Index of Species Information

SPECIES:  Tsuga heterophylla

Introductory

SPECIES: Tsuga heterophylla
AUTHORSHIP AND CITATION : Tesky, Julie L. 1992. Tsuga heterophylla. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [].
ABBREVIATION : TSUHET SYNONYMS : NO-ENTRY SCS PLANT CODE : TSHE COMMON NAMES : western hemlock Pacific hemlock west coast hemlock TAXONOMY : The scientific name for western hemlock is Tsuga heterophylla (Raf.) Sarg. [57,60]. There are no recognized subspecies, varieties, or forms. A natural hybrid between western hemlock and mountain hemlock (Tsuga mertensiana), Tsuga x jeffreyi (Henry) Henry, has been reported [57]. LIFE FORM : Tree FEDERAL LEGAL STATUS : No special status OTHER STATUS : NO-ENTRY

DISTRIBUTION AND OCCURRENCE

SPECIES: Tsuga heterophylla
GENERAL DISTRIBUTION : Western hemlock occurs in the Coast Ranges from Sonoma County California to the Kenai Peninsula in Alaska. Inland it occurs along the western and upper eastern slopes of the Cascade Range in Oregon and Washington and west of the Continental Divide in the northern Rocky Mountains of Montana and Idaho, north to Prince George, British Columbia [10,56,57,78]. ECOSYSTEMS : FRES20 Douglas-fir FRES21 Ponderosa pine FRES22 Western white pine FRES23 Fir - spruce FRES24 Hemlock - Sitka spruce FRES25 Larch FRES26 Lodgepole pine FRES27 Redwood FRES28 Western hardwoods STATES : AK CA ID MT OR WA AB BC BLM PHYSIOGRAPHIC REGIONS : 1 Northern Pacific Border 2 Cascade Mountains 4 Sierra Mountains 5 Columbia Plateau 8 Northern Rocky Mountains KUCHLER PLANT ASSOCIATIONS : K001 Spruce - cedar - hemlock forest K002 Cedar - hemlock - Douglas-fir forest K003 Silver fir - Douglas-fir forest K004 Fir - hemlock forest K005 Mixed conifer forest K006 Redwood forest K008 Lodgepole pine - subalpine forest K012 Douglas-fir forest K013 Cedar - hemlock - pine forest K014 Grand fir - Douglas-fir forest K015 Western spruce - fir forest SAF COVER TYPES : 202 White spruce - paper birch 205 Mountain hemlock 206 Engelmann spruce - subalpine fir 210 Interior Douglas-fir 212 Western larch 213 Grand fir 215 Western white pine 218 Lodgepole pine 221 Red alder 222 Black cottonwood - willow 223 Sitka spruce 224 Western hemlock 225 Western hemlock - Sitka spruce 226 Coastal true fir - hemlock 227 Western redcedar - western hemlock 228 Western redcedar 229 Pacific Douglas-fir 230 Douglas-fir - western hemlock 231 Port-Orford-cedar 232 Redwood SRM (RANGELAND) COVER TYPES : NO-ENTRY HABITAT TYPES AND PLANT COMMUNITIES : Western hemlock commonly occurs as a dominant or codominant on low- to mid-elevation moist sites. In northern Idaho, plant communities dominated by western hemlock occupy the moist, moderate temperature sites within the maritime-influenced climatic zone of the northern Rocky Mountains. Here, western hemlock can be found as the climax dominant from 2,500 to 5,500 feet (760-1,680 m) and can dominate sites of all exposures and landforms except wet bottomlands where it is replaced or codominant with western redcedar (Thuja plicata) [19]. In the Gifford Pinchot National Forest of Washington, the western-hemlock-dominated zone includes the lower elevation moist forests of the western Cascades [68]. In Mount Rainier National Park, Washington, the western hemlock/devil's club (Oplopanax horridus) community occupies wet benches, terraces, and lower slopes at low elevations [32]. The western hemlock riparian dominance type in Montana described by Hansen and others [39] is an infrequent cover type restricted to northwestern Montana on toe-slope seepages, moist benches, and wet bottoms adjacent to streams. Published classifications identifying western hemlock as a dominant or codominant are as follows: Classification and management of riparian and wetland sites in northwest Montana [14]. Classification of montane forest community types in the Cedar River drainage of western Washington, U.S.A. [54]. The forest communities of Mount Rainier National Park [32]. Forest habitat types of Montana [59]. Forest habitat types of northern Idaho: A second approximation [19]. Forest types of the North Cascades National Park Service complex [5]. Forest vegetation of eastern Washington and northern Idaho [21]. A guide to the interior cedar-hemlock zone, northwestern transitional subzone (ICHg), in the Prince Rupert Forest Region, British Columbia [36]. Natural vegetation of Oregon and Washington [31]. Plant association and management guide [41]. Plant association and management guide for the western hemlock zone. Gifford Pinchot National Forest [68]. Plant association and management guide for the western hemlock zone: Mt. Hood National Forest [37]. Plant association and management guide. Willamette National Forest [42]. A preliminary classification of forest communities in the central portion of the western Cascades in Oregon [25]. Preliminary forest plant association management guide. Ketchikan area, Tongass National Forest [23]. Preliminary forest plant associations of the Stikine area Tongass National Forest [70]. Preliminary plant associations of the Siskiyou Mountain province [12]. Preliminary plant associations of the southern Oregon Cascade Mountain Province [11]. Reference material Daubenmire habitat types [69]. Riparian dominance types of Montana [39]. A study of the vegetation of southeastern Washington and adjacent Idaho [73]. Vegetation mapping and community description of a small western cascade watershed [40]. Vegetation of the Abbott Creek Research Natural Area, Oregon [53].

