Pre-Settlement Forests of Southwest Washington: Witness Statements

Abstract

In the mid-nineteenth century overland immigration into western Washington State passed through lands bracketed by the lower Columbia River and the Pacific Ocean. Witness trees from the region’s first GLO surveys (General Land Office), which preceded settlement, are used to reconstruct the composition, character, and distribution of the region’s natural forests. As such, this investigation augments a similar study of early forests around Puget Sound, situated immediately to the north (Schroeder, 2019). A retrospective species map is constructed from locational information from more than thirty-five thousand witness trees; accompanying tree diameters elucidate size differences by species and geographic locales. Three principal forest types were noted: western hemlock in the rainy western hills, with some Sitka spruce near the coast; Douglas-fir with woodland tree species in the rain-shadowed central plains; and hemlock/Douglas-fir/redcedar mixtures on the lower flanks of the Cascade Range. Although the majority of trees were small or medium in size, a significant fraction was large. All forest types displayed significant amounts of old growth, as judged by screening witness trees against a quantitative model. Mensuration exercises estimate that the region’s pre-settlement tree population approached one-half billion specimens with a timber volume of nearly 50 billion cubic feet.