DecAID Wildlife Habitat Types are based on Wildlife Habitats from Chapter 2 in Wildlife-Habitat Relationships in Oregon and Washington (Chappell et al. 2001) (WHR). Click on the links below to see complete descriptions of the WHR Wildlife Habitats.
#1 WESTSIDE LOWLANDS CONIFER-HARDWOOD FOREST
Summary: Lowland to low montane forests on upland sites in most of western Washington, and in the Coast Range, the western slopes of the Cascades, and around the margins of the Willamette Valley in Oregon. Corresponds with the western hemlock and Sitka spruce zones, exclusive of very dry sites. Dominated by western hemlock, western redcedar, Douglas-fir, Sitka spruce, red alder, Port-Orford cedar, bigleaf maple, and/or shore pine.
Habitat Description
Structure: This habitat is a forest dominated by evergreen conifers or deciduous broadleaf trees or both. Late seral stands typically have an abundance of large (giant-sized, >50 m tall) coniferous trees, a multi-layered canopy structure, large snags, and many large logs. Early seral stands typically have smaller trees, single-storied canopies, and may be dominated by conifers, broadleaf trees or both. Coarse woody debris is abundant in early seral stands after natural disturbances but is much less so after clearcutting. Forest understories are very diverse in structure: evergreen shrubs tend to dominate on more nutrient-poor or drier sites; deciduous shrubs, ferns, and/or forbs tend to dominate on relatively nutrient-rich or moist sites. Shrubs may be low (.5 m tall), medium-tall (1-2 m), or tall (2-4 m). Almost all structural stages are represented to some degree in the successional sequence within this broad habitat category.
Composition: Western hemlock (Tsuga heterophylla) is the most characteristic species and is usually at least present. Most stands are dominated by one or more of the following: Douglas fir (Pseudotsuga menziesii), western hemlock, western redcedar (Thuja plicata), sitka spruce (Picea sitchensis), red alder (Alnus rubra), or bigleaf maple (Acer macrophyllum). Trees of local importance include shore pine (Pinus contorta var. contorta) (on dunes), Port-orford cedar (Chamaecyparis lawsoniana), grand fir (Abies grandis), and paper birch (Betula papyrifera). Western white pine (Pinus monticola) is frequent but subordinate in importance through much of this habitat. Pacific silver fir (Abies amabilis) is largely absent except on the wettest low-elevation portion of the western Olympic Peninsula where it is common and sometimes co-dominant. Common small subcanopy trees are cascara buckthorn (Rhamnus purshiana) in more moist climates and Pacific yew (Taxus brevifolia) in somewhat drier climates or sites.
Dominant or co-dominant understory shrub species of more than local importance include salal (Gaultheria shallon), dwarf Oregongrape (Mahonia nervosa), vine maple (Acer circinatum), Pacific rhododendron (Rhododendron macrophyllum), salmonberry (Rubus spectabilis), trailing blackberry (Rubus ursinus), red elderberry (Sambucus racemosa), fools huckleberry (Menziesia ferruginea), oval-leaf huckleberry (Vaccinium ovalifolium), evergreen huckleberry (V. ovatum), and red huckleberry (V. parviflorum). Salal and rhododendron are particularly associated with low nutrient or relatively dry sites.
Swordfern (Polystichum munitum) is the most common herbaceous species and is often dominant on nitrogen-rich or moist sites. Other forbs and ferns that frequently dominate the understory are Oregon oxalis (Oxalis oregana), deerfern (Blechnum spicant), bracken (Pteridium aquilinum), vanillaleaf (Achlys triphylla), twinflower (Linnaea borealis), false lily-of-the-valley (Maianthemum dilatatum), Siberian springbeauty (Claytonia siberica), foamflower (Tiarella trifoliata), inside-out flower (Vancouveria hexandra), common whipplea (Whipplea modesta), and beargrass (Xerophyllum tenax).
Other Classifications and Key References
This habitat includes most of the forests and their successional seres within the Tsuga heterophylla and Picea sitchensis zones (Franklin and Dyrness 1973). Also referred to as Douglas-fir-western hemlock and Sitka spruce-western hemlock forests (Franklin 1988); spruce-cedar-hemlock forest (Picea-Thuja-Tsuga) # 1 and Cedar-hemlock-Douglas fir forest (Thuja-Tsuga-Pseudotsuga) # 2 (Kuchler 1964); Red Alder 221 in part, Sitka Spruce 223, Western Hemlock 224 in part, Sitka Spruce-Western Hemlock 225, Western Redcedar-Western Hemlock 227 in part, Western Redcedar 228 in part, Pacific Douglas-fir 229 in part, Douglas-fir-Western Hemlock 230, and Port-Orford-Cedar-Douglas-fir 231 in part; Oregon Gap vegetation types 501, 510, 512. The Washington Gap Vegetation map includes this vegetation as conifer forest, mixed hardwood/conifer forest, and hardwood forest in the sitka spruce, western hemlock, Olympic Douglas-fir, Puget Sound Douglas-fir, Cowlitz River and Willamette Valley zones. Important references that describe this type include Atzet and McCrimmon (1990), Bigley and Hull (1995), Chappell et al. (in prep.), del Moral and Long (1977), Franklin et al. (1988), Hemstrom and Logan (1986), Henderson et al. (1989, 1992), Halverson et al. (1986), Hemstrom et al. (1987), and Topik et al. (1986).
Habitat Dynamics
Natural Disturbance Regime: Fire is the major natural disturbance in all but the wettest climatic zone (sitka spruce zone), where wind becomes the major source of natural disturbance. Natural fire-return intervals generally range from about 100 years or less in the driest areas to several hundred years (Henderson et al. 1989, Morrison and Swanson 1990, Agee 1993). Mean fire-return interval for the western hemlock zone as a whole is probably about 250 years, but the variation around this figure is great. Major natural fires are associated with occasional extreme weather conditions (Agee 1993). Fires are typically high-severity, with few trees surviving. However, low- and moderate-severity fires that leave partial to complete live canopies are not uncommon, especially in drier climatic areas. Occasional major wind storms hit outer coastal forests most intensely, where fires are rare. Severity of wind disturbance varies greatly, with minor events being extremely frequent and major events occurring once every few decades. Bark beetles and fungi are significant causes of mortality that typically operate on a small-scale. Landslides are another type of natural disturbance that occur naturally in some areas. On forested coastal dunes, wind-blown sand becomes an important disturbance that can set succession back and revert this habitat to Coastal Dunes habitat.
Succession and Stand Dynamics: After a severe fire or blowdown, a typical stand will be briefly occupied by annual and perennial ruderal forbs and grasses, as well as pre-disturbance understory shrubs and herbs that resprout (Halpern 1989). Herbaceous species generally give way to dominance by shrubs or a mixture of shrubs and young trees within a very few years. If shrubs are very dense and trees did not establish early, the site may remain as a shrubland for an indeterminate period. Early seral tree species can be any of the potential dominants for the habitat, depending on environment, type of disturbance, and seed source. All of these species except the short-lived red alder are capable of persisting for at least a few hundred years. Douglas fir is the most common dominant after fire, but is uncommon in the wettest environmental zones. It is also the most fire-resistant of the trees on this habitat and survives moderate-severity fires well. After the tree canopy closes, the understory may become very sparse for a time corresponding with the stem-exclusion stage (Oliver 1981). Eventually tree density will decrease and the understory will begin to flourish again, typically at about stand age 60-100 years. As trees grow larger and a new generation of shade-tolerant understory trees (usually western hemlock, less commonly western redcedar) grows up, a multi-layered canopy will be gradually developed and be well expressed by stand age 200-400 years (Franklin et al. 1981). Another fire is likely to return prior to the loss of shade-intolerant Douglas fir from the canopy at stand age 800-1000 years, unless the stand is in the wet maritime zone. Throughout this habitat, western hemlock tends to increase in importance as stand development proceeds. Coarse woody debris is most abundant in late-seral stands and for about 30 years after disturbance and least abundant at about stand age 80-120 years (Spies and Franklin ).
Franklin, Jerry F.; Cromack, Kermit, Jr.; Denison, William; [and others]. 1981. Ecological characteristics of old-growth Douglas-fir forests. Gen. Tech. Rep. PNW-118. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 48 p.
Effects of Management and Anthropongenic Impacts: Red alder is more successful after typical logging disturbance than after fire alone on moist, nutrient-rich sites, perhaps because of the species' ability to establish abundantly on scarified soils (Haeussler and Coates 1986). Alder is much more common as a dominance type now than prior to large-scale logging activities (Franklin 1981). Alder grows more quickly in height early in succession than the conifers, thereby prompting many forest managers to apply herbicides for alder control. If alder is allowed to grow up when it does dominate early in succession, it will decline in importance after about stand age 70 years and die-out completely by age 100. Often there are suppressed conifers in the subcanopy that potentially can respond to the death of the alder canopy. However, salmonberry sometimes forms a dense shrub layer under the alder that excludes conifer regeneration (Franklin and Dyrness 1973). Salmonberry responds positively to soil disturbance, such as that associated with logging (Barber 1976). Bigleaf maple sprouts readily after logging and is therefore well adapted to increase after disturbance as well. Clearcut logging and plantation forestry have also resulted in less diverse tree canopies focused mainly on Douglas fir, reductions in coarse woody debris over natural levels, a shortened stand initiation phase, and succession truncated well before late-seral characteristics are expressed.
Barber, William Hollis, Jr. 1976. An autecological study of salmonberry (Rubus spectabilis, Pursh) in western Washington. Seattle, WA: University of Washington. 154 p. Thesis.
Haeussler, S.; Coates, D. 1986. Autecological characteristics of selected species that compete with conifers in British Columbia: a literature review. Land Management Report No. 33. Victoria, BC: Ministry of Forests, Information Services Branch. 180 p.