MANAGEMENT CONSIDERATIONS

SPECIES: Tsuga heterophylla
WOOD PRODUCTS VALUE : Western hemlock wood is recognized as an all-purpose raw material. It is one of the best pulpwoods for paper and paper board products [57,72]. It is the principal source of alpha cellulose fiber used in the manufacture of rayon, cellophane, and many plastics [10]. Other uses are lumber for general construction, railway ties, mine timbers, and marine piling. The wood is suited also for interior finish, boxes and crates, kitchen cabinets, flooring, and ceiling, gutter stock, and veneer for plywood [57,72]. IMPORTANCE TO LIVESTOCK AND WILDLIFE : Roosevelt elk and black-tailed deer browse western hemlock in coastal Oregon, Washington, and British Columbia [57]. In the Oregon Cascades deer mice consumed about 22 percent of the western hemlock seed fall. This consumption occurred just before or during the germination process [76]. Black bear girdle pole-size western hemlock and larger saplings or damage the bark at the base of the trees. Snowshoe hare and rabbit clip off the main stems of western hemlock seedlings. Mountain beaver clip the stems and lateral branches of seedlings and girdle the base of saplings [57]. Old-growth western hemlock stands provide hiding and thermal cover for many wildlife species. In the southern Selkirk Mountains of northern Idaho, northeastern Washington, and adjacent British Columbia, grizzly bear have been known to use heavily timbered western hemlock forests [48]. In the western Oregon Cascades, western hemlock provides habitat for many species of small mammals, including the northern flying squirrel and red tree vole [7,67]. In Washington and Oregon, the northern spotted owl is often found in forests dominated by Douglas-fir (Pseudotsuga menziesii) and western hemlock. The majority of barred owls observed in British Columbia have occurred in the Columbia Forest Biotic Area in which western hemlock and western redcedar are the major climax species [6]. Western hemlock is used for nest trees by cavity nesting bird species such as the yellow-bellied sapsucker and northern three-toed woodpecker [51]. PALATABILITY : NO-ENTRY NUTRITIONAL VALUE : NO-ENTRY COVER VALUE : NO-ENTRY VALUE FOR REHABILITATION OF DISTURBED SITES : Western hemlock is suitable for planting on moist, nutrient very poor to nutrient medium sites in pure or mixed species stands (mainly with Pacific silver fir [Abies amabilis], Sitka spruce [Picea sitchensis], alder [Alnus spp.], or western redcedar). Natural regeneration is preferred over planted stock [44]. Western hemlock is difficult to grow in outdoor nurseries. Container-grown stock appears to result in higher quality seedlings with less damage to roots and better survival than bareroot stock [57]. Methods for collecting, storing and planting western hemlock seeds and seedlings have been detailed [63]. OTHER USES AND VALUES : Alaska Indians made coarse bread from the inner bark of western hemlock [72]. Young western hemlock saplings can be sheared to make excellent hedges. In Britain western hemlock is often planted as an ornamental [46]. OTHER MANAGEMENT CONSIDERATIONS : Insects and disease: The major root and butt pathogens of western hemolock are: Armillaria mellea, Heterobasidion annosum, Phaeolus schweinitzii, Laetiporus sulphureus, Inenotus tomentosus, Poria subacida, Phellinus weiri, and Indian paint fungus (Echinodontium tinctorium) [30,57]. Western hemlock is severely damaged by Indian paint fungus in the high Cascades; cull due to this rot may run as high as 80 percent in old-growth stands [30]. Dwarf mistletoe (Arceuthobium campylopodum) is a common parasite on western hemlock which causes wide-spread growth loss and mortality in old-growth stands [62]. Important insects attacking western hemlock are a weevil (Steremnius carinatus), western larch borer (Tetropium velutinum), western blackheaded budworm (Acleris gloverana), western hemlock looper (Lambdina