Evidence of Climate Change Related Shifts in Epiphytic Vegetation Communities in the Pacific Northwest

Linda Geiser1, Sarah Jovan2 and Doug Glavich1

Within the US Pacific Northwest, one of many anticipated effects of climate change is a shift in species distributions, including extirpation. The Forest Health Monitoring lichen indicator is designed to track climate-related changes in epiphyte communities, a type of forest vegetation that is diverse, ecologically integral, and particularly sensitive to climate. Ten year re-measurements of lichen communities in western Oregon and Washington provide some of the first evidence of climate impacts on regional vegetation. Lichen communities in the coastal ranges are shifting towards cooler climate species, possibly associated with greater moisture and cooling from more frequent storms. No change has been detected in communities of low elevation valleys, including the Columbia River Gorge NSA. Shifts in species composition towards warmer-climate communities are widespread in the Oregon Cascades, especially at mid to high elevations. These results are consistent with PRISM modeled temperature and precipitation data. With regard to other vegetation, the results suggest that managers can anticipate earliest biodiversity threats to arcticalpine and boreal species in the mid to high elevation Cascades and less imminent threats to coast range and low elevation communities.

1US Forest Service, Pacific Northwest Air Resource Management Program, PO Box 1148, 17 Corvallis, OR 97339
2US Forest Service, Pacific Northwest Research Station, 620 SW Main, Suite 400, Portland, OR 15 97205