Franklin, Jerry F. 1981. Vegetation and habitats. In: Maser, Chris; Mate, Bruce R.; Franklin, Jerry F.; Dyrness, C. T., compilers. Natural history of Oregon Coast mammals. Gen. Tech. Rep. PNW-133. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 17-34.
Landscape Setting
This is the most extensive habitat in the lowlands on the westside, except in southwest Oregon, and forms the matrix within which other habitats occur as patches, especially Westside Riparian - Wetlands and less commonly Herbaceous Wetlands or Open Water. It also occurs adjacent to or in a mosaic with Urban or Agriculture habitats. In the driest areas, it occurs adjacent to or in a mosaic with Westside Oak and Dry Douglas-fir Forest and Woodlands. Bordering this habitat at upper elevations is Montane Mixed Conifer Forest. In Southwest Oregon, it may border Southwest Oregon Mixed Conifer - Hardwood Forest. The primary land use for this habitat is forestry. On the outer coast, it sometimes occurs adjacent to or in a mosaic with Coastal Dunes.
Physical Setting
Climate is relatively mild and moist to wet. Mean annual precipitation is mostly 35-100 inches, but can be more or less locally. Snowfall ranges from rare to regular but transitory. Summers are relatively dry. Summer fog is a major factor on the outer coast in the sitka spruce zone. Elevation ranges from sealevel to a maximum of about 2000 feet in much of northern Washington and 3500 feet in central Oregon. Soils and geology are extremely diverse. Topography ranges from relatively flat glacial till plains to steep mountainous terrain.
Geographic Distribution
Occurs throughout low elevation western Washington, except on extremely dry or wet sites. In Oregon occurs on the western slopes of the Cascades, around the margins of the Willamette Valley, in the Coast Range, and along the outer coast. Global distribution extends from Southeast Alaska south to southwestern Oregon.
Sitka spruce is found as a major species only in the outer coastal area at the lowest elevations where summer fog is a significant factor. Bigleaf maple is most abundant in the Puget Lowland, around the Willamette Valley, and in the central Oregon Cascades, but occurs elsewhere also. Douglas fir is absent to uncommon as a native species in the very wet maritime outer coastal area of Washington, including the coastal plain on the west side of the Olympic Peninsula. However, it has been extensively planted in that area. Port-Orford cedar occurs only in southern Oregon. Paper birch occurs as a co-dominant only in Whatcom County, Wash. Grand fir occurs as an occasional co-dominant only in the Puget Lowland and Willamette Valley. Pacific silver fir occurs commonly only on the coastal plain on the western Olympic Peninsula, primarily in Jefferson Co.
Status and Trends
Extremely large areas of this habitat remain. Some loss has occurred, primarily to development in the Puget Lowland. Condition of what remains has been much degraded by industrial forest practices at both the stand and landscape scale. The majority of the habitat is probably now in Douglas-fir plantations. Only a fraction of the original old-growth remains, most of that in National Forests in the Cascade and Olympic Mountains. Areal extent continues to be reduced gradually, especially in the Puget Lowland. An increase in alternative silviculture practices may be improving structural and species diversity in some areas. However, intensive logging of natural-origin mature and young stands, and even small areas of old-growth, continues. Of the 62 plant associations listed in the National Vegetation Classification, 17 are globally threatened or endangered.
#2 WESTSIDE OAK AND DRY DOUGLAS-FIR FOREST AND WOODLANDS
Summary: This is a forest or woodland located mostly at low elevations, primarily in the Puget Lowland, and the valleys and surrounding foothills of the Willamette, Rogue, and Umpqua Rivers. It is dominated by Douglas fir, Oregon white oak, Pacific madrone, and/or California black oak. For Douglas-fir-dominated forests, it only includes those outside of southwestern Oregon that are located on topoedaphically dry sites where western hemlock and western redcedar are largely absent, mainly in the San Juan Islands and around southern Puget Sound. In southwest Oregon, only oak-dominated communities are included here and dry conifer forests or conifer-madrone are considered are part of Southwest Oregon Mixed Conifer - Hardwood Forest.
Habitat Description
Structure: This is a forest or woodland dominated by evergreen conifers, deciduous broadleaf trees, evergreen broadleaf trees, or some mixture of conifers and broadleaf trees. Canopy structure varies from single-storied to multi-storied. Large conifers, when present, are typically emergent above broadleaf trees in mixed canopy stands . Large snags and logs are less abundant than in other westside forest habitats, but can be prominent, especially in unlogged old stands. Understories vary in structure: grasses, shrubs, ferns or some combination will typically dominate. Deciduous broadleaf shrubs are perhaps most typical as understory dominants in the existing landscape. Early successional stand structure varies depending on understory species present and if inititated following logging or fire.
Composition: The canopy is typically dominated by one or more of the following species: Douglas-fir (Pseudotsuga menziesii), Oregon white oak (Quercus garryana), Pacific madrone (Arbutus menziesii), lodgepole pine (Pinus contorta var. contorta), or California black oak (Quercus kelloggii). Grand fir (Abies grandis) is sometimes co-dominant with Douglas-fir in the northern Puget Lowland or in the Willamette Valley. Oregon ash (Fraxinus latifolia) is occasionally co-dominant with white oak in riparian oak stands. Several other tree species may be present, but western hemlock (Tsuga heterophylla) and western redcedar (Thuja plicata) are generally incapable of regenerating successfully due to dry conditions. This lack of very shade-tolerant tree regeneration, along with understory indicators like tall Oregongrape (Mahonia aquifolium), common snowberry (Symphoricarpos albus), serviceberry (Amelanchier alnifolia), and blue wildrye (Elymus glaucus), helps distinguish dry Douglas-fir forests from mid-seral Douglas-fir stands on more mesic sites, which are part of the Westside Lowlands Conifer - Hardwood Forest. Tree regeneration, when present, is typically Douglas-fir, less commonly grand fir. Sweet cherry (Prunus avium) has invaded and now dominates a subcanopy layer in many oak forests of the Willamette Valley.
Deciduous shrubs that commonly dominate or co-dominate the understory are oceanspray (Holodiscus discolor), common snowberry, baldhip rose (Rosa gymnocarpa), poison-oak (Toxicodendron diversilobum), serviceberry, hazelnut (Corylus cornuta), trailing blackberry (Rubus ursinus), indian plum (Oemleria cerasiformis), creeping snowberry (Symphoricarpos mollis), wedgeleaf ceanothus (Ceanothus cuneatus), and oval-leaf viburnum (Viburnum ellipticum). Evergreen shrubs that sometimes are dominant where conifers are important in the canopy include salal (Gaultheria shallon), dwarf Oregongrape (Mahonia nervosa), Pacific rhododendron (Rhododendron macrophyllum), hairy honeysuckle (Lonicera hispidula), evergreen huckleberry (Vaccinium ovatum), and Piper's Oregongrape (Mahonia piperiana).
Native graminoids that commonly dominate or co-dominate the understory are western fescue (Festuca occidentalis), Alaska oniongrass (Melica subulata), blue wildrye, and long-stolon sedge (Carex inops). Swordfern (Polystichum munitum) or, less commonly, bracken (Pteridium aquilinum) sometimes co-dominate the understory, especially on sites that formerly supported grasslands and savannas. Forbs, many of which are characteristic of these dry sites, are often abundant and diverse, but typically do not dominate. Common camas (Camassia quamash) or cleavers (Galium aparine) are occasionally co-dominant with graminoids.
Other Classifications and Key References
This habitat has been described as oak groves and dry site Douglas fir forest in the Tsuga heterophylla zone of western Washington and northwestern Oregon as well as oak woodland in the interior valleys of western Oregon (Franklin and Dyrness 1973). Also referred to as Oregon oakwoods #22 and a minor part of Cedar-hemlock-Douglas-fir forest #2 (Kuchler 1964); Oregon white oak #233 and part of Pacific Douglas-fir #229 (SAF 1954); Oregon Gap vegetation types 475, 476, 505, and 506; and parts of hardwood forest, mixed hardwod/conifer forest, and conifer forest in the Woodland/Prairie Mosiac (most of forest in this zone is this habitat), Puget Sound Douglas-fir, and, to a minor degree, Cowlitz River, and Willamette Valley zones of the Washington Gap project.
Other important references describing this habitat include Fonda and Bernardi (1976), Chappell and Crawford (1997), Chappell et al. (in prep.), Henderson et al. (1989), Topik et al. (1986), Atzet and McCrimmon (1990), Hemstrom et al. (1987), Riegel et al. (1992), and Thilenius (1968).
Habitat Dynamics
Natural Disturbance Regime: Fire is the major natural disturbance in this habitat. In pre-settlement times, fire frequency in this habitat probably ranged from very frequent (every few years) to moderately frequent (up to once every 50-100 years), corresponding to Agee's (1993) low-severity and moderate-severity fire regimes. Fire frequency has been much lower in the last 100 years. Windstorms are an occasional disturbance, most important in the San Juan Islands and vicinity. Understories are sometimes browsed heavily by deer in the San Juan Islands, thus preventing dominance by deciduous shrubs and favoring grasses and forbs.
Succession and Stand Dynamics: Many of these forests and woodlands were formerly either grasslands or savannas that probably burned very frequently, thus preventing dominance by trees (Chappell and Crawford 1997, Crawford and Hall 1997). Some portions of this habitat in the central Puget Lowlands may have formerly been dominated by shrubs (salal, beaked hazel, evergreen huckleberry, hairy manzanita) for lengthy periods, probably also due to a particular combination of fire frequency and intensity. Other areas were woodlands to semi-open forests that burned moderately frequently, as evidenced by the existence of relictual stands of old-growth Douglas-fir. The dominant trees in this habitat establish most abundantly after fire. Moderate-severity fires often kill many trees and leave many alive, creating opportunities for establishment of new cohorts of trees and increasing structural complexity (Agee 1993). The oaks and madrone resprout after fire if they are top-killed. Given time without fire, most oak-dominated stands will eventually convert to Douglas-fir forests (Agee 1993). Animal dissemination of acorns may be important in dispersal of oaks. Lodgepole pine, where present, is an early-seral upper canopy species that grows quickly and dies out after about 100 years, yielding a mature Douglas-fir stand unless another fire intervenes prior to the death of the pine.
