Population Monitoring of Disjunct Pacific Dogwood (Cornus Nuttallii) on the Clearwater and Nez Perce National Forests: Second Year

摘要

Pacific dogwood (Cornus nuttallii) is a small, native tree that is disjunct in Idaho, far outside its main range in the Cascade and Sierra Nevada ranges. In Idaho, it is restricted to the lower Lochsa and Selway Rivers within 20 miles of their confluence, where it occurs on lower slopes and benchlands along the two rivers. Pacific dogwood is a US Forest Service Region 1 sensitive species due to its restricted range, a high rate of mortality due to disease, and the potential value of the isolated gene pool. Most of the Idaho population occurs on Forest Service land administered by the Clearwater and Nez Perce National Forests. High mortality among Idaho's Pacific dogwoods was noted in 1987 and documented shortly thereafter by Johnson (1988). Plant pathologists later identified several root diseases as probable causes of the observed mortality (Bertagnolli and Partridge 1990). Both of the above studies were part of a conservation plan developed by the US Forest Service and the Idaho Conservation Data Center (ICDC) to assess trends in the Idaho Pacific dogwood populations and to determine what could be done to save them (Lorain 1991).