continued changes in stream channel position and encroachment of later- 

 successional vegetation may eventually result in a localized decline. But not 

 all occurrences are confined to riversides. It is also found in valley meadows 

 where agricultural practices (grazing and haying) reduce competition under 

 some conditions by an appropriately-timed removal of competing vegetation 

 (Arft 1995a). 



In the cases of the Montana occurrences, its habitat is not directly associated 

 with riverside succession. Instead, they are along shallow, wetlands set back 

 from the rivers in broad, open valleys. They are highly meandered shallow 

 wetland complexes and they are part of alluvial fans possibly attributed to 

 structural/tectonic activity (Locke pers. conmiun.). 



In Montana, it appears restricted to localized edaphic conditions rather than 

 serai stages in order to compete with other vegetation and persist. It was 

 most consistently found in small zones and meander segments where calcium 

 carbonate and possibly peat concentrations are high. The density and stature 

 of the vegetation in these locales was usually sparse and short compared to 

 surrounding wetland habitat. These meadow settings are analgous to those of 

 meadow occurrences in other states. 



The Montana sites are in a landscape that was historically grazed by bison 

 and periodically burned by Native Americans. Abundant buffalo sign were 

 noted in what is now the Whitehall area, and recent fires set by Indians noted 

 both upstream and downstream by Lewis and Clark (Nell and Taylor 1996). 

 In the areas where Spiranthes diluvialis occurs, Lewis reported traversing the 

 high bordering plains rather than the "wide bottoms" because of the "meriads 

 of deep holes" where they also noted "mineral salts" and "some excellent terf 

 or peat" (Nell and Taylor 1996). 



Wildfire burned throughout one segment of a population (EO#004) that was 

 also the only observed species' setting with extensive pools of standing water. 

 The fire was concentrated in the surrounding upland. It is believed to 

 correspond with newspaper reports of lightening-started fire in the drought- 

 conditions of 1994. The fire charred the few willows in the middle of the 

 wetland habitat, most of which resprouted. This suggests that fire can bum 

 the wetland meadow habitat and that the species survives fire under some 

 circumstances, but it is inadequate circumstantial information lacking in 

 details and controls for making any other inferences. 



7. Other unusual physical features: The meandered wetland channels are 



highly convoluted and found in parallel series, sometimes in high density. 

 The Spiranthes diluvialis is fovmd in discontinuous bands on either side of the 

 wetland margin. There can be several miles of potential habitat within a given 



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