Level IV (9c) Oak/Conifer Foothills
The Oak/Conifer Foothills ecoregion is lower and drier than the Grand Fir Mixed Forest and more diverse than other parts of the Eastern Cascades. It consists of foothills, low mountains, plateaus, and valleys from 500 to 3500 feet (152 to 1067 m).
Marine weather enters the region via the Columbia River Gorge, moderating the otherwise continental climate. As a result, soil, climate, and vegetation share characteristics of both eastern and western Oregon.
The region is characterized by Oregon white oak woodlands and ponderosa pine forests in the east and Douglas-fir and western hemlock forests in the west. Some grasslands also occur. Understory plants include Idaho fescue, bluebunch wheatgrass, antelope bitterbrush, Oregon grape, hazel, and snowberry.
The region covers 563 square miles (1,458 km2) in Washington and 461 square miles (1,194 km2) in Oregon along the Columbia River corridor, including the lower reaches of the White Salmon and Klickitat River drainages.