969; Chapman and Bjorrn, 1969), interaction among species (Hartman, 1965; Chapman and Bjorrn, 1969), season (Hartman, 1965; Chapman, 1966), and fish size (Allen, 1969; Chapman and Bjorrn, 1969). The present study was undertaken in order to ascertain whether streambank logging practices adversely alter available cover. Chapter I deals with research in north central British Columbia re-lated to this problem. A particular component of cover, stream cutbank, was selected for measurement. Undercut banks were defined for this study as any projection of the bank protruding at least 15 centimeters over the stream surface.^ Undercut banks are a portion of what might _ This figure was used by Hunt (1971) when measuring cover. 2 constitute cover; also important are overhanging vegetation, submerged objects (rocks, logs), f l o a t i n g and fixed debris (log jams, stumps), and water turbulence. Undercut banks were chosen for measurement because they constitute a component of cover that i s e a s i l y disturbed by logging a c t i v i t y . Preliminary observations indicated that i n second and t h i r d order streams where there i s l i t t l e active erosion, re-estab-lishment of cutbanks i s l i k e l y to take a number of years, whereas some other components of cover (e.g. overhanging vegetation) are re-established more rapidly and can be adjusted r e l a t i v e l y quickly by r e h a b i l i t a t i o n measures. The occurrence of cutbanks i s a r e s u l t of interactions between the stream and the channel bank material. Chapter I I relates bank mat-e r i a l s and landforms to the occurrence of cutbanks on a watershed on Vancouver Island. Land surveys of wildlands i n Canada generally employ a bio-physical system as a basis for mapping; the mapping i s done on air- photos using photo features related to geomorphology and s u r f i c i a l deposits as w e l l as vegetation (Lacate, 1969). A similar system i s used i n Chapter I I ; the streams of the watershed were categorized into homogeneous units on the basis of stream pattern, v a l l e y shape, and landform adjacent to the streams. Reaches of streams with these s i m i l a r i t i e s could be expected to have comparable cutbank cha r a c t e r i s t i c s since the flow patterns and the bank materials adjacent to the section of stream are somewhat s i m i l a r . This i s a similar approach to that taken by P l a t t s (1974) when he t r i e d to relate factors relevant to f i s h habitat to the geomorphic mapping of an area. The aim in Chapter II is to develop an approach to surveys of streams that takes the land component into account. When land use activities adjacent to streams are being contemplated, the sensitivity to damage of the particular reach of stream is important in addition to the biological values of the streams. The f i e l d work in north central British Columbia was done during July and August, 1973 with the help of a f i e l d assistant. The f i e l d work on Vancouver Island took approximately five days and was done in August, 1974. 4 CHAPTER I INTRODUCTION This study examined stream morphology and the stream land i n t e r -face dealing p r i m a r i l y with the fate of undercut streambanks a f t e r logging and the implications f o r f i s h h a bitat. The purpose was to document a change i n a p a r t i c u l a r component of cover, undercut banks, i n four streams i n north c e n t r a l B r i t i s h Columbia. The s p e c i f i c objectives of t h i s study were: a. to determine the e f f e c t of logging on the channel dimensions of small streams flowing through erodible materials; b. to determine the e f f e c t of logging on the area of undercut streambanks; c. to measure the extent of p h y s i c a l disturbance of the stream-banks by logging equipment; d. to compare the e f f e c t s of winter and summer logging on the disturbance of streambanks; e. to examine the ph y s i c a l composition of the undercut banks ( i . e . whether the mosses, the forb r o o t s , the shrub r o o t s , the tree roots, or the s o i l was important i n binding the streambanks); and f. to determine which stream and watershed c h a r a c t e r i s t i c s are important i n assessing a stream's s e n s i t i v i t y to logging damage. 5 A number of studies have demonstrated a positive correlation between salmonid populations and available overhead cover. The methods which generally have been used are: 1) to compare fish populations in adjacent sections of streams with differing amounts of cover; and 2) to compare the populations in a given section of stream before and after manipulation of cover. Boussu (1954), Gunderson (1968), and Elser (1968) used the f i r s t approach, measuring the amount of cover in different reaches of a stream and relating this cover to fi s h populations. Hunt (1971), using the second approach, was able to significantly increase brook trout (Salvelinus fontinalis) populations in a given area by building cover devices and deflectors to scour deeper pools. Similarly, Saunders and Smith (1962) found, in a short term study, that the number of one-year-old and older brook trout was approximately doubled with installation of cover devices and current deflectors. Overhead cover functions primarily to enable predator avoid-ance. However, during the winter, i t could also serve as a refuge to prevent unprofitable energy expenditure and physical damage (Chapman and Bjorrn, 1969). A number of variables including species, fish size, and season, influence the relationship between cover and salmonid populations. The importance and role of cover, varies with the species and size of salmonid. Stewart (1970) in a study of physical factors affecting trout density in a small stream, found that mean section depth and under-water, overhanging rock cover were important in determining brook trout density and rainbow trout (Salmo gairdneri) density. Undercut banks and 6 areas of deep turbulent water were of importance to brook trout density, but not to rainbow trout density. Bustard (1973), in a study of winter habitat, found that steelhead fry were most often associated with rubble whereas coho and older steelhead were associated with upturned roots, logs, debris, and overhanging banks. Butler and Hawthorne (1969), in a laboratory study, found that brown trout (Salmo trutta) u t i l i z e over-head cover to a greater extent than do rainbow trout. The importance of cover also varies with season or, more specifically, temperature. A number of studies (Hartman, 1965; Everest, 1969; Bustard, 1973) indicate that juvenile salmonids occupy different habitat areas in summer than in winter, being more closely associated with cover and exhibiting a characteristic hiding response with lower temperatures. Although there is considerable variation with location and species, Chapman and Bjorrn (1969) cite references from around the world where salmonids take on this hiding behavior at temperatures below 7 degrees Celsius. Similarly, in their own work they found that for young steelhead and chinook salmon (Oncorhynchus tshawytscha) a decrease in temperature resulted in increased hiding behavior in a flume with rock substrate (Chapman and Bjorrn, 1969). Suitable winter cover may be quite different from summer cover for the same species. Coho, for example, have been found associated with bank cover and submerged logs and stumps in the winter (Hartman, 1965; Bustard, 1973) while during their f i r s t summer they occupy shallow waters in small bays at the stream margin and small, shallow r i f f l e s (Hartman, 1965). The amount of effective cover w i l l vary with the level of water in a stream. Kraft (1972) mapped overhead cover on streams in which water 7 flow was a r t i f i c i a l l y reduced. With flow reductions of 25 to 75 percent of long term base flow, loss of cover was not substantial. A cover loss of 39 to 56 percent was reported with 90 percent flow reduction. However, Kraft (1972) concluded that overhead cover was not greatly influenced by flow reduction. In order to measure cover useful for salmonids, i t is necessary, therefore, to define species and size of f i s h , season, and perhaps stream-flow level at the site in question. 8 THE STUDY AREA A. Criteria for the Study Site In the planning stages the following c r i t e r i a were suggested as requirements of the study area. a. The stream should flow through a forested area and then through a clearcut. b. The stream should be small enough in order to f a c i l i t a t e measurement of the cutbank. c. The stream should have obvious undercut banks. d. The terrain and s u r f i c i a l geology of the forested stand and the clearcut should be reasonably similar. The lower mainland and Vancouver Island were explored for study sites. However, there were few areas l e f t unlogged in which small streams flowed through a l l u v i a l materials. The Slim-Tumuch watershed, located 100 kilometres east of Prince George, was therefore chosen. Advantages of this site were: there were at least four small streams in the area that would be suitable for the study; a co-operative study by the Fish and Wildlife Branch and the Fisheries Service of the Department of the Environment was already in progress in the area; the Forestry Department of Northwood Pulp and Timber Ltd. was interested in the study and offered to provide assistance; the terrain in logged and unlogged sections of the streams was reasonably similar. 