fiscellaria lugubrosa), green striped forest looper (Melanolophia imitata), saddleback looper (Ectropis crepuscularia), and hemlock sawfly (Neodiprion tsugae). The western hemlock looper has caused more mortality of western hemlock than any other insect pest. Outbreaks can last 2 to 3 years on any one site. Although mortality is greatest in old-growth western hemlock, vigorous 80- to 100-year-old stands can also be severely damaged by this insect. The hemlock sawfly is considered the second most destructive insect of western hemlock in Alaska [57]. Other damaging agents: Pole-sized and larger stands of western hemlock are subject to severe windthrow. Uprooting is increased in areas where a high water table or impenetrable layer in the soil causes trees to be shallow rooted [62]. Blowdown is a major problem in western hemlock forests, and the need to leave windfirm borders is always present. If only part of the stand will be removed, the leave trees need to be as windfirm as possible [64]. Western hemlock suffers frost damage in the Rocky Mountains, especially along the eastern edge of its range [57]. On droughty sites, top dieback is common; in exceptionally dry years, entire stands of western hemlock saplings die [57]. Western hemlock seedlings and saplings are susceptible to sunscald following exposure of young stems by thinning. Sunscald lesions often become infected with decay organisms [62]. Western hemlock is one of the conifers most sensitive to damage by sulfur dioxide. Spring applications of the iso-octyl esters of 2,4-D and 2,4,5-T in diesel oil can kill up to 3 years of leader growth [57]. Fertilization: The response of western hemlock to nitrogen fertilizer is extremely variable. For overstocked stands, a combination of precommercial thinning and fertilizer often gives the best response [57]. Silvicultural considerations: In terms of biomass production, western hemlock forests are among the most productive forests in the world. Natural stands of western hemlock along the Pacific Coast attain higher yields than Douglas-fir stands having the same site index [57,64]. Pure stands of western hemlock are so densely stocked that an acre of 100-year-old western hemlock forest can yield more timber (150,000 to 190,000 board feet on a good site) than a comparable stand of larger, less dense Douglas-fir [10,64]. Western hemlock can be regenerated by most standard harvest methods. In the past, clearcutting was the most common method used in western hemlock stands [64,74]. As an aesthetically viable alternative to clearcutting, shelterwood cutting has been proposed as a means of controlling brush competition and favoring western hemlock seedlings [77]. The shelterwood method has been used successfully in even-aged stands. Observations suggest that cutting of uneven-aged stands by the individual tree selection method will be successful in obtaining western hemlock regeneration [38,64]. In the grand fir (Abies grandis)-cedar-hemlock ecosystem, Graham and Smith [34] found that the individual tree selection method of harvest promotes the regeneration and growth of shade-tolerant species, such as western hemlock. The seed tree method will work, but rarely is used in harvesting of western hemlock stands because many seed trees blow down during wind storms [64]. A common problem in regeneration of western hemlock is overtopping by competing vegetation such as alder, thimbleberry (Rubus parviflorus), and salmonberry (Ribes spectabilis). When exposed to full sunlight after clearcutting, these brush species tend to form dense thickets and exclude hemlock regeneration. These species can be controlled with herbicides [64]. Western hemlock responds well to release after long periods of suppression. Advance regeneration up to 4.5 feet (1.4 m) tall appears to respond better to release than taller individuals. Poor response to release has been noted for suppressed trees over 100 years old [57].

