ENDANGERED, THREATENED, AND SENSITIVE PLANTS OF FORT-LEWIS, WASHINGTON - DISTRIBUTION, MAPPING, AND MANAGEMENT RECOMMENDATIONS FOR SPECIES CONSERVATION

The loss of native species and their habitats has increased with urban development, agriculture, and resource utilization. According to the Washington Natural Heritage Program, 20 plants listed as endangered, t hreatened, or sensitive are suspected to occur on the glacial outwash soils of south Puget Sound. In our study, more than 3,000 ha of prairi e, wetland, and moist-forest plant communities were systematically sam pled at Fort Lewis, Washington, and rare plant species, their habitats , and associated species were mapped. Four rare species, Aster curtus, Trillium parviflorum, Carex comosa, and C. interrupta, were found. As ter curtus, the most abundant of these four species, attained highest cover and frequency on prairies dominated by Festuca idahoensis, other graminoids, and native forbs. It also was present on some sites domin ated by trees or non-native species. Trillium parviflorum was found in moist-forest communities with an overstory of conifers and hardwoods. Carex comosa was found on the margins of two wetlands, and C. interru pta was found growing on a gravel bar of the Nisqually River. Major th reats to the four rare species are discussed, and recommendations are made for management of rare plant habitats with the goal of preserving the species.