9 B. Description of the Area 1. Location. The locations of the four streams are shown in Figure 1 while Figure 2 shows the locations of the logged sections on Rosanne and Karolyn Creeks and Figure 3 shows Hah and Pseudohah Creeks. The winter logged section on Karolyn is compared to a downstream control 90 metres in length where the stream passes through a buffer strip adja-cent to Centenial Creek. An upstream section above the winter logged clearcut i s compared to the winter logged area. On Rosanne Creek the control section is above the summer logged section. A downstream control was not used because the stream passes through a swamp in this section. Karolyn and Rosanne Creeks do not con-tain indigenous populations of salmonids. Hah and Pseudohah Creeks drain into the Bowron River.^ An upstream and downstream control were established on Pseudohah. Two adja-cent sections are compared on Hah Creek. These streams have natural pop-ulations of rainbow trout. 2. Geology. The area is classified by Holland (1964) as being in the Fraser physiographic region. The terrain exhibits abundant evidence _ Both of these creeks have been referred to as "Hah" Creek. In the report of Slaney, Chamberlin and Halsey (1973), an unnamed stream was re-ferred to as "Hah" Creek. Another stream located north of this stream is labelled "Hah" Creek in the National Topographical Series. To distinguish between these two streams, the unnamed stream w i l l be referred to as "Pseudohah". Hah Creek runs through the area assigned cutting permit 307; Pseudohah runs through the area assigned cutting permit 311. Figure 1. Map showing the location of study streams with respect to nearby rivers with an inset showing the location of the study area in B.C. Figure 2. Map of the stream study sections on Rosanne and Karolyn Creeks and the adjacent cutting units. 12 Figure 3. Map of the stream study sections on Hah and Pseudohah Creeks and the adjacent c u t t i n g u n i t s . 13 of glaciation. The s u r f i c i a l material surrounding upper Rosanne and Karolyn Creeks is colluvium. The lower portions are surrounded by org-anic and a l l u v i a l materials. The study sections on Hah and Pseudohah Creeks run through coarse t i l l materials. 3. Vegetation. The study streams are in the Interior Western Hemlock Biogeoclimatic Zone proposed by Krajina (1965). Principal conifer tree species are white spruce, subalpine f i r , and western hemlock.^ Deciduous species are mainly speckled alder, black cottonwood, and trembling aspen. The principal trees found along the streambanks are alder, willow, white spruce, and subalpine f i r . The shrub component is dense with black twinberry, thimbleberry, and red raspberry. Adjacent to the stream there is a dense layer of forbs and mosses. In this area the mosses appear to play an important role in protecting the streambanks from erosion. 4. Flow characteristics of streams. The flow variations in the study streams are not as pronounced as they are on the coast despite reasonably high r a i n f a l l s . The fluctuations in flow are exemplified by measurements taken in Centenial Creek below the confluence of Rosanne and Karolyn Creeks. The area drained at this point is approximately 50 square kilometres. Freshets in the spring and f a l l have been measured at 4.5 and 5.0 m /s respectively. _ The s c i e n t i f i c and common names of plant species are listed in Appendix 1. 14 The baseflow in the summer is approximately 0 . 4 m /s. The stream has risen to 1.7 and 2 . 3 m /s during the summer but shows a slow response to precipitation because of a moisture d e f i c i t in the s o i l . The flow characteristics are somewhat similar in Rosanne and Karolyn Creeks. Spring maximum and minimum flows, in the streams in 1973 were as follows: Area Maximum Minimum Rosanne 11 .7 km2 1.10 m3/s 0 .11 m3/s Karolyn 4 . 4 km2 0 .91 m3/s 0 . 03 m3/s The maximum and minimum flows for July and August in 1973 were as follows: Rosanne 11 .7 km2 0 . 2 0 m3/s 0 . 06 m3/s 2 o o Karolyn 4 . 4 km 0 .42 m°/s 0 . 006 i r i/s The areas indicated are approximate since the watershed divides were d i f f i c u l t to define on the topographic maps. C. Logging Techniques Two distinct types of logging take place in the northern inter-ior. On poorly drained organic, a l l u v i a l , and lacustrine s o i l s , the logging takes place in the winter when the ground is frozen and there is a snow cover. If the stream is too large to cross directly, a temporary bridge i s installed using available logs. If the stream is small i t is often not seen and logging proceeds as i f i t were not there. Many of the 15 problems with this type of logging arise during spring break-up. With skidder tractors, the logs are yarded as tree lengths to a landing where they are limbed and bucked. During the summer season, logging is carried out on the well drained, steeper terrain which provides better traction and a firm footing for skidding equipment. Often the skidding pattern is regulated by the shape of the terrain. Problems can arise where the skid roads are adja-cent to the stream. The methods used in the winter logged study sections are typ-i c a l of those used in the area. Special guidelines were used on the summer harvested areas on Rosanne and Karolyn Creeks. These guidelines (as reported by Slaney, Chamberlin, and Halsey, 1973) are: a. Where feasible, f a l l trees away from, streambanks. b. Locate skid t r a i l s so as to avoid in-stream ac t i v i t y by placing them parallel to the stream and approximately 5 m. (15 ft.) away. c. Contour skid t r a i l s to adjacent slopes. d. Employ a different contractor on each side of the stream. Both contractors are to u t i l i z e similar operating procedures. Since the contractors knew a watershed study was to take place, extra care was probably exercised when yarding along Rosanne and Karolyn Creeks. There was some manual removal of debris from these streams by the con-tractors. The logging practices employed on Pseudohah and Hah Creeks were more typical of the region i n that l i t t l e concern was given for stream-bank protection. 16 MATERIALS AND METHODS Various parameters of channel morphology were studied in the f i e l d and the following measurements were made: a. Each 25 metre section of stream was classified as either heavily or moderately disturbed. If there was obvious disturbance of the streambank by logging equipment, timber f e l l i n g , or road building, the stream was classified as heavily disturbed. The remaining portion of the stream which showed less evidence of disturbance by logging was classified as moderately disturbed. Examples of sections of the stream classified as heavily disturbed are shown in Figure 4. Figure 8.B is an example of a section of stream cla s s i f i e d as moderately disturbed. b. The widths, bankful widths, and depths of the streams were measured every 5 metres except in some relatively uniform or inaccessible areas where measurements were made every 25 metres. On Rosanne Creek measurements were taken every 25 metres. The measurements were made during low summer flows in July and August of 1973. Bankful width is the width measured between the high water raarks on the stream-banks . c. The plan areas of the undercut streambanks were measured. The length of each cutbank was measured. The width of the cutbank was measured every 50 cm. along i t s length by pro-bing under the cutbank with a metre stick. The cutbank area was computed using the formula 17 F i g u r e 4. Examples o f h e a v i l y d i s t u r b e d s e c t i o n s o f Rosanne Creek i n c l u d i n g : A. the s i t e o f a s k i d d e r c r o s s i n g ; and B. heavy d e b r i s a c c u m u l a t i o n s . 18 Area = Length x Summation of widths (Number of widths + 1) The numerator is divided by the number of width readings plus one to account for 0 width at each end. d. Samples 20 cm. wide were taken from 31 typical cutbanks. The total volume of s o i l in the sample and the total lengths of roots in 6 size classes (0.3 - 0.5 cm; 0.5 cm 1.0 cm; 1.0 cm - 2.0 cm; 2.0 cm - 3.0 cm;~>3.0 cm) were measured. Using these data, root volume as a percentage of total s o i l volume of the samples was computed. The experimental design assumes that widths, bankful widths, and cutbank areas are similar in harvested and control sections before logging and any differences between stream sections are the result of harvesting a c t i v i t i e s . Notes were taken on the vegetative composition of these cut-banks. Typical cutbanks are shown in Figures 5 and 6. Observations of the following were recorded: a. Damage obviously resulting from logging activity within each 25 metre section was noted, e.g. introduction of logging debris, evidence of skidding in the stream, or post-logging scouring of the banks. b. Instances of natural slumping or debris accumulations in the control section were recorded. c. Presence and extent of s i l t accumulation in the streams were noted but not measured. 1 9 Figure 5. A cutbank i n the upstream control section of Pseudohah Creek. 