BOTANICAL AND ECOLOGICAL CHARACTERISTICS

SPECIES: Tsuga heterophylla
GENERAL BOTANICAL CHARACTERISTICS : Western hemlock is a large, native, evergreen tree. At maturity it is generally 100 to 150 feet (30-46 m) tall and 2 to 4 feet (0.6-1.2 m) in trunk diameter [72]. On best sites, old-growth trees reach diameters greater than 3.3 feet (1 m); maximum diameter is about 9 feet (3 m). Heights of 160 to 200 feet (49-61 m) are not uncommon; maximum height has been reported as 259 feet (79 m) [57]. Western hemlock has a long slender trunk often becoming fluted when large and has a short, narrow crown of horizontal or slightly drooping branches. The needles are short-stalked and 0.25 to 0.87 inch (6-22 mm) long, flat and rounded at the tip. The twigs are slender [72]. The bark is thin (1 to 1.5 inches [0.39-0.59 cm]) even on large trees; young bark is scaly and on old trunks it is hard with furrows separating wide flat ridges [60]. Western hemlock is shallow rooted and does not develop a taproot. The roots, especially the fine roots, are commonly most abundant near the surface and are easily damaged by harvesting equipment and fire. Maximum ages are typically over 400 years but less than 500 years. The maximum age recorded is in excess of 700 years [57]. RAUNKIAER LIFE FORM : Phanerophyte REGENERATION PROCESSES : Seed production and dissemination: Western hemlock is generally a good cone and seed producer. Cones may form on open-grown trees that are less than 20 years old, but good cone crops usually do not occur until trees are between 25 and 30 years old. Individuals usually produce some cones every year and heavy cone crops every 3 or 4 years. Each cone contains 30 to 40 seeds. The number of viable seeds ranges from fewer than 10 to approximately 20 per cone [18,56]. Seeds are light and small, ranging from 189,000 to 508,000 cleaned seeds per pound, with an average of 260,000 seeds per pound (371,000-900,000/kg, average 530,000 seeds/kg) [56,63]. Western hemlock seeds have large wings enabling them to be distributed over long distances. In open, moderately windy areas, most seeds fall within 1,968 feet (600 m) of the parent tree. Some seeds can travel as far as 3,772 feet (1,150 m) under these conditions. In dense stands, most seeds fall much closer to the base of the tree [56]. Germination: Germination is epigeal. Stratification for 3 to 4 weeks at 33 to 39 degrees Fahrenheit (1-4 deg C) improves germination. The optimum temperature for germination is 68 degrees Fahrenheit (20 deg C) [57,63]. For each 9 degrees Fahrenheit (5 deg C) below the optimum, the number of days required for germination is nearly doubled [63]. Given sufficient time (6-9 months) and an absence of pathogens, western hemlock will germinate at temperatures just above freezing. Western hemlock seeds remain viable only into the first growing season after seedfall [57]. Viability seems to vary between 36 and 55 percent with an average of about 46 percent [76]. Western hemlock seed appears to germinate well and seedlings grow well on almost all natural seedbeds whether rotten wood, undisturbed bed duff and litter, or bare mineral soil. The principal requirement for adequate development on any seedbed appears to be adequate moisture. For drier situations, mineral soils appear to be best for hemlock seedlings [76]. Seedling development: Most seedling mortality occurs in the first 2 years after germination [76]. Seedlings are very shade tolerant but are sensitive to heat, cold, drought and wind [56]. In British Columbia, the main cause of mortality appeared to be either drought or frost [76]. Initial growth is slow; 2-year-old seedlings are commonly less than 8 inches (20 cm) tall. Once established, seedlings in full light may have an average growth rate of 24 inches (60 cm) or more annually [57]. In inland regions, one study