aspen internet cover - british columbia

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5.2 Desired Densities of Regeneration to Meet Stocking Standards

• Especially in the ICH zone, paper birch management is hampered bycurrent Ministr y of Forests free-growing stocking standards thatdiscriminate against mixed-species stands.

• The current target and minimum stocking standards for Interior broadleafspecies are only small upward modifications of conifer stocking standards,and do not necessarily indicate desirable goals for good birch management.

Stocking standards for British Columbia’s broadleaf species have not yet beendifferentiated by forest region, biogeoclimatic zone, or site series to the degree thathas been achieved for conifers. For a forest manager concerned with birch in silvicultureprescriptions, the simplest approach is to follow the Establishment to Free GrowingGuidebooks, released in April 1995 under the Forest Practices Code of British ColumbiaAct. The guidebooks simplify the procedure by making no distinctions between anyforest regions with respect to broadleaf free-growing stocking standard guidelines.The only distinction is between coastal broadleaf species and Interior broadleaf species.The target, minimum, preferred, and acceptable stocking standards for Interior broad-leaf species, including paper birch, are reproduced in Table 16.

Experience to date indicates that the most important goal is to keep broadleafstocking standards flexible to meet a variety of timber and integrated resourcemanagement objectives. Broadleaf stocking standards could differ for pulp, plywood,lumber, or oriented strandboard products. In British Columbia, progress to definestocking standards for broadleaf species has centred on refinements of the CorrelatedGuidelines for Tree Species Selection (First Approximation) and Stocking Standards(Second Approximation) for the Ecosystems of British Columbia, prepared by theSilviculture Interpretations Working Group (1994).

Current Ministry of Forests stocking standards for broadleaf species in BritishColumbia (Table 16) are a first draft and should be used in an adaptive manner. Giventhe silvics of birch and how it grows in natural stands, the stocking standards suggestedin Table 16 are probably too low; the targets and minimums are only small upwardmodifications of conifer stocking standards, and do not necessarily indicate desirablegoals for good birch management. An important proviso is that these standardsrecommend much lower densities than those in which birch grows naturally. Therefore,a research need is to monitor effects of various birch stand densities on stem qualityand total productivity. Also, the current stocking standards do not have specific criteriato define a “healthy” broadleaf crop tree. The last condition is important because it is abasic assumption for all conifers and broadleaf species that a tree classified as free-growing must be “healthy.”

Biogeoclimatic zone, subzone, or site series distinctions have not yet been madefor appropriate planting densities for paper birch in British Columbia. Recentlyestablished birch density trials, such as those at Spey Creek in the Prince GeorgeForest Region and at Malakwa, North Adams, and Hidden Lake in the Kamloops ForestRegion, are too new to yield guidelines for managers. However, it is important for forestmanagers to be aware of some of the current stand densities recorded for birch standsin British Columbia. In naturally regenerated clearcuts in the ICH zone, initial densitiesranged between 5000 and 30 000 stems per hectare, with some microsites reaching60 000 stems per hectare. Dense stands appear to self-thin rapidly after age 9, and mostpure birch stands are within 1500 stems (burned sites) to 5000 stems (unburned sites)per hectare by age 9.

The main need forrefinement of stockingstandards is to clarify theupper limit of the numberof acceptable birch atvarious stand ages.

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76

77

A manager can begin density management by selecting an appropriate sitepreparation method. In a survey of ICH plantations in interior British Columbia, birchdensity averaged 6500 stems per hectare on mechanically disturbed soils and only3500 stems per hectare on moderately burned soils. Once birch is established,intermediate cuttings may be required to enhance birch stemwood production or toimprove light availability to conifers.

5.3 Regulating Density of Paper Birch Stands

• Birch thinning trials in the southern interior of British Columbia anddensity guidelines from the eastern United States suggest that anappropriate density for full site occupancy of sawlog birch trees with13 cm dbh is 1000 stems per hectare. Birch commonly reach 13 cmdbh by age 10 on mesic sites in the ICH zone.

• Pre-commercial thinning should be applied at approximately age 10–15 years, once dominance is well established. The straightest, fastest-growing and healthiest stems should be selected.

Even-aged birch stands may be candidates for thinning for the same reasons thatother species are thinned—for example, to increase yield by salvaging trees that wouldotherwise die and to concentrate growth on the best trees in the stand, therebyincreasing stem value. In addition to questions about the economics of thinning, theremay be other negative effects of thinning, such as delay of natural pruning, growthof large and lower branches, increased taper of crop trees, and decreased totalbiomass yield.

Little information is available on the effects of thinning paper birch in BritishColumbia. The best information to date is from the ICH zone. In four trials establishedin 9- to 13-year-old pure paper birch stands on medium-quality sites in the ICH zone,stands that initially ranged between 11 000 and 31 000 stems per hectare (mean of20 000 stems per hectare, at an average spacing of 0.7 m) were thinned to 400, 1000,and 3000 stems per hectare (Figure 28). During the first and second growing seasonsafter thinning, photosynthetic rate, foliage nitrogen concentration, and water useefficiency were significantly greater in thinned than in unthinned stands. This wasattributed to reduced intraspecific competition for light, soil nitrogen, and soil water.Although the best physiological response occurred at 400 stems per hectare, therewas little difference between 400 and 1000 stems per hectare. Thinning such stands to1000 stems per hectare seems more appropriate, however, because of the uncertaintyabout mortality and the possible undesirable effects of lower stand densities on woodquality, branching, and stem form.

A 1991 review of 30 different crop-release studies in northeastern United Statesbroadleaf species—including paper birch—concluded that long-term effects of spacing

Information Sources:

Solomon and Leak 1969;Zasada et al. 1977;Safford 1983; Saffordet al. 1990; Simard 1990;Simard and Vyse 1992;Robinson 1994; Silvicul-ture InterpretationsWorking Group 1994;B.C. Ministry of Forestsand B.C. Ministry ofEnvironment, Lands andParks 1995c; Comeau etal. 1995; Puttonen 1996;Simard 1996a, b.

Relatively little informa-tion exists about thedensity dynamics innatural stands of birchin British Columbia.Guidelines for birchmanagement requiremore data on a rangeof product objectives,densities, and site series.

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FIGURE 28. This example of thinning in a 12-year-old paper birch stand is from Lee Creek, a mesic site in theICHmw subzone in the Salmon Arm Forest District, British Columbia. Densities of paper birch are(a) control, mean of 20 000 stems per hectare (mean spacing 0.7 m), (b) 3000 stems per hectare(spacing 1.8 m), (c) 1000 stems per hectare (spacing 3.2 m), and (d) 400 stems per hectare (spacing5.0 m). (Photographs by S. Simard)

ba

79

FIGURE 28. Continued

d

c

80

on stem quality were still unknown, but early growth responses are positive followingthinning. Some northeastern United States researchers have been more definite bysuggesting that thinning does improve stem quality for high-value veneer and sawlogs.Uncertainty about the effects of spacing of paper birch upon subsequent stem qualityof birch is one of the reasons for a current spacing study at Spey Creek in the PrinceGeorge Forest District.

Research has indicated that photosynthetic rate of trees in thinned standsincreased significantly compared to that in unthinned stands. This increase wasattributed to increases in photosynthetically active radiation and foliage nitrogen concen-tration and a decrease in specific leaf area. Thinning to 400, 1000, and 3000 stems perhectare indicated that the 400 stems per hectare treatment had the best physiologicalresponses to thinning. If physiological performance of individual trees is better inthinned than in unthinned stands, what does this mean for a manager involved withbirch? The optimal thinning objective, in the range of 400–1000 stems per hectare forstands under 15 years old, will depend on management objectives. For example,silvicultural steps to enhance wildlife habitat may favour higher or more variable birchstand densities than management to encourage birch timber production. Where theobjective is to produce knot-free, straight, large-diameter birch stems, there is evidencethat stem straightening and self-pruning are more efficient at higher than at lowerbirch stand densities. Because there seem to be no major physiological differences inbirch stands thinned to 400 or 1000 stems per hectare, a current guideline for managersis to opt for 1000 birch stems per hectare. This relatively high density could encouragewildlife habitat values without hampering birch stemwood production. District forestersand researchers will need to determine the optimal birch thinning regimes in varioussubzones, variants, and site series in British Columbia.

Where birch is managed in the Scandinavian countries, the current practice is tothin young birch stands when they reach a height of 4–6 m and to retain a speciesmixture when thinning. The first commercial thinning of birch is then done when thestand is 13–15 m high, at which time a density of 1200 birch stems per hectare is thegoal. After this first thinning, mixtures are thinned once or twice more before finalfelling. Final felling occurs when the mixed stand has a mean diameter of 25–30 cm,with large-diameter conifers going to lumber production, other conifer biomass intopulp, and high-quality birch into plywood. The significance of this managementapproach, which may be predictive of future mixed-forest management in BritishColumbia, is that birch is now Finland’s most valuable commercial species; it can havea commercial value double that of medium-quality Scots pine. Added to these benefitsof thinning and other silvicultural encouragement of birch is that this genus lends itselfto short rotations, is an adaptable species for restoration forestry and afforestation,has high aesthetic value compared to single-species conifer plantations, and can enhancebiodiversity values. One thing that birch managers may need to contend with, basedon the experience of European foresters with Betula pendula, is that with faster growthof birch stems (for maximum biomass production) there is also production of thickerbranches. This is a disadvantage for production of small-knot or knot-free stemwood.

Managing birch–conifer mixtures makes ecological and economic sense in thesouthern interior of British Columbia, where most natural ICH stands are composed ofbirch and one or more conifer species in varying densities, proportions, and spatialpatterns. Conifer plantations that have natural ingress can be managed to optimize pro-duction of several species at once. For example, a retrospective study in 5- to 10-year-old mixtures of naturally regenerated birch and planted Douglas-fir in the ICH zoneshowed that approximately 350 stems per hectare of paper birch can be maintainedwithin operational planting densities (1200–1600 stems per hectare) without significant

81

growth loss to Douglas-fir. This represents 20% or less as paper birch. The proportionof birch may be increased to 50% in Armillaria root disease pockets, for example to1000 stems per hectare birch and 1000 stems per hectare Douglas-fir. Planting birchimparts greater control over the mixture pattern, but a less expensive approach issimply to manage the density and spatial arrangement of naturally regenerated birch.The approach chosen depends on management objectives, capital investment level,and desired outcome. The greater the capital investment, the greater the control that isexercised over mixture composition and density of stems.