20 Figure 6. A t y p i c a l s ection of overhanging cutbank i n the co n t r o l section of Pseudohah Creek. The differences in cutbank areas and in stream widths were compared using analysis of variance completely randomized design (Snedecor and Cochran, 1967). A Duncan's multiple range test was used to test for differences between individual means (Walpole, 1968). In those instances where only two groups were being compared a group com-parison test (t - test) was used. Since both of these tests require homogeneous variances, Bartlett's test for homogeneous variances was carried out after performing logarithmic transformations. In those instances where the variances were heterogeneous, a t-test for data with heterogeneous variances and unequal sample size was used (Snedecor and Cochran, 1967). A significance level of 0.05 was used throughout the s t a t i s t i c a l analysis. 22 RESULTS AND DISCUSSION A. Extent of Disturbance of Streambanks The percentage of the streambanks disturbed by logging activity varied between 12% and 83% (Table 1 and 2). Table 1. Length of stream sections surveyed in the study (metres) Karolyn Rosanne Pseudohah Hah Winter Logged Heavily Disturbed Moderately Disturbed Control Summer Logged Heavily Disturbed Moderately Disturbed Control 75 225 90 200 450 400 408 86 None 275 350 500 NA NA NA 575 1125 600 50 350 325 NA NA NA * NA - Not applicable, Table 2. Percentage of the streambanks (by length) within the logged areas which are disturbed by logging activity (classified as heavily disturbed) in summer and winter logged sections. Stream Winter Logged Summer Logged Karolyn Rosanne Pseudohah Hah 25 83 NA 12 31 44 34 NA 23 Both the highest and lowest values occurred in the winter logged sections suggesting that the amount of disturbance is probably dependent on the snow level during the harvesting operation. An obvious skid t r a i l cros-sing on Rosanne Creek (Fig. 4.A) indicates that snow did not completely cover the stream during logging and consequently a considerable quantity of debris accumulated in this section (Fig. 4.B). This debris caused diversions and scouring of the stream during the high flows of spring break-up. Hah Creek, with only 12% of i t s length disturbed, probably had a deep covering of snow during logging. The summer logged sections in the three streams have a r e l -atively constant percentage of their length heavily disturbed (between 31% and 44%). B. Width and Bankful Width Measurements 1. Karolyn Creek. The widths and bankful widths of the winter harvested section (both moderately and heavily disturbed) are significantly larger than in the control section (Table 3).^ These differences may or may not be attributable to logging ac t i v i t y in the experimental section. For example, the control section had a well-defined channel as compared to a slightly braided pattern in the harvested section, which suggests that differences in stream width and bankful width may have occurred prior to logging. The large difference in bankful width between the heavily disturbed and the moderately disturbed areas may be attributed -A P=0.05 has been used throughout this study to test for significant differences. 24 Table 3. Mean widths and bankful widths of Karolyn Creek in winter and summer logged study sections and adjacent forested sections. Winter Logged Control Moderately Heavily Disturbed Disturbed Stream width (metres) 2.50 2 .99 3.99* Bankful width (metres) 3.68 5.58 10.41 Summer Logged Control Moderately Heavily Disturbed Disturbed Stream width (metres) 3.38 3.43 4.07 Bankful width (metres) 5.10 4.64 7.48 * The means connected by a line are not significantly different at P=0.05; those not connected are significantly different. to a skidder crossing site in an area of finely textured, poorly drained s o i l s . During winter harvesting, this stream was not visible and skidding took place as i f i t were not there. In comparing the summer logged section with i t s control, i t would seem that logging had l i t t l e affect except possibly where bankful widths were increased in the heavily disturbed section. However, since the stream flows through a V-shaped gully for most of the summer har-vested section, skidder activity adjacent to the channel did not occur. Where bankful widths were significantly wider (i.e. in the heavily dis-turbed section) there was a skid road directly in the stream as shown in Figure 7.A. 25 F i g u r e 7. A. A h e a v i l y d i s t u r b e d s e c t i o n o f K a r o l y n Creek f l o w i n g through c o a r s e , b o u l d e r y m a t e r i a l s . B. An a r e a o f Kenneth Creek f l o w i n g through s i l t y l a c u s t r i n e m a t e r i a l w i t h e x t e n s i v e streambank e r o s i o n . The summer harvested section of Karolyn Creek with i t s coarse bouldery material is not as susceptible to widening as the winter har-vested section of Karolyn Creek with i t s a l l u v i a l material, or nearby Kenneth Creek with lacustrine material (Figure 7.B). 2. Rosanne Creek. Widths i n the heavily disturbed section were almost double those in the moderately disturbed section (Table 4).^" Despite these apparent differences, results were not s t a t i s t i c a l l y sign-i f i c a n t , possibly because the widths were measured every 25 metres rather Table 4. Mean widths and bankful widths of Rosanne Creek in summer and winter logged sections and adjacent forested areas. Winter Logged Moderately Disturbed Heavily Disturbed Stream width (metres) Bankful width (metres) 2.40 4.13 4.47 8.32 Control Summer Logged Moderately Disturbed Heavily Disturbed Stream widths (metres) 3.39 Bankful widths (metres) 4.40 3.66 4.87 3.27 4.87 than every 5 metres resulting in a small sample size. Observations indi-There was no suitable section available to serve as a control. cated that in the heavily disturbed section the stream channel was widened by skidder t r a f f i c on the streambed. Accumulations of debris below a skid road crossing of the stream caused extensive diversions (Figure 8). The widths and bankful widths in the summer logged section are similar to those in the control section (Table 4). The stream widths in the heavily disturbed section (3.27 m.) are smaller than those in the moderately disturbed section (3.66 m.) because s o i l from the adja-cent skid road was pushed into the stream. 3. Pseudohah Creek. Results indicate that logging distur-bance caused an increase in stream widths and bankful widths (Table 5). The comparison is particularly valid due to the relatively long study Table 5. Mean widths and bankful widths of Pseudohah Creek. Summer Logged Control Moderately Heavily Disturbed Disturbed Stream width (metres) 1.99 2 .42 2 .52 Bankful width (metres) 2.34 2.89 3.62 reaches and the considerable uniformity of s o i l materials and landforms between the control and harvested sections. Damage to the streambanks was evident in swampy areas where the streambed was used for skidder t r a f f i c . There were heavy debris accumu-Figure 8. Stream diversions caused by debris accumulations in the winter logged section of Rosanne Creek. 29 lations on portions of this stream (Figure 9.A). In some sections this debris protected the streambanks while in others i t formed small dams up to 70 cm. in height. 4. Hah Creek. Hah Creek had relatively l i t t l e damage to i t s banks from harvesting activity (Table 6). While some debris accumulated Table 6. Mean widths and bankful widths of Hah Creek. Winter Logged Control Moderately Heavily Disturbed Disturbed Stream width (metres) 2 .88 2.99 3.54 Bankful width (metres) 3.25 3.50 4.23 in the stream, i t was not as dense as in Rosanne Creek. Probably part of the reason for this difference is the relatively shallow gully shape. If the stream is well covered by snow during logging activity, there is no depression where excessive amounts of debris can accumulate. In some cases debris can create better fish habitat by forming deeper pools. C. Cutbank Areas 1. Karolyn Creek. Results in Table 7 would seem to indicate that winter logging caused a decrease in cutbank area. However, this assumption cannot be made since streambank materials differed in the winter logged section from those in the control. F i g u r e 9 . Heavy a c c u m u l a t i o n s o f d e b r i s above Pseudohah Creek. 31 Table 7. Mean cutbank area per 25 metres section of Karolyn Creek (metres^/25 metre section of stream) Control Moderately Heavily Disturbed Disturbed Winter Logged 5.52 0.56 0.71 Summer Logged 1.15 1.19 0.29 The cutbank area in the moderately disturbed part of the summer logged section is not appreciably different from the control cutbank area. The decrease in cutbank area in the heavily disturbed section resulted from skidder activity in and adjacent to the stream. 2. Rosanne Creek. Cutbank area was smaller where logging activity was more extensive as indicated in Table 8. Table 8. Mean cutbank area per 25 metres (metres2/25 metres of stream) section of Rosanne Creek Control Moderately Disturbed Heavily.-Disturbed Winter Logged NA* 2.55 0.52 Summer Logged 1.74 1.62 1.09 * Not applicable The reduction in cutbank area was the result of yarding activity in the stream, scouring of the banks, and s i l t deposition on the banks. 32 Summer logging did not significantly affect cutbank area (Table 8). The main cause of disturbance on this section was the en-croachment of skid roads. 