Wyoming Big Sagebrush and Herbaceous Cover Relationships

Abstract

<p class="emsd"><span lang="EN-GB">We measured 328 sites in northern, central, and southern Montana and northern Wyoming during 2003 to test the competitive relationship of herbaceous cover in the interspaces to Wyoming big sagebrush (<em>Artemisia tridentata wyomingensis)</em> 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 R<sub><span>a</span></sub><sup><span>2</span></sup> 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 (<a name="OLE_LINK2"></a><a name="OLE_LINK1"></a>R<sub><span>a</span></sub><sup><span>2</span></sup> = 0.16, P < 0.001, n = 87). In central Montana, the model was Y = 14.0 – 0.00X (R<sub><span>a</span></sub><sup><span>2</span></sup> = 0.00, P = 1.0, n = 155). In southern Montana, the model was Y = 35.9 – 0.39X (R<sub><span>a</span></sub><sup><span>2</span></sup> = 0.14, P < 0.001, n = 86). When all sites were combined, the best fit model was Y = 23.7 – 0.15X (R<sub><span>a</span></sub><sup><span>2</span> </sup>= 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 long-term herbaceous production for greater sage-grouse (<em>Centrocercus urophasianus</em>) would not be recommended.</span></p>