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A Study of slash burning and its effect on a British Columbia forest soil Rideout , Eldon Fowler 1949

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L & z tMci fit A Study of Slash Burning and i t s ef f e c t on a B r i t i s h Columbia Forest S o i l by Eldon Fowler Rideout 0 O 0 A Thesis submitted i n P a r t i a l Fulfilment of The Requirements f o r the Degree of MASTER OF SCIENCE IN AGRICULTURE i n the Department of AGRONOMY (SOILS) 0 O 0 THE UNIVERSITY OF BRITISH COLUMBIA APRIL, 1949 A Study o f S l a s h B u r n i n g and i t s E f f e c t on a B r i t i s h Columbia F o r e s t S o i l E l d o n Fowler R i d e o u t , B. S. A. A b s t r a c t : S l a s h b u r n i n g has been p r a c t i c e d i n B r i t i s h Columbia s i n c e 1 9 3 0 w i t h l i t t l e r e g a r d f o r the r e g e n e r a t i o n o f f o r e s t s or the s o i l s w h i c h support them. A s t u d y o f burned s o i l s on Vancouver I s l a n d was c a r r i e d out i n o r d e r to determine whether or not the i n h e r e n t s i t e q u a l i t y o f f o r e s t s o i l s i s a l t e r e d t h r o ugh b u r n i n g and whether any such a l t e r a t i o n i s permanent or e x h i b i t s a c y c l i c t r e n d . F o r t h i s purpose samples were taken from the s u r f a c e and s u b s u r f a c e of s i t e s w i t h the same s o i l type burned i n d i f f e r e n t y e a r s and were compared t o s i m i l a r samples from an a d j a c e n t v i r g i n s i t e . I t was c o n c l u d e d t h a t s l a s h b u r n i n g on c o n i f e r o u s f o r e s t s o i l s o f Vancouver I s l a n d c a u ses: ( l ) l a c k of n a t u r a l r e g e n e r a t i o n f o r 1 0 - 13 y e a r s . (.2) a g r a d u a l i n c r e a s e i n s u r f a c e s o i l pH due t o the "pumping" a c t i o n of f a s t - g r o w i n g herbs and shrubs w h i c h causes bases t o be brought to the s u r f a c e from the s u b s o i l . ( 3 ) i n c r e a s e d exchangeable hydrogen i n the s u b s o i l s of burned s i t e s a p p a r e n t l y due to a c t i o n o f herbaceous growth i n removing bases to the s u r f a c e and a l s o to i n c r e a s e d b i o l o g i c a l a c t i v i t y . ( 4 ) an i n i t i a l i n c r e a s e i n exchangeable base c o n t e n t of the "burned s u r f a c e which b e g i n s to d i s a p p e a r due t o l e a c h i n g i n 3 or 4 y e a r s . (:3>) i n c r e a s e d magnesium and p o t a s s i u m i n the s u b s o i l s o f burned s i t e s as a r e s u l t of l e a c h i n g these elements from the accumulated ash. ( 6 ) i n i t i a l i n c r e a s e i n phosphorus c o n t e n t of the s u r f a c e burned s o i l w i t h a subsequent removal of t h i s element to the s u b s o i l due t o the s o l v e n t a c t i o n of p e r c o l a t i n g r a i n w a t e r . T h i s phenomenon i s e s p e c i a l l y t r u e i n the case of s e v e r e l y burned s o i l s . (7). i n c r e a s e i n ammonia c o n t e n t i n both s u r f a c e and s u b s u r f a c e s o i l s a f t e r b u r n i n g due t o s t i m u l a t e d a m m o n i f i c a t i o n . ( 8 ) i n c r e a s e d n i t r i f i c a t i o n and l o s s of n i t r a t e by l e a c h i n g w i t h severe b u r n i n g . ( 9 ) m i g r a t i o n of c o l l o i d a l o r g a n i c m a t t e r and c l a y p a r t i c l e s t o the s u b s o i l . (10) i n c r e a s e d t o t a l n i t r o g e n c o n t e n t and a consequent de-c r e a s e i n the c a r b o n - n i t r o g e n r a t i o o f the s u b s o i l . Cl l ) a r e d u c t i o n i n the m o i s t u r e h o l d i n g c a p a c i t y o f the s u r f a c e s o i l i m m e d i a t e l y f o l l o w i n g b u r n i n g . As a r e s u l t of t h i s s t u d y the f o l l o w i n g recom-mendations were made: ( l ) due to the i n h e r e n t v a r i a b i l i t y of a l l s o i l s i t i s a d v i s a b l e to c a r r y out any f u r t h e r s t u d i e s o f s l a s h b u r n i n g on s e v e r a l s i t e s over a p e r i o d o f lj> "to 20 y e a r s w i t h annual s a m p l i n g and a n a l y s i s of the s o i l ( 2 ) ( 3 ) from each s i t e . Only in this way is i t possible to eliminate s o i l v a r i a b i l i t y so that the effects of burning are elucidated. in conjunction with s o i l studies after burning, i t i s important to analyze the herbaceous growth invading burned sites as a means of correlating changes in s o i l nutrients with changes in vegetative growth, careful studies with respect to seedling survival and response on burned s o i l in this area are necessary to determine whether or not a r t i f i c i a l regeneration w i l l be economically feasible. ACKNOWLEDGEMENTS The writer wishes to express his sincere appreciation to the following: to Dr. D. G. La i r d f o r h i s guidance i n t h i s study, to Dr. C. A. Rowles f o r his suggestions, to Mr. R. H. Spilsbury f o r suggesting the problem and for giving invaluable advice throughout the study. TABLE OF CONTENTS Page INTRODUCTION I - H i REVIEW OF LITERATURE 1 - 2 3 A Summary of Logging Practices i n B r i t i s h Columbia 1 The E f f e c t s of Slash Burning on Reduction of F i r e Hazard 4 The E f f e c t s of Burning on the Natural Regeneration of Conifers..... 6 The E f f e c t s of Burning on the Flora of Forest S o i l s 1 1 The E f f e c t s of Burning on the Chemical Properties of Forest S o i l s 1 4 The E f f e c t s of Burning on the Physical Properties of Forest S o i l s 17 The E f f e c t s of Burning on the E r o d a b i l i t y of Forest S o i l s 2 1 EXPERIMENTAL 2 4 - 5 8 Geology of the Ni t i n a t River Valley 2 5 Climate of the Area 28 Description of S o i l Profiles, Vegetation and Burns 28 Methods of Analysis 4 0 Discussion of Natural Regeneration 47 Data and Discussion 47 Conclusions. 5 7 Recommendations . 5 8 BIBLIOGRAPHY 5 9 - 6 7 APPENDIX 68 MAP Back Cover. INTRODUCTION Since the early days of settlement,logging has occupied an important place i n the economic l i f e of B r i t i s h Columbia and yet the care of our forests and the s o i l s which "produce them have u n t i l recently been almost e n t i r e l y ignored. Forested areas have been logged and the slash r e s u l t i n g has been burned without regard f o r future regeneration of tree growth. In other instances, some areas, a f t e r being burned, have been put to e n t i r e l y d i f f e r e n t uses such as grazing or cropping regardless of s u i t a b i l i t y of the s o i l f o r such pur-poses. Thus serious losses of our natural and basic resources have resulted because of t h i s waste and misuse of forests and forest s o i l s . In some quarters an e f f o r t i s being made to focus attention on the factors which determine the success of both natural and a r t i f i c i a l r e f o r e s t a t i o n . A number of factors are involved but three outstanding ones are the ef f e c t of slash burning, the forest s i t e s , and the s o i l s . The f i r s t named, i n spite of years of discussion i s s t i l l a contro-v e r s i a l t o p i c . The study of forest s i t e indices i s now re-ceiving some attention and the conception that s o i l i s the basic resource of fore s t r y i s s t i l l scarcely acknowledged. Lutz and Chandler ( 4 $ ) , enumerating the differences between forest and a g r i c u l t u r a l s o i l s simply designate forest s o i l s as those which are r e l a t i v e l y unsuitable f o r agriculture. Such, f o r instance, include s o i l s extremely low i n f e r t i l i t y or moisture holding capacity, ie. sands and loamy sands, stony and rock outcrop areas, and those of rough topography. Since s o i l s f o r farming purposes have been selected i t may be assumed that they do not vary as much as do for e s t s o i l s of the same region. Bates (7) observes that forest s o i l s are often i n s i t u , simple i n derivation, and quite unbalanced with respect to chemical, physical, and b i o l o g i c a l properties. This i s especially the case when a s o i l develops from a single geological formation and consequently the parent material i s extremely important i n studying forest s o i l s . The problem of f i r i n g has been a controversial one i n agriculture and i n fo r e s t r y f o r many years. The burning of slash accumulating as a r e s u l t of modern logging methods on the B r i t i s h Columbia coast i s now compulsory and has been practiced since about 1930. Large areas are broadcast burned every year to reduce the f i r e hazard r e s u l t i n g from accumula-t i o n of large quantities of dry slash. The usual logging operation leaves an average of 9000 cubic feet of logs and a large branchwood per acre. In addition, there is/considerable amount of bark, chips, twigs, branchwood, and slabs averaging about 15000 cubic feet per acre. This tremendous accumulation of material becomes a f i r e hazard of prime importance i n t h i s area during the hot, dry summer period. Controlled slash burning has been advocated i n the past few years to remove t h i s excessive logging debris and thereby eliminate the p o s s i b i l i t y of accidental f i r e s spreading to adjacent v i r g i n f o r e s t s . The object of the study reported at t h i s time i s to I l l determine whether or not the inherent site quality or the potential productivity of forest land is altered through •burning and whether any such alteration is permanent or ex-hibi ts a cycl ic trend. The main factors which one would l og i ca l l y expect to influence the effects of burning on a s o i l are: the intensity of burn, loca l climate, t'opography, s o i l type, rapidity of plant succession, and amount and type of slash. A chemical investigation w i l l be the prime approach to the problem and i s , in fact, the only feasible means of study since in s i t u samples for physical analyses could not be procured due to the extreme stoniness of the area sampled. In -the author's opinion, i t i s doubtful that the physical properties of most of our coast forest soi ls vary materially under natural conditions or due to burning. However, physical studies such as determinations of non-capillary pore space, i n f i l t r a t i o n capacity, et cetera, should be made on any heavier textured forest s o i l s . Such research would enable one to determine more fu l ly the effect of burning on the erodabili ty of the s o i l . The chemical changes caused by burning forest soi ls have been studied to a certain-extent in Oregon ( 3 8 ) but no such research has been carried out on B r i t i s h Columbia s o i l s . 