3. Pseudohah Creek. The disturbance of the banks on Pseudohah Creek was particularly severe (Table 9). Table 9. Mean cutbank area per 25 metre section of Pseudohah Creek (metres'/25 metres of stream) Control Moderately Heavily Disturbed Disturbed Summer Logged 5.27 2.13 0.79 The control area adjacent to the winter logged section had the highest value (5.27 metres'/25 metres of stream) measured in this study. The stream runs through a small gully with uniform terraces of a l l u v i a l materials forming the banks. The comparison between the control, mod-erately disturbed, and heavily disturbed sections is probably more valid in this stream than any of the others examined. The comparatively long study reaches add to the va l i d i t y of the comparison (Table 2). A. Hah Creek. There is l i t t l e difference between the area of cutbank in the control and the moderately disturbed sections (Table 10). There were no cutbanks in the heavily disturbed sections. The banks of Hah Creek were relatively l i t t l e disturbed. 33 Table 10. Mean cutbank area per 25 metre section of Hah Creek (metres /25 metres of stream) Control Moderately Heavily Disturbed Dis turbed Winter Logged 2.75 2.68 None 5. Comparison with results in the literature. An extensive comparison of the values of cutbank area reported elsewhere with those reported here would be of limited use because of variation in stream conditions. However, several comparisons of a g'eneral nature can be made. In Hunt's (1967) study of responses of a brook trout stream to habitat alteration, the lengths of cutbank per 100 metre length of stream is reported. His median values are in the range of 10 m./lOO m. - 25 m./ 100 m. of stream. The median value in the Slim-Tumuch data is 22 m./lOO m. of stream which is the value for the moderately disturbed summer logged section of Karolyn Creek. The ranges of values appear to be reasonably comparable. To classify as bank cover in Hunt's study, the bank had to extend at least 15 cm. over the stream and cover 30 cm. of water depth. In this study, a minimum water depth was not required. Hunt, did not measure the area of bank cover. Two other workers, Gunderson (1968) and Elser (1968) measured the amount of cover and compared altered and unaltered sections of streams. Elser (1968) reported that two unaltered sections of a Montana trout stream in mountainous terrain had 44% and 81% more cover than the adjacent 34 altered section. The cover measured included overhanging brush, under-cut banks, stumps, rocks, and log jams. A median value for cover which he reported was 739 m /ha. of stream. For comparison purposes, median value of cutbank area reported here was converted to the units Elser used. The value of 177 m /ha. for the moderately disturbed section of Rosanne Creek is reasonably comparable considering that cover as used in this study was more narrowly defined. Gunderson (1968) compared the amount of cover in grazed and ungrazed portions of a stream in Montana. Although there was 76% more total cover in the ungrazed zone, the amount of undercut banks in the two zones was relatively similar. Values of 150 m'/ha. and 163 m'/ha. of undercut bank were reported in the grazed and ungrazed sections res-pectively. These values are comparable to the value of 177 m /ha. re-ported herein. A major problem in the present study is the quantification of fis h habitat. The water depth under a number of the cutbanks included in the survey is too shallow to be used by f i s h during low summer flow. The mean depths in the study reaches varied between 12 cm. and 18 cm. during low summer flows. The water depths under the cutbanks measured were usually less than 15 cm. The usefulness of the banks as cover would vary with water level. D. Composition of the Cutbanks A number of samples were taken from typical undercut banks to determine which components of vegetation were important in maintaining 35 the integrity of the banks (Figure 5). The banks were usually covered with a thick layer of mosses, the main species of which are given in Appendix II. The mosses shield the surface of the banks from erosion during high flows. They do not bind the s o i l to any extent because their rhizoids do not penetrate the s o i l . Forbs do not appear to be important except in areas with thick growths of lady-fern. The rhizomes of this plant often form thick mats within the surface 10-15 cm. of s o i l . In almost a l l instances in the streams examined, the s o i l i t -self, rather than a mat of vegetation or roots on top of the so i l , , was important in maintaining the banks. In 31 s o i l samples of cutbanks from the study, only 1.5% of the s o i l volume consisted of roots greater than 0.3 cm. in diameter. There were also numerous smaller roots but these were d i f f i c u l t to separate from the s o i l . Although small roots may bind the s o i l , their role in this regard is d i f f i c u l t to determine. Obser-vations indicated that the very small roots of trees and shrubs function to bind the s o i l mass. Large tree roots are relatively unimportant in forming the banks. Roots greater than 2 cm. in diameter occupied only 0.6% by volume of the cutbank sections. In the moderately disturbed areas, the streambanks were gener-a l l y intact i f the vegetation was not disturbed. If guideline b. on page 12 had been s t r i c t l y followed, the streambanks would have been relatively undisturbed by logging. This guideline states that skid roads are to be placed so as to avoid in-stream activity by placing them parallel to the stream and approximately 5 m. away. MANAGEMENT IMPLICATIONS The problems of streambank management arc different with summer and winter logging since the terrain and lodging conditions d i f f e r somewhat in each. A. Winter Logging 1. During winter logging the positions of streams are often not obvious. If the streams were marked prior to snowfall, the skidder operators could avoid crossing the streams. 2. Stream crossings should be carefully constructed and as few in number as possible. In the study streams there were con-siderable amounts of exposed s o i l at skidder crossings which served as a sediment source. 3. Accumulations of debris in stream channels should be removed before break-up since this debris can cause scouring of the channel during break-up. B. Summer Logging 1. During the skidding operation, care should be taken to preserve the integrity of the stream and the stre<unbanks . The banks of the streams can provide important cover for H;\lmonids. 2. Equipment operating in the stream Itself can modify the character of the stream. Natural stream channel.'! have a character-i s t i c r i f f l e - p o o l sequence. The r i f f l e areas are often areas of high production in the stream whereas the pool arc.'iM .'ire usually more im-portant as fis h habitat. Alterations of thin Mcquence can cause a decrease in fish populations (Whitney and Ballry, 1959; Elser, 1968). 3. Care should be taken to avoid 1 <H;I 1 i.ng skid roads im-mediately adjacent to the stream. Material from these roads can act as a sediment source. 38 CHAPTER II INTRODUCTION A second study was undertaken i n an attempt to develop a model for stream surveys which would include consideration of stream cutbanks. The hypothesis was that cutbank areas could be predicted on the basis of landform characteristics v i s i b l e on air photos. The objectives of the study were: a. to measure cutbank area on selected reaches of streams within the Robertson River, B.C., watershed; and b. to relate the occurrence of stream cutbanks to land and stream characteristics that can be detected on a i r photographs. If i t were possible to identify land characteristics associated with cutbanks, i t would be possible to predict their occurrence. This would be of practical importance in conducting stream inventories with the use of air photos. Stream characteristics such as cutbanks are not visible on readily available air photographs (scales 1:15,000 and 1:63,000) but larger features of the landscape such as landforms are v i s i b l e . The occurrence of stream cutbanks is a function of the flow processes of the stream and the relative e r o d i b i l i t y of the streambank. Leopold et a l . (1964) state that the shape of the cross-section of a river channel at any location is a function of the flow, t:ho quantity and character of the sediment in movement through the section, and the character or composition of the mat-erials making up the bed and banks of tho channel. The flow and i t s sediment load impose a shear stress on the banks and bed of the channel. The relative strength of the bed and bank material w i l l determine the depth-width relationship of the channel; the stronger the bank material in relation to the bed material, the deeper the channel w i l l be. In uniform, noncohesive materials the channel cross-section w i l l be sinusoidal (Leopold et a l . , 1964). In most cases in nature, a stream does not flow through uniform, noncohesive materials and the channel cross-section is trapezoidal in straight stretches and asymmetric at curves or bends (Leopold et_al., 1964). The shape of the banks is dependent on the strength of the streambank materials, vegetation, roots, and various kinds of debris such as log jams, a l l of which are considered as part of the streambank. It is almost impossible to detect biological parameters such as presence of salmonids with the use of air-photos, but i t is possible to identify stream characteristics relevant to salinonid habitat. Many workers have attempted to divide streams into physio-graphic units that correspond with the fauna of that reach. Allen (1951) divided the Horokiwi stream into six distinct zones based on differences in physical features and their trout population. Iltiet (1959) identified four major fauna zones in Western European stream.