5.4 Nursery Production and Quality of Paper BirchPlanting Stock

• British Columbia nurseries focus on production of plug planting stock(mostly 1 + 0 and 0.5 + 0) rather than bareroot stock. For nursery-produced seedlings, a good indication of robust planting stock is healthybuds and branches all along the stem.

• Paper birch can be reproduced through layering, cuttings, budding,grafting, and micropropagation from nodal stem sections or callus tissue.

Identification of desirable seed sources is a first step for production of nurserystock. That important step is normally planned according to local or regional criteria.In British Columbia, the most recent criteria are contained in the Seed and VegetativeMaterial Guidebook under the Forest Practices Code of British Columbia Act and in theTree Cone, Seed, and Vegetative Material Regulation under the Forest Act. As well asprocuring an appropriate source of seed, managers will need to make arrangementswith a qualified nursery to obtain birch planting stock in a timely manner. Nurseries inBritish Columbia continue to develop new practices for producing consistently high-quality birch planting stock (Figure 29). However, the quality of seedlings can varyconsiderably and, as recommended by Ahrens et al. (1992) for red alder, forest managersare advised to work closely with their local nursery to ensure seedling quality thatmatches site requirements. Grading seedlings and culling inferior stock is essential.Seedlings with the best survival, growth, and resistance to damage over a range ofconditions are:

• 30–90cm high, with a basal diameter (caliper) of at least 4 mm;

• stocky, rather than tall and thin;

• characterized by healthy buds or branches along the entire length of the stem,particularly the basal portion, and

• full, undamaged fibrous root systems; and

• free of disease.


Safford et al. 1990;Simard 1990; Heitzmanand Nyland 1991;Simard and Vyse 1992;Marquis 1994; Simardand Vyse 1994; Comeauet al. 1995; Niemistö1995a, b; Nigh 1995;Wang et al. 1995;Mielikäinen 1996;Puttonen 1996;Simard 1996a.

Paper birch is well suitedto intensive productionthrough nursery andplantation procedures.This approach is expectedto gradually increase inBritish Columbia.

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FIGURE 29. Most paper birch seedlings that are produced in British Columbia are grown in styroblocks.(Photograph by M. Carlson)

The criterion of stocky seedlings with healthy buds and branches all along thestem is very important and easily assessed visually. Non-morphological features ofseedling quality, such as cold hardiness and root growth potential, are also importantattributes, although there are no tests or standards developed for these characteristics.

Wild birch seedlings (wildlings) can be an alternative source of stock wheresmaller numbers of seedlings are needed, or in emergency situations such as deliveryshortages on nursery orders. A good strategy is to keep notes on current locations ofrecently disturbed sites, since these are often good sources of birch wildlings. Standardsused for grading nursery-produced birch seedlings can also be applied to wildlings.

There is more experience in nursery production of paper birch from thenortheastern United States, the Lake states, Scandinavia, and Britain than there is fromBritish Columbia or eastern Canada. In the late 1940s, selection of birch (Betula pendula)breeding material began in Finland with the selection of plus trees, work that waspromoted by interest from the veneer industry. European birch propagation programshave emphasized crop reliability, maximum sustainable productivity, silviculturalfeasibility, and resistance against mammalian herbivores (hares, moose, and voles).The international experience has shown that excellent early survival and growth ofpaper birch can be achieved when good-quality stock is planted on good soils incompetition-free sites. However, ideal soil and site conditions are often not available inplaces where British Columbia forest managers may wish to plant birch.

83

Experience to date with planting container birch in British Columbia indicatesthat post-planting mortality can be low when planting is done under cool, wet weatherconditions and soil moisture is adequately available for the first month after planting.Under hot, dry conditions, several problems occur:

• With stock that is planted directly, without cold storage, leaf area can be so highthat transpiration exceeds uptake (under such conditions, cold-stored stock ismuch preferred).

• Sun scald is prevalent where there is not enough bud development along themain stem.

• Sun scald can lead to secondary effects such as infection by Septoria cankers(this damage can be lessened by growing stock at wider spacing in the nurseryso that healthy buds and branches form along the entire stem).

• Very hot, dry spells in the summer can cause mortality of seedlings that havebeen established for 2–3 years.

• Where mortality does not occur, die-back of tops may still be common, causingnew shoots to sprout from adventitious buds at the root collar and giving theseedling a bushy appearance.

As birch management intensifies, there could be increased interest in micro-propagation (production of plantable shoots from laboratory culture using cell materialfrom sections of branchlets or callus tissue). By the time trees are mature enough toallow selection of genotypes that show superior field performance, they are usuallydifficult to clone by conventional methods of vegetative propagation. Tests with Betulapendula in Britain indicated that micropropagation offers an alternative approach toclonal propagation of mature trees. In that species of birch, conventional clonalpropagation is increasingly difficult after the trees are 6 years or older. Birch producedby micropropagation from nodal stem sections or callus tissue of a 20-year-old Betulapendula grew at a similar rate as seedling birch during 6 years of field testing.Micropropagated trees were more uniform in height and stem diameter than trees ofseedling origin. About 80% of the micropropagated birch flowered within 3 years ofplanting, compared to 39% for seedling origin trees. To date, micropropagation of paperbirch has not been tried in British Columbia nurseries and is unlikely to be used formass seedling production in the foreseeable future.


Pinney and Peotter 1966;Bjorkbom 1969;Hanks 1969; Krizekand Zimmerman 1973;Hoyle 1975, 1984;Hanover et al. 1978;Van Cleve et al. 1986;Hannah 1987; Perala1990a, 1990b; Safford etal. 1990; Ahrens et al.1992; Meier-Dinkel 1992;Morgan 1992; Young andYoung 1992; B.C. Minis-try of Forests and B.C.Ministry of Environ-ment, Lands and Parks1995d; Jones, O.P. et al.1996; Puttonen 1996.

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5.5 Seedling Handling and Outplanting

• Good-quality seedlings, planted on well-prepared sites, should reach aheight of 50 cm at the end of the first growing season. However, manyinitial planting efforts have failed due to poor-quality seedlings, extremeweather, and other hazards.

• The optimal time for outplanting should be selected according to localsite conditions. The goal is to minimize the risks of frost damage or summerdrought stress. Early March to mid-May is a good planting window forthe southern interior of British Columbia.

Proper handling of birch seedlings requires most of the precautions used forother broadleaf species. Experience with planting red alder is considered applicable tobirch and is summarized in this subsection. Consistent success in establishment ofbirch plantations requires a careful evaluation of site factors, regeneration hazards,and damaging agents (Sections 3.7.4, 5.1, and 5.8), along with adequate seedling quality(Section 5.4), proper site preparation (Section 5.6), and good seedling handling andoutplanting practices. Experience has shown that failure in any one of these areas willoften result in excessive mortality or poor growth and stem form, even on otherwisesuitable sites.

In general, larger planting stock will be more resilient than small stock tovegetation competition, or to damage from weather or animals. Pervasive hazards fromphysical or biotic site factors can be avoided by proper site selection and site preparation,and by the assured use of appropriate seedling stock quality. As summarized below,many of the hazards on microsites can also be anticipated and avoided or mitigated.

Sun and heat Avoid planting birch on exposed southerly aspects. With moderateexposure exposure, basal portions of seedlings may need protection with

shade cards or non-toxic white paint. Plant robust seedlings withlarge basal diameter, and with abundant buds or branches that willself-shade the lower stem.

Frost Avoid areas where frost hazard from cold-air drainages is severe.Without this precaution, mortality and poor form will result.

Animals If deer or moose browsing is only low to moderate, fast-growingstock can be successful. In areas of moderate browsing, robust plant-ing stock should be used. Avoid using birch in areas of concentratedanimal use.

Soil drainage In coarse or droughty microsites, plant seedlings with the best rootsystems and highest root-to-shoot ratios. Plant seedlings deeply.

Birch stems are relatively brittle and sensitive to physical damage and must behandled carefully during transport and outplanting. The following guidelines for redalder can also be used by planting crews handling birch:

• Ensure planting holes are deep enough to accommodate the planting stock.

• Pack soil carefully around planting stock, without stomping, and take care toavoid injuring the stem and roots while packing soil.

Optimum birch plantingrequires assessment ofthe best planting times,use of appropriate sitepreparation treatments,and control of competingvegetation.

85

• On exposed microsites, do not scalp planting spots more than is necessary toopen the planting hole.

• Wherever possible, plant seedlings in the shelter of debris.

• Ensure the entire root system is in mineral soil or mixtures of mineral soil, or-ganic layers, or decayed wood.

5.6 Site Preparation to Encourage Paper Birch

• Site preparation that exposes mineral soil is necessary to control com-peting vegetation and provide an optimum medium for birch seedgermination and seedling growth.

• Burns of light or moderate intensity are best for good density of birchregeneration. Severe burns kill many of the birch stumps that could besources of sprouts and destroy organic material, creating less-than-optimalmoisture and nutrient conditions.

The need for site preparation to ensure successful regeneration of paper birch isnot uniform over its east–west range in North America. Experience with birch in theeastern part of its range suggests that scarification is nearly always necessary to ensurebirch regeneration if one is using a strip cut system. There are strong links betweensite preparation, seedling establishment, and length of the leave period for uncut strips.For eastern paper birch, a leave period of 2 years is considered sufficient to achievebirch regeneration on the first-cut strips. However, newly established birch on first-cutstrips requires at least 15 years to produce seed. Therefore, a delay of at least 15 yearsis required before new birch on first-cut strips can provide seed for the next adjacentcut strip. It is for this reason that new birch’s regeneration in eastern birch managementis often less successful on the last-cut strips than on the first-cut strips.