1. REVIEW OF LITERATURE  A Summary of Logging Practices in B r i t i s h Columbia Garman and Barr (24) made a study of natural regeneration of logged-over lands on Vancouver Island and the adjacent mainland. They surveyed the problem as i t was in the year 1930 and stated that the so i l s and climate of this area are ideal for the s i l v i c a l characteristics of the native species (Douglas f i r , Western hemlock, Western red cedar, and true f i r s ) . Consequently natural regeneration was rapid and p r o l i f i c so that most of the blocks of cut-over land, typical of logging operations on the west coast prior to 1915, had become well-stocked with thr i f ty stands of second growth. The earliest logging operations were definitely selective in nature and only the largest and best trees were fe l l ed . As a result of this selection many defective or misshapen mature trees were lef t standing and since horses or oxen were used to haul logs, l i t t l e or no damage was done to smaller trees and saplings. Thus, a considerable amount of advance growth remained to p a r t i a l l y restock the cut-over area, and there was no lack of seed trees to regenerate the openings. The logging slash consisted of only a few tops and branches of fe l led trees which were prevented from drying too rapidly during the summer by the remaining trees and under-growth which shaded them. Later, horses and oxen were replaced by steam-powered machinery and more intense cutting methods followed with the result that more timber was exploited and many small trees were knocked' down in skidding logs. However, these machines were slow enough to leave some unfelled trees standr. ing as a source of seed. The f i re hazard "became greater be-cause of larger areas and more slash "but any f i res which . occurred were usually res t r ic ted to a comparatively small area. After the f i r s t World War the "high lead" and "sky l i n e " systems of logging were developed. The use of high-speed machinery with these methods caused prac t ica l ly every l i v i n g tree not selected for cutting to "be knocked down in skidding the logs. Consequently, an enormous amount of debris accumulated and became exceedingly inflammable during the summer since i t was f u l l y exposed to the dehydrating action of sun and wind. Under such conditions disastrous f i res were inevitable. These f i res destroyed not only seeds on the ground but also the few surviving small or broken trees which were the only means of producing seeds within the boundaries of the cut-over areas. logging in this region was conducted on such a large scale and at such high speed that a company covered several hundred acres in one year. Fires sweeping through these large areas resulted in complete devastation with no reproduction or seed supply on the burned land. This was the situation as reported by Garman and Barr in 1930. Today the logging method i s the same except that even larger areas are logged every year by each company since faster and more powerful machines are now being used. To reduce the f i r e hazard i n these tremendous accumulations, of slash the practice of slash burning has been inaugurated. There has been no study made of the ef f e c t s of slash burning on B r i t i s h Columbia f o r e s t s o i l and only one such study (3&) has been c a r r i e d out on Washington and Oregon s o i l s . There i s , however, an abundance of l i t e r a t u r e on the general e f f e c t s of burning i n a l l parts of North America, Europe, and Asia. The writings pertinent to t h i s study w i l l be dealt with mainly. 4. The E f f e c t s of Slash Burning on Reduction of F i r e Hazard McCulloch, Assistant State f o r e s t e r i n Oregon (52), states that "the purpose of most burning i s not only immediate protection but long time hazard reduction so that a new forest can be grown on the area within economic l i m i t s and with some assurance of safety from f i r e s . " He i s also of the opinion that slash should not be burned where 30 percent or l e s s of the stand has been cut, where the residual stand i s made up of thin-barked or young trees, where s i t e damage w i l l r e s u l t , or where "loss of advanced reproduction w i l l outweigh the gain of temporarily decreased f i r e danger." However, he s t i l l advocates burning on clear cut areas; where large areas of slash adjoin or make i t d i f f i c u l t to get into an area of high r i s k ; and where slash i s so deep as to prevent reproduction. Munger and Mathews (54) have found that slash burned areas i n south-western Washington generally have a lower f i r e hazard f o r a 10 year period following burning but a f t e r ,15 years there i s no difference between burned and unburned areas i n t h i s respect. Thus, from the point of view of pro-tecti o n , slash burning has a s l i g h t advantage. However, t h i s i s not the case i n the fog b e l t along the P a c i f i c Coast. One logging company has burned about one-half of i t s area of slash i n the past 20 years and reports that almost 100 percent of t h i s burned area has been reburned accidentally at l e a s t once whereas only 50 percent of the unburned area has had accidental f i r e s . These writers also say that unburned slash usually de-composes quickly but the bracken, fireweeds, and vines which soon develop on burned-over areas build up an immediately hazardous source of fuel for conflagrations. As an example, a total of 6 0 , 0 0 0 acres of logged-over lands have been accidentally burned during a recent 4-year period. Of this total, 1 7 , 0 0 0 acres occurred in unburned slash 1 to 3 years old, whereas only 2 4 5 acres were in unburned slash over 3 years old. In the same period 1 5 , 5 0 0 acres of recently burned lands were reburned thereby augmenting any injurious effects of the first fire. The authors conclude that this circumstantial evidence is a good argument for the preservation of residual timber in logging and in burning. Thus, i t seems that although many workers favour the practice of slash burning to reduce fire hazards, it is worth considering the facts presented in the above example where slash burning has proven to be economically unsound as a means of hazard reduction. 6. The E f f e c t s of Burning on the Natural Regeneration of Conifers Isaac (37) studied the e f f e c t of burning on seedling s u r v i v a l i n plots near the Wind River Experimental Forest i n south-western Washington. The f i r s t hot weather i n May, 1929, k i l l e d 100 percent of the seedlings on the burned and blacken-ed s o i l as compared to a loss of 16 percent on the yellow unburned s o i l . The tremendous losses suffered on the darken-ed surfaces were e n t i r e l y due to heat injury of the seedlings at the s o i l surface where a temperature of 135°F. was register-ed. Higher temperatures a month l a t e r did not cause further l o s s of plants on the yellow s o i l . Throughout the duration of the experiment there was a heavy loss of seedlings on the yellow s o i l due to insects, damping-off, and drought which was i n addition to the loss already suffered through heat i n j u r y . Obviously, seedling losses are serious i n the south-western Washington region and as Isaac points out, shading through debris or vegetation i s e f f e c t i v e i n aiding seedling s u r v i v a l . This observation i s further supported by Garman and Barr (24) who carried on s i m i l a r studies i n B r i t i s h Columbia. At the same time, they reported that the l o s s of organic matter due to burning reduces the moisture holding capacity of fo r e s t s o i l s , and t h i s i s substantiated by Bouyoucos (11). With the high surface temperatures produced by dir e c t exposure of the blackened s o i l to the sun these burned s o i l s become extremely dry during the prevalent summer drought. Munger and Mathews (54) also support the observa-t i o n that seedling establishment i s retarded by slash burning and add that burning i s disadvantageous to most r e s i d u a l seeds. In contrast to the foregoing, Godwin (26) observed that r e -peated f i r e s cause f a i l u r e s i n restocking but he showed that f i r e s occurring before logging seem to aid reproduction on Vancouver Island i n that p a r t i a l removal of l i t t e r permits f r e e r contact of the seed with s o i l . Isaac (37) stresses the importance of burned s o i l s being unable to r e t a i n moisture as well as unburned s o i l s i n the dry summers of the P a c i f i c Northwest where s o i l moisture i s a c r i t i c a l f actor i n forest regeneration. He reports that, i n general, severe broadcast burns are detrimental to establishment of seedlings, whereas a l i g h t burn usually does l i t t l e harm and sometimes may be s l i g h t l y b e n e f i c i a l . Isaac (39) studied the vegetative succession follow-ing logging i n the Douglas f i r region with s p e c i a l reference to f i r e s . After destruction by f i r e the plant association i n t h i s region goes through four stages of succession before reaching the climax type unless subjected again to f i r e s or logging. Isaac named these stages the "moss-liverwort", "weed-brush", "intolerant even-aged Douglas f i r " , and the "tolerant all-aged hemlock-balsam f i r " , the l a s t of which w i l l p e r s i s t . The weed-brush stage i s very subject to f i r e and perpetuation of t h i s stage i s r e a d i l y brought about by success-ive f i r e s . Light cover seems to be b e n e f i c i a l to the s u r v i v a l of coniferous seedlings whereas heavy cover i s detrimental. This weed-brush stage i s often so dense that forest regenera-t i o n i s prohibited. A minor part of the weed-brush stage i s formed from some v i r g i n f orest ground-cover species whose underground parts survive f i r e s . The remaining portion of t h i s stage i s made up of such species as bracken, fireweed, blackberry, and snowbrush. Some species soon disappear but others p e r s i s t u n t i l crowded out by the vigorous brush cover and the regenerating f o r e s t . Isaac concludes that "success-ive f i r e s impoverish the s o i l , favor the herbaceous species, retard the brush species and eliminate from the succession the coniferous seedlings.that would go to make up the new f o r e s t . " In.Washington and Oregon the re l a t i o n s h i p of slash burning and natural regeneration has been studied f o r over twenty years ( 5 4 ) . It has been shown that although t h i c k -barked trees u s u a l l y survive severe f i r e s the re s i d u a l stand seed production declines appreciably aft e r a f i r e . Repro-duction studies showed only 2 5 percent restocking on burned areas as compared to 5 0 percent on unburned areas. After 3 0 years had passed since logging, BO percent regeneration was observed on burned areas whereas i t was 9 5 percent on unburn-ed areas. Mathews and Munger ( 5 4 ) also report that restocking i s retarded by large amounts of slash on a heavy burn. Less slash or a les s severe burn are more conducive to stocking but the best reproduction i s found on very l i g h t burns or on areas covered with a sparse layer of slash. In s e l e c t i v e l y logged stands, slash burning i s disastrous to both young and old stands due to f i r e i n j u r y degrading the timber. Garman and Barr ( 2 4 ) state that seed i s disseminated by. wind i n e f f e c t i v e quantities up to only one-quarter of a mile. McArdle and Isaac (50) report that 1000 feet i s the average distance from the nearest timber that adequate re-stocking w i l l occur. Since the only source of seed on large burns r e s u l t i n g fromnodern logging methods i s marginal timber, much of the burned over land i s too f a r away from the seed source. These workers state also that single seed trees scattered over logged-off areas are of l i t t l e or no value since many are permanently injured by logging, burning or being blown down by the wind. Five years a f t e r logging, l e s s than half the o r i g i n a l number of seed trees were l e f t stand-ing i n one area of observation. About 40,000 seeds are pro-duced i n a good year by an average seed tree (seed production i s a c t u a l l y very e r r a t i c from year to year) but at l e a s t 400,000 seeds are required to restock an acre. Since Douglas f i r seeds are very desirable to birds and rodents there i s seldom enough seed l e f t over f o r regeneration of the f o r e s t unless a s u f f i c i e n t amount of seed over and above that re-quired f o r the animal population i s made a v a i l a b l e . McArdle and Isaac say that 66 - 95 percent of the annual seedling crop at the P a c i f i c Northwest Forest Experiment Station die from the following causes i n approximate order of t h e i r importance: heat i n j u r y to the stem (sun scald), drought, rodents, com-p e t i t i o n of other vegetation, and f r o s t . Max Paulik (55) condemns the present logging methods because no natural regeneration occurs unless clear cutting i s r e s t r i c t e d to areas of about h a l f an acre and ample seed source i s present. He claims that 2 , 0 0 0 to 3 f 0 0 0 board-feet should be l e f t on each acre i n the form of middle aged viable timber i n order to secure proper regeneration. From t h i s review, i t would appear obvious that the practice of burning slash i s detrimental to the sur v i v a l of coniferous seedlings thereby preventing natural regenera-t i o n . l i e The E f f e c t s of Burning on the Flora of Forest S o i l s Fowells and Stevenson (23) found that n i t r i -f i c a t i o n i n Oregon forest s o i l s i s stimulated by burning and the consequent l i b e r a t i o n of basic elements. Wahlenberg et a l (66) showed that both burning and grazing are causative factors i n increasing b a c t e r i a l numbers i n s o i l but i t i s well to observe that t h e i r observations are based on only one determination. These r e s u l t s are, however, i n agreement with those of Sushkina (64) who reports that f i r e always has a stimulating e f