-! which he related to 40 stream slope, cross-section of the stream, and valley cross-section. He suggested that valid biological zones can be established on the basis of stream gradient and valley shape. Hartman and G i l l (1968) examined data from 66 streams in southwestern Br i t i s h Columbia i n order to detect relationships between juvenile steelhead and cutthroat trout distribution and physical chara-cte r i s t i c s of streams such as gradient, pH, total dissolved solids, temperature, and discharge. The principal differences in distribution of these two species appeared to be related to stream size and p r o f i l e . Recently, Platts (1974) has attempted to qualitatively relate f i s h populations to the geomorphic land units on the streams of a 1000 2 km area in Montana. The geomorphic land classification was found to be a good indicator of the physical structure of streams. Also, certain structural characteristics of streams ( i . e . stream depth, stream width, and elevation of the channel) were found to influence f i s h populations and fi s h species composition, and consequently the geomorphic units can be used as an indicator of f i s h density and species. The approach used here is somewhat similar. Landforms are an expression of the geomorphology of a region and are therefore a useful basis for separating the streams into geomorphic units. If particular landforms are reliable indicators of stream cut-banks, then identification of such characteristics on air photos should prove useful in conducting stream surveys. The study reported here relates only one aspect of the aquatic 41 environment to landforms but the approach could be extended to include other relevant physical stream data. 42 DESCRIPTION OF THE STUDY AREA A. Location The Robertson River watershed, which drains approximately 130 square kilometres, is located on the southern shore of Lake Cowichan on Vancouver Island (Figure 10). The main stem of the Robertson River has a mean annual flow estimated to be 6 m^/s. B. Geology The bedrock in most of the valley is volcanic with some gran-odiorites in the southeastern portion of the watershed. There is a large U-shaped valley running through the center of the watershed. The sur-f i c i a l materials on the valley bottom are undifferentiated gl a c i a l d r i f t and a l l u v i a l terrace deposits. The tributaries are streamcut V-shaped valleys showing l i t t l e evidence of glaciation. The valley walls are covered with a thin capping of glac i a l t i l l and colluvium. There is an area of fine textured a l l u v i a l material on a tributary stream in the southern portion of the watershed. C. Vegetation The study streams are in the Coastal Western Hemlock Biogeo-climatic Zone proposed by Krajina (1965). Principal conifer species are Douglas-fir , western hemlock, western redcedar, and Pacific silver f i r . ^ The main deciduous-species are red alder and bigleaf maple. I The s c i e n t i f i c names are listed in Appendix I. 43 44 Salmonberry, stink current and various willows are the main shrubs adjacent to the streams. 45 MATERIALS AND METHODS A reconnaisance survey of cutbank cover was undertaken on streams within the Robertson River, B.C., watershed on Vancouver Island (Figure 10). With the use of 1:63,000 air photos, the streams were divided into homogeneous units on the basis of the landform adjacent to the stream, the valley shape and the stream pattern (Figure 10). Landforms were classified and mapped using 1:15,000 air photos on the basis of their mode of origin according to the system described by Lacate (1969). Landforms identified were: a. a l l u v i a l terrace; b. colluvium; c. outwash terrace; d. gla c i a l t i l l ; e. bedrock; and f. a l l u v i a l fan. A description of the landform units and the associated materials is presented in Table Vb. Valley shape was ar b i t r a r i l y designated as: a. V-shaped; or b. truncated V. With reference to the classification of channels by Bray and Kellerhals (1972), the stream pattern was designated as: a. straight: very l i t t l e curvature within the reach; b. sinuous: slight curvature with a belt width or deviation of less than approximately two channel widths; or c. irregular: a channel pattern which cannot be considered Table II. Description of landform units. SYMBOL LANDFORM DESCRIPTION Tc Tv At Af DEGREE OF SORTING COMPACTION TEXTURE Glacial t i l l and colluvium Glacial t i l l A l l u v i a l terrace A l l u v i a l fan Ac Channel alluvium Av Valley alluvium 0 QJutwash terrace Thin d r i f t of vary- Unsorted ing thickness on slopes generally greater than 15% Undifferentiated Unsorted d r i f t on valley bottom with slopes less than 15% Valley f l a t adjac- Well ent to present sorted stream Fan shaped deposit Poorly adjacent to sorted present stream Material deposited Well by present stream sorted Material that has Poorly accumulated adjacent sorted to present stream by colluvial and alluv-i a l processes Flat surfaced bench Well above present river sorted level Compact Compact Loose Loose Loose Loose Loose Moderately coarse Moderately fine Moderately coarse to very coarse Coarse Very coarse Very coarse Very coarse 47 straight or sinuous and does not have a repeatable pattern. This includes structurally controlled patterns. Although the term "homogeneous units" has been used, i t must be under-stood that the sections were not entirely uniform throughout. Design-ation of units on the basis of the physical characteristics described above resulted from subjective judgments rather than precise measurements. For practical purposes, slight deviations from predominant configurations were ignored. For example, Sixteen Creek (Figures 25 and 27) has a V-shaped valley for most of i t s length with the exception of a short a l l u v i a l fan deposit at i t s mouth. The fan deposit was not considered large enough to warrant designation of a separate stream unit. A further qualification of the homogeneity of the units must be made because most of the stream segments had a variety of adjacent landforms. For example, stream section No. 4 on the Robertson River is bordered by an outwash terrace on one bank and by a l l u v i a l fan and t i l l on the other bank. It was not practical to designate a separate stream unit with each change of landform. Therefore section 4 was separated from section 5 on the basis of valley shape. Representative study reaches were marked on 1:15,000 ai r photographs near the centres of each of the 9 study sections.^ These reaches were located on the ground and the cutbanks were measured for distances of between 150 and 400 metres. The cutbank areas were measured -The 9 lengths of stream separated on air photos w i l l be called sections (numbered 1-9) and the parts of the sections sampled for cut-banks w i l l be called study reaches. 48 as described in Chapter I using 25 metre lengths of stream as sampling units. Widths and depths of the stream were measured at each end of the study reaches. Graphs of the valley cross sections were prepared using 1:50,000 National Topographic Series contour maps. Gradients of the study sections were computed using these maps. The total lengths of the study sections were measured using 1:15,000 air photos. The differences in cutbank areas were compared using analysis of variance completely randomized design (Snedecor and Cochran, 1967). A Duncan's multiple range test was used to test for differences between individual means (Walpole, 1968). On the basis of f i e l d notes, schematic diagrams were drawn of the channel cross section within each reach. These diagrams represent an interpretation of the probable streambank structure throughout the study reach. Several of the larger tributaries of the Robertson, particu-larly those on the west side of the river, were not sampled. These streams had extremely steep gradients which made them unsuitable for fish habitat. Preliminary examination revealed excessive bedload and debris movement in these streams with l i t t l e a l l u v i a l bank material where cutbanks might be formed. Because of .the low probability of find-ing cutbanks, negligible value as fish habitat, and poor access, these reaches were not sampled. 49 RESULTS AND DISCUSSION Results of a study of land and stream characteristics ass-ociated with cutbanks are summarized in Tables 12 and 13. These data are best discussed on a stream section basis to permit evaluation of the survey technique and interpretation of results. A. Section 1 Section 1 (Figures 11 and 12) is a rapidly aggrading portion of the stream with bedload accumulating to the extent that during late summer and early autumn there is l i t t l e surface flow. There were no cutbanks in the study reach (Table 13).^ The banks were too high above the streambed to provide cutbanks that would be useful as fish habitat except during peak flows. Also, the streambed is extremely wide and the streamflow impinges on the bank only on the outer bends which constitute a very small percentage of this section (Figure 11.B). Section 1 is separated from Section 2 on the basis of stream pattern. In Section 1, the stream forms wide bends impinging on the channel banks as indicated' by Figure 11.B. There does not appear to be restraining bedrock that might limit lateral erosion. 