Results 



Meadow communities supporting populations of Carex parryana 

 ssp. idahoa were dominated by the graminoids, Carex praegracilis , 

 Juncus balticus and Muhlenbergia richardsonis (Table 1) . Common 

 forbs included Antennaria microphylla, Aster occidentalis , 

 Potentilla gracilis and Taraxacum officinale. Shrubs {Potentilla 

 fr^ticosa) were common at only two sites (Table 1) . 



Density of Carex parryana ssp. idahoa flowering stems was 

 strongly positively correlated with total graminoid cover and 

 negatively correlated with total forb cover (Table 2) . 

 Muhlenbergia richardsonis was positively correlated with density 

 of Carex parryana ssp. idahoa. Species most strongly negatively 

 correlated with Carex parryana ssp. idahoa stems were of Poa 

 pratensis, Antennaria microphylla and Aster occidentalis (Table 

 2). 



Density of Carex parryana ssp. idahoa flowering stems varied 

 from 4 to 310 stems/ 100 m^ with a mean of 67 stems/ 100 m^. Total 

 forb cover varied from 5 to 75% with a mean of 42%, and total 

 graminoid cover varied from 60 to 100% with a mean of 86%. Log- 

 transformation of the dependent variable increased the negative 

 relationship with forb cover (r=0.68, P=0.007) and the positive 

 relationship with graminoid cover (r=0.38, P=0.182). 



Discussion 



Flowering by rhizomatous species may be affected by the 

 degree of stress experienced by the clone. Some species flower 

 sparsely when in a dense sward. This does not appear to be the 

 case with Carex parryana ssp. idahoa as there was a positive 

 relationship between canopy cover of graminoid plants and the 

 density of C. parryana stems. 



All of the study sites appeared to have been subjected to 

 livestock grazing in the recent past and were most likely 

 subjected to livestock or bison grazing in the more distant past. 

 Nonetheless, Carex parryana ssp. idahoa has persisted at these 

 sites and was abundant at some of them, suggesting that it can 

 tolerate at least light to moderate grazing. 



Although Carex parryana ssp. idahoa has persisted at many 

 sites subjected to grazing, results of the study suggest that it 

 does decrease under grazing pressure strong enough to cause 

 significant increases in unpalatable forb cover. Cattle 

 preferentially graze graminoids rather than most forbs, so that 

 among similar habitats those with higher forb cover have usually 

 experienced stronger grazing pressure (Ross and Hunter 1976, 

 Hansen et al. 1995) . Poa pratensis also increases with livestock 

 grazing (Hansen et al 1995) . Across the 14 study sites there was 

 a negative correlation between the canopy cover of forbs and Poa 



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