f e c t upon n i t r i f i c a t i o n i n the forest s o i l s of Russia. Moderate burning i s more favourable and n i t r i f i c a -t i o n apparently starts within two days or so af t e r burning. This e f f e c t of burning on s o i l s l a s t s f o r f i v e years accord-ing to Sushkina. Waksman (69) made a thorough study of the l i t e r a t u r e i n addition to his own experimentations on the effe c t s of p a r t i a l s t e r i l i z a t i o n of s o i l s which i s heating to 140°F. or treatment with v o l a t i l e a n t i s e p t i c s . This treat-ment was found to increase the rate of oxidation as well as the numbers of bacteria according to Russell and Hutchinson, Hi l t n e r and Stormer, and Wahlenberg et a l . Complete s t e r i l i z -ation of a s o i l can only be accomplished under f i f t e e n pounds steam pressure f o r two hours or fo r one hour on seven con-secutive days i n flowing steam. Thus the degree of s t e r i l i z -ation depends upon the temperature and the length of tr e a t -ment and numerous workers have found that heavier s o i l s re-quire a longer heating period to s t e r i l i z e p a r t i a l l y than do sandy s o i l s . Par t ia l s t e r i l i z a t i on of s o i l causes destruc-t ion of certain groups of organisms leaving certain groups of fungi and bacteria uninjured with their growth enhanced by the more favourable medium. Thorn and Ayers^show that temperatures of 1 4 0 ° - 150°F. cause the destruction of large forms of l i v i n g protozoa, fungus mycelium and spores, as well as vegetative ce l l s of various bacteria. Kruger and Schneindewind suggest that the so lub i l i ty of s o i l minerals i s increased due to heating. Their results are summarized as follows: Yield of mustard, in grams per pot No NO3 plus corn-No Complete plete Mineral F e r t i l i z a t i o n : Manure: No NO^: Min. Fer t . : F e r t i l i z e r : Untreated s o i l 1 7 . 3 1 7 . 5 3 3 . 7 5 0 . 9 Heated s o i l 3 3 . 2 3 6 . 5 4 6 . 9 6 2 . 4 Increased so lub i l i t y of mineral constituents and s o i l organic matter due to heating was also observed by Franke,. These workers results are in agreement with those quoted previously. Heating of the s o i l thus causes a definite change in the microbial population and on subsequent remoistening of the s o i l non-spore forming bacteria showed the greatest i n -crease in numbers. The fungi make very rapid growth once introduced into s t e r i l i zed s o i l (Tokugama and Emoto). Elveden says that the n i t r i fy ing bacteria are destroyed by s t e r i l i z a t i o n and ammonia accumulates due to greater rate of organic matter decomposition by micro-organisms. Temperatures 1 Names of authors referred to on this page were selected from a l i terature survey by Waksman ( 6 9 ) , higher than 212°F. render the s o i l less f e r t i l e due to formation of toxic substances such as guanine, arginine, and dihydroxy-stearic acid which i n h i b i t the growth of higher plants (Pickering). On the other hand, temperatures lower than 212°F. generally improve the s o i l as a medium f o r b a c t e r i a l growth by rendering i t more f e r t i l e due to the i n -crease of soluble organic matter and bases. The increased number s of bacteria decompose more organic matter thus caus-ing greater l i b e r a t i o n of available nitrogen which favours the growth of plants. Waksman (70) states that i f a s o i l which has been p a r t i a l l y s t e r i l i z e d becomes reinfected with a disease pro-ducing organism, the i n f e c t i o n may become more severe. He suggests that a mixture of saprophytic organisms be i n t r o -duced into such a s o i l to counteract any inj u r i o u s e f f e c t of parasites. Anderson (2) reports that damping-off of seed-l i n g s i s induced when wood ashes accumulate. This i s ap-parently due to the higher pH and i s more extreme with s o f t -wood ashes than with hardwood ashes. Wakely and Muntz (67) found that l i g h t burning controlled the brown spot disease of longleaf pine but did not injure the trees. Daubenmire (17) discusses parasitism r e s u l t i n g from f i r e i n j u r y of tr e e s . P a r t i a l s t e r i l i z a t i o n due to slash burning forest s o i l s i s , therefore, a p o s s i b i l i t y to be considered and i t s e f f e c t would, i n a l l p r o b a b i l i t y , manifest i t s e l f i n seedling response. The Effects of Burning on the Chemical Properties of Forest  Soils Wahlenberg et a l l (66) found that frequently burn-ed-over Mississ ippi so i l s had a higher pH, contained more organic matter, to ta l nitrogen and replaceable calcium than adjacent unburned s o i l s . On the other hand, Isaac and Hopkins (38) showed that the usually heavy slash f i r e almost destroyed the duff layer of western Washington so i l s and i n so doing caused the following: (1) Loss of 25 tons (89%) organic matter per acre (2) pH change i n duff from 4 . 9 5 - 7 . 6 (3) Loss of about 435 pounds of nitrogen per acre (4) An increased supply of available plant nutrients in the surface s o i l (5) A loss of some duff mineral constituents in smoke (6) Some dehydration of secondary minerals Isaac and Hopkins state that the increased supply of available plant nutrients immediately after a slash f i r e tends to cause luxuriant crowns and shallow root systems on f i r s t year seedlings of Douglas f i r so that they cannot sur-vive normal summer drought. They corroborate the statement of Garman and Barr (24) that drought conditions of the Pacific Northwest are accentuated by losses of organic matter due to burning. They add that replenishment of this loss cannot be expected during the 10 year period required for reseeding of Douglas f i r . The authors are of the opinion that the harmful effects of f i res outweigh any beneficial effects. 15. Barnette and Hester (6) studied the effects of burning l i t t e r i n F l o r i d a and showed by analyses that a t o t a l loss of 2 , 8 3 3 pounds of organic matter per acre per year occurred due to burning annually f o r 42 years. This was accompanied by a loss of 27 pounds of nitrogen per acre per year and an increase i n replaceable calcium i n the surface 9 inches of s o i l due to accumulation of ash constituents i n t h i s surface s o i l . They also found an increase i n pH and a decrease i n hygroscopic moisture due to burning and state that burning indubitably causes the p o t e n t i a l supply of plant nutrients to be depleted i n addition to destroying the p o t e n t i a l organic matter supply of the s o i l . Wilde (76) says that potash and phosphates from organic remains are made r e a d i l y available and a c i d i t y i s decreased by the "old practice of ground f i r i n g . " His opinion i s one of objection due to loss of nitrogen and l o s s by leaching of released bases i n the absence of organic c o l l o i d s . Alway and Rost (1) studied burning i n Minnesota and report loss of organic material, r i s e i n pH-of the surface s o i l and loss of nitrogen. They maintain that any injury or benefit to productivity due to burning can be attributed to the destruction of the surface layer (forest f l o o r ) and that calcium, phosphorus and potassium do not escape i n smoke as Isaac and Hopkins (3$) have stated. Eneroth's (20) work i n Sweden led him to conclude that higher pH values and higher content of available c a l -cium after f i r e s were associated with better development of tree seedlings to make conditions more favorable f o r conifer growth. Sims et a l (62) say that the es s e n t i a l bases made available by burning are leached deeply into sandy s o i l s e s p e c i a l l y and are consequently l o s t as f a r as plant use i s concerned. The r e s u l t s reported by various workers as out-l i n e d here have been substantiated by numerous other ex-perimenters (17,18,23,24,41,48,61,67). Thus, the consensus of opinion seems to be that burning i s detrimental to the chemical nature of forest s o i l s due to loss of organic materials, nitrogen, and soluble bases. 1 7 . The Effects of Burning on the Physical Properties of Forest  S o i l s The i n f i l t r a t i o n rate of forest s o i l s was studied (3) i n Missouri under hardwood stands on seven s o i l types which were loamy and sandy loam i n texture. It was found that burning annually reduced the i n f i l t r a t i o n rate of water into the s o i l an average of 38% as compared to rates i n s o i l s pro-tected from f i r e and grazing for approximately f i v e to s i x years. The di r e c t e f f e c t of the hardwood l i t t e r was tested by removal of the forest f l o o r from four s o i l .types and the i n f i l t r a t i o n rates were found to be reduced an average of 1&% because of t h i s removal. Arend states that both these average differences were s t a t i s t i c a l l y s i g n i f i c a n t . The i n d i r e c t e f f e c t of the forest f l o o r on i n f i l t r a t i o n was tested by com-paring the i n f i l t r a t i o n rates of these four s o i l types with l i t t e r removed to the rates of the same types which had been subjected to annual burning. The i n f i l t r a t i o n rate was 18% lower for the burned forest f l o o r condition and t h i s difference was also s i g n i f i c a n t . Lutz and Chandler (4$) report also.that repeated burning usually decreases i n f i l t r a t i o n capacity and that t h i s effect i s most pronounced on heavy-textured s o i l s . They recognize that an organic matter covering usually favours i n f i l t r a t i o n but state that a fibrous; mor type of humus layer i s less desirable than other mor or mull types of humus as an aid to rapid i n f i l t r a t i o n . Heyward (32) found that a dense, r e l a t i v e l y im-penetrable, single-grained to massive structure (depending on texture) developed in the A^_ horizon of longleaf pine forest soils, which were annually burned. If fires were excluded for a ten year period the forest floor smothered out the ground cover and the A-^  became very penetrable and porous. Sandy loams or heavier soils developed crumb structures and the humus layer became mull-like. Beneath the Aj_ horizon the burned and unburned soil profiles were the same. Heyward at-tributes the characteristically poor structure after burning to the "absence of a vigorous soil fauna and to exposure of the surface soil to the elements when annual fires remove ground cover." An active soil fauna was observed when fires were excluded. Wahlenberg et al (66), in studying physical properties of soil under longleaf pine in Mississippi, found that porosity, mechanical penetrability, and ability to ab-sorb water were greater on areas protected from grazing and fire. These findings are in agreement with those of Auten (5) who found that if forest cover is adequately maintained the soil under second-growth timber does not lose its porosity unless grazing has been practiced to excess or the litter has been destroyed by fire. In these cases it is difficult to separate the effects of burning from the effects of over-grazing. In a series of tests in the Ozarks (4) Auten found that the rate of water absorption per square foot of soil was six to eight times greater in unburned forests than in burned .forests. Alway and Rost (1) determined moisture equivalents of mineral forest soils in Minnesoto and showed that those s o i l s which had been heated s u f f i c i e n t l y to destroy the organic matter had consistently lower equivalents. Heyward (34) also found unburned forest s o i l s i n F l o r i d a were as much as 52$ more moist than burned s o i l s down to a ten inch depth. This difference was esp e c i a l l y noticeable i n the top two inches of surface s o i l . The temperature of the surface s o i l i s apparently higher aft e r burning because the surface becomes black and therefore absorbs heat more r e a d i l y than an unburned l i g h t colored surface. As mentioned previously, temperatures may r i s e s u f f i c i e n t l y on burned s o i l s to cause heat deaths of Douglas f i r seedlings while seedlings on adjacent unburned s o i l are not affected ( 3 9 , 5 0 ) . In heat injury the seedling stem i s l i t e r a l l y cooked at the s o i l surface according to McArdle and Isaac of Oregon. At a s o i l surface temperature of approximately 