1 The study reach refers to that section of the stream sampled for cutbanks (z-z 1 on Figure 11.A). Table 12. Land and stream c h a r a c t e r i s t i c s of the study reaches . STREAM SECTION LANDFORM TEXTURE VALLEY SHAPE STREAM PATTERN FLOW TYPE Robertson R ive r Robertson R iver Robertson R i v e r Robertson R i v e r Robertson R i v e r Unnamed Creek Nineteen Creek Swamp Creek S i x t e e n Creek A l l u v i a l te r race A l l u v i a l terrace A l l u v i a l te r race g l a c i a l t i l l bedrock o u t -crops G l a c i a l t i l l outwash te r race a l l u v i u m Well sor ted Bands and g r a v e l s Well sor ted sands and g r a v e l s Wel l sor ted sands and g r a v e l s . g r a v e l l y sandy loan G l a c i a l t i l l a l l u v i u m a l l u v i u m G l a c i a l t i l l a l l u v i u m G l a c i a l t i l l G l a c i a l t i l l a l luv ium G r a v e l l y sandy loam w e l l s o r t e d graveIs w e l l so r ted sands and g r a v e l s G r a v e l l y sandy loam v e i l s o r t e d sands S i l t s and f i n e sands G r a v e l l y sandy l o a n w e l l s o r t e d sands and g r a v e l s G r a v e l l y sandy loam-G r a v e l l y sandy loam w e l l so r ted sands and g r a v e l s Truncated V Truncated V Truncated V Truncated V V-shaped Truncated V V-shaped Truncated V V-shaped I r r e g u l a r R i f f l e pool sequence I r r e g u l a r R i f f l e pool sequence I r r e g u l a r R i f f l e pool sequence I r r e g u l a r R i f f l e poo l sequence Sinuous Tumbling I r r e g u l a r R i f f l e p o o l sequence Sinuous Tumbling f low and r i f f l e p o o l Sinuous R i f f l e p o o l Sinuous Tumbling flow and r i f f l e poo l Table 13. Measurements of stream characteristics of the study reaches. SECTION SLOPE (%) MEAN DEPTH (cm.) LENGTH (m.) MEAN WIDTH (m ) LENGTH SAMPLED (m ) AREA OF CUTBANK (m2) AREA OF CUTBANK / 25 m. (km2/25m) 1. Robertson River 0.4 * 4523 * 400 none 0.00 2. Robertson River 0.6 25 2331 9.25 375 4.88 0.33 3. Robertson River 0.7 15 1276 9.30 400 14.64 1.28 4. Robertson River 0.4 15 3866 5.10 200 1.90 0.24 5. Robertson River 3.9 11 5457 3.65 375 none 0.00 6. Unnamed Creek 0.4 11 2608 4.00 250 13.30 1.33 7. Nineteen Creek 4.0 10 4273 6.82 150 • 3.51 0.58 8 . Swamp Creek 1.3 6 1221 1.70 375 2.41 0.16 9. Sixteen Creek 3.8 10 2747 3.73 400 20.32 1.13 * no surface flow at the time of the survey, August, 1974. LEGEHO Figure 11. Section 1 - Robertson River. A. Location of section 1 in the watershed, x t c G l a c i a l t i l l and co11uv1uro Tv G l a c i a l t i l l A t A l l u v i a l t e r r a c e Af A l l u v i a l fan Ac Channel a l l u v i u m Av Boulder a l l u v l u r e 0 Outwash t e r r a c e Boundary between landforms Stream channel Edge of v a l l e y f l a t Ephemeral stream channel 52 200 m B. Landform map. The reach z-z 1 was sampled for cutbanks . V a l l e y c r o s s s e c t i o n n t x-x 1 . The t o h o r i z o n t a l a x i s i s 1:2. r a t i o o f v o r t i c a l 53 Figure 12. Section 1 - Robertson River. A. Schematic representation of the channel cross section at y-y 1 of the landform map. (Fig. 11.B). * The above and the following schematic representations do not imply any particular depth of material below the channel ( eg. valley alluvium in the above diagram). B. B. Photograph taken near y-y' of the landform map (Fig. 11.A). A large quantity of coarse bedload has been deposited in this section. 54 Rehabilitation measures in this portion of stream would have to consist of gravel removal. Fish habitat is provided by debris in the form of stumps and trees on the streambed and this material should not be removed in any stream improvement program. B. Section 2 This section of stream (Figures 13 and 14), directly upstream from Section 1, i s characterized on air photos by a narrow channel and tight bends which are li k e l y the result of bedrock control, although no bedrock outcrops were observed in the study reach. The area of cutbank in the study reach is very small (0.33 m / 25 m.). The adjacent valley alluvium is made up of cohesionless gravels similar to those in Section 1 (Figure 13.B). The cutbanks present are the result of alder roots slumping into the stream (Figure 14.B). How-ever, since the banks are generally about 2 metres above the stream, they do not provide suitable cover for fish except perhaps during periods of high discharge (Figure 14.A). C. Section 3 The streambanks of this section are made up of t i l l and collu-vium on the right bank and alluvium on the l e f t bank (Figure 15.B). The relatively large amount of cutbank (1.28 m /25 m) is formed by the roots of trees, particularly alder, slumping into the stream (Figure 16.). The s o i l materials are relatively cohesionless and coarse textured and 0 I 2K Figure 13. Section 2 - Robertson River. A. Location of section 2 in the watershed. Tc Tv At Af Ac Av 0 Landform map, for cutbanks, 200 m The reach z-z' was sampled LEGEND G l a c i a l t i l l and c o l l u v l u r a G l a c i a l t i l l A11uvI a I t e r r a c a A l l u v i a l fan Channel a l l u v i u m B oulder a l luvlun) Outwash t e r r a c e Boundary between landforms Stream channel Edge of v a l l e y flat <D 4-£ 300 200 x - x ' C. Valley cross section at x-x'. 56 A. Figure 14. Section 2 - Robertson River. A. Schematic representation of the channel cross section at y-y' of the landform map. (Fig.13.B). The forest floor is too high above the channel to form cutbanks. B. B. Photograph looking downstream near y-y' (Fig. 13.B). O 1 2K • — i — J Figure 15. Section 3 - Robertson River. A. Location of section 1 in the watershed. / Tv / Av — "N* ^ z y' Tc Tc Tv At Af Ac Av 0 LEGEND Glac ia l t i l l and col luvluia Glac ia l t i l l A l l u v i a l terraca A l l u v i a l fan Channel alluvium Boulder alluvlura Outwash terrace Boundary between landforms Stream channel Edge of va l ley f l a t Ephemeral stream channel 200 m Landform map. The reach z-z 1 was sampled for cutbanks. C. V a l l e y c r o s s s e c t i o n a t x - x ' . 58 Figure 16. Section 3 - Robertson River. Schematic representation of the channel cross section at y-y 1 of the landform map(Fig. 15.B). could not in themselves provide cutbanks (Figure 15.B). The streambanks are relatively lower in this reach than in Section 2 permitting form-ation of cutbanks. On the right bank there are several bedrock outcrops. Willows are colonizing the gravel bars in the study reach but are not providing bank cover. D. Section 4 There is bedrock control of the channel pattern throughout Section 4 as indicated by the sharp bends seen on the map (Figure 17.B). Much of this section is a canyon with steep bedrock walls (Figure 18) which allow l i t t l e opportunity for formation of cutbanks o as shown in the low value (0.24 m /25 m) of cutbank measured in the study reach. The outwash on the right bank is on a bedrock terrace and consequently has l i t t l e effect on channel characteristics. For the part of Section 4 adjacent to Nineteen Creek, the channel is bordered by a l l u v i a l fan material consisting of coarse rubble deposited by Sixteen Creek. This section is a transition zone between the broad valley of Sections 1, 2, and 3 and the V-shaped valley of Section 5 (Figures 11.C, 13.C, 15.C, 19.C and 21.C). E. Section 5 The stream flows through a V-shaped valley in this section with Figure 17. Section 4 - Robertson River. A. Location of section 4 in the watershed, LEGEND ' Tc Glacial t i l l and colluvlura Tv Glacial t i l l At Alluvial terrace Af Alluvial fan Ac Channel alluvium Av Boulder alluvlum 0 Outwash terraca Boundary between landforms Stream channel M.M.JL. Edge of valley flat X ° 200 m Landform map. The reach y-y1 was sampled for cutbanks. The channel pattern of the upstream part of section 4 i s under bedrock control. c 300 <B l _ +- 200 <D o o CM «> metres C. Valley cross section at x-x'. 61 Figure 18. Section 4 - Robertson River. Schematic representation of the channel cross section at z-z' of the landform map (Fig.17.B). the valley walls rising steeply on each side of the channel (Figure 19 . C). Small pockets of al l u v i a l materials have accumulated on the valley bottom as depicted in Figure 20. Cutbanks did not occur in the por-tion surveyed and are not lik e l y to occur on the remainder of Section 5. Cover is provided, however, by debris in the channel. Several tributaries enter the Robertson River in this section. These were not established as study reaches because their steep gradients would limit their value for f i s h habitat. F. Section 6 Section 6 flows through a large, relatively f l a t area adjacent to a pasture (Figure 21.B and C). It is underlain by fine textured, slightly cohesive a l l u v i a l materials and surrounded by dense shrub vegetation. This combination provides ideal conditions for the form-ation of cutbanks. The study reach (z-z' on Figure 21.B) is bordered by cutbanks along most of it s length. Although the area of cutbank (1.33 m2/25 m) is comparable to that in Nineteen Creek (0.58 m2/25 m), Sixteen Creek (1.13 m2/25 m), and Section 3 of Robertson River (1.28 m2/25 m), the cutbanks are more important as fish habitat in this reach. Water covers the entire streambed (Figure 22.) and consequently the cutbanks provide cover at any water level. The federal fishery officer and the provincial conservation officer for the area have stated that this small stream is one of the most important spawning and rearing streams in the Robertson River Tv At Af Ac Av 0 Figure 19. Section 5 - Robertson River, A. Location of section 5. B LEGEND Glacia l t i l l and co11uv1um Glacia l t i l l A l l u v i a l terrace A l luv ia l fan Channel a Iluvlum Boulder alluvlum Outwash terrace Boundary between landforms Stream channel Edge of val ley f l a t 300 o o CM o o o o o o o metres C. Valley cross section at x-x' 64 Figure 20. Section 5 - Robertson River. Schematic representation of the channel cross section at y-y' of the landform map (Fig.19.B). Although the valley bottom is extremely narrow small pockets of alluvium have been deposited adjacent to the channel. 