Monday, November 13, 2006

Do Microsite Conditions Affect the Survival of Native Prairie Species in Western Washington?.

Samantha M. Sprenger and Darlene Zabowski. Univ of Washington, College of Forest Resources, Box 352100, Seattle, WA 98195

Native prairie ecosystems in western Washington have been greatly reduced in size due to factors such as development, conifer encroachment, and exotic species. The loss of these ecosystems has resulted in the subsequent decline of certain plant species that rely on these unique habitats.  One such species, Castilleja levisecta (golden paintbrush), is now listed as an endangered species in Washington State, and efforts to introduce this species to sites in the Puget Sound region have been met with limited success.  One explanation for low survival rates may be the variability in microsite conditions within prairie environments.  Five different sites in the Puget Sound region—consisting of thirty-one plots where C. levisecta introductions have been successful (high survival) and thirty-one plots where introductions have failed (no survival) are being examined for soil moisture, temperature and nutrient availability.  Comparisons will be made between these plots to determine if soil moisture and temperature significantly affect C. levisecta survival rates. Preliminary results indicate limited differences in soil moisture and temperature between the high and low survival plots during summer months, but relevance of these results to survival and growth is not yet clear.