1997-06-13_REPORT - M1981302 (11)

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EXECUTIVE SUMMARY Current Status: The Ute ladies'-tresses (Soiranthes diluvialis) is an orchid that occurs in relatively low elevation riparian, spring, and lakeside wetland meadows in three general areas of the interior western United States: near the base of the eastern slope of the Rocky Mountains in southeastern and central Wyoming and north-central and central Colorado, and Montana; in the upper Colorado River basin, particularly in the Uinta Basin; and along the Wasatch Front and westward in the eastern Great Basin, in north-central and western Utah and extreme eastern Nevada. The total population is approximately 20,500 individuals. The riparian and wetland habitats required by this species have been heavily impacted by urban development, stream channelization, water diversions and other watershed and stream alterations that reduce the natural dynamics of stream systems, recreation, and invasion of habitat by exotic plant species. These activities are expected to intensify, threatening remaining Ute ladies'-tresses populations and habitats. Habitat Requirements and Limiting Factors: The Ute ladies'-tresses is endemic to moist soils in mesic or wet meadows near springs, lakes, or perennial streams. The elevational range of known Ute ladies'-tresses occurrences is 4,300 and 7,000 feet (1,310 to 2, 134 meters) . Most of the occurrences are along riparian edges, gravel bars, old oxbows, and moist to wet meadows along perennial streams, but some localities in the eastern Great Basin are in similar situations near freshwater lakes or springs. Ute ladies'-tresses seem to require 'permanent sub-irrigation' , indicating a close affinity with floodplain areas where the water table is near the surface throughout the growing season and into the late summer or early autumn. The orchid occurs primarily in areas where the vegetation is relatively open and not overly dense or overgrown, although a few populations in eastern Utah and Colorado are found in riparian woodlands. Plants usually occur in small scattered groups and occupy relatively small areas within the riparian system. These preferred habitat features imply that the orchid requires early to mid-seral riparian habitats created and maintained by streams active within their floodplains. Suitable orchid habitat is being reduced in area and becoming increasingly fragmented due to conversion of land to urban and suburban uses and certain water and stream system management practices associated with municipal , agricultural , and recreational uses. The naturally small size and scattered distribution of Ute ladies'-tresses populations makes the species particularly vulnerable to the effects of habitat fragmentation and overall decline of suitable habitat. Recovery Objective: The continued existence of the Ute ladies'-tresses along a stream system and in floodplain wet meadows requires either 1) direct manipulation of habitat to maintain necessary hydrologic and vegetation community conditions or 2) assurance of the continual creation and evolution of favorable habitat conditions resulting from natural stream dynamics. Of these options, the latter, ensuring the conditions that allow natural stream dynamics to create and maintain preferred orchid habitat, is in the long run the most dependable and ecologically desirable way to guarantee the viability of the orchid in perpetuity. Recovery objectives for the Ute ladies'-tresses include: iii it