Surveys in the ICH zone of British Columbia have indicated that birch canregenerate in clearcuts with or without site preparation, but site preparation providesconsiderable control over species composition, seedling distribution, and seedlingquality. In all cases, most birch establish within 2–3 years after a disturbance. With nosite preparation, paper birch can regenerate in high densities (>15 000 stems perhectare), but a high proportion will likely be of sprout origin. As moisture availabilityincreases beyond mesic conditions, broadleaf composition shifts towards blackcottonwood. Following light to moderate burns, birch dominates many plantcommunities and densities generally range between 1000 and 10 000 stems per hectare,with a high proportion of individuals of seedling origin. Moderate-intensity broadcastburns, particularly when combined with mechanical scarification (such as bunch-and-burn), are considered the best choice for creating ideal conditions for birch regeneration.Following severe fires, birch densities are patchy and severely reduced (<1000 stemsper hectare), and mortality risk following stand establishment is too high for pure birchstands to develop.

The effects of various site preparation treatments on birch regeneration aredocumented for southern British Columbia. In relation to severity of burn, birchregeneration was abundant after light or moderate burns, where birch stumps sprouted


Ahrens et al. 1992;Dobkowski et al. 1994;Peterson et al. 1996.

Prepared seedbedsremain receptive tobirch germination andestablishment for only2–3 years followingtreatment, and in somesites where there is rapidregrowth of grass or herbsthere is only a 1-yearperiod of opportunity forbirch establishment.

86

prolifically and seeds germinated readily on exposed mineral soil and mixed mineral-organic layers. Mechanical bunch-and-burn treatments that mixed soil and burnedstumps resulted in the highest birch densities. Where paper birch and black cottonwoodcoexist, cottonwood regeneration is dominant on compacted skidroads and areas withcompletely exposed mineral soil, whereas birch dominates openings away fromskidroads, especially where there are mixed organic-mineral seedbeds.

The opportunities for site preparation are influenced by the type of silviculturalsystem favoured by a birch manager. Also, there may be conflicts between the amountof site preparation desired for optimal encouragement of birch regeneration and theminimum amount of soil disturbance recommended under the Site PreparationGuidebook of the Forest Practices Code of British Columbia Act. This guidebook providesrecommendations, too detailed to reproduce here, on the allowable soil disturbanceand allowable forest floor displacement in areas to be reforested.

In British Columbia, the main silvicultural activities where birch regenerationmay be involved are clearcutting followed by mechanical site preparation and light ormoderate broadcast burning, and either natural seeding or planting. In most cases,high birch densities are discouraged and conifer regeneration encouraged throughplanting and weeding practices, usually resulting in mixtures with a low proportion ofpaper birch. If desired, relatively pure stands of paper birch or mixtures with a highbirch composition could be encouraged with this silviculture system, by modifyingstand-tending practices that promote free-growing status of conifers.

5.7 Management to Enhance Production of High-QualityBirch Stems

• The low shade tolerance of birch encourages rapid branch mortality.Therefore, one strategy for producing high-quality stems with few, smallknots is to maintain reasonably high densities in the early stages of standdevelopment.

• Mature and overmature birch stands that have reduced usable volumebecause of stem decay should be managed by a series of silviculturalsteps that combine salvage harvesting with stand regeneration to youngerage classes.

Thinning treatments depend strongly on management objectives, whether fortimber production (lesser densities) or for creation of particular kinds of wildlife habitat(variable densities). For birch stem production, spacing regimes must balance increasesin crown size and stem diameter with the need to develop clear boles and small knotsize. Physiological responses of paper birch to thinning are known to improve withdecreasing density. Results confirming this are reported from the ICHmw subzone inBritish Columbia and from Ontario, the New England states, and Great Britain. Fieldobservations of naturally regenerated birch stands indicate that stem straighteningand self-pruning are more efficient at higher than lower stand densities, which canserve as a rough guide to birch density responses in managed stands.


Safford 1983; Zasada etal. 1983; Leak et al. 1987;Presslee 1989; Newtonand Comeau 1990;Otchere-Boateng andHerring 1990; Perala andAlm 1990b; B.C. Minis-try of Forests 1990;Hornbeck and Leak1992; Simard and Vyse1992; B.C. Ministry ofForests and B.C. Minis-try of Environment,Lands and Parks 1995e.

Thinning birch stands toless than 1000 stems perhectare may increase therisk of developing sharperstem taper and larger liveor dead branches, therebyreducing timber quality.

87

In Great Britain, the effects of heavy thinning on stem quality and wood propertiesof silver birch (Betula pendula) indicated that, in general, trees from lightly thinnedstands had similar characteristics to those in unthinned stands. In these comparisons,lightly thinned stands were those in which high stocking levels were maintained sothat growth was slow and about one-third of the tree height was live crown. In contrast,with heavy thinning (where the canopy was opened at an early age by thinning toencourage rapid growth so that half the height of the tree was living crown), bothdiameter increment and ring width were enhanced. Heavily thinned birch had greaterstem taper, as well as more and bigger live or dead branches, than in the lightly thinnedstands. The British thinned birch met the Finnish standards for birch veneer, andalthough heavily thinned birch produced more dead branches, the number of brancheswas below the maximum allowed by the Finnish veneer standards. This study suggestedthat, for logs of veneer quality, birch on rotations as short as 40 years on good sitescould be adopted if heavy thinning were applied. In Finland, high-quality birch isproduced on 40- to 50-year rotations on fertile sites with one to three thinnings. SomeBritish foresters believe that good-quality birch timber is unlikely from wide spacing(1100 stems per hectare) because of excessive branch development, unless standsare pruned. Cameron, A.D. (1996) provides detailed silvicultural recommendations formanaging Britain’s Betula pendula and B. pubescens stands for production ofquality timber.

Management practices to increase the proportion of high-quality single stemsinvolve planting, brushing, thinning, and conversion of multi-stem clusters to singlestems. From experience in Ontario and northeastern United States, the following aresome guidelines for converting multi-stem clumps to single stems or smaller clusters:

• Thin clumps at an early age, preferably before 20 years old, to one or two sproutsper clump.

• Leave the best-formed, most widely spaced, low-origin dominant or codominantsprouts with U-type connections between companion sprouts. Treat V-type sproutconnections as one unit, either leaving both or cutting both.

• Leave only dominant or codominant well-formed sprouts that originate at groundlevel or are not more than 15 cm above ground level and are widely spaced onthe stump.

• On steep terrain, select sprouts on the uphill side of the stump.

• Provide maximum space for crown development.

Paper birch is a nutrient-sensitive species; seedling, sapling, pole, and saw-timbertrees have all been reported in the literature as responding positively to fertilizertreatment. Responses to fertilization result in increased production rates of stemwood,bark, branches, and foliage. Seedling height and biomass have been increased markedlyby additions of nitrogen-phosphorus-potassium fertilizer. Seedling response seems moreresponsive to nitrogen than to phosphorus or potassium. Fertilization following thinningof birch stands has also been shown to result in increased diameter growth of theremaining trees during the subsequent 10-year period.


Bjorkbom 1973a, b;Ohmann et al. 1978;Czapowskyj and Safford1979; Schmitt et al. 1981;Chapin et al. 1983;Lamson 1983; Stroempl1983; Safford andCzapowskyj 1986; VanCleve et al. 1986;Leak et al. 1987; Saffordet al. 1990; Simard andVyse 1992; Nichols et al.1994; Cameron et al.1995; Wang et al. 1995;Wedeles et al. 1995;Cameron, A.D. 1996.

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5.8 Management to Reduce Damaging Agents and to MaintainForest Health

• Paper birch is immune to Phellinus weirii and is more resistant toArmillaria root rot than its associated conifers. The presence of birchamong conifers may reduce the biological and economic impact ofArmillaria in such mixed stands.

• In general, the risk of stand losses to insects or disease is less in mixedthan in single-species stands. This principle applies to birch as much asto other tree species.

Native fungi and insects are an integral component of healthy forests. Diseasesand insects, like fire, have shaped the composition of today’s forests. Diseases andinsects are a concern for forest managers mainly because they are competitors forbiomass that has commercial value. However, because there is not widespread successin controlling diseases or insects by direct silvicultural methods, managers of birch inpure or mixed stands generally find that the most cost-effective approach is adapting tonatural occurrences of these organisms.

Insect and disease relations in birch are not as well known as in conifers. Asexamples, in the eastern parts of paper birch’s geographic range, it has been notedthat in areas where spruce budworm has killed overstorey conifers, birch regenerationis most successful where there are intermediate levels of mortality from budworm(about 20% loss of original coniferous basal area). Shrubs, rather than birch, dominatethe regeneration where budworm mortality is at or near 100%. In British Columbia, themain disease research involving birch has been in relation to Armillaria. Research andstand surveys indicate that the spread of Armillaria is reduced in mixtures of birchand conifers compared to that within pure stands of susceptible conifers (Figure 30).However, documentation of root disease relations in birch–conifer stands needsexamination over a wider area of British Columbia. Other examples of research needsrelate to influences of birch stand density upon severity of insect attack and possibleeffects of drought upon populations of leafminers and bronze birch borers.

Discoloration of birch stemwood is mainly initiated by injury to the roots or stems.To minimize the effects of discoloration, birch trees with wounds greater than a certainsize should be salvaged to prevent further loss. In addition, silvicultural managementthat eliminates or reduces injury from logging, and steps that promote early self-pruningof the lower branches, can help to reduce discoloration effects.

Damage by wildlife is mainly related to browsing. Repeated browsing by moosecan retard the height growth of paper birch, but at the same time can increase thedensity of stems and the amount of biomass in the 0–3 m height class.