65 LEGEND Glacial t i l l and col Iuvlum Glacial t i l l A l l u v i a l terrace A l l u v i a l fan Channel at luvlum Av Boulder alluvium 0 Outwash terrace Boundary between landforms Stream channel LJI. JI Edge of val ley flat i00 m1 B. Landform map. The reach z-z' was sampled for cutbanks. c — 1 1 1 o o o o o o CM Jt U 3 metres C. Valley cross section at x-x'. 66 Figure 22. Section 6 - Unnamed Creek. Schematic representation of the channel cross section at z-z' of the landform map (Fig.21.B). Cutbanks are found on both sides of the channel for most of this section. Dense shrub vegetation borders the stream. Watershed.1" It has a stable flow regime which provides a relatively large amount of habitat for most of the season. It flows from a swamp, which buffers the intensity of peak discharge. Although the stream is important for the fishery, i t s small size makes i t d i f f i c u l t to detect on the 1:15,000 or 1:63,000 scale aerial photographs. G. Section 7 Nineteen Creek flows through a V-shaped valley for most of i t s length (Figure 23). The cutbank area is moderate relative to the other study reaches (0.58 m^ /25 m). The right bank is composed of bedrock for much of i t s length and therefore there is l i t t l e opportunity for the establishment of vegetation. Most of the cutbanks are formed on the l e f t bank under the roots of alder trees situated adjacent to the channel (Figure 24 )• The s u r f i c i a l material on the l e f t bank is mostly large rubble 20 to 80 cm. in diameter, although there are some small pockets of a l l u v i a l sand immediately adjacent to the channel. The bed and bank materials are relatively coarse textured i n comparison to the materials of the other reaches considered i n this study. H. Section 8 Section 8 is a relatively short, low energy stream flowing through glacial t i l l material (Figure 25.B). The stream flows in a gully about 8 m. deep and 20 m. across. A l l u v i a l material has not been deposited adjacent to the stream; the streambanks are composed of the same coarse material as that found in the streambed (Figure 26.). 1 A. Ackerman and E.W. Armstrong personal communication Figure 23. Section 7 - Nineteen Creek. A. Location of section 7 in the watershed. B ' C. Valley cross section at x-x' • T / \ Z V Z ' Tc { 1 Tc \ I Li>\ r IJ-^ * / v ». **" I s—sLf 1 i <--<< >* V \ A v < / / i Av N£ I **> / I \ T c Tv At Af Ac Av 0 LEOENO Glacial f i l l and coI IuvIum Glacial t i l l AIluvial terraca Alluvial fan CnanneI a M uvlum Bouleer a I 1uvium Outwash terrace • Boundary between landforms Stream channel Edge of valley flat CO B. Landform map. The reach z-z' was sampled for cutbanks. ^00 m' 69 A, Figure 24. Section 7 - Nineteen Creek. A. Schematic representation of the channel cross section at y-y'(Fig.23.B). The valley f l a t consists of coarse rubble. The few cutbanks in the study reach are formed under roots or logs embedded in the streambank. B. Photograph looking upstream at y-y 1(Fig.23.B). 70 Tc Tv At Af Ac Av LEGEND Glac ia l t i l l and colluvium Glac ia l t i l l A l l u v i a l terrace A l l u v i a l fan Channel al luvium Boulder alluvlum Outwash terrace • Boundary between landforms Stream channel Edge of va l ley f l a t Landform map. Section 8 is located between 1 and 2. Section 9 is located between 3 and 4. Reaches v-v* and z-z' were sampled for cutbanks. C. Valley cross section at x-x'. 71 Figure 26. Section 8 - Swamp Creek. Schematic representation of the channel cross section at t - t ' of the landform map (Fig.25.B). 72 In order for cutbanks to be formed, the streamflow must impinge on an erodible bank. There are almost no cutbanks in the study reach (0.16 m /25 m). Although there is dense shrub and deciduous vegetation adja-cent to the channel, the roots of this vegetation have had l i t t l e oppor-tunity to form cutbanks that might be useful as habitat. The relatively large rubble and dense shrub vegetation adjacent to the stream probably supplies adequate cover for coho fry in the stream. I. Section 9 Sixteen Creek has a relatively steep gradient with bed and bank material composed of large rubble approximately 30-100 cm. in diameter. The stream flows over a fan deposit (Figure 25.B). Very small pockets of alluvium have accumulated immediately adjacent to the channel. Cutbanks have been formed under the roots of vegetation growing alongside the channel (Figure 27 A. and B) . The relatively large cutbank area in this reach (1.13 m2/25 m) is a result of dense alder vegetation adjacent to the stream. These cutbanks are probably not extremely useful as cover for fish; they are relatively high above the level of the water surface and usually do not provide cover over water deeper than 10 cm. Section 9 is located in a transition zone between the V-shaped valley on the southern portion of Sixteen Creek and the a l l u v i a l fan near i t s mouth. This stream poses the same sampling problem that was encountered 73 Figure 27. Section 9 - Sixteen Creek. A. Schematic representation of the channel cross section at y-y' of the landform map (Fig.25.B). B. B. Photograph looking upstream at y-y 1 (Fig.25.B). Cutbanks have formed under the roots of the alder trees adjacent to the channel. in the headwater portions of other study reaches (5,6,7,8, and 9): that of deciding the upper extent of the study reach. On a watershed such as this, the terrain makes i t impractical to investigate those portions of streams close to headwater areas. Often there is a barrier to fish passage making these reaches inaccessible to anadromous fish. While these streams may support resident populations such as cutthroat trout, the fish are often extremely small. While i t may be useful to know of their presence, i t may not be worthwhile to undertake extensive analysis of their habitat. The economic and social value of the downstream pop-ulations are much greater and therefore their habitat warrants more intensive study. J. General Discussion Analysis of variance and Duncan's multiple range test were used to determine s t a t i s t i c a l differences among sections with regard to mean cutbank area. Each of the nine sections of stream is considered a separate treatment since different land and stream conditions prevail in each. The sections f e l l into two overlapping, homogeneous subsets as indicated by Table 14. Table 14. Duncan 's Multiple Range Test of cutbank areas. Stream Section 5 1 8 4 2 .7 9 3 6 Cutbank -Area 0.00 0. ,00 • 0.16 0.24 0.33 0.58 1.13 1.28 1.331 m2/25 m 1 Figures connected by a line are not significantly different at P=0.05. 75 The above could be interpreted to mean that certain conditions are conducive to cutbank formation (i.e. those in sections 9, 3, and 6) while other conditions are not (i.e. those in sections 5, 1, and 8). One disadvantage of the multiple range test is that i t sometimes gives ambiguous results (Woolf, 1968) as is the case here where there is some degree of overlap between the two homogeneous groups making i t impos-sible to appraise conditions in Sections 4, 2, and 7 with respect to cutbank-forming capabilities. The above sections have been compared without reference to specific conditions prevailing in each. In an attempt to find relation-ships between treatments (i.e. land and stream characteristics in each section) and cutbank area, reference is made to Tables 12 and 13 which summarize section characteristics. The sections are grouped in Table 15 according to the characteristics which may be conducive to cutbank formation. Table 15. Summary of section characteristics Predominantly a l l u v i a l banks Sections 1, 2, 3, 6 Low gradient - 0-2% Sections 1, 2, 3, 4, 6, 8 Truncated-V valley Sections 1, 2, 3, 4, 6, 8 Predominantly glacial t i l l banks Sections 4, 5, 7, 8, 9 Steeper gradient- 3-5% Sections 5, 7, 9 V-shaped valley Sections 5, 7, 9 The largest values for cutbank area might be predicted for sections 1, 2, 3, and 6 since they have predominantly a l l u v i a l stream-banks, low gradients, and truncated V-shaped valleys. However, only Sections 3 and 6 from this group had relatively large cutbank areas (1.28 and 1.33 m2/25 m of stream, respectively) while Section 1 had no cutbanks and Section 2 had a small cutbank area (0.33 m2/25 m stream). Hence, factors other than those described in the above Table must have intervened. The streambed in Section 1 is extremely wide and the flow impinges on the banks only at the outer bends, providing l i t t l e oppor-tunity for cutbank formation. Furthermore, in Sections 1 and 2 the ground surface is too high above the water level to provide useful cover for f i s h . Sections 5, 7, and 9 do not appear to have the potential for cutbank formation due to few a l l u v i a l banks, steep gradients, and V-shaped valleys. Section 5 was lacking in cutbanks but Sections 7 and 9 had relatively large cutbank areas (0.58 and 1.13 m2/25 m of stream, respectively). The cutbanks in these sections were formed by alder roots and logs embedded in the coarse channel bank material which contained very l i t t l e soil.