Historical Vegetation of the Willamette Valley, Oregon, circa 1850

Abstract

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Historical Colonization of South Puget Sound Prairies by Douglas-Fir at Joint Base Lewis-McChord, Washington

“…Although GLO Douglas-firs included a few large scattered trees, the average GLO Douglas-fir diameter was only 55 cm (the mean modern tree diameter was 73 cm). It is noteworthy that typical GLO Douglas-fir diameters from coniferous savannas in the Willamette Valley were similar to what we found (Christy and Alverson 2011). In the late 1700s through the early 1800s local Native American populations were coping with disease epidemics introduced through increasingly frequent European contacts (Boyd 1985).…”

“…Grimm (1984) found in Minnesota where a buffer zone of fire tolerant oaks and aspen separated prairie from forest. This zoned structure, so clearly demonstrated in our GLO edge analysis, was also described for this area in detail by Magnum et al (1911) and is evident in GLO data from the Willamette Valley (Christy and Alverson 2011). At JBLM, the Oregon white oak/Douglas-fir boundary appears to have been used by GLO surveyors to divide "timber" from "prairie."…”

Stand Structures of Oregon White Oak Woodlands, Regeneration, and their Relationships to the Environment in Southwestern Oregon

“…Historical records (e.g., General Land Office [GLO] surveys), however, document that dense oak woodlands occupied substantial portions of the landscape in southwestern Oregon during the 1850s (Hickman 2005, Hosten et al 2007b. Ponderosa pine-oak and oak woodlands formed the most dominant vegetation class recorded in southwestern Oregon GLO surveys, in contrast with surveys from the Willamette Valley where prairie was the most dominant class (Hickman 2005, Christy andAlverson 2011). It is likely that there was a great deal of landscape patchiness in the past, which included both historical woodlands and openoak patches.…”

Climate Change Impacts on Western Pacific Northwest Prairies and Savannas

“…Establishing natural prairie and oak savanna habitats in these less productive areas may be an ecologically sensible alternative. Given that Willamette Valley prairies and oak savannas used to occupy what later became top quality agricultural soils (Christy and Alverson 2011), such extensions of prairie and savanna habitat may be seen as restoring some of the historical range of variability of these ecosystems. To prepare for such opportunities, conservationists should consider a) developing and demonstrating restoration techniques that will efficiently establish native species under those new conditions, and b) work to establish the regulatory framework and public awareness to ease such land use changes.…”