showed partial shade to be beneficial in reducing mortality caused by high temperatures and drought. Once seedlings are over 2 years old, survival appears to be very good [76]. Vegetative reproduction: Western hemlock will reproduce vegetatively by layering or cuttings. Seedlings that die back to the soil surface commonly sprout from buds near the root collar. Sprouting does not occur from the roots or the base of larger saplings. Western hemlock grafts readily. Growth of grafted material is better than that of rooted material [57]. SITE CHARACTERISTICS : Western hemlock thrives in humid areas of the Pacific Coast and northern Rocky Mountains. Growth is best in mild, humid climates where frequent fog and precipitation occur during the growing season. The best stands occur in the humid coastal regions. In subhumid regions with relatively dry growing seasons, western hemlock is confined primarily to northerly aspects, moist stream bottoms, or seepage sites [10,57,59]. In Alaska, western hemlock attains its largest size on moist flats and low slopes [72]. Precipitation and temperature: In the coastal range, western hemlock occurs on sites with a mean annual precipitation of less than 15 inches (380 mm) in Alaska to at least 262 inches (6,650 mm) in British Columbia. In the Rocky Mountains it occurs on sites with mean annual precipitation ranging from 22 inches (560 mm) to at least 68 inches (1,730 mm). Mean annual temperatures where western hemlock commonly occurs range from 32.5 to 52.3 degrees Fahrenheit (0.3-11.3 deg C) on the coast and 36 to 46.8 degrees Fahrenheit (2.2-8.2 deg C) in the Rocky Mountains. The frost-free period within the coastal range of western hemlock averages less than 100 to more than 280 days. In the Rocky Mountains the frost-free period is 100 to 150 days [57]. Elevation: The elevational range of western hemlock is from sea level to 7,000 feet (2,130 m). On the coast, western hemlock develops best between sea level and 2,000 feet (610 m); in the Rocky Mountains, it develops best between 1,600 and 4,200 feet (490-1,280 m) [57]. Soils: Western hemlock grows on soils derived from all bedrock types (except serpentines) within its range [57]. It grows well on sedimentary, metamorphic, and igneous materials. Western hemlock is found on most soil textures. Height growth, however, decreases with an increase in clay content or soil bulk density. This is attributed to inadequate soil aeration or the inability of roots to penetrate compact soils. Western hemlock does not do well on sites where the water table is less than 6 inches (15 cm) below the soil surface. The pH under stands containing western hemlock ranges from less than 3.0 to nearly 6.0 in the organic horizons. The pH in the surface mineral horizons ranges from 4.0 to 6.3 and that of the C horizons from 4.8 to 6.2. The optimum range of pH for seedlings is 4.5 to 5.0. Western hemlock is highly productive on soils with a high range of available nutrients. The productivity of western hemlock increases as soil nitrogen increases [57]. In the Coast Range, western hemlock is commonly associated with the following shrub species: vine maple (Acer circinatum), dwarf Oregongrape (Mahonia nervosa), Pacific rhododendron (Rhododendron macrophyllum), stink currant (Ribes bracteosum), salmonberry, trailing blackberry (R. ursinus), Pacific red elder (Sambucus callicarpa), Alaska blueberry (Vaccinium alaskaense), big huckleberry (V. membranaceum), oval-leaf huckleberry (V. ovalifolium), evergreen huckleberry (V. ovatum), and red huckleberry (V. parvifolium) [12,31,32,57]. In the Rocky Mountains, western hemlock is commonly associated with the following shrub species: Oregon grape (Mahonia repens), russet buffaloberry (Shepherdia canadensis), birchleaf spirea (Spiraea betulifolia), dwarf blueberry (Vaccinium caespitosum), globe