Effects of Management and Anthropongenic Impacts: Clearcut or similar logging reduces canopy structural complexity and abundance of large woody debris. Dry Douglas-fir stands are well-suited to alternative silvicultural practices, such as uneven-aged management or maintaning two-storied stands. Oaks and madrone will typically resprout after logging and thus can increase in importance relative to conifers in mixed canopy stands. Selective logging of Douglas-fir in oak stands can prevent long-term loss of oak dominance. With fire exclusion, stands have probably increased in tree density and grassy understories have been replaced by deciduous shrubs (Chappell and Crawford 1997). Moderate to heavy grazing or other significant ground disturbance, especially in grassy understories leads to increases in non-native invader species, many of which are now abundant in stands with grassy or formerly grassy understories. Scots broom (Cytisus scoparius) is an exotic shrub particularly invasive and persistent in oak woodlands. Exotic herbaceous invaders include colonial bentgrass (Agrostis capillaris), common velvetgrass (Holcus lanatus), Kentucky bluegrass (Poa pratensis), tall oatgrass (Arrhenatherum elatius), rigid brome (Bromus rigidus), orchardgrass (Dactylis glomerata), hedgehog dogtail (Cynosurus echinatus), tall fescue (Festuca arundinacea), and common St. Johns wort (Hypericum perforatum).
Landscape Setting
This habitat is found in a mosaic with, or adjacent to, Westside Grasslands, Westside Lowlands Conifer - Hardwood Forest, Westside Riparian - Wetlands, Urban, and Agriculture. Inclusions of Open Water or Herbaceous Wetlands may occur. In the Puget Lowland, this habitat is sometimes found adjacent to the Puget Sound. Landuse of this habitat includes forestry (generally small scale), livestock grazing, and low-density rural residential.
Physical Setting
This habitat occupies either very dry sites or occurs in very dry climatic areas for the westside. The climate has an annual mean precipitation ranging from from 17 to 60 inches, occasionally higher. Elevation ranges from sea level up to a maximum of about 3500 feet in the Olympic Mountains, but is mainly below 1500 feet. Topography ranges from nearly flat to very steep slopes. If on a slope, aspect tends to be southern or western. Soils on dry sites are typically shallow over bedrock, very stony, or very deep and excessively drained. Willamette Valley soils are typically much older and have more moderate drainage and water availability. Parent materials include various types of bedrock, shallow or very coarse glacial till, alluvium, and glacial outwash.
Geographic Distribution
Primarily in the Willamette Valley, Puget Lowlands, and Klamath Mountains ecoregions. Most common in Puget Lowlands in and around the San Juan Islands and in Thurston, Pierce, and Mason counties. In southwestern Oregon, mainly in the valleys of the Rogue and Umpqua rivers. Minor occurrences also in the northeast Olympic Mountains and western Cascades.
California black oak is a co-dominant only in southwestern Oregon. Lodgepole pine is only important in the Puget Lowland, mainly in San Juan and Mason counties. Dry Douglas-fir forests (without oak or madrone to speak of) are mainly in the Puget Lowland and rarely in the Olympic Mountains, west Cascades, and Willamette Valley. Pacific madrone and Douglas-fir -Pacific madrone stands without oak are limited to the Puget Lowland and the southern Willamette Valley foothills. Mixed oak-madrone stands are primarily in Oregon, especially southwestern Oregon.
Status and Trends
This is a habitat that occupies small areas over much of its distribution, except in three geographic areas where it is most common: 1) along fringes and foothills of the Willamette, Rogue, and Umpqua valleys, 2) in the San Juan Islands, and 3) in the southern Puget Sound prairie landscape in Pierce, Thurston, and Mason counties. This habitat has had both gains in area and losses since pre-settlement times, with the losses probably being greater than the gains. With the cessation of regular burning 100-130 years ago, many grasslands and savannas were invaded by a greater density of trees and thus became this habitat. Conversely, large areas of this habitat have been converted to development or agriculture, due to its location in the most urbanized ecoregions. Most of what remains has been considerably degraded by invasion of exotic species or by logging and consequent loss of structural diversity. This habitat is currently declining in extent and in condition. Ongoing threats include residential development, increase and spread of exotic species, and fire suppression effects (the latter especially in oak-dominated stands). Thirteen of 27 plant associations listed in the National Vegetation Classification are considered threatened or endangered globally.
#3 SOUTHWEST OREGON MIXED CONIFER-HARDWOOD FOREST
Summary: Upland forest and woodland habitat, typically conifer or mixed conifer - hardwood, found at low and middle elevations in the Klamath Mountains ecoregion and the adjacent southern Cascade Mountains in southwestern Oregon. Douglas-fir, white fir, Jeffrey pine, incense cedar, or ponderosa pine are typically dominant or co-dominant. Other trees of importance include tanoak, Pacific madrone, Port-Orford cedar, and Oregon white oak. Early-seral shrublands part of this habitat are distinguished from Ceanothus - Manzanita Shrublands habitat by their differing species composition, especially the predominance of Ceanothus velutinus.
Habitat Description
Structure: This forest or woodland habitat is dominated by conifer trees. In some areas, a well-developed subcanopy layer of smaller evergreen broadleaf trees is present. Occasionally, deciduous broadleaf trees are co-dominant. Complex multi-layered canopies are typical, though single-layered canopies also occur especially in areas of intensive forest management. Dominant canopy trees vary from 60 feet to over 300 feet tall at maturity. Large woody debris in the form of snags and logs is typically common, though quite variable. Understories are most often dominated by shrubs, but can be dominated by forbs, graminoids, or largely depauperate.
Composition: The tree canopy can be diverse. Dominant species include the ubiquitous Douglas-fir (Pseudotsuga menziesii). White fir (Abies concolor), incense cedar (Libocedrus decurrens), and sugar pine (Pinus lambertiana) are common in mixed stands except on the driest sites in the Cascades and central and eastern Siskiyous. White fir dominates moist, cool sites at higher elevations. Ponderosa pine (Pinus ponderosa) is found with the former species in mixed stands and also on the driest sites with Douglas-fir. Jeffrey pine (Pinus jeffreyi) and knobcone pine (P. attenuata) are limited primarily to serpentine bedrock. Port-Orford cedar (Chamaecyparis lawsoniana) dominates some more moist sites near the coast. Brewer's spruce (Picea breweri) is an uncommon dominant at high elevations in the Siskiyous. Coast redwood (Sequoia sempervirens) dominates some stands on the far southern Oregon coast. The broadleaf subcanopy is most prominent on the western sides of the Coast Range and Siskiyous, where tanoak (Lithocarpus densiflorus) is most abundant, with Pacific madrone (Arbutus menziesii), golden chinquapin (Castanopsis chrysophylla), or canyon live oak (Quercus chrysolepis) also sometimes dominating the subcanopy.
Dominant or co-dominant evergreen shrubs are diverse and include pinemat manzanita (Arctostaphylos nevadensis), greenleaf manzanita (A. patula), white-leaved manzanita (A. viscida), kinnikinnick (A. uva-ursi), Piper's barberry (Mahonia piperiana), dwarf Oregongrape (M. nervosa), tobacco brush (Ceanothus velutinus), mahala mat (C. prostratus), salal (Gaultheria shallon), deer oak (Quercus sadleriana), huckleberry oak (Q. vacciniifolia), snow bramble (Rubus nivalis), Pacific rhododenron (Rhododendron macrophyllum), and evergreen huckleberry (Vaccinium ovatum). Major deciduous shrubs are serviceberry (Amelanchier alnifolia), sticky currant (Ribes viscosissimum), oceanspray (Holodiscus discolor), creeping snowberry (Symphoricarpos mollis), baldhip rose (Rosa gymnocarpa), hazelnut (Corylus cornuta), Rocky Mountain maple (Acer glabrum), vine maple (A. circinatum), poison-oak (Toxidodendron diversiloba), big huckleberry (Vaccinium mumbranaceum), deer brush (Ceanothus integerrimus), and trailing blackberry (Rubus ursinus).
Graminoids that are most prominent are long-stolon sedge (Carex inops), Idaho fescue (Festuca idahoensis), and California fescue (F. californica). Forbs that are indicative of site conditions or dominate understories include common whipplea (Whipplea modesta), twinflower (Linnea borealis), sidebells wintergreen (Orthilia secunda), rattlesnake plantain (Goodyera oblongifolia), vanillaleaf (Achlys triphylla), beargrass (Xerophyllum tenax), and starry false solomons seal (Maianthemum stellatum).
Other Classifications and Key References
This habitat includes the conifer-dominated forests, and their successional seres, within the Interior Valley, Mixed-Conifer, Mixed-Evergreen, and Abies concolor zones of southwestern Oregon, plus Redwood forests in the Picea sitchensis Zone (Franklin and Dyrness 1973). Also referred to as Klamath Mountains mixed evergreen forests and Sierran-type mixed conifer forests (Franklin 1988); Pseudotsuga menziesii/hardwood forests and Abies concolor forests (Agee 1993); Mixed conifer forest # 5, Redwood forest #6, California mixed evergreen forest #29, and Montane chaparral #34 (Kuchler 1964). Oregon Gap vegetation types # 509, 508, 523, 502, 507. Other important references describing this habitat include Atzet and McCrimmon (1990), Atzet and Wheeler (1984), Hopkins (1979b), and Hemstrom et al. (1987).