123°F. t h i s injury begins, e s p e c i a l l y i f seedlings are less than one week old. Seedlings older than t h i s are le s s susceptible to heat i n j u r y . With an a i r temperature of 90°F. under shelter, a surface yellow s o i l had an average temperature of 132°F. while the same s o i l blackened by burning had a surface temperature of 150°F. These r e s u l t s indicate that burning may destroy a crop of seedlings quite r e a d i l y ( 5 0 ) . Heyward (33) recorded temperatures during forty-four experimental f i r e s using several types of f u e l i n the longleaf pine forests of F l o r i d a and found that the temperature of the s o i l at a depth of l/& to k inch averaged 1 5 0 ° - 175°F. and persisted two to four minutes only. He 2.0, states that heat i n t h i s region may favour plant n u t r i t i o n . However, he did not record temperatures a f t e r burning nor did he experiment with seedling s u r v i v a l on these blackened sur-faces. Thus the concensus of opinion of those who- have studied the physical properties of forest s o i l s subjected to burning i s that t h i s practice i s decidedly detrimental to the structure, porosity, p e n e t r a b i l i t y , and the heat and water absorptive capacities of the s o i l . The e f f e c t on the f i r s t three properties seems to be most noticeable i n the case of heavy s o i l s whereas the l a t t e r two properties would probably show more s i g n i f i c a n t changes i n a l i g h t s o i l . The E f f e c t s of Burning on the E r o d a b i l i t y of Forest Sals Lowdermilk (45) studied the influence of forest l i t t e r on the rate of water run-off and percolation, and on s o i l erosion i n C a l i f o r n i a . The l i t t e r i n these experiments s i g n i f i c a n t l y reduced run-off e s p e c i a l l y on f i n e r textured s o i l s even after complete saturation. When the mineral s o i l was exposed due to destruction of t h i s protecting layer of l i t t e r the absorptive rate of the s o i l was reduced and the' amount of s o i l l o s t by erosion was increased. Some of the s o i l p a r t i c l e s suspended i n run-off water sealed the s o i l pores thus causing noticeable differences i n the absorption rates of bare and protected s o i l s . Sims et a l (62) also ob-served that s o i l channels became clogged by suspended s o i l p a r t i c l e s thereby causing accelerated surface run-off and erosion. Lowdermilk concludes that "the capacity of forest l i t t e r to absorb r a i n f a l l i s i n s i g n i f i c a n t i n comparison with i t s a b i l i t y to maintain the maximum percolating capacity of s o i l p r o f i l e s . " Lutz and Chandler ( 4 8 ) have made a comprehensive study of erosion under forest vegetation and they report that accelerated erosion i s n e g l i g i b l e from s o i l s under properly managed forest stands. This i s due to the favourable s o i l porosity which develops as a r e s u l t of the r e l a t i v e l y large annual applications of organic matter. The protective cover-ing of unincorporated organic matter breaks raindrop impact thus preventing s o i l dispersion and thereby keeps percolation water free of suspended p a r t i c l e s . Under forest stands snow i s delayed i n melting so that gradual run-off occurs. Forests also decrease the e r o d a b i l i t y of s o i l because of pro-t e c t i o n against wind action, and the a b i l i t y of root systems to hold the s o i l . Lutz and Chandler quote Kotok who reported a case i n C a l i f o r n i a where burning of vegetation and l i t t e r increased erosion up to 1000 times that on unburned areas. Numerous other such disastrous instances of erosion on burned-over land lead these workers to conclude that removal of native negetation, decreasing stand density, and damaging the s o i l due to f i r e are important causes of accelerated erosion i n f o r e s t s . Gustafson (27) i s i n d e f i n i t e agreement with the findings of Lutz and Chandler. He says that steep slopes now i n forests should be maintained as such and a l l abandoned slopes i n c u l t i v a t i o n i f o r i g i n a l l y timbered should also be reforested. Sims et a l (62) state that erosion i s not-a factor on l i g h t sandy forest s o i l s of low gradient but i n -stead there occurs a d i s s i p a t i o n of f e r t i l i t y a f t e r burning due to excessive leaching of more soluble bases. In the Adircndacks, Diebold (18) observed active sheet erosion on slopes of ten to f i f t e e n percent due to baring the bedrock i n burning o f f the humus layer. In that area, severe f i r e s are "a major calamity" because the cover which invades burns i s sparse and therefore cannot prevent severe erosion. The destruction of the humus layer under white pine by f i r i n g has caused the loss of 1-4 inches of forest f l o o r and 0-2 inches of mineral s o i l as a r e s u l t of subsequent erosion. This has occurred over most of the a r e a and c o n s t i t u t e s a-tremendous l o s s s i n c e the n a t u r a l depth o f s o i l on t h e s e mountains i s s h a l l o w and i r r e g u l a r . Carman and B a r r (24) r e p o r t t h a t "burned f o r e s t s o i l s i n the B r i t i s h Columbia c o a s t r e g i o n are s u b j e c t e d t o c o n s i d e r a b l e e r o s i o n and s l i d i n g o f the l o o s e s o i l e x p e c i a l -l y d u r i n g heavy r a i n s . These w o r k e r s observe t h a t s i g n i f i -cant l o s s e s o f r e c e n t l y p l a n t e d s e e d l i n g s o c c u r due to t h e e r o d a b i l i t y of s t e e p l y s l o p i n g burned s o i l s . L u t z and C h a n d l e r (48) mention t h a t e r o s i o n o f f o r e s t s o i l s i s a c c e n t u a t e d by l o g g i n g e s p e c i a l l y a l o n g s k i d r o a d s . They contend t h a t e r o s i o n g e n e r a l l y i s not s e r i o u s u n l e s s the l o g g e d - o f f a r e a s are burned or l i e bare f o r a few y e a r s . However, areas seldom remain bare f o r l o n g e r than one or two y e a r s s i n c e a p r o t e c t i v e c o v e r i n g of h e l i o p h y t e s u s u a l l y d e v e l o p . Thus, i t can be r e a d i l y a p p r e c i a t e d t h a t i n c r e a s e d e r o d a b i l i t y and consequent d e g e n e r a t i o n o f f o r e s t s o i l s s h o u l d be c o n s i d e r e d as a p o s s i b l e r e s u l t of b u r n i n g . 24. EXPERIMENTAL The object of the study, as already intimated, i s to-determine whether or not the inherent s i t e quality of forest s o i l i s altered through burning and whether any such a l t e r a t i o n i s permanent or simply exhibits a c y c l i c trend. For t h i s purpose the Nit i n a t River Valley situated just west of Cowichan Lake on Vancouver Island was selected. The area has been progressively logged and burned by the B r i t i s h Columbia Forest Products Company over a period of approximate-l y t h i r t y years. The s o i l throughout the v a l l e y i s r e l a t i v e -l y uniform i n texture as may be observed from a study of the data on mechanical analyses. The f i r e reports and maps published by The B r i t i s h Columbia Forest Service yielded information as to the date of logging and the date, extent and severity of burning. With t h i s information as a guide, seven burned s i t e s and a "control" v i r g i n s i t e were selected. The burns ranged from two months to twenty years o l d . In order to eliminate as many variables as possible, the s i t e s were chosen with sim i l a r elevation, exposure, r e l i e f , and s o i l p r o f i l e s . V a r i a b i l i t y due to sampling was o f f s e t by taking both surface and subsurface samples from f i v e c a r e f u l l y selected p i t s dug within 100 feet of one another at each s i t e . The surface samples were obtained just below the Ao horizon, or the burned remains of the duff layer, while the subsurface samples repre-sented a depth of approximately IS inches depending on the depth of the solum. A study of these samples should disclose 25. any movement through the s o i l p r o f i l e of c o l l o i d s i n suspension or s a l t s i n s o l u t i o n . Geology of the Nitinat River Valley This v a l l e y has not been subjected to a detailed geological survey but a reconnaissance party under Clapp covered the area i n 1909. Since most of the surrounding d i s t r i c t s were subjected to g l a c i a t i o n , i t had been assumed by geologists that t h i s v a l l e y was no exception. However, 1 Mr. R. H. Spilsbury and the author found that angular rocks increased i n size and numbers down through the mantle u n t i l bedrock was reached. They therefore concluded that the surface mantle of the v a l l e y represents^a r e s i d u a l s o i l . The parent material of the Nitinat River Valley i s composed of rocks belonging to the Vancouver volcanic formation which i s one of f i v e formations c o l l e c t i v e l y named the Vancouver Group (14). The Vancouver volcanics are the main rocks of Vancouver Island and make up the greater part of the Vancouver group. The p r i n c i p a l rock type of the Vancouver volcanic formation i s a meta-andesite which i s often associated with augite and i s usually phorphyritic with an aphanitic ground mass. The phenocrysts are small but numerous commonly consisting of s t r i a t e d feldspar and altered hornblende (43). The rocks have been sheared and altered and are dark green or dark grey i n c o l o r . The green color indicates the presence of secondary c h l o r i t e . They are also cut by v e i n l e t s of quartz, epidote, c a l c i t e , and are Mr. R. H. Spilsbury gave invaluable aid i n s e l e c t i o n of the s i t e s j arranging f o r shipment of the samples, and i n general giving advice and encouragement thraghout the study. 26. commonly impregnated with p y r i t e . These rocks were meta-morphosed from basic lavas of Mesozoic time and so are 1 alkaline i n reaction. Since no analysis has been carried out on the parent rock of t h i s p a r t i c u l a r area, the analysis of an augite ande-s i t e rock from Rockland Ridge, State of Washington i s present-ed i n Table 1. This rock i s reported to contain plagioclase, augite, apatite, magnetite, and re s i d u a l glass and i s b e l i e v -ed to be similar to that i n the Nit i n a t Valley. x 2 Table 1. Analysis of an Augite Andesite and i t s Derived S o i l . Compound: Fresh Rock: Derived Si0 2 50.85 58.16 AI2O3 12.54 15.03 Fe 20 3 10.03 10.59 FeO 7.11 - - -MgO 5.57 1.99 CaO 9.33 4.57 Na20 2.37 2.56 K 20 1.13 1.68 H20 0.34 1.77 Organic _ - - 3.52 P 2 O 5 O.76 0.43 SO3 0.05 0.07 Total 100.08 100.37 x A l l r e s u l t s are percentages by weight. 1 The reaction of ground parent material averaged pH#.33 2 Taken from "The Data of Geochemistry", by F. W. Clarke, 1924, Government Prin t i n g O f f i c e , Washington, Bui. 770, p.490. The andesitic parent rock of the Nit i n a t Valley-f i r s t cracks into large boulders and then to smaller rocks and shale-like fragments as weathering proceeds. This gradual breakdown i s i l l u s t r a t e d i n Figures 1, 2 , and 3 . Figure 4 shows how herbaceous growth, such as s a l a l seems to f l o u r i s h on the shalv fragments of weathered rock. Figure 1, Figure 2, Figure 4» 1 Climate of the Area No climate report i s available f o r the actual area studied but reports are given from Port N i t i n a t which i s 23 miles west of the sampling area and from Lake Cowichan (the v i l l a g e ) which i s 21 miles east. The l a t t e r reports 70.77 inches of p r e c i p i t a t i o n annually as a 30 year average. Port Nitinat reports 1 1 2 . 4 9 inches as a 3 0 year average. From these two figures one would l o g i c a l l y expect an annual pre-c i p i t a t i o n i n the upper N i t i n a t Valley of about 90 - 95 inches. Also reported from Lake Cowichan and Port Nitinat are the average annual temperatures which are 50°F. and 48°F. respect-i v e l y . Thus the P r e c i p i t a t i o n Effectiveness or PE index of 2 Thorthwaite can be calculated (approximately 304) and places the area i n the "wet" humidity province according to Thorn-waite's c l a s s i f i c a t i o n . Despite t h i s very wet climate the months of June, July, and August are r e l a t i v e l y dry. Description of S o i l p r o f i l e s , Vegetation t and Burns The s o i l samples are designated by the year the s i t e was burned and so the surface samples from the s i t e burned i n 1948 are c o l l e c t i v e l y referred to as 1948-A and the corres-ponding subsurface samples as 1948-B. The samples procured . from under v i r g i n timber are named Virgin-A or Virgin-B as the case may be. The 5 p i t s dug i n each s i t e were observed as to t h e i r p r o f i l e s and the average of these 5 was described i n de-1 : ;  "Climate of B r i t i s h Columbia", Report for 1944, Dept. of Agriculture, Province of B r i t i s h Columbia. 