* Therefore, although certain characteristics are associated with undercut banks, they are not reliable indicators of cutbank forming potential since other factors may intervene. The survey technique described is useful provided i t is supplemented with ground checks. Air photos can be used to st r a t i f y streams into relatively homogeneous units on the basis of landscape characteristics which are not obvious on the ground. This technique provides an ef f i c i e n t , systematic approach to making ground checks . Extensive land surveys are presently being carried out in British Columbia providing a bank of data which might be of use in performing stream surveys. However, since only one factor influencing salmonid habitat was examined in the present study, further studies are required to determine useful correlations between land and stream characteristics. Because no simple relationships were found between stream cutbanks and land characteristics, i t was not possible to develop a reliable model for predicting cutbanks on the basis of landforms as viewed on air photos. However, the sampling technique described is useful for stream surveys provided additional procedures (eg. supple-mental ground checks) are employed to compensate for limitations in the method for predicting cutbanks. SUMMARY Following the assumption that certain land characteristics are conducive to the formation of stream cutbanks, a survey of a descriptive nature was conducted in order to ascertain possible r e l -ationships between land characteristics and cutbank area. The ultimate aim was to develop a model for predicting cutbank-forming potential on the basis of landforms visible on air photographs. Cutbanks of a significant size were found to be present in a limited number of stream segments within the watershed. No simple relationships between land and stream characteristics were found, per-haps due to various factors which interfered with predicted outcomes regarding cutbanks. It was not possible to develop a model for predicting cut-bank formation with the use of a i r photos alone. It was concluded that the survey techniques described are useful for geomorphic inter-pretation of the stream, establishment of units that might be used when undertaking stream surveys, and the determination of locations which warrant ground checks. 79 REFERENCES CITED Allen, K.R. 1951. The Horokiwi Stream - A study of a trout population. New Zealand Marine Department Fisheries Bulletin No. 10. 288p. Allen, K.R. 1969. Limitations on production in salmonid populations in streams,p. 3-18. In T.G. Northcote (Ed.) Symposium on Salmon and Trout in Streams. H.R. MacMillan Lectures i n Fisheries. University of B.C., Vancouver. Boussu, M.F. 1954. Relationship between trout populations and cover on a small stream. Jour. Wildl. Mgmt., 18: 229-239. Bray, P.I., and R. Kellerhals 1971. Numeric coding of the major geo-morphic and physiographic characteristics of a river reach. Unpublished report. Dept. of C i v i l Engineering, University of Alberta, Edmonton. Burns, J.W. 1972. Some effects of logging and associated road con-struction on northern California streams. Trans. Amer. Fish. Soc. 101: 1-17. Bustard, D.R. 1973. Some aspects of the winter ecology of juvenile salmonids with special reference to possible habitat alter-ation by logging in Carnation Creek, Vancouver Island. Un-published M.Sc. thesis, University of B.C. 85p. Butler, R.L. and V.M. Hawthorne. 1968. The reactions of dominant trout to changes in overhead a r t i f i c i a l cover. Trans. Amer. Fish. Soc. 97: 37-41. Chapman, D.W. 1962. Effects of logging upon fis h resources of the west coast. J. Forestry 60: 533-537. Chapman, D.W. 1966. Food and space as regulators of salmonid populat-ions in streams. Am. Natur. 100: 345-357. Chapman, D.W. and T.C. Bjorrn 1969. Distribution of salmonids in streams with special reference to food and feeding, p. 153-176. In_ T.G. Northcote (Ed.) Symposium on Salmon and Trout in Streams. H.R. MacMillan Lectures in Fisheries. University of B.C., Vancouver. Elser, A.A. 1968. Fish populations of a trout stream in relation to major habitat zones and channel alterations. Trans. Amer. Fish. Soc. 97: 389-397. 80 Everest, F.H. 1969. Habitat selection and spatial interaction of juvenile chinook salmon and steelhead trout in two Idaho streams. Ph.D. thesis. University of Idaho. 77p. Gunderson, D.R. 1968. Floodplain use related to stream morphology and fish populations. Jour. Wildl. Mgmt. 32: 507-514. Hall, J.D. and R.L. Lantz. 1969. Effects of logging on the habitat of coho salmon and cutthroat trout in coastal streams, p. 355-375. In T.G. Northcote (Ed.) Symposium on Salmon and Trout in Streams. H.R. MacMillan Lectures in Fisheries. University of B.C., Vancouver. Hartman, G.F. 1965. The role of behavior in the interaction-of under-yearling coho and steelhead (Oncorhynchus kisutch and Salmo  gairdneri ). Ph.D. thesis, University of B.C., Vancouver. Hartman, G.F. and C.A. G i l l . 1968. Distributions of juvenile steel-head and cutthroat trout (Salmo gairdneri and Salmo clarki  clarki) within streams i n southwestern British Columbia. J. Fish. Res. Bd. Canada 25: 33-48. Holland, S.S. 1964. Landforms of British Columbia a physiographic outline. Bulletin No. 48. B.C. Dept. of Mines and Petroleum Resources, Victoria, B.C. Huet, M. 1959. Profiles and biology of western European streams as related to fish management. Trans. Amer. Fish. Soc. 88: 155-163. Hunt, R.C. 1971. Responses of a brook trout population to habitat development in Lawrence Creek. Tech. Bull. No. 48. Wis. Dep. Nat. Resour., Madison, Wis, Kraft, M.E. 1972. Effects of controlled flow reduction on a trout stream. J. Fish. Res. Bd. Canada 29: 1405-1411. Krajina, V.J. 1965. Biogeoclimatic zones and classification of British Columbia. Ecol. West. N.A. 1:1-19. Dept. of Botany, University of B.C., Vancouver. Lacate, D.S. 1969. Guidelines for bio-physical land c l a s s i f i c a t i o n . Canadian Forestry Service Publication No. 1264. 61p. Leopold, L.B., M.G. Wolman and J.P. Miller. 1964. Fluvial Processes in Geomorphology# Freeman. San Francisco. 522p. Lewis, S.L. 1969. Physical factors influencing fish populations in pools of a trout stream. Trans. Amer. Fish. Soc. 98:14-19. 81 Platts, W.S. 1974. Geomorphic and aquatic conditions influencing salmonids and stream cla s s i f i c a t i o n in the Salmon River drain-age, Idaho, 1970-1972. Unpublished Ph.D. thesis. Utah State University. Logan, Utah. Saunders, J.W., and M.W. Smith. 1962. Physical alteration of stream habitat to improve brook trout production. Trans. Amer. Fish. Soc. 91: 185-188. Slaney, P.A., T.W. Chamberlin, and T.G. Halsey. 1973. Effects of forest harvesting on the aquatic environment of watersheds i n the central interior of British Columbia, A progress report of fishery-forestry studies at the Slim-Tumuch Watershed. Fish and Wildlife Branch, Fisheries Research Section, University of B.C., Vancouver. Snedecor, G.W. and W.G. Cochran. 1967. S t a t i s t i c a l Methods. Sixth Edition. Iowa State University Press, Ames, Iowa. 593p. Stewart, P.A. 1970. Physical factors influencing trout density in a small stream. Ph.D. thesis. Colorado State University, Fort Collins. 78p. Walpole, R.E. 1968. Introduction to St a t i s t i c s . MacMillan Publishing Co. Inc. New York. 365 p. Whitney, H.N. and J.E. Bailey. 1959. Detrimental effects of highway construction on a Montana stream. Trans. Amer. Fish. Soc. 88:72-73. Woolf, CM. 1968. Principles of Biometry. Van Nostrand. Toronto. 359p. 82 APPENDIX I A List of Plants Mentioned in the Text Nomenclature is according to the following manual. Hitchcock, C.L. and A. Cronquist. 1973. Flora of the Pacific North-west, An Illustrated Manual. University of Washington Press Seattle. 730p. Trees Scientific Names Abies amabilis (Dougl.) Forbes Abies lasiocarpa (Hook.) Nutt. Acer macrophyllum Pursh Alnus rubra Bong. Alnus incana (L.) Moench Picea glauca (Moench) Voss Populus tremuloides  Populus triocharpa Pseudotsuga menziesii (Mirbel) Franco Thuja plicata Donn. Tsuga heterophylla (Raf.) Sarg. Common Names Pacific sil v e r f i r subalpine f i r bigleaf maple red alder speckled alder white spruce trembling aspen black cottonwood Douglas f i r western redcedar western hemlock Shrubs Lonicera involucrata (Rich.) Banks Ribes bracteosum Dougl. Rubus idaeus L. Rubus parviflorus Nutt. black twinberry stink current red raspberry thimbleberry Scientific Names Rubus spectabilis Pursh Salix sp. Common Names salmonberry willow Ferns Athyrium filix-femina (L.) Roth lady fern 84 APPENDIX II A Lis t of Common Mosses Found on the Streambanks of Study Streams  in North Central B.C. Nomenclature i s according to the following manual. Lawton, E. 1971. Moss Flora of the Pacific Northwest. Hattori Botan-i c a l Laboratory. Nichinan, Japan. 362p. Brachythecium rivulare B.S.G. Bryum sp. Bryum weigsIii Spreng. Drepanocladus uncinatus (Hedw.) Warnst. Hylocomium sp. Rhizomnium personii Koponen Rhytidiadelphus triquetrus (Hedw.) Warnst. Rhytidiadelphus squarrosus (Hedw.) Warnst. Timmia austriaca Hedw. 

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