In the eastern North American part of paper birch’s range, birch die-back hasbeen a major concern for forest managers. The die-back symptoms have not yet beenidentified as a silvicultural problem in British Columbia, but the circumstances that arenow thought to be the cause of this problem could occur in this province. The generalconclusion is that birch die-back is caused by spring frost in the vulnerable stage ofbud burst. This vulnerable stage can be brought on by prolonged early spring thawsfollowed by temperatures low enough to freeze buds. Death of birch rootlets, whichhas been observed in association with birch die-back, is now considered to be asecondary symptom resulting from the initial frost damage to buds in the tree crown.For birch managers in British Columbia, there are no apparent silvicultural steps toreduce the risk of frost-induced birch die-back.

Aside from insects anddiseases, other agentscontributing to thedecline of birch standsinclude stress fromcompetition, drought,and storm damage. Ofthese, competition is theonly factor over whichsome silvicultural controlmay be possible.

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FIGURE 30. An ecologically sound prescription for management of sites with Armillaria root disease is plantingor encouraging mixtures of paper birch and disease-susceptible conifers. These 15-year-old planta-tions in the ICHmw subzones demonstrate (a) Douglas-fir mortality due to infestation by Armillariaostoyae and (b) the management of mixtures of paper birch and conifers for disease mitigation. (Pho-tographs by S. Simard and J. Mather)

a

b

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Visible symptoms of damage to birch from air pollutants are illustrated in Malhotraand Blauel (1980). Of the three interior and boreal broadleaf species (birch, aspen, andbalsam poplar), birch is generally the most sensitive to metal mining and smelterpollutants. Moderate concentrations of smelter emissions cause severe foliardiscoloration and multiple fumigations result in necrotic foliage and premature leaffall. Birch is also the most sensitive of the three boreal broadleaf species to sulfurdioxide exposure, with symptoms ranging from light chlorosis to almost completenecrosis, extensive discoloration, leaf curling, shrivelling, and premature leaf drop.Birch can tolerate acid soils with elevated levels of nickel, copper, and aluminum, asshown by studies surrounding smelter sites at Sudbury, Ontario. Pioneer species withhigh concentrations of leaf nitrogen and magnesium, such as paper birch, may have ahigher capacity than shade-tolerant species to buffer their internal pH against highexternal acidity from acidic wet deposition.

Some forest health principles developed from birch–conifer mixedwood exper-ience in Scandinavian countries may be applicable to birch–conifer mixtures in BritishColumbia, even if the tree species that make up mixed stands, and the diseases andinsects that influence the forest health of mixed stands, are different in these two partsof the world. One hypothesis about why mixed stands are often preferable over purestands is that individual trees of the same species have less root and crown contact inmixed stands than in pure stands, which reduces the possibility of disease transmission.The other general principle is that mixed stands are better able to survive if there is anoutbreak of one forest pest specific to only one of the tree species in the stand. Althoughit has not been fully documented for birch–conifer mixed stands in British Columbia,there are suggestions that some tree species in mixed stands may benefit from damageto other tree species in the stand. In principle, this could be one way that mixed standsprovide the best opportunity to sustain woody biomass productivity, as well as overallforest health and biodiversity values.

5.9 Role of Short Rotations for Paper Birch and Features ofImportance to Private Woodlot Managers

• Because birch’s early growth rate does not match that in young standsof black cottonwood, red alder, or aspen, birch is a less likely candidatefor short-rotation management than are the other broadleaf species inthe province.

• As with any of British Columbia’s broadleaf species, short-rotation manage-ment of birch should be considered only on the most productive sites.

Birch can be managed on shorter rotations (40–60 years) than its associatedconifers (80 or more years). However, paper birch in British Columbia is not a candidatefor extremely short rotations (under 20 years) as is the case for black cottonwood orred alder. If birch is to be harvested at very young ages, it is most likely to be asindividual tree removal in a thinning program. Management of paper birch on shortrotations for firewood, pulpwood, or specialty products may be well suited to smallwoodlots.

In British Columbia, the woodlot sector has only recently been organized, althoughwoodlots have existed for a long time. Data on the number of woodlots and the products


Malhotra and Blauel1980; Norby andKozlowski 1983; Jamesand Courtin 1985;Crabtree and Bazzaz1993; Liu and Cote 1993;Osawa 1994; Braathe1995; Hagle 1995; Hall1995; Allen 1996; Allen etal. 1996; Comeau 1996;Mielikäinen 1996.

Firewood and rawmaterial for panelboardand pulp products are themost likely sources ofeconomic return for birchharvested at smalldiameters on shortrotations.

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rendered are difficult to assess. An assessment of the need for a birch inventory inAlberta noted that smaller birch in stands could be bucked and split for firewood. Bulkfirewood has a market in locations near to urban centres and is a current focus forwoodlot operations. In relation to firewood, paper birch’s calorific value (MJ/kg, whereMJ = 1 x 106 joules) is not markedly different from some of its companion species:white spruce, 19.834 MJ/kg; birch, 18.875; aspen, 18.744; and balsam poplar, 18.474.Birch has relatively high mean ovendry wood density (ovendry weight/ovendry volume,g/cm3) compared to some of its common companion species: birch, 0.607; lodgepolepine, 0.444; aspen, 0.424; balsam poplar, 0.409; and white spruce, 0.404.

Birch is often an important component of public or private lands used for livestockgrazing in interior British Columbia (Figure 31). As outlined in Section 6.1, birch addsbiodiversity to the province’s forest ecosystems. For example, pure birch stands areprized sites for bird-watchers. For all of these reasons, birch stands on private wood-lots in British Columbia have potential for management for a broad range of specialforest products.


Singh 1984; Singh andKostecky 1986; JasperMillworks Ltd. andWoodland ResourceServices Ltd. 1988;Massie et al. 1990;Safford et al. 1990;Sterling Wood GroupInc. 1991; Reid Collinsand Associates 1992;Sanders 1994.

FIGURE 31. Paper birch on private woodlots often occurs in conjunction with other agricultural land uses.

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6 MANAGING PAPER BIRCH FORNON-TIMBER VALUES

Managers today must balance timber production with the need to maintain forestbiodiversity and the health of forest ecosystems. Paper birch plays several importantroles in ecosystem functioning, of which wildlife interactions and habitat diversity aretwo key concerns. Table 17 summarizes the importance of paper birch to wildlife andbiodiversity. Birch’s biodiversity role is most evident aboveground, but important anddiverse processes are also prevalent underground, partly because birch is host to awide variety of ectomycorrhizal fungi (Figure 32).

Birch also has non-timber values for site stabilization, landscaping in visuallysensitive areas, and ecosystem restoration (Section 6.2). Part of birch’s biodiversityvalue is the range of non-timber products that it provides for artisans and others whocreate value-added products from various parts of birch trees (Section 6.3).

FIGURE 32. Paper birch is host to a wide diversity of ectomycorrhizal fungi, some of which are specific to birchand others which are shared by birch and other deciduous and coniferous tree species. Manyectomycorrhizal fungi form highly prized edible mushrooms. (Photograph by C.Y. Li)

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TABLE 17. General importance of characteristics of paper birch in pure and mixed stands with respect to wild-life and biodiversity

Element of valueto wildlife orbiodiversity

Importance of paper birchin pure stands

Importance of paper birchin mixed stands

vertical canopy structure Minimal structural development within purepaper birch stands.

Provides substantial contribution to canopystructure in older conifer–paper birch orcottonwood–alder stands.

ecosystem productivity Often enhances overall ecosystem produc-tivity.

Often enhances overall ecosystem produc-tivity; key contributor to aquatic systems.

ecosystem biodiversity Valuable for early growth and in providingcontrasting habitat, shrub companions, anddiversity to conifers.

Valuable for early growth, and in providingcontrasting habitat, shrub companions, anddiversity to conifers. Valuable in small gaps inconifer-dominated stands; seeds-in to Armil-laria areas.

large trees or snags Larger paper birch are important to somespecies for foraging and nesting, especiallycavity-nesting birds.

Larger paper birch are important to somespecies for nesting; persisting for longerperiods in mixed versus pure stands due toprotection by taller conifers.

down wood, large woodydebris

Provides important though short-lived,medium-sized woody debris; riparian treescontribute to streamside woody debris.

Provides important though short-lived,medium-sized woody debris; riparian treescontribute to streamside woody debris.

live but decadent or hollowtrees

Provides some habitat for cavity-nesters;more persistent than dead paper birch.Clumps of birch and brush provide cover forseveral wildlife species.

Provides some habitat for cavity-nesters,more persistent than dead paper birch;persisting for longer periods in mixed versuspure stands due to protection by tallerconifers.

understorey cover andproductivity

Shrub composition and productivity keyfeatures for several species. Young regen-erating stands of paper birch and associatedspecies provide cover and browse for deerand moose.

Shrub composition and productivity keyfeatures for several species; increases shrubdiversity mixed with conifer-associatedunderstorey.

forage value of browse Important to white-tailed deer and moose;moderately important winter browse forRocky Mountain elk, caribou, and mountaingoat. Peak browse occurs 10–16 years afterdisturbance.

Important to white-tailed deer and moose;moderately important winter browse forRocky Mountain elk, caribou, and mountaingoat. Peak browse occurs 10–16 years afterdisturbance.

value of leaves and litter Birch litter and life processes improve soilsby cycling nutrients efficiently, and improvesoil structure and permeability; in pure ormixed stands with conifers, birch increasessurface soil N, P, K, Ca, Mg, and Mn by about10 years.

Birch litter and life processes improve soilsby cycling nutrients efficiently, and improvesoil structure and permeability; in pure ormixed stands with conifers, birch increasessurface soil N, P, K, Ca, Mg, and Mn by about10 years.

food value of bark, sap, andcambium

Important to squirrels, porcupines, snowshoehares, and sapsuckers.

Important to squirrels, porcupines, snowshoehares, and sapsuckers.

food value of seeds andcatkins

Redpoll, Pine Siskin, Chickadees, mice andvoles feed on seeds; Ruffed Grouse eat malecatkins and buds.

Redpoll, Pine Siskin, and Chickadees feed onseeds; Ruffed Grouse eat male catkins andbuds.

