Vegetation Zones of Washington State

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The vegetation zones within these ecoregions are further distinguised by soils, rainfall, fire history, elevation, aspect (i.e., if the landform is facing north, south, etc.) and slope (i.e. flat, a steep slope, etc.).

The Ponderosa Pine vegetation zone (bright purple) is where the dominant vegetation is Ponderosa Pine forests. These forests are found along the edges of the following ecoregions: Columbia Basin, Southeast, Central and Northeast Cascades, Okanogan, Northeast corner and the Blue Mountains.

The Vegetation Zones are:

• Woodland/Prairie Mosaic--localized western Washington grasslands and woodlands
• Puget Sound Douglas-fir--low, flat Puget Sound
• Cowlitz River--drainage from plains of central Lewis County to the Columbia River
• Willamette Valley--northernmost extent of the Willamette Velley
• Sitka Spruce--low-elevation coastal forest zone in the fog belt of th Pacific Ocean
• Western Hemlock--low- to mid-elevation wet forest zone covering most of western Washington
• Silver Fir--mid- to high-elevation wet forest zone covering most of western Washington
• Olympic Douglas-fir--mid-montane forest on the rain-shadowed northeast side of the Olympic Mountains
• Oak zone--Garry Oak and Oak/conifer savanna, woodlands, and forest at lower elevations in the Southeast Cascades
• Ponderosa Pine--Open Ponderosa Pine forest bordering the eastern Washington steppe
• Interior Douglas-fir--Eastern Washington forest zone above the Ponderosa Pine zone
• Grand Fir--Eastern Washington forest zone usually above the Interior Douglas-fir zone
• Interior Western Hemlock and Interior Redcedar--most mesic eastern Washington zones; in the Northeast, East Central Cascades, and Southeast Cascades, usually above the Grand Fir zone
• Subalpine Fir--subalpine forest zone up to the end of continuous timber; mostly eastern Washington, but also includes the dry subalpine forests in the Olympic Mountains rain shadow
• Blue Mountain - HIgh Open Conifers--minor Blue Mountain zone characterized by shrubs and open conifer woodland at high elevations
• Blue Mountain - High Basalt Ridges--minor Blue Mountain zone characterized by sparse vegetation on high basalt ridges
• Low-elevation Lava Flows--minor Mt. Adams zone on recent lava flows below 4000 ft.
• High-elevation Lava Flows--minor Mt. Adams zone on recent lava flows above 4000 ft.
• Blue Mountain Steppe--Steppe zone to the northeast of the Blue Mountains
• Palouse--lush meadow steppe of eastern Washington
• Wheatgrass/Fescue--grasslands to the north and south of the Snake River
• Big Sage/Fescue--Intermediate between the driest and most mesic steppe in the northeast part of the Columbia Basin
• Central Arid Steppe--driest, central part of the Columbia Basin
• Canyon Grassland--warm, dry grasslands along the Snake River and part of the Columbia Raiver
• Three-tip Sage--northern and northeastern periphery of the Columbia Basin
• Klickitat Meadow Steppe--Fescue-dominated grass and herb meadow steppe of Klickitat County
• Bitterbrush--Bitterbrush- and fescue-dominated zone in Klickitat County
• Alpine/Parkland--treeless alpine vegetation, subalpine parkland, and patchy subalpine woodlands mixed with subalpine meadows
• Permanent Ice/Snow--unvegetated tops of high mountain peaks and ridges