Modeling Regions

Overview

This modeling region encompasses the Washington Olympic Peninsula, the Washington Western Lowlands, and the Washington Western Cascades physiographic provinces. The Olympic Peninsula is dominated by moist, productive coniferous rain forest on the western slope of the Olympic Mountains, and drier Douglas-fir forest in the rain shadow on the eastern slope. Fire frequency is very low. Current vegetation is a mosaic of early- to late-successional forests resulting from extensive forest management. Federally managed lands occupy the interior half of the province, the core being Olympic National Park girded by the Olympic National Forest. Most of the Western Lowlands are in private and state ownership, with very little federal land. The province includes extensive urban and agricultural areas. The province is dominated by wide, glaciated valleys, except for the Willapa Hills in the coastal section. Lowland coniferous forest, deciduous forest, and native prairie were the natural dominant vegetation types. Along the western slope of the Cascades, lower-elevation forest dominated by Douglas-fir and western hemlock gives way to Pacific silver fir at mid-elevations, and to mountain hemlock and subalpine vegetation at higher elevations. Historical fire frequencies were low to moderate, resulting from a north-to-south moisture gradient. About two-thirds of the western Cascades is administered by federal agencies.