Information Sources: Green and Salter 1987; Haeussler et al. 1990; Perala and Alm 1990a; Safford et al. 1990; Simard and Vyse1992; Steeger et al. 1993; BC Ministry of Forests and BC Ministry of Environment, Lands and Parks1995a; Keisker 1995; Norris 1995.

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6.1 Managing Paper Birch to Enhance Wildlife Habitat andForest Biodiversity

• Paper birch is highly palatable and provides important food and habitatto a wide variety of ungulates, birds, small mammals, and insects inBritish Columbia.

• Peak browse production in young birch occurs 10–16 years after fire,logging, or other disturbance when sufficient buds and young twigs areavailable. Mature birch stands provide little or no browse from the birchitself, although associated shrubs may be important for browse.

Managing forests for biodiversity involves maintaining the native diversity ofgenes, species, populations, and habitats, and maintaining the diversity of standstructures and seral stages in the landscape. Harvesting practices that emulate naturaldisturbances (insects, disease, fire, and wind) help to maintain biodiversity. Wildlifehabitat handbooks prepared by the B.C. Ministry of Environment, Lands and Parksprovide guidelines on the biodiversity importance of maintaining upland broadleafstands. The desired management approach is fairly simple because it is primarily amatter of ensuring that not all sites are committed to conifer production all of the time.For the southern interior of British Columbia, habitat specialists have estimated that atleast 10% of the bird fauna would be seriously affected if all broadleaf cover were elimi-nated. However, most birds and large mammals that use upland broadleaf ecosystemsare relatively mobile so that the patches of broadleaf species can be separated.

Young regenerating stands of paper birch and associated species provide primebrowse and summer cover for deer and moose. Birch is also a moderately importantwinter browse for mule deer, Rocky Mountain elk, caribou, and mountain goat. Moosebrowse paper birch throughout the year. Ontario data indicate that, in winter, birchmay amount to about 30% of moose diet. Loss of paper birch from herbicide treatmentof mixed cutovers may significantly affect winter browsing by moose. The degree ofbrowsing by deer can affect birch height growth; light browsing has no effect, butheavy browsing can result in reduced height growth. Porcupines debark birch to feedon the cambium and snowshoe hares clip twigs and stems of seedlings. Voles andother rodents can consume large amounts of birch seeds and girdle young stems ofpaper birch.

Buds, young twigs, and seeds of birch are also an important food source for severalbird species. Redpolls, Pine Siskins, and chickadees feed on seeds, and Ruffed Grouseeat male catkins and buds. Many birds nest in paper birch including woodpeckers,owls, hawks, sapsuckers, flycatchers, and vireos. Mature paper birch and aspen areamong the most important nest trees for woodpeckers and sapsuckers (Figure 33); inthe Nelson area, Red-naped Sapsuckers in particular use birch for nesting and foraging.Use of sapsucker cavities by secondary cavity-nesting species can include red andnorthern flying squirrels, Flammulated Owls, Mountain Chickadees, House Wrens,and three species of swallows. Snags of birch and other broadleaf species are significantcomponents of wildlife habitat where live trees, dead trees, and trees with dead topsare used by sapsuckers, Red-breasted Nuthatches, Northern Flickers, and DownyWoodpeckers. Sapsucker feeding excavations provide further biodiversity as feedingsites for other birds, insects, and small mammals.

Fast-growing broadleafspecies such as birch,aspen, and cottonwoodare valuable for provid-ing a supply of snags aswildlife trees in less timethan conifers, and theymay be more windfirmthan conifers.

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Bird management should consider diverse community-level habitat needs whichinclude maintenance of tree-dependent species by retention of broadleaf wildlife treesand snags, and provision for future snags. Forest and woodland management for wildlifeshould aim to provide a range and succession of deadwood habitats, each of whichprovides particular ecological niches for specialized organisms. These roles include:dead limbs on living trees; decay columns in trunks and main branches; rot holes instanding trees; standing dead trees; fallen deadwood; stumps and old coppice stools;and deadwood in watercourses. Although birch is short-lived and rapidly decays, it cancreate deadwood and rot holes within 70 years; other tree species may require muchlonger time periods to reach this capacity.

Riparian zones are used by wildlife disproportionately more than any other foresthabitat. Such zones are important to wildlife because the close proximity to watermaintains high soil moisture that promotes dense vegetation, in turn offering nestingand feeding opportunities, increased plant biomass, and greater structural and speciesdiversity. The linear structure of riparian zones maximizes the edge developmentpreferred by many wildlife species. In the interior of British Columbia, paper birch iscommon on floodplains and in riparian zones along valley bottoms. In coastal areas,birch seldom occurs on floodplains and is primarily an upland species. Implementationof riparian guidelines based on the Forest Practices Code of British Columbia Act ofteninclude birch in the interior of British Columbia.

Tables 18 and 19 list British Columbia wildlife species that use or depend onpaper birch in mixed and pure stands. In addition to the species listed in these tables,many small mammals nibble at the stem or bark of birch, often damaging or girdlingtrees. Buds, catkins, and new leaves provide food to beaver, porcupines, snowshoehares, squirrels, mice, and voles. Some paper birch management practices to meetwildlife diversity objectives are listed in Table 20.

FIGURE 33. This opening created by a Pileated Woodpecker indicates the impor-tance of paper birch snags as habitat for cavity-nesting birds. (Photo-graph by T. Berkhout.)


McNichol and Timmer-man 1981; Cannings etal. 1987; Harestad andKeisker 1989; DeGraafand Healy 1990;Freemark 1990;Haeussler et al. 1990;Klenner and Kremsater1993; Kremsater andBunnell 1993; Steeger etal. 1993; B.C. Ministry ofForests and B.C. Ministryof Environment, Landsand Parks 1995b;Enoksson et al. 1995;Keisker 1995; Machmerand Steeger 1995;Machmer et al. 1995;Steeger and Machmer1995; Steeger et al. 1996.

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TABLE 18. Wildlife species in British Columbia using or depending on paper birch in mixed or pure stands(based on B.C. Ministry of Environment, Lands and Parks 1991 and Enns et al. 1993)

Species Use of paper birch Management concern

Red-listed species none none

Blue-listed speciesBlack-crowned Night-heron Freshwater marshes with dense birch

and willow in Interior.Harvesting in riparian areas has un-known impact.

Black-throated Green Warbler Preferred breeding habitat is coniferforest with mixture of birch or aspen.

Poorly known for inventory and habitatutilization.

Brewer’s Sparrow Nests in dense clumps of birch in nor-thern parts province.

Management of birch could influencespecies, habitat use in northeast andcentral northern British Columbia;some birch should be maintained inplantations.

Yellow-listed speciesBeaver Riparian areas; uses birch in addition

to aspen (primarily) for dam and lodgeconstruction.

Harvesting of habitat and loss of cover.

Moose Birch is one of five broadleaf browsespecies used from early successionalforests.

Proximity of browse to late and earlywinter cover; disturbance of riparianfeeding areas; shape of cuts to limitcover-to-cover distance, and creation ofshelter patches in cutovers.

Mule deer Early successional stages of broadleafspecies are needed for year-round foodsupply.

Maintenance of early successionalstages adjacent to winter shelter.

Rocky Mountain elk Show preference for recent burns withabundant seral birch and aspen.

May be compatible with mixed seralstages over rotations; niche overlapwith cattle.

Blue Grouse Summer range for females with broodsincludes grassland with scatteredbroadleaf trees, mainly aspen, butsome birch.

Needs elements of seral and matureforest over local ranges; mixedwoodconversions to conifers may erodehabitat values.

Sharp-tailed Grouse Preferred year-round habitat is openlowland adjacent to brushy woodlands,which includes birch woodlands insouthern Interior and young seraldeciduous forest in northeast BritishColumbia.

Loss of deciduous shrubs through veg-etation management and conversion ofmixedwood to conifers may affect thisspecies; possible compatibility withmixed rotations on local ranges.

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TABLE 18. Continued

Species Use of paper birch Management concern

Non-listed speciesBoreal Owl Nests in tree cavities, especially those

of flickers; known to use birch, aspen,alder and conifers for nesting inAlaska.

Maintenance of deciduous elements inreforestation planning.

Broad-winged Hawk Preferred habitats are aspen wood-lands and mixed-deciduous woodlands(birch and aspen).

Harvesting may impact habitat; may becompatible with mixed rotations thatinclude seral and mature forest overlocal ranges.

Cooper’s Hawk Breeding habitat includes deciduousthickets such as birch, although blackcottonwood is more commonly used.

Harvesting of habitat; mixed rotationstages of seral and mature morecompatible.

Great Horned Owl Deciduous forest including birch usedin wide variety of forest habitats.

May be sensitive to logging; impacts ofharvesting need evaluation.

Long-eared Owl Preferred breeding habitat is densedeciduous trees and shrubs, includingwestern birch.

Conversion of deciduous and mixed-wood to coniferous and deciduous mayerode habitat; mixed rotations may bemost compatible.

Northern Saw-whet Owl Breeding habitat includes deciduous;nests in tree cavities, commonly Popu-lus spp. and birch (min. dbh is 30 cm).

Removal of large dbh stems may erodehabitat; mixed rotations preferable.

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TABLE 19. Animal species using birch stands and mixed-species stands involving birch in British Columbia(based on Massie et al. 1994)

Animal species associated with birch Animal species associated with mixed forests

Black-crowned Night Heron Barn Owl (edges)Black-throated Green Warbler Northern Goshawk (edges)Brewer’s Sparrow Sharp-shinned HawkSharp-tailed Grouse Western Screech OwlBoreal Owl Northern Saw-whet OwlCooper’s Hawk Northern Hawk OwlGreat Horned Owl Three-toed WoodpeckerLong-eared Owl Yellow-bellied SapsuckerNorthern Saw-whet Owl Downy WoodpeckerCalliope Hummingbird Veery, Hutton’s, Warbling, and Philadelphia VireoRed-naped Sapsucker Orange-crowned WarblerRed-breasted Sapsucker Nashville WarblerNashville Warbler OvenbirdCanada Warbler Tree SwallowConnecticut Warbler Black-capped Chickadee

Bushtit

California Big-horned Sheep Black BearBeaver MooseRocky Mountain Elk Muskrat

White-tailed deer

Animal species associated with deciduous–riparian forests

Fringed Myotis Western Small-footed MyotisKeen’s Long-eared Myotis BobcatTownsend’s Big-eared Bat MuskratPacific Water Shrew White-tailed DeerNorthern Long-eared Myotis Painted TurtleTownsend’s Chipmunk

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TABLE 20. Management practices with paper birch to meet wildlife diversity objectives

• Assess paper birch for wildlife values before approving silviculture prescriptions.

