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near the surface throughout the growing season and into the late summer or
<br /> early autumn. This observation has been corroborated by ground water
<br /> monitoring research conducted in Dinosaur National Monument (Martin & Wagner
<br /> 1992) and in Boulder, Colorado (Tamara Naumann, pers. comm. 1993) .
<br /> Ute ladies'-tresses occur primarily in areas where the vegetation is
<br /> relatively open and not overly dense or overgrown (Coyner 1989, 1990 and
<br /> Jennings 1989, 1990) . A few populations in eastern Utah and Colorado are found
<br /> in riparian woodlands, but the orchid seems generally intolerant of shade,
<br /> preferring open, grass and forb-dominated sites instead. Plants usually occur
<br /> as small scattered groups and occupy relatively small areas within the
<br /> riparian system (Stone 1993) . Common associated species in the eastern range
<br /> (Colorado's Front Range) of the orchid include Agalinis tenuifolia, Aarostis
<br /> stolonifera, Ascleoias incarnata, Calamagrostis spp. , Cirsium arvense,
<br /> Eguisetum spp. , Lobelia siohilitica, Sisvrinchium spp. , Solidago spp. ,
<br /> Triglochin spp. , and Verbena hastata. In the central section of the orchid's
<br /> range (the Uinta Basin) , common associated species are Aarostis stolonifera,
<br /> Calamagrostis spp. , Carex spp. , Cirsium spp. , Dactvlis glomerata, Eoioactis
<br /> gigantea, Eguisetum spp. , Oenothera elata, Prunella vulcaris, Salix exi ua,
<br /> and Solidago canadensis. Species commonly associated with the orchid in the
<br /> western part of the range (the Wasatch Front and the eastern Great Basin)
<br /> include Aarostis stolonifera, Alnus incana, Aster hesoerius, Carex spp. ,
<br /> Castille.ia exilis, Cirsium arvense, Eguisetum laevigatum, Juncus spp. ,
<br /> Melilotus spp. , Pooulus angustifolia, Salix spp. , Solidago occidentalis, and
<br /> Trifolium nratense.
<br /> Soils typically range from fine silt/sand to gravels and cobbles. The orchid
<br /> is sometimes found in highly organic or peaty soils. It is not found in heavy
<br /> or tight clay soils or in extremely saline or alkaline soils (pH >8.0) .
<br /> The orchid appears to be well adapted to disturbances caused by water movement
<br /> through floodplains over time (Tamara Naumann, pers. comm. 1992, Lynn Riedel ,
<br /> pers. comm. 1994) . It often grows on point bars and other recently created or
<br /> °raw" riparian habitat. It is tolerant of flooding and flood disturbance.
<br /> For example, point bars and backwater areas (old oxbows, side channels, etc.)
<br /> are often flooded for several months in the spring during snowmelt. At least
<br /> one-third of the Hog Canyon population is buried under flood debris (1 to 8 cm
<br /> of sandy debris was deposited by an August, 1993 flood) every few years (Lynn
<br /> Riedel , pers. comm. 1994) .
<br /> Once established, the orchid appears to be tolerant of somewhat drier
<br /> conditions (Riedel 1992) , but lases vigor and may gradually die out if the
<br /> groundwater table begins to consistently drop during late summer (Riedel 1992,
<br /> Anna Arft, University of Colorado, pers. comm. 1994) .
<br /> Some of the sites where the orchid occurs have a history of and are currently
<br /> managed for agricultural uses, typically late winter and early spring grazing
<br /> and mowing for hay. These sites may be naturally wet meadows or may be
<br /> supplied with irrigation water.
<br /> The habitat alteration resulting from agricultural use (such as from mowing,
<br /> grazing, and burning) may be beneficial , neutral , or detrimental to the orchid
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