We measured 328 sites in northern, central, and southern Montana and northern Wyoming during 2003 to test the relationship of herbaceous cover to Wyoming big sagebrush (Artemisia tridentata wyomingensis) cover. Long term annual precipitation at all sites was approximately 31 cm. Sagebrush and total herbaceous cover varied from 5 to 45 percent and 3.5 to 55 percent, respectively. Simple linear regression was the best fit model for predicting herbaceous cover from sagebrush cover using the highest Ra2 values as the model selection criteria. In northern Montana, herbaceous vegetation was predicted by sagebrush cover with the following model: Y = 37.4 – 0.61X (Ra2 = 0.16, P < 0.001, n = 87). In central Montana, the model was Y = 14.0 – 0.00X (Ra2 = 0.00, P = 1.0, n = 155). In southern Montana, the model was Y = 35.9 – 0.39X (Ra2 = 0.14, P < 0.001, n = 86). When all sites were combined, the best fit model was Y = 23.7 – 0.15X (Ra2 = 0.01, P < 0.061, n = 328). This analysis determined that only 1 percent of the variation in herbaceous vegetation cover was associated with Wyoming big sagebrush cover. Management suggestions to reduce Wyoming big sagebrush in order to increase herbaceous production for greater sage-grouse (Centrocercus urophasianus) or livestock do not appear to be biologically sound. Keywords: Artemisia tridentata wyomingensis, line intercept, grass cover, Centrocercus urophasianus, forb cover, greater sage-grouse, sage-grouse habitat.
Sowell, Bok F.; Wambolt, Carl L.; Woodward, Jennifer K.; and Lane, Vanessa R.
"Relationship of Wyoming Big Sagebrush Cover to Herbaceous Vegetation,"
Natural Resources and Environmental Issues:
Vol. 16, Article 14.
Available at: http://digitalcommons.usu.edu/nrei/vol16/iss1/14