• Retain birch in a range of available sizes and conditions: live and healthy, live and decayed, dead and with defects(broken tops and heartrot).

• Include hazardous birch with other deciduous and coniferous species for mixed species composition in wildlifetree patches or no-work zones.

• Retain live single birch or green tree clumps incorporating birch with or without wildlife tree patches.

• Target upland birch with commercial management procedures such as:— when planting birch, use a mixture of birch and site-adapted conifers to maintain or increase tree species

diversity;— leave untreated patches interspersed on a site when brushing and thinning;— cut stems >20 cm dbh as high as possible with fellerbunchers, creating stubs for use by cavity-nesters; and

— retain veteran (live and dead) wildlife trees whenever possible for their very high habitat value.

The following formula for wildlife tree retention has been proposed in place of the 5–10 wildlife trees per hectare inan earlier provincial guideline:

W = A × B × C, whereW = number of wildlife trees to be retained per hectare.A = number of wildlife trees per hectare currently used for nesting and feeding.B = proportion of A in preferred dbh, height, and decay classes.C = proportion of A that should be retained based on landscape-level habitat integrity (C = 1: se-

verely disturbed habitat; C < 1: relatively intact habitat; the value for C in an undisturbed habitatshould be the minimum proportion of the habitat required for viable population levels of wildlifetree-dependent species; further research is required to quantify Cmin).

Note: The number of live trees required to ensure a constant rate of wildlife tree recruitment is not part of this formula andrequires more research and discussion. It is, to some extent, dependent on death rate of trees, falling rate of snags, andthe rotation time used in different silvicultural systems.

Information Sources: Steeger et al. 1993; Machmer et al. 1995.

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6.2 Birch for Landscaping Visually Sensitive Areas, SiteReclamation, and Ecosystem Restoration

• Birch’s status as a pioneer species and its adaptability to disturbed sitesmake it a prime broadleaf species for revegetating forest landings, minespoils, and other sites requiring forest ecosystem restoration.

• Birch’s prized urban ornamental values (attractive form, colourful foliage,white bark) can also be applied by forest managers responsible for thevisual enhancement of scenic viewpoints, campgrounds, roadside vistas,and interpretive areas.

Birch has a significant role in foresting landings, mine spoils, drained peatlands,landslides, gravel pits, abandoned and derelict lands, previously flooded lands, andsites with high pollution effects. When birch becomes established on these difficultsites, within a few decades soils may improve to the point that conifers can be graduallyintroduced. Birch’s important revegetation role is shown in Figure 34 with an examplefrom the Liard River drainage in northeastern British Columbia. In that region, siltstoneparent materials that are very susceptible to talus flow slides often support paper birch.These trees provide a major portion of the coarse woody debris in slide-prone areas.Canada Warblers have been observed using this birch debris, and it is also importanthabitat for martin (K. Enns, pers. comm., July 1996). In such areas of downed birchstems, the stemwood decays quickly compared to the more decay-resistant bark. Incases where this results in a hollow cylinder of bark, tunnel habitat is provided for mink.

The prevalence of bircharound mining andsmelter sites, as insoutheastern BritishColumbia, is one of thebest indicators of birch’sability to occupy siteswhere other forest specieshave difficulty becomingestablished.

FIGURE 34. Paper birch’s ability to establish on difficult sites, as on this colluvial slope in northeastern BritishColumbia, makes it a potentially valuable ecosystem restoration species. (Photograph by K. Enns)

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The abundance of birch on forest slopes around smelter sites in southeasternBritish Columbia is evidence of this tree’s ability to regenerate sites where other treesare restricted after high levels of airborne pollutants. Elsewhere, in tests to revegetategravel pits in Terra Nova National Park, Newfoundland, paper birch nursery stockplanted out on a fertilizer-treated site showed the best survival rate (89% after 2 years)among the six species tested. Experience from Britain with the natural colonization ofabandoned urban sites, ranging from lightly to intensely urbanized, found that birch,in this case Betula pendula, is among the most common species likely to colonize, andit was one of two species most prevalent on infertile sites.

Paper birch enhances the landscape beauty of roadsides, campgrounds, scenicviewpoints, and hiking areas. For such sites, management of individual birch trees, orgroups of birch, for aesthetic purposes can be an important objective for a manager. Inaddition to its aesthetic value, birch is a useful companion plant in gardens and a widelyused species in city parks and landscapes. Birch has been recommended for use on theoutskirts of compost piles, based on the idea that substances secreted by birch rootsencourage fermentation of compost. Introducing birch into landscaping projects alsohas the added benefit of attracting certain species of birds.

6.3 Value-added Special Products from Birch

• The range of artisan and special product uses of paper birch trees indicatesthat this species is a source of products much broader than the usualfocus on firewood, lumber, veneer, and particleboard products.

• Particularly in the boreal part of its North American range, paper birchis the source of a wide range of raw materials for local entrepreneurs whoproduce marketable items made from birch wood, bark, and sap.

Birch’s biodiversity value includes a wide range of traditional craft, food, andmedicinal uses. These include: vitamin-rich birch sap; young leaves and cambium asfood; use of bark and leaves because of their methyl salicylate content as medicinal tea,salve, liniment or massage oil; European use of birch leaf extract as an ingredient incommercial hair preparations; and a wide variety of birch bark and birch wood-craftproducts. Birch wood and birch bark are two of several forest products commonlyused in the weaving and dyeing of materials, basketry, and special-purpose woodproducts, one of which is “spalted” wood—wood that has begun to decompose and inwhich bacteria create “ink” lines that can be very decorative.

In many locations, birch bark is a principal value-added product for a variety ofcraft products. To date, research suggests that there is little, if any, opportunity toenhance regrowth of bark so that bark harvest could occur more than once. If only theouter papery bark layer is removed, the remaining corky bark layer will regeneratelayers of paper bark. However, birch can be managed to enhance the yield of high-quality bark. One step is to maintain and encourage development of large trees thatcan yield large single pieces of bark for use by artisans. The degree to which quality ofbark for basketry or canoes declines with age is not well documented.


Noyes 1969; Waldronand Dyck 1975;Richardson 1978;Watson et al. 1980;Gibberson 1988; Peralaand Alm 1990b; Saffordet al. 1990; Hodge 1995;MacDonald 1995.

Paper birch, as acomponent of Interiormixed stands, providesthe potential for greaterproduction of value-added special productsthan would be possiblefrom conifers alone.

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Paper birch has a long tradition of spiritual importance and practical bushcraftuses. Many northern Native groups regard paper birch as the most useful of all trees.Bushcraft products made or derived from birch wood, twigs, bark, or cambium includecanoes, woven bark strips for containers and shoes, cutting-boards, tea, distilled oils,and emergency food and medicines from the inner bark. The inner bark of birch isedible, raw or cooked. Birch wood is harder than that from most northern trees, idealfor sleds and snowshoes. Numerous tools have been crafted from birch wood includingpaddles, canoe ribs, bows, arrows, drums, axe handles, and spoons. Birch sap can be asource of syrup. A recent text, The Birch: Bright Tree of Life and Legend, describes anOjibway practice of individual tree selection of birch for spiritual and practical uses in away that sustained sacred birch groves.

Perhaps there are some guidelines from places where the forestry role of birchis better established than it is in British Columbia at present. For example, birch geneticsresearch in Finland and Sweden has demonstrated the gains possible by greenhousestimulation of seed production in as little as 3 years after germination. This approach isconsidered to have potential application to paper birch in British Columbia. Finnishbirch genetics research has also shown the importance of propagating types of birchthat are more valuable than the general population. An example is the development of“curly” birch in which the unique wood properties allow virtually every piece of wood,including branches, to be used for value-added production of items such as decorativeand durable knife handles. The search for valuable genotypes of this kind has not yetbegun for paper birch in its natural range. The value-added opportunities for birchproducts (bark, sap, or genotypes with distinctive wood characteristics) raises thequestion of whether communities and local artisans can manage birch more intensively,and with greater economic return from special forest products, than is possible in today’straditional approach to mixed-forest management. As the content of this handbookreveals, there is not yet adequate information to define specific silvicultural practicesto encourage the harvest and conservation of non-industrial special forest productsfrom paper birch. The significance of these kinds of value-added uses of birch is thatthere is a broad base of products usable from this species throughout the life of thetree instead of only at the end of the rotation.


Tubbs et al. 1983;Haeussler et al. 1990;Perala 1990a; Safford etal. 1990; Wilkinson 1990;Thomas and Schumann1993; Massie et al. 1994;Peyton 1994; de Geus 1995.

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7 BIRCH AS PART OF BRITISH COLUMBIA’SFUTURE FOREST MANAGEMENT

• The single most important data need is information on the proportion ofBritish Columbia’s working forest that is occupied by pure birch, standswith birch as the leading species, stands with birch as a minor component,and stands without birch.

• Forest managers should pay more attention to the different silviculturalprescriptions associated with birch stands of wildfire origin versus birchstands resulting from forest harvesting.

Paper birch’s emerging forestry role in British Columbia centres around the needto change forest practices from those that minimize the presence of birch in coniferplantations to practices that successfully manage birch–conifer mixtures. For example,recent research in the Kamloops Forest Region has shown that the complexity of mixed-species forests precludes application of simple silvicultural prescriptions across thebroad range of circumstances associated with birch–conifer mixed stands.