Habitat Dynamics
Natural Disturbance Regime: Fire is the predominant natural disturbance. Fire regime varies depending on environmental conditions (Agee 1993). Drier, hotter sites within this area had a low-severity fire regime. Cooler and/or more moist sites typically had a moderate-severity fire regime. Pre-settlement mean fire return intervals vary from about 10 years or less to about 80 years (McNeil and Zobel 1980, Greenlee and Langenheim 1990, Agee 1993). Lightning ignitions are more frequent here than anywhere else in the region and Native Americans probably burned some areas intentionally (Agee 1993). Wind is a somewhat importance disturbance at higher elevations. Root rot fungi and insects are other important disturbances in some forests, mostly operating at small-scales compared with fire.
Greenlee, Jason M.; Langenheim, Jean H. 1990. Historic fire regimes and their relation to vegetation patterns in the Monterey Bay area of California. American Midland Naturalist. 124(2): 239-253. [15144]
Succession and Stand Dynamics: Evergreen broadleaf trees, when present, are top-killed by moderate-severity fires but resprout vigorously to dominate or co-dominate after most fires (Atzet and Wheeler 1982, McDonald and Tappeiner 1987). Conifers are at a relative disadvantage as regeneration, because of dependence on seedfall. Many conifers are able to survive moderate-severity fire well, including, in decreasing order of fire resistance, ponderosa pine, Jeffrey pine, Douglas-fir, sugar pine, and incense-cedar. These species are fairly well represented throughout the successional sequence, unless there have been two high-severity fires not far apart in time, in which case the subcanopy broadleaf species are likely to dominate (Agee 1993). Development of complex multi-layered canopies of conifers and broadleaf evergreens are typical under a moderate-severity fire regime.
McDonald, Philip M.; Tappeiner, John C., II. 1987. Silviculture, ecology, and management of tanoak in northern California. In: Plumb, Timothy R.; Pillsbury, Norman H., technical coordinators. Proceedings of the symposium on multiple-use management of California's hardwood resources; 1986 November 12-14; San Luis Obispo, CA. Gen. Tech. Rep. PSW-100. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station: 64-70. [1441]
Atzet, Thomas; Wheeler, David L. 1982. Historical and ecological perspectives on fire activity in the Klamath Geological Province of the Rogue River and Siskiyou National Forests. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Region. 16 p. [6252]
Where the hardwoods are absent and white fir is prominent, succession differs from that described above. Under a low-severity fire regime with frequent fires, white fir is relatively unimportant and fire-resistant conifers, especially Douglas-fir and ponderosa pine, dominate. White fir increases in the absence of fire (Parsons and DeBennedetti 1979). With a moderate-severity fire regime, i.e. less frequent fires, white fir can dominate or co-dominate, especially on cooler sites (Agee 1993). Small gaps created by moderate-severity fires, blowdown, or disease, afford opportunities for regeneration of less shade-tolerant tree species thus maintaing a diverse tree canopy for lenghty periods. Evergreen shrubs, especially tobacco brush, often dominate after high-severity fire and may persist as a dominance type for decades, especially if they are reburned (Franklin and Dyrness 1973, Conrad and Radosevich 1981). On the driest, hottest sites in this habitat white fir does not grow and tree regeneration is limited to Douglas-fir and ponderosa pine, with the former tending to increase in the absence of fire.
Parsons, David J.; DeBenedetti, Steven H. 1979. Impact of fire suppression an a mixed-conifer forest. Forest Ecology and Management. 2: 21-33. [7618]
Effects of Management and Anthropongenic Impacts: Clearcut logging where hardwoods are present favors post-disturbance dominance of tanoak or madrone (Radosevich et al. 1976). Control of this competing vegetation has been a major focus of timber management in this habitat. Fire control over the last 100 years has decreased fire frequencies and altered stand structure through increases in small tree density, especially where low-severity fire regimes were prevalent. White fir has increased dramatically on drier sites where it occurs, creating dense subcanopy thickets and increasing the risk of high-severity fire (Kilgore 1973, Agee 1993). Evergreen shrubs often dominate after clearcut logging and in some cases hinder the establishment of conifers (Laacke and Fiske 1983). Clearcut logging, as in other forest types, tends to decrease tree species diversity, coarse woody debris loads, and structural diversity. The exotic species white pine blister rust (Cronartium ribicola) and Phytophthora lateralis, a root rot disease, have had significant negative impacts on the abundance of, respectively, sugar pine and Port-Orford cedar.
Laacke, Robert J.; Fiske, John N. 1983. Red fir and white fir. In: Burns, Russell M., technical compiler. Silvicultural systems for the major forest types of the United States. Agric. Handb. No. 44. Washington, DC: U.S. Department of Agriculture, Forest Service: 41-43.
Landscape Setting
This habitat is typically bounded at its upper elevational limits by Montane Conifer Forest, and at its lower limits along the coast, by Westside Lowlands Conifer - Hardwood Forest. At lower elevations in the Rogue and Umpqua Valleys it can be found in a mosaic with Westside Oak and Dry Douglas-fir Forest and Woodland, Ceanothus-Manzanita Shrublands, Urban, and Agriculture. Small inclusions of Open Water, Herbaceous Wetlands, Westside Riparian - Wetlands, and Ceanothus-Manzanita Shrublands occur scattered throughout this habitat. The predominant land use is forestry. Low-density residential is prominent in the Rogue and Umpqua Valleys. Grazing occurs on some areas, especially at lower elevations.
Physical Setting
The climate varies from relatively dry and very warm to moderately moist and cool to slightly warm and very moist. Mean annual precipitation ranges from about 20 to about 140 inches. Snow is uncommon except at the highest elevations, where a winter snowpack occurs for a few months. Summers are dry. Elevation ranges from near sea level to 6000 feet maximum. Topography is mostly quite mountainous but also includes two fairly large valleys, and a corresponding variety of terrain. Soils are very diverse as is the bedrock geology. Serpentine bedrock is common in portions of the Siskiyou Mountains where it has a major effect on vegetation.
Geographic Distribution
This habitat occurs in southwestern Oregon, northwestern California, and the Sierra Nevada. In our region, it occurs in the Klamath Mountains, Cascades, Coast Range, and Eastern Cascade Slopes and Foothills ecoregions, but only in southern Oregon. Portions of Curry, Josephine, Jackson, Douglas, Lane, and Klamath counties are included. Jeffrey pine is dominant on serpentine parent materials in the Siskiyou Mountains. Douglas-fir/evergreen broadleaf communities, as well as Port-Orford cedar, occur primarily on the western side of the Siskiyous and in the southern Coast Range. Redwood occurs only in a very small area near the coast in far southern Oregon. White fir is common in the southern Cascades and the eastern and central Siskiyous.
Status and Trends
This habitat covers most of southwestern Oregon and has declined little in areal extent. Condition of many communities has been degraded by forestry practices or fire suppression. The low-elevation, driest of these communities have been altered by grazing and invasion of exotic species. Port-Orford cedar has been especially hard hit by logging and a non-native root disease, Phytophthora lateralis (Zobel et al. 1985). Effects of fire suppression and logging-related impacts continue to be threats. Fourteen out of 68 plant associations listed in the National Vegetation Classification are listed as globally threatened or endangered.
Conard, S. G.; Radosevich, S. R. 1981. Photosynthesis, xylem pressure potential, and leaf conductance of three montane chaparral species in California. Forest Science. 27(4): 627-639.
Kilgore, Bruce M. 1973. The ecological role of fire in Sierran conifer forests - its application to National Park management. Quaternary Research. 3: 496-513.
Parsons, David J.; DeBenedetti, Steven H. 1979. Impact of fire suppression on a mixed-conifer forest. Forest Ecology and Management. 2: 21-33.
McNeil, Robert C.; Zobel, Donald B. 1980. Vegetation and fire history of a ponderosa pine-white fir forest in Crater Lake National Park. Northwest Science. 54(1): 30-46.
Zobel, D.B., L.F. Roth & G.L. Hawk. 1985. Ecology, pathology and management of Port-Orford cedar (Chamaecyparis lawsoniana). General Technical Report PNW-184. USDA Forest Service. 161 pp.
#4 MONTANE MIXED CONIFER FOREST
Summary: This upland forest habitat is found at middle to high elevations in the mountains from the Cascade Crest west and primarily at high elevations east of the Cascade Crest. It is usually a dense forest, but can include woodlands with >30% canopy cover. One or more of the following diagnostic species is always prominent: Pacific silver fir, mountain hemlock, subalpine fir, Engelmann spruce, Shasta red fir, Alaska yellow-cedar, or noble fir.
Habitat Description
Structure: This is a forest, or rarely a woodland, dominated by evergreen conifers. Canopy structure varies from single-storied to multi-storied. Tree size also varies from small to very large. Large snags and logs vary from abundant to uncommon. Understories vary in structure: shrubs, forbs, ferns, graminoids or some combination will dominate or understories can be depauperate. Deciduous broadleaf shrubs are perhaps most typical as understory dominants. Early successional structure after logging or fire varies depending on understory species present.
Composition: This forest habitat is recognized by the dominance or prominence of one of the following species: Pacific silver fir (Abies amabilis), mountain hemlock (Tsuga mertensiana), subalpine fir (Abies lasiocarpa), Shasta red fir (Abies X shastensis), Engelmann spruce (Picea engelmannii), noble fir (Abies procera), or Alaska yellow-cedar (Chamaecyparis nootkatensis). Several other trees may co-dominate: Douglas-fir (Pseudotsuga menziesii), lodgepole pine (Pinus contorta), western hemlock (Tsuga heterophylla), western redcedar (Thuja plicata), or white fir (Abies concolor). Tree regeneration is typically dominated by Pacific silver fir in moist westside middle-elevation zones; by mountain hemlock, sometimes with silver fir, in cool, very snowy zones on the westside and along the Cascade Crest; by subalpine fir in very cold, drier eastside zones; and by Shasta red fir in the snowy mid- to upper elevation zone of southwestern and south-central Oregon.
