The University of Arizona

Effects of short-duration on winter annuals in the Texas Rolling Plains.

J.R. Weigel, G.R. McPherson, C.M. Britton


A study was conducted in the Texas Rolling Plains to test the hypotheses that short-duration grazing increases plant density and diversity in grasslands. Densities of 9 species of winter annual forbs and 2 species of annual grass were compared in short-duration grazed and ungrazed areas for 2 years. Livestock grazing in spring and early summer affected density of 8 winter annuals the following winter. Densities of 2 grasses [little barley (Hordeum pusillum Nutt.) and six-weeks fescue (Vulpia octoflora [Walt.] Rydb.)] and 3 forbs [common broomweed (Xanthocephalum dracunculoides [DC.]), Gordon's bladderpod (Lesquerella Gordonii [Gray] Wats.), and Texas filaree (Erodium texanum Gray.)] were higher in grazed areas; 3 forbs [bitterweed (Hymenoxys odorata DC.), spurge (Euphorbia sp.), and woolly plaintain (Plantago patagonica Jacq.) were more abundant in exclosures. Richness and diversity of winter annuals generally were not affected by grazing. Increased precipitation during germination and establishment greatly increased the density of winter annuals.


annuals;rotational grazing;grazing intensity;Texas;botanical composition

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