Individual study: Grazing maintains native plant diversity and promotes community stability in an annual grassland
Beck J.J., Hernández D.L., Pasari J.R. & Zavaleta E.S. (2015) Grazing maintains native plant diversity and promotes community stability in an annual grassland. Ecological Applications, 25, 1259-1270
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Other biodiversity: Exclude grazers
A replicated, randomized, controlled study in 2007–2013 in grasslands in central California, USA, found that native plant species were lost from plots from which cattle were excluded, but increased in grazed plots, in one of two experiments. There were also differences in the plant community between plots with and without grazers, in one of two experiments. Plants: The number of native plant species decreased in plots from which cattle were excluded but increased in plots grazed by cattle, in one of two experiments (experiment 1: 4.5 species/year lost vs 0.5 species/year gained; experiment 2: 2.2 species/year lost vs. 0.5 species/year gained). The cover of native non-grass species increased more slowly in ungrazed plots, compared to plots grazed by cattle (data reported as log response ratios). The cover of grasses was higher in ungrazed, compared to grazed plots, in one of two experiments (experiment 1: 25–61% cover vs 8–47%; experiment 2: 17–58% for both). The diversity of native non-grass species increased more slowly in plots from which grazers were excluded, compared to plots grazed by cattle, in one of two experiments (data reported as log response ratios). Community composition varied between ungrazed and grazed plots, in one of two experiments (data reported as canonical regression coefficients). The number of native species, cover of native, non-grass species, and the diversity of measures were also less stable over time in plots from which grazers were excluded, compared to cattle-grazed plots (data reported as the ratio of average to standard deviations). Methods: Experiment 1 was established in 2007 and experiment 2 was established in 2009, both in cattle-grazed grassland. In each experiment, ten 5 x 5 m plots were established, with cattle excluded from half and allowed to graze the other half. Plants were monitored in March–April 2008–2013 in two 0.5 x 0.5 m quadrats within each plot.