2 Jenny, Hans, "Factors of S o i l Formation", New York, McGraw - H i l l , 1941, pp. 110 - 111. 29. t a i l as being representative of the s i t e . A p r o f i l e descrip-t i o n f o r each s i t e i s presented i n Tables 2 to 9 i n c l u s i v e . Table 2. P r o f i l e description of s o i l under mature forest Structure Consistence Stones Roots Depth Texture Color  2" humus black aggregated s t i c k y 0-4" g r a v e l l y red to sandy loam dk. br. f r i a b l e 4-22" red-brown some ag-gregation 22-30 stony, yellow s i n g l e -sandy loam ' grained n i l many -interwoven many some 80% few 30 + bedrock P r o f i l e development: poor Topography: 500 feet elevation, southerly slope, spots sampled were on a shoulder. M i c r o - r e l i e f of p i t : uniform gentle slope S o i l drainage: subsoil drainage excessive. Vegetation: Forest cover: Douglas f i r - dominant Red cedar - codominant Herbs: sword fe r n - dominant lichen - codominant Other species: huckleberry, deer fern, lady fern, maiden-hair fern, may l e a f , t i o r e l l a , bracken, blackberry, n e t t l e s . Site q u a l i t y : excellent. Table 3 - P r o f i l e description of s o i l burned 1 % 8 Depth Texture Color Strudure Consistence Stones Roots 0 - 3 " gravelley red - s i n g l e -sandy loam brown grain f r i a b l e 3 - 6 " 6 - 8 " n it yellow " red - cloddy brown K5% 50% 50% 80% many quite a few n i l 8 - 3 0 " stony yellow " " 3 0 " 4 bedrock Note: Ao burned o f f P r o f i l e development: some tendency f o r leached A 2 but i s probably mostly due to color change of minerals. Topography: 700 feet elevation, shoulder on mountain M i c r o - r e l i e f of p i t s : uniform gentle slope S o i l drainage: some surface runoff, subdrainage excessive Vegetation: Forest cover: n i l Herbs: sword fern - dominant , _ # J . •» bracken - codominant ^ e r Y f e w o £ either) Site quality: no reproduction as yet but stumps indicate a good s i t e index before logging. Figure 6: - 1948 burn This burn was carried out during the f i r s t week of May and since the samples were collected i n July of 194$ the burn was only two months old when sampled. The photograph shows the t y p i c a l blackened appearance of a recent burn with the large quantity of p a r t i a l l y burned slash strewn over the surface. Table 4* P r o f i l e description of s o i l burned 1947 Depth Texture Color Structure Consistence Stones Roots burned humus 0-4" gravelly reddish single - f r i a b l e many numerous sandy loam brown grain 50% 4-18" « red-brown some ag- " larger few gregation 60% large 18-30 gravel drab s i n g l e -grained " 90$ n i l 30 + bedrock P r o f i l e development: l i t t l e development, s l i g h t accumulation of iron oxide at about 16". Topography: 600 feet elevation, south-east exposure, shoulder on mountain side. M i c r o - r e l i e f of p i t : gently sloping S o i l drainage: subdrainage excessive Vegetation: Forest cover: n i l Herbs: senecio - dominant bracken - codominant Also blackberry, t h i d l e , sword fern and elderberry. Surface i s 50c/o covered Site q u a l i t y : no reproduction as yet but size of stumps i n -dicate that i t was an excellent s i t e . Figure 7:- 1947 burn This area was burned accidentally according to the P r o v i n c i a l Fire Reports (22) and was a surface f i r e which burned through f e l l e d and bucked timber i n June, 1947 with periodic outbreaks u n t i l August of that year. Its appearance 33. i s s i m i l a r to the 1948 burn except that herbaceous growth has commenced. Table 5. P r o f i l e description of s o i l burned 1945 Depth Texture Color Structure Consistence Stones Roots burned humus 0 - 2 " g r a v e l l y dk. red-sandy loam brown crumb f r i a b l e numerous many small 2 - 1 2 " 1 2 - 2 4 " reddish- nut-like brown drab to s i n g l e -red br, grained " 60$ some "' 80-90$ few 2 4 " - 1 bedrock P r o f i l e development: may be a s l i g h t concretionary layer at 2 4 " depth otherwise l i t t l e development. Topography:. 4 0 0 feet elevation, s l i g h t northerly slope situated on a benchland on two k n o l l s . M i c r o - r e l i e f of p i t : gently sloping. Drainage: subsoil drainage excessive. Vegetation: Forest cover: n i l Herbs: senecio i s dominant fireweed i s codominant also s a l a l , hawkspur, salmonberries, bracken, huckleberries and an unknown white clustered flowering plant. Surface 75$ covered Site q u a l i t y : t h i s s i t e was apparently an excellent one as can be seen i n the accompanying photograph. Large stumps were observed but no reproduction has occurred as yet. Figure 8:- 1945 burns This area was slash burned i n the f a l l of 1945 and according to the f i r e report was a "good burn." Table 6. P r o f i l e description of s o i l burned 1942  Depth Texture Color Structure Consistence Stones Roots h-ln humus (mostly moss) 0-2" gravelly red-br. granular sandy loam to black 2-16" stony red- quite sandy loam brown granular f r i a b l e 50$ many l6"-30" gravel l i g h t s i n g l e -red-br. grained -- some aggregate 75$ a l l stones few 30" + bedrock P r o f i l e development: p r a c t i c a l l y none. Topography: 500 feet elevation, northerly slope, shoulder of a small h i l l . S o i l drainage: subsoil drainage excessive Vegetation: Forest cover: n i l Herbs: Fireweed - dominant Bracken - codominant Other species - huckleberry, thimbleberry, s a l a l , l ichens, hawkspur, white clustered flower. 100 % cover Site quali ty: stumps indicate a very good s i t e , as yet no reproduction. Figure 9:- 1942 burn This burn was a "good burn" according to the f i re report. The photograph i l lus t ra tes the density which f i r e -weed can reach on a site after burning. 36 Table..7• P r o f i l e description of s o i l burned 1937 Depth Texture Color Structure Consistence Stones Roots 2" humus black many roots holding together t h i s layer 0-3" gravelly dark red-sandy loam brown granular f r i a b l e 50% many 3-12" stony red-br. " • " 70% some sandy loam more and larger 12-24" " drab single - " many few grained 24" T bedrock P r o f i l e development: very l i t t l e , the fine s o i l i s more loamy i n texture here but rocks are very numerous. Topography: 900 feet elevation, north-west exposure i n draw of Vernon Creek.. M i c r o - r e l i e f of p i t s : gentle slope S o i l drainage: subsoil drainage excessive Vegetation: Forest cover: Hemlock - dominant Cedar - codominant "Also Douglas f i r , alder. Herbaceous cover: S a l a l - dominant fireweed - codominant other species - huckleberry, blueberry, bracken, lichens, hawkspur, white cluster, may l e a f , blackberry, blackcap, Oregon grape, swamp grasses, sword f e r n . Site q u a l i t y : t h i s s i t e was excellent judging by the stump size and number. Reproduction i s about 10% i n the spot sampled and t h i s i s low when one con-siders the proximity of seed trees which can be seen i n the background of the photograph. 37 Figure 1 0 : - 1 9 3 7 burn This burn was a slash burn started i n f a l l of 1 9 3 7 * The f i re report indicates that a generally good burn resulted. Table 8 . Prof i le description of s o i l burned 1 9 3 2  Depth: Texture: Color: Structure: Consistence:Stones:Roots: 2 " - 3 " humus black granular fr iable few 0 - 4 " 4 - 1 4 " gravelly dark sandy loam red-brown red-brown 6 0 % many many roots which bind many fibrous single-drab yellow grained many many fewer 1 4 - 2 4 " gravel 2 4 " + bedrock Profi le development: A and B horizons quite dis t inct as com-pared to other areas. Humus layer thicker than any other burned or v i rg in area. Topography: 6 0 0 feet elevation, southerly exposure, gentle slope from adjacent mountain. Micro-re l ief of p i t s : gentle slope S o i l drainage: subsoil drainage excessive Vegetation: Forest cover: Douglas f i r - dominant Hemlock - codominant Also cedar and some alder Herbaceous cover: Oregon grape - dominant huckleberry - codominant other species - sword fern, lichens, white cluster, thimbleberry, blackberry, hawkspur, fireweed, s a l a l . Site quali ty: this s i te has streams close by and judging by stump size i t has been a very good s i t e . The accompanying photograph indicates the good re-production taking place. Figure 11:- 1931-32 burn This area was slashed burned in 1931 and burned again accidentally in 1932. Both burns occurred in the f a l l . 39 Table 9. P r o f i l e description of s o i l burned 1929 Depth Texture Color Structure Consistence Stones Roots 1" 0-4" 4-13" humus gravelly sandy-loam black granular f r i a b l e red-brown s l i g h t l y granular l i g h t red-brown single grained - - moss, roots many many small fibrous many fibrous large roots 80-90% 13-24" gravel drab .  " " 24-36" bedrock P r o f i l e development: not well developed. Topography: 600 feet elevation, southerly exposure, i s o l a t e d k n o l l i n center of wide v a l l e y . M i c r o - r e l i e f of p i t s : uniform gentle slope S o i l drainage: subsoil drainage excessive Vegetation: Forest cover: western red cedar - dominant hemlock - codominant also - alder, willow, f i r Herbaceous cover: S a l a l - dominant huckleberries - codominant other species - sword fern, salmonberry, fireweed, thimbleberry, bracken, lichens, blueberry. 100% ground surface covered. Site q u a l i t y : about 50% regeneration has occurred on t h i s 19 year old burn. It was a good s i t e previous to logging. Figure 1 2 : - 1929 burn. No record of this old burn is available but a f a i r l y severe slash burn must have occurred from indications i n the area. Methods of Analysis Mechanical analysis:- A l l samples were passed through a 2 mm. seive preparatory to analysis and the relat ive pro-portion of rocks and fine s o i l was determined by averaging the weights of the five replicates at each s i t e . Mechanical analyses were carried out on the fine s o i l fraction by the Bouyoucos method (10) and interpreted using the textural triangle ( 5 3 ) . Determination of pH:- Five grams of the sieved s o i l were weighed into a 50 -ml . beaker and 10 ml. of fresh tap water at a temperature of 25°C. were added. The s o i l and water were mixed thoroughly with a s t i r r i ng rod and allowed to slake for 30 minutes. The mixture was s t i r red well and the pH read using a Beckman meter. The method outlined was adopted be-cause of v a r i a b i l i t y noted when d i s t i l l e d water was used which, 41 on standing, absorbed carbon dioxide and became quite acid. Even though the carbonic acid formed is very weak, it seemed to affect the pH of these soils materially. Since it was inconvenient to keep sufficient quantities of freshly boiled distilled water on hand, fresh tap water was used instead as it had a neutral reaction. Reed and Cummings (59) discuss dilution as it affects pH readings and on the strength of their arguments the dilution of 1:2 (soil to water) was employed. The Determination of Exchangeable Hydrogen and Total Ex-changeable Bases:- The method as outlined by Brown (12) was used for determinations of exchangeable hydrogen and total exchangeable bases with certain modifications, i.e. - 10 grams of soil were used with 100 ml. of extracting solution and the sample slaked with a shaking apparatus for 15 minutes. After this thorough shaking, the mixtures.had reached their ultimate pH values and no changes were noticed with further slaking. The two graphs shown in Figure 13 are the standard graphs made up by titrating the leaching solutions as described by Brown. From the results of the exchangeable hydrogen and total exchangeable bases the percent base saturation was calculated. The Determination of Readily Soluble Plant Nutrients:- The principles underlying the method of Peech and English (56) were used to determine the amounts of readily available chemical constituents.. This rapid microchemical test provides a ready means for determining the chemical components in soil i i i i l • i ; -1 f i i . i i 1 i I , ; i ' i ' ! 