Deciduous shrubs that commonly dominate or co-dominate the understory are oval-leaf huckleberry (Vaccinium ovalifolium), big huckleberry (V. membranaceum), grouse whortleberry (V. scoparium), dwarf blueberry (V. cespitosum), fools huckleberry (Menziesia ferruginea), Cascade azalea (Rhododendron albiflorum), copperbush (Elliota pyrolifolius), devils club (Oplopanax horridus), and, in the far south only, baldhip rose (Rosa gymnocarpa), currants (Ribes spp.), Sadler's oak (Quercus sadleriana), and creeping snowberry (Symphoricarpos mollis). Important evergreen shrubs include salal (Gaultheria shallon), dwarf Oregongrape (Mahonia nervosa), Pacific rhododendron (Rhododendron macrophyllum), pinemat manzanita (Arctostaphylos nevadensis), and Oregon boxwood (Pachistima myrsinites).
Graminoid dominants are found primarily just along the Cascade Crest and to the east and include pinegrass (Calamagrostis rubescens), Geyer's sedge (Carex geyeri), smooth woodrush (Luzula glabrata var. hitchcockii), and long-stolon sedge (Carex inops). Deerfern (Blechnum spicant) and oakfern (Gymnocarpium dryopteris) are commonly co-dominant. The most abundant forbs include Oregon oxalis (Oxalis oregana), single-leaf foamflower (Tiarella trifoliata var. unifoliata), rosy twisted-stalk (Streptopus roseus), queens cup (Clintonia uniflora), beargrass (Xerophyllum tenax), bunchberry dogwood (Cornus canadensis), twinflower (Linnea borealis), princes pine (Chimaphila umbellata), five-leaved bramble (Rubus pedatus), and dwarf bramble (R. lasiococcus), sidebells wintergreen (Orthilia secunda), avalanche lily (Erythronium montanum), Sitka valerian (Valeriana sitchensis), false lily-of-the-valley (Maianthemum dilatatum), and Idaho goldthread (Coptis occidentalis).
Other Classifications and Key References
This habitat includes most of the upland forests and their successional stages, except lodgepole pine dominated forests, in the Tsuga mertensiana, Abies amabilis, Abies magnifica shastensis, Abies lasiocarpa zones of Franklin and Dyrness (1973). Portions of this habitat have also been referred to as Abies amabilis-Tsuga heterophylla forests, Abies magnifica var. shastensis forests, and Tsuga mertensiana forests (Franklin 1988). It is equivalent to Silver fir-Douglas-fir forest #3, closed portion of Fir-hemlock forest #4, Red fir forest #7, and closed portion of Western spruce-fir forest #15 (Kuchler 1964); Oregon Gap types 513, 518 in part, 519, 517, 533, 536, 548; much of conifer forest in the Silver Fir, Mountain Hemlock, and Subalpine Fir Zones of Washington Gap.
Other important references describing the habitat include Atzet and McCrimmon (1990), Atzet and Wheeler (1984), Bigley and Hull (1992), Bigley and Hull (1995), Brockway et al. (1983), Franklin et al. (1988), Hemstrom et al. (1982), Hemstrom et al. (1987), Henderson et al. (1989), Henderson et al. (1992), Lillybridge et al. (1995), Marsh et al. (1987),Volland (1976), Chappell (1991), Hopkins (1979b), Mitchell and Moir (1976), Williiams et al. (1995), and Johnson and Simon (1987).
Habitat Dynamics
Natural Disturbance Regime: Fire is the major natural disturbance in this habitat. Fire regimes are primarily of the high-severity type (Agee 1993), but also include the moderate-severity regime (moderately frequent and highly variable) for Shasta red fir forests (Chappell and Agee 1996). Mean fire return intervals vary greatly, from 800 years or longer for some mountain hemlock - silver fir forests to about 40 years for red fir forests. Windstorms are a common small-scale disturbance, and occasionally result in stand replacement. Insects and fungi are often important small-scale disturbances. They may locally affect larger areas also. For example, laminated root rot (Phellinus weirii) is a major natural disturbance, affecting large areas, in mountain hemlock forests of the Oregon Cascades (Dickman and Cook 1989).
Succession and Stand Dynamics: After fire, a typical stand will be briefly occupied by annual and perennial ruderal forbs and grasses, as well as pre-disturbance understory shrubs and herbs that resprout. Stand initiation can be very lengthy, especially at higher elevations, resulting in shrub/herb dominance (with or without a scattered tree layer) for extended periods (Hemstrom and Franklin 1982, Agee and Smith 1984). Early seral tree species can be any of the potential dominants for the habitat, or lodgepole pine, depending on the environment, type of disturbance, and seed source. Fires tend to favor early seral dominance of lodgepole pine, Douglas-fir, noble fir, or Shasta red fir, if their seeds are present (Agee 1993). In some areas, large stand-replacement fires will result in conversion of this habitat to the lodgpole pine forest and woodland habitat, distinguished by dominance of lodgepole. After the tree canopy closes, the understory typically becomes very sparse for a time. Eventually tree density will decrease and the understory will begin to flourish again, but this process takes longer than in lower elevation forests, generally not until at least 100 years after the disturbance, sometimes much longer (Agee 1993). As stand development proceeds, relatively shade-intolerant trees (lodgepole pine, Douglas-fir, western hemlock, noble fir, Englemann spruce) typically decrease in importance and more shade-tolerant species (Pacific silver fir, subalpine fir, Shasta red fir, mountain hemlock) typically increase in importance. Complex multi-layered canopies with large trees will typically take at least 300 years to develop, often much longer, and on some sites may never develop. Tree growth rates, and therefore the potential to develop these structual features, tend to decrease with increasing elevation.
Agee, James K.; Smith, Larry. 1984. Subalpine tree reestablishment after fire in the Olympic Mountains, Washington. Ecology. 65(3): 810-819.
Dickman, Alan; Cook, Stanton. 1989. Fire and fungus in a mountain hemlock forest. Canadian Journal of Botany. 67(7): 2005-2016.
Effects of Management and Anthropongenic Impacts: Forest management practices, such as clearcutting and plantations, have in many cases resulted in less diverse tree canopies with an emphasis on Douglas-fir, reductions in coarse woody debris over natural levels, and a truncation of succession well before late-seral characteristics are expressed. Post-harvest regeneration of trees has been a perpetual problem for forest managers in much of this zone (Gordon 1970, Atzet et al. 1984). Planting of Douglas-fir has often failed at higher elevations, even where old Douglas-fir were present in the unmanaged stand (Henderson et al. 1989). Slash burning often has negative impacts on productivity and regeneration (Ruth 1974). Management has since shifted away from burning and toward planting noble fir or native species, natural regeneration, and advance regeneration (Halverson and Emmingham 1982, Atzet et al. 1984). Noble fir plantations are now fairly common in managed landscapes, even outside the natural range of the species. Advance regeneration management tends to simulate wind disturbance but without the abundant downed wood component. Shelterwood cuts are a common management strategy in Engelmann spruce or subalpine fir stands (Williams et al. 1995).
Ruth, Robert H. 1974. Regeneration and growth of west-side mixed conifers. In: Camer, Owen P., ed. Environmental effects of forest residues in the Pacific Northwest: A state-of-knowledge compendium. Gen. Tech. Rep. PNW-24. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific NorthwestForest and Range Experiment Station: K-1 to K-21.
Halverson, Nancy M.; Emmingham, William H. 1982. Reforestation in the Cascades Pacific silver fir zone; a survey of sites and management experiences on the Gifford Pinchot, Mt. Hood and Willame. U.S. Department of Agriculture Forest Service R-6 Area Guide R6-ECOL-091-1982. Pacific Northwest Region, Portland, Oregon 37 p. [12491]
Atzet, Tom; Wheeler, David; Riegel, Gregg; [and others]. 1984. The mountain hemlock and Shasta red fir series of the Siskiyou Region of southwest Oregon. FIR Report. 6(1): 4-7. [9486]
Landscape Setting
This habitat is found adjacent to Westside Lowlands Conifer-Hardwood Forest, Eastside Mixed Conifer Forests, or Southwest Oregon Mixed Conifer - Hardwood Forest at its lower elevation limits and to Subalpine Parkland at its upper elevation limits. Inclusions of Montane Forested Wetlands, Westside Riparian/Wetlands, and less commonly Open Water or Herbaceous Wetlands occur within the matrix of montane forest habitat. The typical landuse of this type is forestry or recreation. Most of this type is found on public lands managed for timber values and most of it has been harvested in a dispersed-patch pattern.
Physical Setting
This habitat is typified by a persistent winter snowpack, ranging from moderately to very deep, and persisting as little as 3 months to as long as 9-10 months. The climate is moderately cool and wet to moderately dry and very cold. Mean annual precipitation ranges from about 40 inches to over 200 inches. Elevation is mid- to upper montane, as low as 2000 feet in northern Washington, to as high as 7500 feet in southern Oregon. On the westside, it occupies an elevational zone of about 2500 to 3000 vertical feet, and on the eastside it occupies a more narrow zone of about 1500 vertical feet. Topography is generally mountainous. Soils are typically not well developed, but varied in their parent material: glacial till, volcanic ash, residuum or colluvium. Spodosols are common.
Geographic Distribution
Occurs in mountains throughout Washington and Oregon, excepting the Basin and Range of southeast Oregon. This includes the Cascade Range, Olympic Mountains, Okanogan Highlands, Coast Range (rare), Blue and Wallowa Mountains, and Siskiyou Mountains.
Subalpine fir and Englemann spruce are major species only east of the Cascade Crest in Washington, in the Blue Mountains ecoregion, and in the northeast Olympic Mountains (spruce absent in Olympics). Lodgepole pine is important east of the Cascade Crest throughout and in central and southern Oregon. Douglas-fir is important east of the Cascade Crest and at lower elevations on the westside. Pacific silver fir is a major species on the westside as far south as central Oregon. Noble fir, as a native species, is found primarily in the western Cascades from central Washington to central Oregon. Mountain hemlock is a common dominant at higher elevations along the Cascade Crest and to the west, in Washington it is usually with silver fir, in Oregon it occurs mainly without silver fir. Western hemlock, and to a lesser degree western redcedar, occurs as a dominant primarily with silver fir at lower elevations on the westside. Alaska yellow-cedar occurs as a co-dominant west of the Cascade Crest in Washington, rarely in northern Oregon. Shasta red fir and white fir occur only from central Oregon south, the latter mainly at lower elevations.