The increasing demand for previously unused stem biomass from broadleafspecies creates unprecedented opportunity for mixed-forest management. However,analysts in British Columbia, Alberta, and Ontario have stressed the need for improvedmill integration and wood exchanges between companies if there is to be fuller use ofwood from all species of mixed-species stands. This does not mean that mixed-speciessilviculture should be driven by mill requirements. Ecosystem dynamics and successionon mixed sites are equally important determinants of silvicultural policies, as birch andother broadleaf species face increasing demands for commercial harvest.

Recent analyses of birch ecology and silviculture in British Columbia suggestthree main points that can guide future research on mixed-stand management:

• Paper birch is a major contributor to British Columbia’s forest biodiversity be-cause it occurs in such a broad range of spatial and temporal scales in the prov-ince, ranging from hundreds of hectares in areas of former large wildfires tosmall birch patches that are a result of disturbances and patch dynamics at astand-level scale.

• Birch is an important contributor to site quality through rapid rates of foliage androot biomass growth, sequestration of nutrients, support of associative nitrogen-fixing bacteria, and birch’s substitution as an alternative forest biomass producerwhere Phellinus and Armillaria make conifer production difficult.

• Birch–conifer mixed stands may provide a new option for sustainable forest man-agement, as a substitute for expensive conifer plantation management that in-volves herbicide removal of broadleaf tree species.

Regarding regeneration, birch seedbed requirements are well known, but there isa need for more information about site preparation techniques on a range of site series.Birch has not been managed in British Columbia long enough to show whether repeatedcoppicing of stump sprouts is a way to sustain today’s birch biomass production rates.

Nobody today has allthe answers on how tomanage and harvestmixed forests, but ifmixed birch–coniferstands are establishednow for 40- to 60-yearrotations, the decadeswhile these standsdevelop will provide timeto work out new waysto sustain and useBritish Columbia’sbirch resource.

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Current research in British Columbia is comparing rates of litter decompositionin pure and mixed stands. Along with boreal spruce and aspen, as well as coastal Douglas-fir and red alder, Interior Douglas-fir and birch is an important mixed-speciescombination being investigated. Results will help to predict differences in nutrientcycling as a guide to different management choices about fertilization needs, sizes ofopenings, and desired proportions of conifer and broadleaf species in mixed stands.

Innovative ideas are needed for future forest management involving birch becausethe complexity of mixed birch–conifer forests precludes application of simple silviculturalprescriptions across a broad range of site series, stand histories, and ecologicalcircumstances. Practical ways to implement sustainable birch–conifer managementrequires more experience with mixed-stand development patterns and ecosystemprocesses. A good knowledge of the ecology and silvics of paper birch is crucial to thesuccess of that endeavour.


Kochanski 1987;MacDonald andWeingartner 1994;Weingartner andMacDonald 1994;Simard 1995; Prescott etal. 1996; J.C. Zasada,pers. comm., Sep. 1996.

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GLOSSARY

adjuvant Anything that helps or assists in a function.

adventitious Buds or roots that develop at a location other than the usual orexpected, such as roots growing from leaves or buds develop-ing at locations other than at leaf axils.

asymbiotic Absence of association; the opposite of symbiosis, a long-termassociation between two different species living together.

asymptotic Tangential but not meeting; from the mathematical expressionfor a line that approaches but does not meet a plane curve.

basidiomycete Any of a large group of fungi that constitute the phylumBasidiomycota, characterized by a spore-bearing structure inthe form of a basidium (sexual spores are borne on the tips ofslender projections).

biodiversity The diversity of plants, animals, and other living organisms inall their forms and levels of organization, including the diver-sity of genes, species, and ecosystems, as well as the evolu-tionary and functional processes that link them.

chlorosis The condition of plants when chlorophyll fails to develop,indicated by leaves that are yellowish to white and poorlydeveloped.

colluvial; colluvium Loose earth material that accumulates at the base of a slope.

coppice An even-aged silvicultural system in which all trees in a foreststand are harvested, and regeneration is secured from sproutsor root suckers.

ectomycorrhizal Referring to mycorrhizae that grow on the surface of roots.

free-growing An established seedling of an acceptable commercial species,meeting minimum height requirements, that is free fromgrowth-inhibiting brush, weeds, and excessive tree competi-tion.

girdling, frilling To kill a tree by severing the cambium layer and interruptingthe flow of food between the leaves and the rest of the tree;frilling is a form of girdling involving a series of downward cutsas overlapping incisions on a tree stem.

genotype The entire genetic constitution, or the sum total of genes, of anorganism.

inoculum Medium used to introduce a micro-organism, or material, suchas bacteria, fungi, virus, or serum into another organism.

leaf area (index) A measure of the amount of foliage per unit area of habitat,commonly expressed as square metres (m2) of foliage surfacearea (either one side or both sides of flat leaves) per squaremetre of land area.

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litter The layer of slightly decomposed organic material on the sur-face of the forest floor.

mixed forest A forest (stand) composed of trees of two or more species; usu-(mixed species, ally at least 20% of the trees are other than the leading species;mixed stands) as used in this handbook, mixed forest refers to birch in mix-

ture with one or more conifers or with other broadleaf species.

mixedwood A type of mixed forest typically associated with the boreal andsub-boreal portions of paper birch’s natural range, to distin-guish it from birch–conifer mixtures typical of southern inter-ior British Columbia.

mutualism An interaction between two species or populations in whichgrowth and survival of both is beneficial, and neither can sur-vive under natural conditions without the other.

mycorrhizae A symbiotic association of the mycelium of a fungus with the(mycorrhizal) roots of certain plants, in which the fungal hyphae form a closely

woven mass around the rootlets or penetrate the cells of theroot. See ectomycorrhizal.

necrosis The death of an organism or one of its parts.

photosynthate Carbohydrate formed from carbon dioxide and water in thepresence of chlorophyll using light as energy, with oxygen as aby-product.

pioneer A plant capable of invading newly exposed soil surfaces andpersisting there until supplanted by successor species.

radicle An embryonic root; a small root-like part or structure.

rhizosphere The soil zone where roots are located.

riparian (zone) Land adjacent to the normal high-water line in a stream, river,or lake extending downwards to that part that is influenced bythe presence of ponded or channelled water.

root collar sprout A sprout that arises from the transitional area, generally justbelow the soil surface, where the stump of a tree flares intorecognizable root segments.

root suckers, root Vegetative reproduction originating primarily from adventi-suckering tious buds within the root cork cambium or from preformed

primordia; suckers also develop from dormant buds, but theseare less vigorous than those from adventitious buds.

saprophyte A plant that obtains food from dead or decaying organic material.

seed bank The collective supply of seeds on living or dead plants and inthe soil.

seral Stages in a sequence of biotic communities that successivelyreplace each other over time as part of ecological successionin a particular environment.

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site index A measure of the relative productivity of a site, based on heightof the dominant trees of a stand at an arbitrary age.

stool(s) A stump, typically of cutting origin, that is repeatedly cut aboveground level to produce more sprouts annually.

stump sprout A sprout that arises from a dormant bud or callus tissue of atree stump above the root collar zone.

surfactant Any surface-active substance, such as a detergent or a naturalor artificial substance that coats a surface; derived fromsurf(ace)-act(ive)-a(ge)nt.

translocation The conductance of a material, such as food material or chemi-cals, from one part of a plant to another, such as from the stemor leaves to the underground parts.

Biogeoclimatic terms, such as site series, site association, variant, and biogeoclimaticzone and subzone, are defined in publications such as Meidinger and Pojar (1991).

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APPENDIX 1 Abbreviations of biogeoclimatic zones and tree species used in thishandbook

Biogeoclimatic zones:BG BunchgrassBWBS Boreal White and Black SpruceICH Interior Cedar–HemlockIDF Interior Douglas-firMS Montane SprucePP Ponderosa PineSBS Sub-Boreal Spruce

Tree species:Acb balsam poplarAct cottonwoodAt aspenBa amabilis firBg grand firBl subalpine firCw western redcedarEp paper birchFd Douglas-firHm mountain hemlockHw western hemlockLt tamarackLw western larchPl lodgepole pinePw western white pinePy ponderosa pineSb black spruceSw white spruceSx hybrid spruceSxw hybrid white spruce

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APPENDIX 2 Biogeoclimatic units and site series where paper birch is a potentialregeneration species (Silviculture Interpretations Working Group 1994)

A. Cariboo Forest Region

Biogeoclimatic unit Site series

ICHdk* CwSxw* - Falsebox - Wintergreen; CwSxw - Falsebox - Feathermoss; CwSxw -Thimbleberry; CwSxw - Raspberry - Oak fern; Sxw - Devil’s club - Lady fern

ICHmk3 CwSxw - Falsebox - Knight’s plume; CwSxw - Oak fern - Cat’s-tail moss

ICHmk3; ICHwk2; ICHwk4 CwHw - Devil’s club - Lady fern

ICHwk2; ICHwk4 CwHw - Oak fern; HwCw - Step moss

IDFdk3 SxwFd - Prickly rose - Sedge; SxwFd - Prickly rose - Sarsaparilla

IDFxm Fd - Prickly rose - Sarsaparilla

IDFxw Sxw - Water birch; Sxw - Prickly rose - Coltsfoot

SBSdw1 SxwFD - Ricegrass; SxwFd - Thimbleberry; Sxw - Twinberry - Coltsfoot; Sxw -Twinberry - Oak fern

SBSdw1; SBSdw2 SxwFd - Pinegrass; Pl - Pinegrass - Feathermoss

SBSdw2 SxwFd - Cat’s-tail moss; Sxw - Twinberry; Sxw - Devil’s club - Knight’s plume

SBSmh SxwFd - Hazelnut; FdPl - Velvet-leaved blueberry - Cladonia; Fd - Douglas maple -Step moss; SxwFd - Feathermoss; SxwFd - Coltsfoot; SxwEp - Devil’s club; Sxw -Ostrich fern

SBSmw SxwFd - Falsebox; FdBl - Huckleberry; Sxw - Devil’s club

SBSmw; SBSwk1 SxwFd - Knight’s plume

SBSwk1 Sxw - Twinberry - Oak fern

SBSmw; SBSwk1 Sxw - Devil’s club

* See Appendix 1 for names of the biogeoclimatic zones listed here and for the tree species whose abbreviation begins the nameof each site series.