1 1 i i 1 1 I I • i '•• ; ; F I G U R E 13 , 42 - r -4— ( - 4 —f- r-- 4 - 4 4 r -!-- -- + 1 - * 1 ; 1 rANDARD ( xRAJ*H for 1 . . . EXCHANGEAI 5LE H Y D R O G 1 . E W x r x i r -_ - . , — \ -1 _ . . i • . ,. - * - • - • - -. . . . . . f . , • + - + . 4 . - • | * • ' ' -- • . i - I * •• - + -4 , * • • - — • — -- - » — * - . -i ' 1 1 - 1 • 1 •• j • . 1 . f ' rxt • f ', -• + 1 1 • 1 1 1 1 [ 1 | i Q J 1 i .. , | t f ~ |. i , M « . • i H 4 i ~ + 4«i * ; I I ' '• • . . ^ , ( - - j l. + | ; • 1 i 1 1 . ! • . ' ' I I -V H : ; ; : : -• - | N ^ . —, + • . . r>y * , + . X . -• - — . 4 - . . . . . i 1 • • , • |. . . ; . ; . j 4 , i , t : • - . j. . , r ; - : ; *:; :.* 1 , • >• * 1 . . . . 1 * ! [ 1 ^ ^ " ^ > 1 '''." * r . ; , 3 S R . , 1 . 1 j t • • * - --{-* * 4 4 - ^ - 4 - ^ 4 . i 1 ' 1 - | ' _4 - l - 4 J 1 : • . + t ; l , • " ! ! - 1 ^ • • •;• •; + I J + -. . . . * , 4 _ . 4 • , - . + i * i ;-1 , • 1 ; • • 1 T + 1 T 1 , ' 1 * 4 ) , 1 -f . - 4 f i "XI z .:: w . ! 1 . | 1 . I - ^ 4 - 4 •*:}.: j : . : : x -ExCHANGEAf • , , 4 . * - - (- - 4 • 1 t 1 ! ' | 1 1 ' • -. 4 i ; ! i ; ; U J A N I J A K D y . K A P H y « r •L£ :DASEi _ , - 4 . 4 - 4 I * - + • • t r • t * * |. L . < • -, . . . . . , '; f T — . . — — • --1 1 - •* + 1 t > • , ^ 4 - • t - • -1 1 i j . . -[ • I _4 . " ' T r 4 *. + + » + * . . . . . . 4 . - - , - r 4 T - -+ * • . . . .4 4 4 f -: : . x : ; ; I:;:: : : :: f - , n . i ; |. 1 > ( . f 1 I , . . 1 - - ^ i . i • .. . .! • y • 4 • -.I 1X_ 1 . . . . - , - . = 1 ' 1 - 1 ' / ., , , . . . , . . . . . . ; : : : " 5 , . . . . . ^ : . - ; - . - ^ i S . ; . . . < . . , 4 - . . 4 1 4 •- < . . . y . - 4 4 . -i . : _ . 'I . - -i , . R . . , . . + - * , 1 | . - . f . I- ' * • I I I I i I I • I 0 S -i - * tJ V 3 _ i — | — j — , — | — , — 1 1 1 I . 1 . I , — — — - 1 — — t — t — * —f—h — 1 1 ' I which are affected by burning. Deviations from the method involved minor changes in technique i n order to adopt i t for use with the rotary shaker, and the Fisher electrophotometer. The standard graphs for the various nutrients determined are shown i n Figures 1 4 , 1 5 , and 1 6 . These were calculated using known standards. The Determination of Organic Matter::- The method used for organic matter determination was essentially that of Wilde and Patzer (75) with a few minor changes such as using a more dilute potassium dichromate solution, ( 0 . 4 Normal) and using a different indicator (barium diphenylaminesulfonate). The Determination of Total Nitrogen:- Total nitrogen was determined by means of the Kjeldahl - Gunning method which requires the use of potassium sulphate, s a l i c y l i c acid, sodium thiosulphate and selenized granules i n addition to concentrated sulphuric acid. The mixture was digested u n t i l white in color and was then diluted with fresh d i s t i l l e d water, sodium hydroxide added to bas ic i ty , and the d i s t i l l a -t ion carried out i n the usual manner. From the percent organic matter the percent organic carbon was calculated by dividing the value by 2 ( 7 5 ) . From the foregoing data carbon-nitrogen ratios were calculated. The Determination of Moisture Equivalent:- The Briggs -McLane method was followed i n determining the moisture equivalents for the fine s o i l f ract ion. 1 j 1 1 1 — —1—(—{—*—!—!"*—.- — -, ; i : i . i , , 1 , , . > 1 f 4 4 . 1 J - - - - ) - - -1 f -+-T--" M J " t ^ .- * '[ • t + • t ' i ! * - t ! t ' ! 1 1 1 1 : • 1 : ; . . . ^ , . , - . 4--ro ; G R / • * - * . - 4 - 4 - 4 - 1 0 T A N DA YAILABLE' L A L C I G M - 4 - 4 - -j . j . . , . - 4 -• + «J--T j t ' >• 1 t ' 1 . - * . - + , 1 . . . 1 , ' '• 1 1 • t • • i 1 . , : T . ' i T j + + -, 4 + -I + + -+ . - . . -, t -( • - !--+- 4-- • 1 • . \ ' + ' . M > > - ^ M M 1 > 1 v l . 4 . t •< . 1 . ., 4 4 '• 4- . . - » -t * UI ] 20 d * UJ ' t" ; 1- + 4 t r I ' 1 4 -t--; * '» i 1 > , . : y 7 ' H i \ 1 1 . , • ! 1 - : i -4 - + .- t ; ! ^ 1 — ; [ JJ- -<< + , . + . J. . r . ^ ,- r - + -4 - * -+ +- • - + J + * - - •= 4- -I • ' • - i- 1 • - |. 4 , -i l l . 1 : 1 T ' 1 ' t ' > 1 + • j z / 5 ' ! M I ; J ->• - - - ' T r - + . - t t J t '• -t + . R _ 4 ^ - i~* - 4 - 1 — 1 T 4 - 4 - - 4 . * - - + -t . . . . . . . (_-„ 4 - 4 . - 4 — . J ; ! 4 • U : t - - 4 4 4 -1 • f f - . ,. 4 4 r: :: i i a * *• 0 • 4 - 4 . 1 r!-r!.-T -t~- + + P ,-<^ • j j -\ ' 1 1 • • : •:!!•! ' t , . 1 ui * j -0 . ... t • i • . 1 . ' [POUNC & PER R £ ' ' . . . . -4 ; 4 4 1. 4- . i I 1 ! t • \ i ,-. 11: • i *" ' T . + , - 4 4 J i 1 I • • - i , SOO' /eoo , i . . . . . . t/SOO' 1 XOOO , 4 4. . . . 4 1 1 ' . ' . I-1 I Spoo 1 r ;! . : . •. + + ^ ^ _^ 4' ST A N D A R ' ! ' ' 1 ' '. . ! . . . . . . . T r D G R A P H VA ILABLE 1 AGiMES\UM . . . . . . j. , M . 4 - - , . . 4. ,. ' 1 j- . . 4 f " • > ' ' " ' 1 - * : ; !.. . . . . 4 . 4 4 . ! - - . 4 i ; 1 ; " i l .. J • + i- -r t--P — i . , - + : . . 4 -• - , . | : • - ! - : - ; ^ . . 4-- j - : 1 1. - • 4 | . - 4 J. 1 - • 1 «!> . . .2 ... a . . •. 4 ) 1 . . . . , • ! i ! ! 1 1 . -/^ . . . . T . ^ ^ 4 . . J +. . , .. i . . . . . . . . .-_+ 4 . 1-4--, 4 - 4 4 4 ; t - 4 -x - • 4 4 4 . - 4 - 4 4 -4 1 * : 1 • -i ; • + i • j J-.l - • -i JO UJ h -UJ 2S I '". 0 . -h . .. a 0 h IS 0 Ui UJ . . . . . / 4 , 4 . -. 4 J r ' • . . . . . . 1 . 1 * | J ' ^ 1 .-4 4- 4--4.- J i - - i -- 4 - 4 - I ' i . - , - . - i - 4 _ - 4 - - L- 4 . - —4 X . t . . . t '. . I ' ' ' 1 | j , • ' . ! • t ; i ; • ! ! ! 1 | ! ! | 70 - 1 ; : i •s \ f- + • j • + - - !• Pour> i ! : 1 1 | | IOS , I PER . A . . . C R £ - - + . . . . 4 .4 4- 4 4 4- 4 -4 4 4 i 4- - - 4 . 4 1 • i • 4 . 4 • t . - -- , - . < so /oo 1 /so . i . 30O tkso 300 4 7 Discussion of Natural Regeneration It-may be- observed from the vegetation reports and accompanying Figures that natural regeneration i s now under way on the two oldest burned s i t e s . Even this regeneration is not as good as i t should be. Apparently, restocking does not begin on a burned si te for 1 0 to 1 5 years depending on the proximity of seed trees and the number of good seed years. These results are i n agreement with numerous workers such as Isaac (39), Reid et a l (60), Mathews and Hunger ( 5 4 ) and Paulik ( 5 5 ) . Data and discussion The results of the mechanical analyses as l i s t e d i n Table 1 0 were determined from composite samples and i t can be seen that a l l the so i l s belong to one textural class — sandy loam. It i s important to note that these results do not represent the true f i e l d s o i l since a l l the part icles larger than 2 mm. i n diameter, about 6 0 percent by weight, had been,removed. I f this large proportion of rocks i s taken into consideration the true textural class of a l l these so i l s would be. stony sandy loam. As one would expect, with a residual s o i l , the percentages of sand and s i l t part icles seem, to be higher in the subsoil than at the surface of an undisturbed Virgin s o i l while percentages of clay and co l lo ida l part icles are higher at the surface. Close observation of Table 1 0 re-veals that the burned so i l s exhibit a marked increase of fine particles i n the subsoil as compared to that of 48 x Table 10. Mechanical Analysis % Sand fo S i l t % Clay % C o l l o i d a l Texture 1948-A 60 .0 2a.3 11.7 9.65 Sandy Loam 1947-A 58.6 29.6 11.a 10.1 tt tt 1945-A 61.0 26.0 13.0 10.5 tt » 1942-A 54.4 32 .1 13.5 10.6 tt tt 1937-A 54.7 25.4 19.9 17.0 tf tt 1932-A 59.a 2a.9 11.3 8.5 tt tt 1929-A 57.2 31.0 11.a 9.2 tt tt VIRGIN-•A 56.6 31.6 11.a a.a tt tt 1948-B 56.9 31.5 11.6 10.2 Sandy Loam 1947-B 54.9 31.9 13.2 9.7 tt tt 1945-B 63.a 23.9 12.3 9.4 tt tt 1942-B 54.6 35.4 10.0 7.6 tt tt 1937-B 54.6 26.1 19.3 16.3 tt tt 1932-B 67.9 23 .0 9.1 7.3 tf tt 1929-B 54.2 29.5 16.3 13.5 tt tt VTRGIN-•B 5a.3 35.9 5.a 5.0 tt tt x Based on oven-dry weight. the unburned s o i l . This phenomenon i s quite noticeable i n the three oldest burns (1929, 1931 - 32, and 1937) and to a certai n degree i n the others. The increase of f i n e p a r t i c l e s i n the subsoil af t e r burning i s undoubtedly the r e s u l t of heat destroying the s o i l aggregates so that the c o l l o i d a l p a r t i c l e s become dispersed and consequently moved down into the profi le by percolating water. In support of th i s , Puri and Ashgar (5&) report that co l lo ida l properties of so i l s are destroyed by heating. However, i t seems probable that a migration such as this could only take place where the electrolytes were f i r s t removed by leaching to prevent flocculation (8). The results of a l l analyses other than mechanical are presented in Table 11. The determination of pH and available nutrients were carried out on each replicate and the results averaged whereas a l l other determinations were performed on composite samples i n duplicate and averaged. A review of the data as presented in Table 11 suggests considerable natural variation in respect to s o i l properties and hence i t i s not proposed to discuss absolute values but rather to indicate trends which appear as a re-sult of burning. The pH data for the Virgin s o i l show a wide range between subsurface and surface, the la t ter being more acidic as i t should be. The surface so i l s of a l l the burned sites are also more acidic than the corresponding subsoils. The 1948 and 1947 burns do not show an increased pH as one might expect and even the "B" appears to be lower. This may be explained as being due to excessive leaching following removal of surface cover. Vegetation high, i n minerals (fireweed and groundsel) has become well established on the 1945 burn and appears to be "pumping'minerals into the surface s o i l from depth thereby T A B L E 1 1 . S V J M M A R Y OF n i l A L Y T l C A L I X E S U L X S . S I T E V I R G I N 19 4 8 I 9 4 T 1 9 4 3 19 42. 1937 J 931 - 3 2 1 9 2 9 H O R I Z O N A B / A E> / A B / A B / A B / ?' A e> / 1 A / A B / P H lf.9Z 5.68 0.76 Oif9 ^.72 5:26 OSLf. 5.13 3.65 O.SZ 5 5 9 5.9y 0.35 3.58 5.79 o.zt 5.29 O.35 3:3/ E X C H A N G E A B L E HYDROGE* is.s * 7 /0.8 12.3 7o /7-0 8.5 17-1 7.8 9.3 /0.8 3*9 /3.o 9.0 v o 6.8 3.6 9.H (0.0 TOTAL EXCHANGEABLE BASIS /3-5 13.1 /o.o 3./ lf.0 /O.S 3.5 /z.o /0.3 A7 i3.S / 2 3 A 2 /*t..o /6.0 -2.0 /O.7 '37 / y .3 -o.b P E R C E N T B A S E ^SATURATION. +6-7 27.y. Sl-6 6 5 3 tfSZ 553 / o . / V-tZ 56.9 5*5>.6 67.6 5/. 9 6 .^0 *ZI 60.7 /V-.3 *+7l 60-V /3.3 A V A I L A B L E C A L C I U M . IfOO / 3 0 270 285 6 5 {90 70 U O y53" /OO 355 2 8 S so 2 0 3 720 290 H- 30 350 /60 / 0 O SCO 90 m i f iO A V A I L A B L E M A & N E S I O W 60 /6 3 6 IO 2*B 3 7 zo <7 3"0 / 8 3 2 + Z. / 2 3 0 70 2 9 <// 6 9 2 6 if 3 BS '7 6 8 AVAILABLE P O T A S S I U M (XI—./fore.) 70 0 70 68 H- 3 2 O 32. 3 8 8 3o 5 b 6 3"0 76 3 8 3B ¥Z 8 36* I3if 9 IZ.S A V A I L A B L E PHOSPHOROUS 3.o /.z A 8 as- z.sr 8.f 6 9 A 5* 8.0 ¥ • ¥ 3.6 3 6 ZS A/ 6.0 2.-9 3 . / 7.3 6 .y 0.9 51 2.6 z-.S A V A I L A B L E A M K O N I A 56 /O 90 V*. * 8 80 5 5 - 5 9 5> S 5" 60 .56 5 8 60.5" S7 56.S O.S A V A I L A B L E N I T R A T E SOS / 8 8 / / 7 ss / 8 7 f 5 0 /07 3 * 3 2fS IZS tzo 3 3 0 109 2.2,/ 2 9 5 223 7 2 320 330 - / o 27V /83 9/ P E R C E N T ORGANIC MATTER •^07 se? 886 333 553 *0.92 7-56 3.36 to.QS 3 / 8 7 6 7 8.03 3.66 ¥37 785 3.6/ 8.// 6OQ 2.03 11 + 3.95 7*5 PERCENT T O T A L NITROGEH .023 .207 .258 .113 ./*5 .too ./5b .228 .09/ ./37 .206 ./03 ./03 -'7/ .037 . / 3y .tet »/33 •oyfi .267 .058 .209 C A R B O M - I I ' T R O C E N RATIO ZJ.b <o70 / 7 2 tz.s 2 / 3 38C /6.7 23.8 /tf.6 ~"3«2 /9.S ' 7 8 - A 7 23.0 57:6 zz-i 0.*. 2 / . 3 / z . 