Monitoring the Habitat of Ute Ladies'tresses ('Spiranthes diluvialis') on the South Fork Snake River, Idaho. Second Year Results

摘要

Spiranthes diluvialis (Ute ladies tresses) is an orchid listed as Threatened under the Endangered Species Act. It is known from 23 occurrences in eastern Idaho. From 1997 to 2002, we monitored the population and habitat of Spiranthes diluvialis occurrences on public land along the South Fork Snake River. In 2001, we developed, tested, and implemented easily repeatable and objective monitoring methods for measuring changes and threats to Spiranthes diluvialis habitat. These monitoring methods use an index of habitat change, incorporating what we have learned about Spiranthes diluvialis habitat characteristics and the effects of disturbance from past monitoring and floodplain dynamics research. The index consists of a checklist of habitat attributes measured at both the population (transect) scale and the landscape scale. The measurements of these habitat attributes use a relative scale, yielding cumulative values representing current habitat conditions at each transect. During 2001, 23 permanently marked habitat monitoring transects, representing 18 Spiranthes diluvialis occurrences on the South Fork Snake River, were established and baseline habitat condition data collected. Data was again collected at 22 transects in 2002. One additional transect was established at the island portion of the Annis Island occurrence. This report summarizes data collected in 2002 and compares the results with baseline data collected in 2001.