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B. Kamloops Forest Region


Bgxh1* Py* - Nookta rose - Poison ivy; Act - Water birch

Bgxh2 Act - Snowberry - Dogwood

ICHmk1 CwSxw - Falsebox; CwSxw - Aspen; SxwFd - Gooseberry - Sarsaparilla; Sxw - Oakfern

ICHmk2 CwSxw - Falsebox - Knight’s plume; Fd - Falsebox - Pinegrass; CwSxw - Douglasmaple - Fairybells; CwSxw - Oak fern - Bunchberry

ICHmk1; ICHmk2; IDFdm1;IDFxh2; SBSmm

Sxw - Horsetail

ICHmw2 CwFd - Falsebox; CwHw - Horsetail

ICHmw2; ICHmw3; ICHvk1;ICHwk1

HwCw - Falsebox - Feathermoss; CwHw - Devil’s club - Lady fern; CwSxw -Skunk cabbage

ICHmw3 HwCw - Feathermoss; Fd - Juniper - Cladina; FdPl - Pinegrass - Feathermoss;CwFd - Soopolallie - Twinflower; CdFd - Falsebox; CwHw - Oak fern

ICHmw2; ICH vk1 CwHw - Oak fern - Foamflower

ICHvk1 CwHw - Oak fern - Spiny wood fern

ICHwk1 CwHw - Oak fern; PlHw - Velvet-leaved blueberry; HwCw - Step moss

ICHvk1; ICHwk1 CwSxw - Devil’s club - Horsetail

IDFdk2; IDFdm1 SxwFd - Dogwood - Gooseberry

IDFdk2 CwSxw - Twinberry - Soft-leaved sedge

ICHmw2; IDFmw1; IDFmw2 FdCw - Falsebox - Prince’s pine; CwFd - Feathermoss

IDFmw1 CwFd - Dogwood; Cw - Devil’s club - Foamflower

IDFmw2 EpAt - Thimbleberry - Falsebox

IDFmw1; IDFmw2 Fd - Pinegrass - Feathermoss

IDFmw2 CwSxw - Oak fern

IDF xh1 SxwFd - Douglas maple - Dogwood

IDFxh2 CwFd - Horsetail

PPxh1 Fd - Water birch - Douglas maple

PPxh2; SBSmm Act - Water birch


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C. Nelson Forest Region


ICHdw* FdPy* - Oregon grape - Parsley fern; CwHw - White pine - Devil’s club

ICHdw; ICHmw1; ICHmw2;ICHmw3; ICHvk1; ICHwk1

CwHw - Devil’s club - Lady fern

ICHmk1 CwSxw - Falsebox; SxwFd - Gooseberry - Sarsaparilla; Sxw - Oak fern

ICHmk1; IDFdm1; IDFdm2 Sxw - Horsetail

ICHmw1 Pl - Juniper - Twinflower; HwCw - Falsebox - Pipecleaner moss; CwFd -Soopolallie - Douglas maple; CwHw - Oval-leaved blueberry - Oak fern

ICHmw1; ICHmw2 CwHw - Horsetail

ICHmw1; ICHmw2; ICHmw3;ICHvk1; ICHwk1

HwCw - Falsebox - Feathermoss

ICHmw2 FdCw - Falsebox - Prince’s pine; CwHw - Oak fern - Foamflower

ICHdw; ICHmw2; ICHmw3 CwFd - Falsebox

ICHmw2; ICHmw3; ICHvk1;ICHwk1

CwSxw - Skunk cabbage

ICHmw3 HwCw - Feathermoss; Fd - Juniper - Cladina; FdPl - Pinegrass - Feathermoss;CwFd - Soopolallie - Twinflower; CwHw - Oak fern

ICHvk1 CwHw - Oak fern - Spiny wood fern; CwSxw - Devil’s club - Horsetail

ICHwk1 CwHw - Oak fern; Act - Dogwood - Twinberry

ICHxw CwFd - Mock-orange

IDFdm1 SxwFd - Dogwood - Gooseberry

IDFdm1; IDFdm2 FdLw - Spruce - Pinegrass

IDFdm2 SxwAt - Sarsaparilla

IDFxh1 SxwFd - Douglas maple - Dogwood

MSdk Sxw - Soopolallie - Grouseberry; Pl - Juniper - Pinegrass; Pl - Oregon grape -Pinegrass; Sxw - Soopolallie - Snowberry

PPdh1 PyAct - Snowberry - Kentucky bluegrass; AtAct - Snowberry - Horsetail

PPdh2 PyAt - Rose - Solomon’s seal; Act - Dogwood - Nootka rose


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D. Prince George Forest Region


BWBSdk1* SwPl* - Soopolallie - Twinflower; Sw - Scouring rush - Step moss

BWBSdk1; BWBSdk2 SwPl - Knight’s plume - Step moss; Sw - Currant - Horsetail

BWBSdk2 Sw - Wildrye - Toad-flax

BWBSmw1 Sw - Currant - Oak fern

BWBSmw1; BWBSmw2 SwAt - Step moss

BWBSmw1; BWBSwk1;BWBSwk2

Sw - Currant - Bluebells

ICHmm HwCw - Spruce - Step moss; CwSxw - Soopolallie; CwHw - Devil’s club - Oak fern

ICHvk2; ICHwk1; ICHwk3;ICHwk4

CwHw - Devil’s club - Lady fern

ICHvk2 Cw - Devil’s club - Ostrich fern

ICHmm; ICHvk2; ICHwk3;ICHwk4

HwCw - Step moss

ICHmm; ICHvk2; ICHwk1;ICHwk3; ICHwk4

CwHw - Oak fern

ICHwk1 PlHw - Velvet-leaved blueberry; Act - Dogwood - Twinberry; HwCw - Falsebox -Feathermoss; CwSxw - Skunk cabbage

ICHwk3 CwSxw - Prince’s pine - Cat’s-tail moss; Hw - Wood horsetail - Sphagnum; CwSxw- Devil’s club - Horsetail

SBSdh SxwFd - Ricegrass; FdPl - Pinegrass - Feathermoss

SBSdh; SBSdw1; SBSvk SxwFd - Thimbleberry

SBSdh; SBSdk; SBSmc3 Sxw - Horsetail

SBSdk` Sxw - Spirea - Purple peavine; Pl - Juniper - Ricegrass; Pl - Feathermoss - Cladina;Fd - Soopolallie - Feathermoss; Sxw - Spirea - Feathermoss

SBSdk; SBSdw1; SBSwk3 Sxw - Twinberry - Coltsfoot

SBSdw1; SBSdw3 SxwFd - Ricegrass

SBSdw1; SBSwk1 Sxw - Twinberry - Oak fern

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Prince George Forest Region (Continued)


SBSdh; SBSdw1; SBSdw2 Pl - Pinegrass - Feathermoss

SBSdw1; SBSdw2; SBSdw3 SxwFd - Pinegrass

SBSdw2 SxwFd - Cat’s-tail moss; Sxw - Devil’s club - Knight’s plume

SBSdw2; SBSdw3 Sxw - Twinberry

SBSdw3 Sxw - Pink spirea - Prickly rose

SBSmh SxwFd - Hazelnut; FdPl - Velvet-leaved blueberry - Cladonia; Fd - Douglas maple -Step moss; SxwFd - Feathermoss; SxwFd - Coltsfoot; SxwEp - Devil’s club; Sxw -Ostrich fern

SBSmk1; SBSmk2; SBSwk1;SBSwk2; SBSwk3

Sxw - Huckleberry - Highbush cranberry

SBSmk1 SxwFd - Toad-flax

SBSdw3; SBSmk1; SBSmk2;SBSmw; SBSvk; SBSwk1;SBSwk2; SBSwk3

Sxw - Oak fern

SBSmk2 Sxw - Huckleberry - Soopolallie

SBSmw SxwFd - Falsebox; FdBl - Huckleberry

SBSmk1; SBSmw; SBSwk1 SxwFd - Knight’s plume

SBSmk1; SBSmw; SBSvk;SBSwk1; SBSwk2; SBSwk3

Sxw - Devil’s club

SBSwk1 Sxw - Pink spirea - Oak fern

SBSwk3 SxwFd - Purple peavine


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E. Prince Rupert Forest Region


BWBSdk1; BWBSdk2* Sw* - Knight’s plume - Step moss; Sw - Currant - Horsetail

BWBSdk1 SwPl - Soopolallie - Twinflower; Sw - Scouring rush - Step moss

BWBSdk2 Sw - Wildrye - Toad-flax

ICHmc1; ICHwc HwBl - Oak fern

ICHmc1a HwBa - Bramble; HwBa - Oak fern; HwBa - Devil’s club - Lady fern

ICHmc2 HwCw - Oak fern; CwHw - Devil’s club - Oak fern; Sx - Devil’s club - Lady fern;PlHw - Feathermoss; SxEp - Thimbleberry - Hazelnut; AtEp - Dogwood; SxEp -Devil’s club

ICHmc1; ICHmc2; ICHvc;ICHwc

Hw - Step moss

ICHmc1; ICHmc2; ICHwc ActSx - Dogwood

ICHvc; ICHwc Sx - Horsetail

ICHmc1; ICHvc; ICHwc HwBl - Devil’s club

ICHvc; ICHwc Sx - Devil’s club

SBSdk Sxw - Spirea - Purple peavine; Pl - Juniper - Ricegrass; Pl - Feathermoss - Cladina;Fd - Soopolallie - Feathermoss; Sxw - Spirea - Feathermoss; Sxw - Horsetail

SBSwk3 Sxw - Oak fern; SwFd - Purple peavine; Sxw - Huckleberry - Highbush cranberry;Sxw - Devil’s club

SBSdk; SBSwk3 Sxw - Twinberry - Coltsfoot


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