huckleberry (V. globulare), and grouse whortleberry (V. scoparium) [55,57,59,69,73]. Common shrub associates of both coastal and Rocky Mountain regions are as follows: Sitka alder (Alnus sinuata), snowbush ceanothus (Ceonothus velutinus), oceanspray (Holodiscus discolor), rustyleaf mensziesia (Menziesia ferruginea), devilsclub, Pacific ninebark (Physocarpus capitatus), prickly currant (Ribes lacustre), thimbleberry, and common snowberry (Symphoricarpos albus) [57]. Common herb associates with western hemlock include maidenhair fern (Adiantum pedatum), ladyfern (Athyrium filix-femina), deerfern (Blechnum spicant), mountain woodfern (Dryopteris austriaca), oakfern (Gymnocarpium dryopteris), swordfern (Polystichum munitum), bracken fern (Pteridium aquilinum), vanillaleaf (Achlys triphylla), wild ginger (Asarum caudatum), princes-pine (Chimaphila umbellata), queenscup beadlily (Clintonia unifora), cleavers bedstraw (Galium aparine), sweetscented bedstraw (G. triflorum), twinflower (Linnaea borealis), one-sided pyrola (Pyrola secunda), feather solomonplume (Smilacina racemosa), white trillium (Trillium ovatum), roundleaf violet (Viola orbiculata), and beargrass (Xerophyllum tenax) [55,57,59,69,73]. SUCCESSIONAL STATUS : Western hemlock is very shade tolerant. Only Pacific yew (Taxus brevifolia) and Pacific silver fir are considered to have equal or greater tolerance of shade than western hemlock. Western hemlock is generally considered a climax species either alone or in combination with its shade-tolerant associates, but it can be found in all stages of succession [57]. It is an aggressive pioneer because of its quick growth in full overhead light and its ability to survive on a wide variety of seedbed conditions [29,57]. It also invades seral stages of forest succession after a forest canopy has formed [35]. If several centuries pass without a major disturbance, a climax of self-perpetuating, essentially pure western hemlock can result [10]. On drier upland slopes in Glacier National Park, western hemlock often achieves dominance over western redcedar. Western hemlock rarely replaces western redcedar entirely [35]. In Idaho, western white pine (Pinus monticola) stands are slowly replaced by a western hemlock-western redcedar climax [52]. SEASONAL DEVELOPMENT : The reproductive cycle of western hemlock occurs over 15 to 16 months from the time of cone initiation in early summer, until seeds are shed in the fall of the following year. Fertilization and seed development occur in the second year. Phenology varies between coastal and interior regions [56,57,76]. Trees in the interior region or at higher elevations begin development later in the spring and complete development earlier in the fall than do trees growing in coastal and low-elevation regions [56]. At low-elevation coastal British Columbia locations, pollination commonly occurs in early to mid-April, whereas in the interior of British Columbia, it may occur from May until mid-June. Records from western Washington and Oregon show that pollination may occur from mid-April until late May [56]. Fertilization occurs in coastal western hemlock about mid-May. The time from pollination to seed release ranges from 120 to 160 days in western hemlock. It can vary according to weather and temperature during cone maturation. Dry, warm weather in late summer may cause more rapid drying and earlier opening of cones with consequently, earlier seed release. Wet, cool weather may delay cone opening and seed release. Most seeds are shed in the fall when cones first open [50,56,76]. Cones may close in wet weather and reopen more fully with subsequent dry weather. As a result, seeds may be shed throughout the winter or even during the next spring. Mature cones often persist on the tree throughout the second year but contain few viable seeds [56,57].