Status and Trends
This habitat occupies large areas of the region. There has probably been no decline to speak of in the extent of this type over time. Large areas of this habitat are relatively undisturbed by human impacts and include much old-growth, other areas have been extensively affected by logging, especially dispersed patch clearcuts. The habitat is stable in area, but is probably still declining in condition in some areas due to continued logging. This habitat is one of the best protected, with large areas represented in national parks and wilderness areas. The only threat is continued road-building and clear-cut logging in unprotected areas. None of the 81 plant associations listed in the National Vegetation Classification are considered threatened or endangered.
#5 EASTSIDE MIXED CONIFER FOREST
Summary: This habitat includes the productive, upland, closed conifer forests of Washington and Oregon in the east Cascades, Okanogan Highlands and Blue Mountains.
Habitat Description
Structure: Eastside mixed conifer habitats are montane forests and woodlands. Stand canopy structure is generally diverse although single layer forest canopies are currently more common than multilayered forests with snags and large woody debris. The tree layer varies from closed forests to more open canopy forests or woodlands. This habitat may include very open stands. The undergrowth is complex and diverse. Stands can be dominated by tall shrubs, low shrubs, forbs or any combination. Deciduous shrubs typify shrub layers. Prolonged canopy closure can lead to development of sparsely vegetated undergrowth.
Composition: The Eastside mixed conifer habitat contains a wide array of tree species (nine) and stand dominance patterns. Douglas-fir (Pseudotsuga menziesii) is the most common tree species in this habitat. It is almost always present and dominates or co-dominates most overstories. Lower elevations or drier sites may have ponderosa pine (Pinus ponderosa) as a co-dominant with Douglas-fir in the overstory and often have other shade-tolerant tree species growing in the undergrowth. On moist sites, grand fir (Abies grandis), western redcedar (Thuja plicata) and/or western hemlock (Tsuga heterophylla) are dominant or co-dominant with Douglas-fir. Other conifers include western larch (Larix occidentalis) and western white pine (Pinus monticola) on mesic sites, Engelmann spruce (Picea engelmannii), lodgepole pine (Pinus contorta), and subalpine fir (Abies lasiocarpa) on colder sites. Rarely, Pacific yew (Taxus brevifolia) can be an abundant undergrowth tree or tall shrub.
Undergrowth vegetation varies from very open to nearly closed shrub thickets with one to many layers. Tall deciduous shrubs at mid to lower elevations include vine maple (Acer circinatum) in the Cascades, Rocky Mountain maple (Acer glabrum), serviceberry (Amelanchier alnifolia), oceanspray (Holodiscus discolor), mallowleaf ninebark (Physocarpus malvaceus), Scouler's willow (Salix scouleriana) throughout the eastside conifer habitat. Medium tall deciduous shrubs at higher elevations include fools huckleberry (Menziesia ferruginea), Cascade azalea (Rhododendron albiflorum), and big huckleberry (Vaccinium membranaceum). Wide-ranging, generally drier site mid to short deciduous shrubs include baldhip rose (Rosa gymnocarpa), shiny-leaf spirea (Spiraea betulifolia), and snowberry (Symphoricarpos albus, S. hesperius and S. oreophilus). Low shrubs of higher elevations include low huckleberries (Vaccinium cespitosum, and V. scoparium) and five-leaved bramble (Rubus pedatus). Evergreen shrubs represented in this habitat are: chinquapin (Castanopsis chrysophylla) a tall shrub in southeast Cascades, low to midshrubs dwarf Oregongrape (Mahonia nervosa in the east Cascades and M. repens elsewhere), tobacco brush (Ceanothus velutinus) an increaser with fire, Oregon boxwood (Paxistima myrsinites) generally at mid to lower elevations, the low shrub beargrass (Xerophyllum tenax), and pinemat manzanita and kinnikinnick (Arctostaphylos nevadensis and A. uva-ursi) trailing low shrubs.
Herbaceous broadleaf plants are important indicators of site productivity and disturbance. Species generally indicators productive sites include western oakfern (Gymnocarpium dryopteris), vanilla leaf (Achlys triphylla), wild sarsparilla (Aralia nudicaulis), wild ginger (Asarum caudatum), queen's cup (Clintonia uniflora), goldthread (Coptis occidentalis), false bugbane (Trautvetteria caroliniensis), windflower (Anemone oregana, A. piperi, A. lyallii), fairybells (Disporum hookeri), Sitka valerian (Valeriana sitchensis), and pioneer violet (Viola glabella). Other indicators forbs are dogbane (Apocynum androsaemifolium), false solomonseal (Maianthemum stellatum), heartleat arnica (Arnica cordifolia), several lupines (Lupinus caudatus, L. latifolius, L. argenteus ssp.argenteus var laxiflorus), western meadowrue (Thalictrum occidentale), rattlesnake plantain (Goodyera oblongifolia), skunkleaf polemonium (Polemonium pulcherrimum), trailplant (Adenocaulon bicolor), twinflower (Linnaea borealis), western starflower (Trientalis latifolia), and several wintergreens (Pyrola asarifolia, P. picta, and Orthilia secunda).
Graminoids are common this forest habitat. Columbia brome (Bromus vulgaris), oniongrass (Melica bulbosa), northwestern sedge (Carex concinnoides) and western fescue (Festcua occidentalis) are found mostly in mesic forests with shrubs or mixed with forb species. Bluebunch wheatgrass (Pseudoroegneria spicata) Idaho fescue (Festuca idahoensis), and junegrass (Koeleria macrantha) are found in drier more open forests or woodlands. Pinegrass (Calamagrostis rubescens) and Geyer's sedge (C. geyeri) can form a dense grass layer under Douglas-fir or grand fir trees.
Other Classifications and Key References
The Eastside mixed conifer forest habitat includes the moist portions of the Pseudotsuga menziesii, the Abies grandis, and the Tsuga heterophylla zones of eastern Oregon and Washington listed in Franklin and Dyrness (1973). This habitat is called Douglas fir (12), Cedar-Hemlock-Pine (13), and Grand fir- Douglas fir (14) forests in Kuchler (1964). It crosswalks to Oregon Gap vegetation types 522 & 528. Quigley et al. (1997) refers to this habitat as Grand fir / White fir, the Interior Douglas-fir, Western larch, Western redcedar / Western hemlock, and Western white pine cover types and the Moist Forest potential vegetation group. Primary references detailing forest associations are Clausnitzer and Zamora (1987), Daniels (1969), Hopkins (1979a, 1979b), Johnson and Simon (1987), Johnson and Clausnitzer (1992), Lillybridge et al. (1995), Marsh et al. (1987), Topik et al. (1988), Topik (1979), Volland (1976), Williams et al. (1995) and Zack and Morgan (1994).
Habitat Dynamics
Natural Disturbance Regime: Fires were probably of moderate frequency (30-100 years) in pre-settlement times. Inland Pacific Northwest Douglas-fir and western larch forests have a mean fir interval of 52 years (Barrett, et al 1997). Typically, stand replacements fire return intervals are 150-500 years with moderate severity fire intervals of 50-100 years. Specific fire influences vary with site characteristics. Generally, wetter sites burn less frequently and are older stands with more western hemlock and western redcedar than drier sites. Many sites dominated by Douglas-fir and Ponderosa pine which were formerly maintained by wildfire, and may now be dominated by grand fir (a fire sensitive, shade tolerant species).
Succession and Stand Dynamics: Successional relationships of this type reflect complex interrelationships between site potential, plant species characteristics, and disturbance regime (Zack and Morgan 1994). Generally early seral forests of shade intolerant trees (western larch, western white pine, ponderosa pine, Douglas-fir) or tolerant trees (grand fir, western redcedar, western hemlock) develop some 50 years following disturbance. This stage is preceded by forb or shrub dominated communities which can obvious landscape features. These early stage mosaics are maintained on ridges and drier topographic positions by frequent fires. Early seral forest develops into mid seral habitat of large trees over the next 50 to 100 years. Stand replacing fires recycle this stage back to early seral stages over most of the landscape. If spared high severity fires, late seral condition develops either single layer or multilayer structure over the next 100-200 years. These structures are typical of cool, bottomlands that usually only experience low-intensity fires.
Effects of Management and Anthropongenic Impacts: This habitat has been most effected by timber harvesting and fire suppression. Timber harvesting has focused on large, shade intolerant species in mid and late seral forests and leaving shade tolerant species. Fire suppression enforces those logging priorities by promoting less fire resistant shade intolerant trees. These resultant forest habitat at all seral stages tend to lack snags, have high tree density, and are composed of smaller and more shade tolerant trees. Quigley et al. (1997) estimate that midseral forest structure is currently 70% more abundant than in historic, native systems. Late seral forests of shade-intolerant species are essentially absent in current times. Early seral forest abundance is similar to historic extent but lack snags and other legacy features.
Landscape Setting
This habitat generally makes up the majority of the continuous montane forests of the inland Pacific Northwest. It lies between the subalpine portions of the Montane Mixed Conifer Forest habitat in eastern Oregon and Washington and lower treeline Ponderosa pine and Eastside Oak Forests and Woodlands.
Physical Setting
The Eastside Mixed Conifer Forest habitat is a primarily a mid-montane habitat. Elevation range is between 1500 and 7000 feet, primarily between 3000 and 5500 feet. Parent material for soil development are varied. Climate supporting this habitat receive some of greatest amounts of precipitation in the inland northwest between 30-80 inches/year. Elevation range of this habitat varies geographically, generally higher elevations to the east.
