EVALUATING GRAZING STRATEGIES FOR CATTLE - DEER FORAGE DYNAMICS

We documented vegetation dynamics (April 1986-July 1989) as part of a larger study to understand botanical composition and nutritional compo nents of cattle and deer diets under 2 grazing systems (continuous and short-duration), and 2 stocking rates (heavy and moderate) at the Wel der Wildlife Refuge, Sinton, Tex. Objectives of the study were to exam ine initial vegetation homo geneity and floral changes over time in th e plant community, and to determine phytomass dynamics. Results indica ted that grazing treatment had no impact on homogeneity of the plant c ommunity. Cattle grazing, regardless of treatment, increased diversity with time until drought conditions persisted and diversity declined. Shannon's diversity index (H) changed from a pre-treatment value of H = 2.41 in April 1986, to H = 3.08 in April 1988, to H = 2.61 in April 1989. There was no difference (P > 0.05) in diversity index between gr azing treatments or replication within years. Stocking rates (heavy = 198 g/m(2) differed (P < 0.05) from moderate = 258 g/m(2)) had a more significant impact on phytomass than grazing system (continuous = 225 g/m(2); short-duration grazing -231 g/m(2); P > 0.05) by the end of th e study period Precipitation was a determinant factor in the seasonal dynamics of phytomass of the various forage classes. Phytomass of forb s was unaffected by grazing system or stocking rate. Phytomass of gras ses and grass-like plants important to deer was lower (P < 0.05) under short-duration than continuous grazing. Phytomass of grasses and gras s-like plants preferred by deer was greater under moderate than heavy stocking rates. We recommend continuous over short-duration grazing, a nd moderate over heavy stocking rates, when white-tailed deer habitat quality is a primary concern. Less intensive grazing systems should be acceptable as well.