FIRE ECOLOGY

SPECIES: Tsuga heterophylla
FIRE ECOLOGY OR ADAPTATIONS : Western hemlock has a low degree of fire resistance [20,58]. It has thin bark, shallow roots, highly flammable foliage, and a low-branching habit which make it very susceptible to fire. Western hemlock tends to form dense stands and its branches are often lichen covered, which further increases its susceptibility to fire damage [15,29,57]. The frequency of fire in western hemlock stands tends to be low because it commonly occupies cool mesic habitats which offer protection from all but the most severe wildfire [22,64]. In western hemlock forests of the Pacific Northwest, the fire regime is generally from 150 to 400 or more years [58]. At Desolation Peak, Washington, western hemlock forest types had a mean fire interval of 108 to 137 years [3]. In the western hemlock/Pachistima habitat type described by Daubenmire and Daubenmire [21], the mean fire interval is 50 to 150 years, and fire intensity in these stands is quite variable [9]. In the Bitterroot Mountains, western hemlock stands are more likely to be destroyed by stand-replacing fires because they often occupy steep montane slopes which favor more intense burning [8]. POSTFIRE REGENERATION STRATEGY : Tree without adventitious-bud root crown Secondary colonizer - off-site seed

FIRE EFFECTS

SPECIES: Tsuga heterophylla
IMMEDIATE FIRE EFFECT ON PLANT : Western hemlock is commonly killed by fire. High-severity fires often destroy all western hemlock [24]. After a severe crown fire at Olympic Mountain, Washington, overstory western hemlock suffered 91 percent mortality [4]. Even light ground fires are damaging because the shallow roots are scorched [57]. Postfire mortality of western hemlock is common due to fungal infection of fire wounds [29]. Most western hemlock seedlings are killed by broadcast burning [27,64]. DISCUSSION AND QUALIFICATION OF FIRE EFFECT : NO-ENTRY PLANT RESPONSE TO FIRE : Burning may or may not benefit natural regeneration of western hemlock. The response of seedlings to burning varies according to aspect, slope, latitude, climate, etc. After broadcast burning in coastal hemlock zones, more seedlings were found in burned areas than in unburned areas due to elimination of brush competition and reduction of dense patches of slash [76]. On Vancouver Island after the third growing season, burned seedbeds had 58 percent more seedlings with better distribution than unburned seedbeds [57]. However, on a site near Vancouver, British Columbia, due to sunscald, all new germinants on burned humus were dead by mid-July [76]. DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : NO-ENTRY FIRE MANAGEMENT CONSIDERATIONS : Fire danger increases with the increasing volume of logging residue. Logging old-growth stands or western hemlock can leave huge volumes of residue compared with logging young stands, which leave little residue. Burning cleans up the area and facilitates planting. Therefore burning is often favored by land managers who intend to plant Douglas-fir to obtain a mixture of Douglas-fir and western hemlock. The general trend in western hemlock management, however, is away from broadcast burning except where a huge accumulation of residues constitutes a fire hazard [64]. Burning in western hemlock stands is a valuable treatment when seedlings and saplings are infected with dwarf mistletoe and need to be destroyed. Fire is helpful in rehabilitation of brushy areas; burning brush to ground level facilitates planting and favors planted seedlings in keeping ahead of the brush sprouts [64]. Fire spreads more slowly in western hemlock slash than in western redcedar slash. Western hemlock slash drops its foliage. The slash of western hemlock is less flammable when chipped [52]. Slash from western hemlock/western redcedar/Alaska-cedar forests produce greater nutrient losses to the atmosphere when the slash composition has a greater proportion of Alaska-cedar and western redcedar. One can expect smaller nutrient losses when western hemlock makes up the majority of the slash [28]. For further details on burning of western hemlock slash, refer to the Fire Case Study in the Alaska-cedar Fire Effects Information System Species Review.

REFERENCES

SPECIES: Tsuga heterophylla
REFERENCES : 1. A. D. Revill Associates. 1978. Ecological effects of fire and its management in Canada's national parks: a synthesis of the literature. Volumes One and Two, literature review and annotated bibliography. Ottawa, ON: Parks Canada, National Parks Branch, Natural Resources Division. 345 p. [3416] 2. Agee, James K. 1988. Successional dynamics in forest riparian zones. In: Raedeke, Kenneth J., ed. Streamside management: riparian wildlife and forestry interactions. Institute of Forest Resources Contribution No. 58. Seattle, WA: University of Washington, College of Forest Resources: 31-43. [7657] 3. Agee, James K.; Finney, Mark; DeGouvenain, Roland. 1990. Forest fire history of Desolation Peak, Washington. Canadian Journal of Forest Research. 20: 350-356. [11035] 4. Agee, James K.; Huff, Mark H. 1980. First year ecological effects of the Hoh Fire, Olympic Mountains, Washington. In: Martin, Robert E.; Edmonds, Donald A.; Harrington, James B.; [and others], eds. 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