Alzerreca-Angelo et al. used a 59-year vegetation database in combination with climate data to determine if the changes in a shadscale plant community, after the implementation of grazing management in 1935, were due to management or climactic factors. Canopy cover was lowest in 1935, when grazing management went into effect, and increased significantly until 1958; possibly due to the release from grazing pressure. However, from 1958 on, it appears that climactic factors have been impacting canopy cover more than grazing. Individual plant species experience different responses to grazing management and climate changes. Plant canopy cover of individual species increases, with and without grazing, with increased moisture. The diversity of plant responses indicate that changes are being driven by a combination of factors that may be greater than the effects of grazing and climate. In summary, from 1935-1994 shrubs increased initially, but have declined in recent years, while grasses have been increasing over the entire 59 year record. As the plant community continues to grow and develop, further studies may reveal the factors causing the shifts in this plant community.
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