Schizachyrium scoparium is a dominant late-seral perennial grass that was grown in competition with another S. scoparium, with Bothriochloa saccharoides, or with Stipa leucotrichaor (two other mid-seral perennials), and clipped four times a year to simulate uniform or selective grazing (towards S. scoparium). Selective defoliation did not significantly (a = 0.1) reduce basal area of S. scoparium, that was 175% greater when grown with the other species and subject to uniform defoliation. Other measures of productivity (tiller mass, number of leaves, xylem pressure potential, etc.) were influenced by species selective interactions. Selectively grazing hurt plants to a degree, depending on competition, for example S. scoparium is as grazing tolerant as the other two species, and selective grazing drives species replacement, not tolerance of mid-seral species relative to late-seral species. The greater competitive ability of S. scoparium that was amplified in uniform grazing situations implies that some types of grazing may inhibit species replacement, rather then inducing it. However, heavy selective grazing may result in a shift in species composition.
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