Geographic Distribution
The Eastside Mixed Conifer Forest habitat appears primarily the Blue Mountains, East Cascades and Okanogan Highland Ecoregions of Oregon, Washington, adjacent Idaho, and western Montana. Douglas-fir - ponderosa pine forests occur along the eastern slope of the Oregon and Washington Cascades, the Blue Mountains, and the Okanogan Highlands of Washington. Grand fir - Douglas-fir forests and Western Larch forests are widely distributed throughout the Blue Mountains and, lesser so, along the east slope of the Cascades south of Lake Chelan and in the eastern Okanogan Highlands. Western hemlock - western redcedar - Douglas-fir forests are found in the Selkirk Mountains of eastern Washington, and on the east slope of the Cascades south of lake Chelan to the Columbia River Gorge.
Status and Trends
Quigley et al. (1997) conclude that the Interior Douglas-fir, Grand fir, and Western redcedar / Western hemlock cover types are more abundant now than prior to 1900, whereas the western larch and Western white pine types are significantly less abundant. Twenty percent of Pacific Northwest Douglas-fir, grand fir, western redcedar, western hemlock, and western white pine associations listed in the 1998 National Vegetation Classification are considered endangered or threatened. These forests have been compromised by roading, timber harvesting, periodic grazing, and altered fire regimes. Even though this habitat is more extensive than pre-1900, natural processes and functions have been modified enough to alter its natural status as functional habitat or many species.
#6 LODGEPOLE PINE FORESTS AND WOODLANDS
Summary: This habitat includes lodgepole pine forest and woodlands the east Cascades, Okanogan Highlands and Blue Mountains.
Habitat Description
Structure: The lodgepole pine habitat is composed of open to closed evergreen conifer tree canopies. Vertical structure is typically a single tree layer. Reproduction of other more shade tolerant conifers is can be abundant in the undergrowth of the forest or woodland habitat. Several distinct undergrowth types develop under the tree layer. Evergreen or deciduous medium-tall shrubs, evergreen low shrub, graminoids with few shrubs. On pumice soils a sparsely developed shrub and graminoid undergrowth appear with open to closed tree canopies.
Composition: The tree layer of this habitat is dominated by lodgepole pine (Pinus contorta var. latifolia and P. c. var. murrayana), but it is usually associated with any number of other montane conifers (Abies concolor, A. grandis, A. X shastensis, Larix occidentalis, Calocedrus decurrens, Pinus lambertiana, P. monticola, P. ponderosa, Pseudotsuga menziesii). Indicators of subalpine environments subalpine fir (Abies lasiocarpa), mountain hemlock (Tsuga mertensiana), Engelmann spruce (Picea engelmannii), and whitebark pine (Pinus albicaulis), are present in colder or higher elevation sites and occur only as scattered individuals or in small patches. Quaking aspen (Populus tremuloides) sometimes occurs in small amounts.
Shrubs can dominate the undergrowth. Tall deciduous shrubs include Rocky Mountain maple (Acer glabrum), serviceberry (Amelanchier alnifolia), oceanspray (Holodiscus discolor) or Scouler's willow (Salix scouleriana). These tall shrubs often occur over a layer of mid-tall deciduous shrubs such as baldhip rose (Rosa gymnocarpa), russet buffaloberry (Shepherdia canadensis), shiny-leaf spirea (Spiraea betulifolia), snowberry (Symphoricarpos albus and/or S. hesperius). At higher elevations, big huckleberry (Vaccinium membranaceum) can be locally very important particularly following fires. Mid tall evergreen shrubs can be abundant in some stands, for example, creeping Oregongrape (Mahonia repens), tobacco brush (Ceanothus velutinus), and Oregon boxwood (Paxistima myrsinites). Colder and drier sites support low growing evergreen shrubs, such as kinnikinnick (Arctostaphylos uva-ursi) or pinemat manzanita (Arctostaphylos nevadensis). Grouseberry (V. scoparium) and beargrass (Xerophyllum tenax) are consistent evergreen low shrubs undergrowth dominants in the subalpine part of this habitat. Manzanita (Arctostaphylos patula), kinnikinnick, tobacco brush, antelope bitterbrush (Purshia tridentata), and wax current (Ribes cereum) are part of this habitat on pumice soil.
Some undergrowths are dominated by graminoids with few shrubs. Pinegrass (Calamagrostis rubescens) and/or Geyer's sedge (Carex geyeri) can appear with grouseberry in the subalpine zone. Pumice soils support grassy undergrowth of long-stolon sedge (C. inops), Idaho fescue (Festuca idahoensis) or western needlegrass (Stipa occidentalis). The later two species may occur with bitterbrush or big sagebrush and other bunchgrass steppe species. Other non-dominant indicator graminoids frequently encountered in this habitat are California oatgrass (Danthonia californica), blue wildrye (Elymus glaucus), Columbia brome (Bromus vulgaris) and oniongrass (Melica bulbosa). Kentucky bluegrass (Poa pratensis), bottlebrush squirreltail (Elymus elymoides) which can be locally abundant where livestock use has persisted.
The forb component of this habitat is diverse and varies with environmental conditions. A partial forb list includes goldthread (Coptis occidentalis), false solomonseal (Maianthemum stellatum), heartleat arnica (Arnica cordifolia), several lupines (Lupinus caudatus, L. latifolius, L. L. argenteus ssp. argenteus var. laxiflorus), meadowrue (Thalictrum occidentale), queen's cup (Clintonia uniflora), rattlesnake plantain (Goodyera oblongifolia), skunkleaf polemonium (Polemonium pulcherrimum), trailplant (Adenocaulon bicolor), twinflower (Linnaea borealis), Sitka valerian (Valeriana sitchensis), western starflower (Trientalis latifolia), and several wintergreens (Pyrola asarifolia, P. picta, and Orthilia secunda).
Other Classifications and Key References
The Lodgepole pine forest and woodland habitat includes the Pinus contorta zone of eastern Oregon and Washington listed in Franklin and Dyrness (1973). It crosswalks to Oregon Gap vegetation types 514 (in part), 515 and 516. Quigley et al. (1997) refers to this habitat as Lodgepole pine cover type and is part of the Dry Forest potential vegetation group. Primary references detailing forest associations are Hopkins (1979a, 1979b), Johnson and Simon (1987), Johnson and Clausnitzer (1992), Lillybridge et al. (1995), Volland (1976, 1985), and Williams et al. (1995).
Habitat Dynamics
Natural Disturbance Regime: These forest and woodland habitats are usually early successional forests which originated with fires. Inland Pacific Northwest lodgepole pine has a mean fire interval of 112 years (Barrett, et al 1997). Summer drought areas generally have low to medium-intensity ground fires occurring at intervals of 25 to 50 years, whereas, areas with more moisture have a sparse undergrowth and slow fuel build up that results in less frequent, more intense fire. With time, lodgepole pine stands increase in flammability. Woody fuels accumulate on the forest floor from insect (mountain pine beetle) and disease outbreaks and residual wood from past fires. Mountain pine beetle outbreaks thin stands that add fuel and create a drier environment for fire or open canopies and create gaps for other conifer regeneration. High-severity crown fires are likely in young stands, when the tree crowns are near deadwood on the ground. After the stand break ups shade-tolerant trees increase in number.
Succession and Stand Dynamics:. Most lodgepole pine forest and woodlands are early to mid seral stages initiated by fire. Typically, lodgepole pine establishes within 10 to 20 years after fire. This can be a gap phase process where seed sources are scarce. Lodgepole stands breakup between 100 and 200 years. Without fires and insects, stands become more closed canopy forests with very sparse undergrowth. Since lodgepole pine cannot reproduce under its own canopy, unburned, very old stands are replaced by shade-tolerant conifers. Lodgepole pine habitats on pumice soils are not seral to another tree species. These extensive lodgepole pine forests, if not burned, thin naturally thinned with lodgepole pine regenerating in patches. On poorly drained pumice soils, quaking aspen sometimes plays a mid seral role being displaced by lodgepole when aspen clones die. Serotinous cones (cones releasing seeds after fire) are uncommon in eastern Oregon (P. c. var. murrayana). On the Colville National Forest in Washington, only 10 percent of lodgepole pine (P. c. var. latifolia) trees in low-elevation Douglas-fir habitats had serotinous cones, whereas, 82 percent of cones in high-elevation subalpine fir habitats were serotinous (http://www.fs.fed.us/database/feis/plants/tree/pinconl).
Effects of Management and Anthropongenic Impacts: Fire suppression has left many single canopy lodgepole pine habitats unburned to develop into more multilayered stands. Thinning of serotinous lodgepole pine forests with fire intervals less than 20 years can reduce its importance over time. In pumice lodgepole, lack of natural regeneration in harvest units has lead to creation of "pumice deserts" within otherwise forest habitats (Cochran 1973).
Landscape Setting
This habitat appears within Montane Mixed Conifer Forest east of the Cascade crest and the cooler Eastside Mixed Conifer Forest habitats. Most pumice soil lodgepole pine habitat is intermixed with Ponderosa pine woodland and Forest Habitats and lies in between Eastside Mixed Conifer Forest habitat and either Western Juniper Woodland or Shrub-Steppe habitat.
Physical Setting
This habitat is located mostly at middle to higher elevations in the mountains at elevations 3000 to 9000 feet. These environments can be cold, relatively dry usually with persistent winter snowpack. few of these forests occur in low-lying frost pockets, wet areas, or under edaphic control (usually pumice) and are relatively long-lasting features of the landscape. Lodgepole pine is maintained as a dominant by the well drained, very deep Mazama pumice in eastern Oregon.