8 M O I S T U R E E Q U I V A L E N T f f / -9 35.y 9.5 333 337 - a y 38.7 </.6 3 * 7 2 ^ 5.3 38.9 35.5 3*/- ¥V3 39./ 3 . Z 372 3Q.y 6 6 if 9.1 370 * B a s e d o n o v e n - d r ^ w e i g h t . ra is ing the pH l e v e l . With the older "burns this process has proceeded further and hence differences between A and B samples are greatly reduced as . is apparent in the table. Once the burn has become suff icient ly old, the shrubbery with high mineral content may give way to coniferous growth of lower mineral content and so- ultimately the condition, as pertaining in the v i rg in s o i l , w i l l develop. It is generally recognized that coniferous trees use smaller amounts of s o i l nutrients than do most agr i -cultrual plants. In addition, support for the postulation that herbaceous ground cover i s high in basic nutrients i s given by Lutz and Chandler (48) who describe Tamm's work in Sweden. The la t ter found that basic igneous rocks and calcareous sedimentary rocks have the highest calcium content and produce so i l s which support Norway spruce forests with p r o l i f i c herbaceous undergrowth. Tamm observed, in contrast, that more acidic rocks supported a different and less p r o l i f i c type of growth. In a l l s i tes , the amount of exchangeable hydrogen is greater in the surface than in the subsurface s o i l . This difference i s less for a l l burned sites than for the v i rg in due no doubt to the added ash. Other.differences are i n -dicated but the lack of definite trends suggest that they are due to natural var ia t ion. The to ta l exchangeable bases are negatively corelat ed with the exchangeable hydrogen as one would expect. The values for the v i rg in si te show that the content of bases i s the same in the surface and subsurface s o i l . The 1948, 1947, and 1945 burns exhibit higher base contents due to the residual ash but in the 1942 burn and older burns the surface and subsurface values approach one another as in the v i rg in s i t e . This would-appear to suggest that under the conditions of the experiment the effect of added ash begins to disappear 3 or 4 years following burning. The percent base saturation data show some apparent differences but none appear to be significant except the fact that the v i rg in subsoil has a higher saturation percentage than any of burned site subsoils. This lower percentage after burning may possibly be due to increased biological ac t iv i ty , to the "pumping" action of herbaceous growth as mentioned with respect to pH increases, or to a combination of the two. One may also observe that a s igni f icant ly greater difference occurs between surface and subsurface samples of the v i rg in s i te as compared to a l l burned s o i l s . This too can be account' ed for by the decrease i n percent base saturation of subsoils. Amounts of available calcium.magnesium,and potassium are invariably higher in the surface so i l s of both burned and unburned s i tes . Calcium shows wide variation and therefore does not indicate any particular trend. With magnesium and potassium, however, i t i s noted that the subsoils of burns are d i s t i nc t ly higher than the unburned v i rg in subsoil . This effect i s undpubtedly the result of salts from the surface ash moving to the subsoil through leaching which supports the explanations given for changes in exchangeable bases and pH. This i s i n agreement with Sims et a l (63), Wilde (76), Wilde and Kopitke (74) and numerous other workers. Available phosphorus i s s ignif icant ly increased i n the surface s o i l after burning and then, over a period of years, gradually declines to the normal amount found i n the v i rg in surface s o i l . After 19 years (1929 burn) the content of phosphorus i s s t i l l high and so considerable time i s requir' ed to return to the normal. This i n i t i a l increase i n phos-phate must result from burning the l i t t e r thereby leaving ex-cesses of the element on the surface i n a soluble form. Alway and Rost (1) and Wilde (76) report increases in phosphorus for th is reason. Since the subsequent decline of phosphorus in the surface s o i l i s accompanied by an increase i n the subsoil , there must be some movement of this element through the pro-f i l e . The s o i l i s high in i ron and aluminum (see Table 1) and so i t i s very probable that much of the phosphorus released by burning i s leached to the subsoil where i t i s fixed as fe r r ic phosphate or perhaps as aluminum phosphate. In support of th i s , much concretionary material i s present in these so i l s as a rock coating and as weakly cemented aggregates. Some-what similar material has been described by Drosdoff and Nikiforoff (19) and by Wheeting (71). The la t ter described s o i l i n western Washington which contained shot part icles high in sesquioxides and phosphorus. He attributed their formation to the dehydration of iron and aluminum during the dry summer season to form permanently insoluble shot which i s , in r ea l i t y , a diffused B horizon. Available ammonia content i s noticeably higher i n both the surface and subsurface s o i l of burned sites as compared to the v i rg in condition. At the same time, i t appears that the surface s o i l of the 1948 and 1947 burns contains even more ammonia than the old burns. This i n i t i a l accumulation after burning i s in agreement with Waks-man and Starkey (68). They state that ammonia-forming organisms are uninjured by heat treatments whereas the n i t r i f i e r s w i l l be eliminated. Sushkina (64) and others (23, 48) report stimulation of the n i t r i f i e r s after burning. The data presented"in Table 11 indicates that there i s stimulated ammonification immediately following burning after which i n -creased n i t r i f i c a t i o n i s noticeable. Both processes are speeded up as a result of better aeration when timber i s re-moved and lack of competition by.fungi which are eliminated by burning. The increased surface s o i l temperatures as a result of blackening i s also a factor contributing to i n -creased b io logica l a c t i v i t y . The figures for available nitrate show, with two exceptions, a decrease in both surface and subsurface s o i l after burning which i s indicative of leaching losses. This effect i s supported by the fact thatthe surface s o i l of the re la t ive ly severe 1947 burn shows a significant increase i n nitrates as do both the surface and subsoil of the doubly burned 1931-32 s i t e . The la t ter exhibits a higher content of nitrate in the subsoil than in the surface s o i l which i s definite evidence that leaching of nitrate has occurred to a 55. considerable extent following increased n i t r i f i c a t i o n at the surface. It i s worth noting that the type of humus layer found under v i rg in stands i n the study area.is apparently a fibrous mor (9, 29, 4$). Lutz and Chandler state that the fungi comprise the most important organisms in mor humus. They observe that th is humus type does not exhibit n i t r i f i c a -t ion readily as a result of exposure alone and that f i res may be used to advantage for this purpose. The results of organic matter determinations show that no significant loss results because of burning. The reader must keep in mind, however, that the surface (A) samples tested were taken from the minera l . so i l , not from the duff remainder. Over much of the burned sites the duff layer had been completely removed. It i s worthy of note that the subsoils of burned sites except 1947 and 1931-32 contain approximately the same percentage of organic matter as the v i rg in subsoi l . The. two exceptions have subsoils d i s t inc t ly higher i n organic matter and as already intimated represent severely burned s i t es . I t i s possible that severe burning causes dispersion of organic aggregates and conse-quent movement of suspended organic particles to the subsoil where a higher degree base saturation causes f loccula t ion . These results therefore support the theory for the movement of co l lo ida l clay par t ic les . Such migrations as these are accepted as normal processes result ing in the characteristic profi le development of heavier so i l s than the one under study. 56. There i s no reason, therefore, why such a phenomenon i s not acceptable for porous so i l s such as these. Observation of the data for to t a l nitrogen determin-ations reveals that no apparent loss results from the burning to which these soi ls were subjected. This seems to be more in agreement with (66) than most other workers. It i s evident, however, that burning has caused an increased sub-surface nitrogen content due to greater bacterial ac t i v i t y and the consequent removal of soluble nitrogenous salts to the subsoil . This movement could be as nitrate in solution or as the ammonium radicle adsorbed to co l lo ida l particles i n sus-pension. The very noticeable decrease in the carbon-nitrogen rat io in the subsoils of a l l burned sites i s naturally due to increased nitrogen since the organic matter content i s only def ini te ly altered in two cases. The 1948 surface s o i l i s the only case where the carbon-nitrogen ra t io i s lower at the surface. This fact supports the theory of increased ammonification and n i t r i f i c a t i o n which has been presented since Lutz and Chandler (48) state that "very l i t t l e nitrogen i s liberated as nitrate u n t i l the carbon-nitrogen ra t io of the organic matter has narrowed." The moisture equivalent of the surface s o i l i s materially reduced by burning and 18 to 19 years are required for this surface s o i l to regain i t s normal water holding capacity. This trend i s quite apparent in the results of the 1948 to 1931-32 burns and the oldest burn (1929) shows a s l i gh t ly increased capacity to hold water as compared to the v i r g i n s i t e . These f i n d i n g s are i n agreement w i t h Alway and Rost ( l ) , Auten (4), Wahlenberg et a l (66), Heyward (34) and Garren (2.5)« C o n c l u s i o n s S l a s h b u r n i n g on c o n i f e r o u s f o r e s t s o i l s of Van-couver I s l a n d c a u s e s : ( 1 ) l a c k o f n a t u r a l r e g e n e r a t i o n f o r 1 0 - 1 5 y e a r s . (2) a g r a d u a l i n c r e a s e i n s u r f a c e s o i l pH due t o the "pump-i n g " a c t i o n o f f a s t - g r o w i n g herbs and shrubs w h i c h causes bases t o be brought -to the s u r f a c e from the s u b s o i l . (3) i n c r e a s e d exchangeable h y d r o g e n . i n the s u b s o i l s o f b u r n -ed s i t e s a p p a r e n t l y due t o a c t i o n of herbaceous growth i n removing bases to the s u r f a c e and a l s o t o i n c r e a s e d b i o l o g i c a l a c t i v i t y . (4) an i n i t i a l i n c r e a s e i n exchangeable base c o n t e n t o f the burned s u r f a c e which b e g i n s to d i s a p p e a r due t o l e a c h i n g i n 3 or 4 y e a r s . (3) i n c r e a s e d magnesium and p o t a s s i u m i n the s u b s o i l s of burned s i t e s as a r e s u l t o f l e a c h i n g t h e s e elements from the a c cumulated ash. (6) i n i t i a l i n c r e a s e i n phosphorus c o n t e n t o f the s u r f a c e burned s o i l w i t h a subsequent removal of t h i s element to the s u b s o i l due to the s o l v e n t a c t i o n of p e r c o l a t i n g r a i n w a t e r . T h i s phenomenon i s e s p e c i a l l y t r u e i n the case o f s e v e r e l y burned s o i l s . ( 7 ) i n c r e a s e i n ammonia c o n t e n t i n b o t h s u r f a c e and s u b s u r f a c e s o i l s a f t e r b u r n i n g due t o s t i m u l a t e d a m m o n i f i c a t i o n . 9 (,8) increased n i t r i f i c a t i o n and loss of nitrate "by leaching with severe burning. (9) migration of co l lo ida l organic matter and clay particles to the subsoil . (10) increased tota l nitrogen content and a consequent de-crease in the carbon-nitrogen ratio of the subsoil . (11) a reduction in the moisture holding capacity of the surface s o i l immediately following burning. Recommendations (.1) ..Due to the inherent va r i ab i l i t y of a l l soi ls i t is advisable to carry out any further studies of slash burning on several sites, over a period of 13 to 20 years with annual sampling and analysis of the s o i l from each s i t e . Only in this way is i t possible to t eliminate s o i l v a r i a b i l i t y so that the effects of burning are elucidated. (2) In conjunction with s o i l studies after burning, i t i s important to analyze the herbaceous growth invading burned sites as a means of correlating changes in s o i l nutrients with changes in vegetative groxA/th. O ) Careful studies with respect to seedling survival and response on burned s o i l in this area are necessary to determine whether or not a r t i f i c i a l regeneration w i l l be economically feasible. . 59. BIBLIOGRAPHY (1) A l w a y , F . J . , and C . 0. R o s t . 1928. E f f e c t o f f o r e s t f i r e s upon t h e c o m p o s i t i o n and p r o d u c t i v i t y o f a s o i l , P r o c . o f t h e I n t e r n a t l . S o c . o f S o i l S c i . , X : 546 ~ 576. (2) A n d e r s o n , M . L . 