II. ASSESSMENT AND MANAGEMENT RECOMMENDATIONS 

 ^ A. THREATS TO KNOWN POPULATIONS 



1. LIVESTOCK GRAZING: Graminoid plants such as 

 sedges are adapted to grazing and are usually able 

 to persist with light to moderate grazing pressure 

 (Dyer et al. 1993, McNaughton 1979). Evidence 

 suggests that Carex parryana ssp. idahoa responds 

 to grazing like a typical palatable graminoid (see 

 I.G.l.b. and Appendix D.), capable of persisting 

 under light to moderate grazing, but declining 

 with chronic heavy grazing. It should be 

 remembered that this assessment is based on 

 correlational data and studies of other, 

 anatomically similar species. Experiments and 

 monitoring studies to determine the actual 

 response of C. parryana ssp. idahoa to grazing 

 have not been conducted. Nonetheless, it is 

 reasonable to assume that C. parryana ssp. idahoa 

 will decline with heavy grazing. 



Almost all known populations of Carex parryana 

 ssp. idahoa on public lands are subject to 

 livestock grazing. Much of the habitat for C. 

 parryana ssp. idahoa on private land is also 

 ^ subject to cattle grazing. The mesic habitat 



W supporting populations of this sedge provides high 



quality, green forage for livestock throughout the 

 summer and is a magnet for cattle which often 

 overgraze. Many small populations of C. parryana 

 ssp. idahoa occur in islands of mesic habitat 

 (springs, seeps or small streams) in semi-arid 

 steppe. Vegetation of these areas often receive 

 ca. 100% utilization annually. Populations 

 occupying larger areas of habitat may not face 

 such severe grazing pressure. However, it is 

 likely that some populations are declining due to 

 livestock grazing. 



Severe livestock grazing can result in streambank 

 destabilization followed by lowering of the water 

 table and a reduction in the extent of hydrophytic 

 vegetation (Platts and Nelson 1989) . Overgrazing 

 could reduce the extent of Carex parryana ssp. 

 idahoa habitat associated with riparian areas. 



2. MOWING FOR HAY: Large areas of likely Carex 

 parryana ssp. idahoa habitat on private land in 

 southern Beaverhead county are mowed for hay. 

 These sites have not been surveyed, so only 



^ conjecture is possible at this time. Many of 



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