Geographic Distribution
Lodgepole pine forest or woodland habitat is found along the eastside of the Cascade Range, in the Blue Mountains, the Okanogan Highlands and ranges north into British Columbia and south to Colorado and California. Lodgepole pine forest or woodland habitat with shrubby undergrowth appears in the Blue Mountains, along the eastern slope of the Cascade Range, and in the Okanogan Highlands. With a grassy undergrowth, this habitat appears primarily along the eastern slope of the Cascade Range and occasional in the Blue Mountains and Okanogan Highlands. Subalpine lodgepole pine habitat occurs on the broad plateau areas along the crest of the Cascade Range and the Blue Mountains, and in the higher elevations in the Okanogan Highlands. On pumice soils this habitat is confined to the east slope of the Cascade Range from near Mt. Jefferson south to the vicinity of Crater Lake.
Status and Trends
Quigley et al. (1997) conclude that the extent of the lodgepole pine cover type across its range is the same as before 1900. Five percent of Pacific Northwest lodgepole pine associations listed in the 1998 National Vegetation Classification are considered threatened. These forests are fragmented by roading, timber harvesting and influenced by periodic grazing, and altered fire regimes. Although this habitat is as extensive than pre-1900, many natural processes and functions have been modified so to alter its natural status as a functional habitat or many species.
#7 PONDEROSA PINE - EASTSIDE OAK WOODLANDS AND FORESTS
Summary: Generally lower elevation upland forests and woodlands across eastern Washington and Oregon.
Habitat Description
Structure: This habitat is typically a woodland or savanna with tree canopy coverage of 10 to 60% although closed canopy stands are possible. The tree layer is usually composed of widely spaced, large conifer trees. Many stands tend to a multilayered condition with encroaching conifer regeneration. Isolated, taller conifers over broadleaf deciduous trees characterize part of this habitat. Deciduous woodlands or forests are an important part of the structural variety of this habitat. Clonal deciduous trees can create dense patches across a grassy landscape rather than scattered individual trees. The undergrowth may include dense stands of shrubs or, more often, be dominated by grasses, sedges, or forbs. Shrub-steppe shrubs may be prominent in some stands and create a distinct tree/ shrub/ sparse grassland habitat.
Composition: Ponderosa pine (Pinus ponderosa) and Douglas-fir (Pseudotsuga menziesii) are the most common evergreen trees in this habitat. The deciduous conifer, western larch (Larix occidentalis), can be a codominant with the evergreen conifers in the Blue Mountains of Oregon, but seldom as a canopy dominant. Grand fir (Abies grandis) may be frequent in the undergrowth on more productive sites giving stands a multilayer structure. In rare instances, grand fir can be codominant in the upper canopy. Tall ponderosa pine over Oregon white oak (Quercus garryana) trees form stands along part of the east Cascades. These stands usually have younger cohorts of pines. Oregon white oak dominates open woodlands or savannas in limited areas.
The undergrowth can include dense stands of shrubs or, more often, be dominated by grasses, sedges, and/or forbs. Some Douglas-fir and ponderosa pine stands have a tall to medium-tall deciduous shrub layer of mallowleaf ninebark (Physocarpus malvaceus) or common snowberry (Symphoricarpos albus). Grand fir seedlings or saplings may be present in these undergrowth. Pumice soils support a shrub layer indicated by greenleaf or white-leaf manzanita (Arctostaphylos patula or A. viscida). Short shrubs, pinemat manzanita and kinnikinnick (Arctostaphylos nevadensis or A. uva-ursi) are found across the range of this habitat. Antelope bitterbrush (Purshia tridentata), big sagebrush (Artemisia tridentata), black sagebrush (Artemisia nova), green rabbitbrush (Chrysothamnus viscidiflorus), and in southern Oregon, curl-leaf mountain mahogany (Cercocarpus ledifolius) often grow with Douglas-fir, ponderosa pine and/or Oregon white oak which typically have a bunchgrass and shrub steppe ground cover.
Undergrowths are generally dominated by herbaceous species, especially graminoids. Within a forest matrix, these woodland habitats have an open to closed sodgrass undergrowth dominated by pinegrass (Calamagrostis rubescens), Geyer's sedge (Carex geyeri), Ross' sedge (Carex rossii), long-stolon sedge (C. inops), or blue wildrye (Elymus glaucus). Drier savannas and woodlands undergrowth typically contain bunchgrass steppe species, such as, Idaho fescue (Festuca idahoensis), rough fescue (Festuca campestris), bluebunch wheatgrass (Pseudoroegneria spicata), Indian ricegrass (Oryzopsis hymenoides), or needlegrasses (Stipa comata or S. occidentalis). Common exotic grasses that often appear in high abundance are cheatgrass ( Bromus tectorum), and bulbous bluegrass (Poa bulbosa). Forbs are common associates in this habitat and are too numerous to be listed.
Other Classifications and Key References
This habitat is referred to as Merriam's Arid Transition Zone, Western ponderosa forest (Pinus) and Oregon Oak wood (Quercus) in Kuchler (1964) and Pacific ponderosa pine - Douglas-fir and Pacific ponderosa pine, and Oregon white oak by the Society of American Foresters. It crosswalks to Oregon Gap vegetation types 475, 503, 504, 511, 527, or 535. Important references describing this habitat are Clausnitzer and Zamora (1987), Daubenmire and Daubenmire (1968), Franklin and Dyrness (1973), Hopkins (1979a, 1979b), Johnson and Clausnitzer (1992), John and Tart (1986), Johnson and Simon (1987), Lillybridge et al. (1995), Marsh et al. (1987), Topik et al. (1988), Volland (1976), Williams et al. (1995), Williams and Lillybridge (1983).
Habitat Dynamics
Natural Disturbance Regime: Fire plays an important role in creating vegetation structure and composition in this habitat. Most of the habitat experienced frequency low-severity fires that maintained woodland or savanna conditions. A mean fire interval of 20 years for ponderosa pine is the shortest of the vegetation types listed by Barrett et al (1997). Soil drought plays a role maintaining an open tree canopy in part of this dry woodland habitat.
Succession and Stand Dynamics: This habitat is climax on sites near the dry limits of each of the dominant conifer species and is more seral as the environment become more favorable for tree growth. With time, open seral stands are replaced by more closed shade-tolerant climax stands. Oregon white oak can reproduce under its own shade but is intolerant of overtopping by conifers. Oregon white oak woodlands are considered fire climax and are seral to conifers. In drier conditions, unfavorable to conifers, oak is climax. Oregon white oak sprouts from the trunk and root crown following cutting or burning and form clonal patches of trees.
Effects of Management and Anthropongenic Impacts: Pre-1900, this habitat was mostly open and parklike with relatively few undergrowth trees. Currently, much of this habitat has a younger tree cohort of more shade tolerant species that consequently, gives the habitat a more closed, multilayered canopy. For example, this habitat includes previously natural fire-maintained stands in which grand fir can eventually become the canopy dominant. Fire suppression has lead to a buildup of fuels that in turn increase the likelihood of stand-replacing fires. Heavy grazing generally produces opposite effects than those of fire, for example, removal of the grass cover by grazing tends to favor shrub and conifer species. Fire suppression combined with grazing influence on fine fuel production create conditions that support cloning of oak and invasion by conifers. Large late seral ponderosa pine, Douglas-fir, and Oregon white oak harvested in much of this habitat. Under most management regimes, typical tree size decreases and tree density increases in this habitat. Ponderosa pine-Oregon white oak habitat is now more dense than in the past and may have more shrubs than pre-settlement habitats. In some areas, new woodlands have been created by patchy tree establishment at the forest-steppe boundary.
Landscape Setting
This woodland habitat typifies the lower treeline zone forming transitions with Eastside Mixed Conifer Forest and Western Juniper and Mountain Mahogany Woodland, Shrub-steppe, Eastside grassland or Agriculture Habitats. Douglas-fir - ponderosa pine woodlands are found near or within the Eastside Mixed Conifer Forest habitat. Oregon Oak woodlands appear in the driest most restricted landscapes in transition to Eastside Grassland or shrub steppe.
Physical Setting
This habitat generally occurs on the driest sites supporting conifers in the Pacific Northwest. It is widespread and variable appearing on moderate to steep slopes, in canyons, foothills, and plateau or plains near mountains. In Oregon, this habitat can be maintained by the dry pumice soils and in Washington it can be associated with serpentine soils. Average annual precipitation ranges from about 14 to 30 inches (35-75 cm) on ponderosa pine sites in Oregon and Washington and often as snow. This habitat can be found at elevations 100 feet in the Columbia River Gorge to dry, warm over 6000 feet. Timber harvest, livestock grazing and pockets of urban development are major land uses.
Geographic Distribution
Variants of this habitat are found along lower treeline the east Cascade, Sierra, and Rocky Mountains of western North America. In the Pacific Northwest, Ponderosa pine-Douglas fir woodland habitats occurs along the eastern slope of the Cascades, the Okanogan Highlands and in the Blue Mountains. Ponderosa pine woodland and savanna habitats occurs in the foothills of the Blue Mountains, along the eastern base of the Cascade Range, the Okanogan Highlands, and in the Columbia Basin in northeastern Washington. Ponderosa pine is widespread in the pumice zone of south-central Oregon between Bend and Crater Lake east of the Cascade Crest. Ponderosa pine-Oregon white oak habitat appears east of the Cascades in the vicinity of Mt. Hood near the Columbia River Gorge north on to the Yakama Nation and south on to the Warm Springs Nation. Eastside Oregon White Oak woodland habitat follows a similar distribution as ponderosa pine-white oak habitat but is more restricted and less common.
Status and Trends
Quigley et al (1997) conclude that the Interior Ponderosa pine cover type is significantly less in extent than pre-1900 and that the Oregon White Oak cover type is greater in extent than pre-1900. They include much of this habitat in their Dry Forest potential vegetation group (Quigley et al 1997) which they conclude has overall departed from natural succession and disturbance conditions. The greatest structural change in this habitat is the reduction of extent of the late-seral, single layer condition. This habitat is generally in degraded condition because of increase in exotic plants and decrease in native bunchgrasses. One-third of Pacific Northwest Oregon white oak, ponderosa pine, and dry Douglas-fir or Grand fir community types list in the 1998 National Vegetation Classification are considered endangered or threatened.