1930. A ca se o f d a m p i n g - o f f i n d u c e d by t h e use o f wood a shes a s a manure on seed b e d s . S c o t t i s h F o r e s t r y J o u r . , : 7 - 16, (3) A r e n d , J o h n L . 1941. I n f i l t r a t i o n as a f f e c t e d by t h e f o r e s t f l o o r . P r o c . o f t h e S o i l S c i , S o c . o f A m e r , , 6 : 430, (4) A u t e n , John T , 1933. P o r o s i t y and w a t e r a b s o r p t i o n o f f o r e s t s o i l s . J o u r , o f A g r , R e s e a r c h , 1*6 : 997 - 1014. (5) A u t e n , John T , 1934. The e f f e c t o f b u r n i n g and p a s t u r i n g i n t h e O z a r k s on t h e w a t e r a b s o r p t i o n o f f o r e s t s o i l s . C e n t , S t a t e s F o r . E x p , S t a , No te 16. ( M i m e o g r a p h e d ) , (6) B a r n e t t e , R . M . and J . B . H e s t e r . 1929. E f f e c t o f b u r n i n g upon t h e a c c u m u l a t i o n o f o r g a n i c m a t t e r i n f o r e s t s o i l s . S o i l S c i . , 2£ : 281 - 284» (7) B a t e s , C . G . 1928, The s p e c i a l p r o b l e m s o f f o r e s t s o i l s . P r o c . and P a p e r s o f t h e F i r s t I n t e r n a t l . Cong , o f S o i l S c i . , W a s h i n g t o n , 1927* C o m m i s s i o n T, P p . 566 « 574. o (8) Baver, L. D. 1%0, S o i l Physics. LX + 370 pp. John Wiley and Sons, New York, (9) Bornebusch, C. H . , and S. 0. Heiberg, 1936. Proposal f o r the nomenclature of forest humus lay e r s . Proc, of the I n t e r n a t l . Soc. of S o i l S c i , , 2 : 2 6 0 •* 2 ( > 1 » (10) Bouyoucos, G. J , 1936, Directions f o r making mechanical analysis of s o i l s by the hydrometer method. S o i l S c i . , y2 : 225. (11) Bouyoucos, G. J . 1939. Water holding capacity of s o i l s . S o i l S c i , , : 382. (12) Brown, I . C. 1943 • A rapid method of determining exchangeable hydrogen and t o t a l exchangeable bases i n s o i l s . S o i l S c i , , %6 : 353» (13) Cheney, E. G. 1906. Slash burning i n Lake States, Forestry Quarterly, 1± t 289 * 291. (14) Clapp, C. H . 1910. Preliminary report on Southern Vancouver Island. Canadian Geological Survey Memoir 13. 208 pp. (15) Clapp, C. H . 1917. Sooke and Duncan map-areas, Vancouver Island. Canadian Geological Survey. Memoir 96, 445 pp. (16) Clements, F. E. 1910. The l i f e history of lodgepole burn fo r e s t s . U.S. Dept. Agr,, Forest Service Bui. 79. 56 pp, (17) Daubenmire, R. F. 1947. Plants and Environment ~~ a textbook of plant autecology. John Wiley and Sons, New York. 61. (18) Diebold, C. H. 1941. Effect of f i r e and logging upon the depth of the forest floor in the Adironiack region. Proc. of the S o i l S c i . Soc. of Amer. 6: 409 - 412. (19) Drosdoff, M . , and C. C. Niki foroff . 1940. Iron-manganese concretions i n Dayton s o i l s . S o i l S c i . , l£: 333 -345. (20) Eneroth, 0. 1928. Bidrag t i l l kannedomen om hyggesbrann-ingens inverkan pa marken. (Contribution to the knowledge we have of the effect on the s o i l from burning of clearing.) Jour, of the Swedish Forestry S o c , U.S. Forest Service. Translation 61. 76 pp. (21) Fehr, D. 1929. Untersuchungen uber den N-stoffwechsel des waldrodeus. (Investigations in N-metabolism of forest s o i l s ) . U.S. Forest Service. Trans-la t ion 12.6 pp. (22) Fire Reports. Dept. of Lands and Forests. Govt, of B.C. (23) Fowells, H.A. , and R. E. Stephenson. 1933. Effect of burning on forest s o i l s . S o i l S c i . , 175-181. (24) Garman, E. H. and P. M. Barr. 1930. A history map study i n B r i t i s h Columbia. Forestry Chronicle,6:158-162. (25) Garren, K.H. 1943. Effects of f i re on vegetation of the Southeastern United States. Bot. Rev., £ : 617. (26) Godwin, Gordon. 1938. A regeneration study of represent-ative logged-off lands on Vancouver Island. Forestry Chronicle, 14: 61. (27) Gustafson, A. F . 1937. Conservation of the s o i l XVlT + 312 pp. McGraw - H i l l Co., New York. (28) Heiberg, S. 0. 1939. Forest s o i l i n r e l a t i o n to s i l v i -culture Jour. Forestry, 22 : 42 - 46. (29) Heiberg, S. 0., and R. F. Chandler. 1941. A revised nomenclature of forest humus layers for the north-eastern United States. S o i l S c i . , 5_2: 87 - 100. (30) Heiberg, S.0. 1941. S i l v i c u l t u r a l significance of mull and mor. Proc. of the S o i l S c i . Soc. of Amer., 6: 404. ( 3 D Heyward, F., and R. M. Barnette. 1934. E f f e c t of frequent f i r e s on chemical composition of forest s o i l s i n the longleaf pine region. F l o r i d a Agr. Exp. Sta., Tech. Bui. 265 .39 pp. (32) Heyward, F. 1936. E f f e c t of frequent f i r e s on p r o f i l e development of longleaf pine forest s o i l s . Proc. of the I n t e r n a t l . Soc. of S o i l S c i . , 1: 35K (33) Heyward, F. 1938. S o i l temperatures during forest f i r e s i n longleaf pine regions. Jour. Forestry, 36: 47$ -491. -(34) Heyward, F. 1939. Some moisture relationships of s o i l s from burned and unburned longleaf pine f o r e s t s . S o i l S c i . , /£: 313 - 328. (35) Ingram, Douglas C. 1928. Grazing as a f i r e prevention measure for Douglas f i r cut-over land. Jour, of Forestry, 26: 998 - 1005. (36) Isaac, L. A., 1930. Seed f l i g h t i n Douglas f i r regions. Jour, of Forestry, 28: 492 - 499. (37) Isaac, L. A., 1930. Seedling s u r v i v a l on burned and (38) Isaac, L. A. and H. G. Hopkins. 1937. The forest s o i l of the Douglas f i r region, and changes wrought upon it. by logging and slash burning. Ecology, 18: 264-279. (39) Isaac, L.A. 1940. Vegetative succession following logging i n the Douglas f i r region with s p e c i a l reference to f i r e . Jour, of Forestry, ^8: 716-721, (40) James, Robert L. 1934. A simpler method of expressing the mechanical analysis of many common s o i l s . S o i l S c i . , 22- 2 71 - 275. (41) Kittredge, Joseph. 1948. Forest Influences. X f 394 pp. McGraw - H i l l Co., Toronto. (42) Leiningen - Westerburg, Wm. 1930. F e r t i l i t y i n f o r e s t r y . U. S. Forest Service. Trans. 201. (43) Longwell, C.R., A. Knopf, R. F. F l i n t . 1941. Outlines of Physical Geology. 3 8 l pp. John Wiley and Sons, New York. (44) Lowdermilk, W. C. 1925. Factors a f f e c t i n g reproduction of Englemann spruce. Jour, of Agr. Research, 30: 995 - 1009. (45) Lowdermilk, W. G. 1930. Influence of for e s t l i t t e r on run-off, percolation, and erosion. Jour, of Forestry, 28: 474 - 491. (46) Lunt, H. A. 1941. A pot.culture experiment with undis-turbed forest s o i l . Proc. of the S o i l S c i . Soc. of Amer., 6: 403. (47) Lutz, H. J . 1944. Determination of certa i n physical 64. properties of forest s o i l s . I Methods of u t i l i z i n g loose samples collected from p i t s . S o i l S c i . , 58: 325 - 333. (48) Lutz, H. J., and R. F. Chandler. 1946. Forest S o i l s . TZ 4 514 pp. John Wiley and Sons, New York. (49) McArdle, R. E. 1930. E f f e c t of f i r e on Douglas f i r slash.. Jour, of Forestry, 28: 568 - 570. (50) McArdle, R. E., and L. A. Isaac. 1934. The e c o l o g i c a l aspects of natural regeneration of Douglas f i r i n the P a c i f i c Northwest. Proc. of the P a c i f i c S c i . Cong., 5_: 4009 - 4015. (51) McComb, A.L. 1943* Mycorrhizae and phosphorus n u t r i t i o n of pine seedlings i n a p r a i r i e s o i l nursery. Iowa. Agr. Exp. Sta., Research Bui. 314. Pp. 5^ 2 - 612. (52) McCulloch, W. F. 1944. Slash burning. Forestry chronicle, 20: 111. (53) M i l l a r , C. E., and L. M. Turk. 1943. Fundamentals of S o i l Science. XT 4 462 pp. John Wiley and Sons, New York. (54) Munger, T. T., and D. N. Mathews. 1944. E f f e c t s of slash burning on forest protection. Forestry Chronicle, 20: 112 - 114. (55) Paulik, Max. 1948. Reforestation p o l i c y of B r i t i s h Columbia. A c r i t i c a l analysis - Foresta Publishers, Vancouver, B. C. (56) Peech, Michael, and Leah English. 1944. Rapid micro-chemical s o i l t e s t s . S o i l S c i . , _5_7_: 167 ~ 195. (57) Powers, W. L., and W. B. Bollen. 1935. The chemical and b i o l o g i c a l nature of certain forest s o i l s . S o i l S c i 40: 321 - 329. (58) P u r i r A. N., and A. G. Ashgar. 1940. E f f e c t of i g n i t i o n on the physical c h a r a c t e r i s t i c s of s o i l s . S o i l Sci., 42: 369 - 373. (59) Reed, J. F., and R. W. Cummings. 1945. S o i l reaction - -Glass electrode and colorimetric methods f o r de-termining pH values of s o i l s . S o i l S c i . , j>2: 97 -104. (60) Reid, E. H.,L» A. Isaac, and G. D. Pickford. 1938. Plant succession on a cut-over, burned, and grazed Douglas f i r area. P a c i f i c Northwest Forest and Range Exp. Sta., Forest Research Note 26. (61) Retan, G. A. 1915. Charcoal as a means of solving some nursery problems. Forestry Quarterly, 12: 25 - 30. (62) Sims, Ivan H., E. N. Munns, and John T. Auten. 1938. Management of forest s o i l s . In S o i l s and Men. Yearbook of Agriculture, 1938. U. S. Dept. of Agr. Pp. 737 - 750. (63) Stoeckeler, J . H. 1933. The use of f e r t i l i z e r s i n the forest nursery. Forest Worker, £, (1): 8 - 9 . (64) Sushkina, N. N. 1933. N i t r i f i k a t s i a v lessnykh pochvakh v zavissimosti ot sostava nasjdenia, rubki i ognevoi ochistoka lessosek. ( N i t r i f i c a t i o n of forest s o i l s with reference to the composition of the stands, cutting and f i r e ) . Bui. of the U.S.S.R. Academy of S c i . , U.S. Forest Service. Translation 56. 49 pp. (65) The Vancouver Daily Province (66) Wahlenberg, W. G., S. W. Greene, and H. R. Reed. 1939* E f f e c t s of f i r e and ca t t l e grazing on longleaf pine lands as studied at McNeil, M i s s i s s i p p i . U. S. Dept. Agr., Tech. Bui. 683. 52 pp. (67) Wakely, P. C., and H. H. Muntz. 1947. E f f e c t of pre-scribed burning on height growth of longleaf pine. Jour, of Forestry, Z^: 503 - 508. (68) Waksman, S. A., and R. L. Starkey. 1931. The S o i l and the Microbe. + 260 pp. John Wiley and Sons, New York. (69) Waksman, S. A. 1932. P r i n c i p l e s of S o i l Microbiology Williams and Wilkins Co., Baltimore, Maryland. (70) Waksman, S. A. 1945. Microbial Antagonisms and A n t i b i o t i c substances, p. 250. The Commonwealth Fund, New York. (71) Wheeting, Lawrence C. 1936. Shot S o i l s of western Wash-ington. S o i l S c i . , l±l: 35 - 45. (72) Wilde, S. A., S. F. Buran, and H. M. Galloway. 1937. Nutrient content and base exchange properties of organic layers of forest s o i l s i n the Lake States region. S o i l S c i . , Z^: 231. (73) Wilde, S. A. 1938. S o i l - f e r t i l i t y standards f o r growing northern conifers i n for e s t nurseries. Jour, of Agr. Research, £7_: 945 - 952. (74) Wilde, S. A. and J . C. Kopitke. 1940. Base exchange properties of nursery s o i l s and the app l i c a t i o n of 67. potash f e r t i l i z e r s . Jour, of Forestry, 330-332. (75) Wilde, S. A., and W. E. Patzer. 1940. S o i l organic matter i n re f o r e s t a t i o n . Jour, of the Amer. Soc. of Agron., 551 - 562. (76) Wilde, S. A. 1946. Forest s o i l s and forest growth. XX + 241 pp. Chronica Botanica Co., Waltham, Mass. APPENDIX Common and Scient i f ic Names of Trees and Herbs. Common Name: Scient i f ic Name: Douglas f i r . . .Ps'eudotsuga t a x i f o l i a Western red cedar ..Thuja pl icata Red alder Alnus rubra (oregana) Engelmann spruce Picea engelmanii Longleaf pine Pinus palustris Western hemlock Tsuga heterophylla True f i r s Abies spp. Sitka spruce Picea sitchensis Groundsel .Senecio vulgaris Fireweed Chaemaeraerion angustifolium Oregon grape Berberis nervosa Tiare l la T ia re l l a t r i o f o l i a t i a Deer fern Struthiopteris spicant Lady fern ...Asplenium cyclosorum Sword fern Polystichum munitumr Maidenhair fern Adiantum pedatum Wild l i l y of the valley Maianthemum bifolium Salmonberry ...Rubus spectabilis Tra i l ing blackberry Rubus macropetalus Mountain blueberry . . . . . . . . . . . . . . . V a c c i n i u m membranaceum Evergreen huckleberry Vaccinium ovatum Red huckleberry .Vaccinium parvifolium Hawkweed (hawkspur) . . . . . . . . . . . . . . H i e r a c i u m albiflorum Thimbleberry Rubus parviflorus Elderberry Sambucus glauca Sala l Gaultheria shallon Hichen Peltigera aphthosa Stinging nettle Urtica l y a l l i i Bracken Pteris aquilina Grass .Bromus sp; May leaves «_....Achlys t r i phy l l a 

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