Human-caused introductions of non-native species are occurring at unprecedented rates and spatial scales. These invasions have become so common and influential that they are considered one of the major drivers of global change. Grasslands throughout California are some of the most heavily invaded systems in the world, having undergone a nearly complete transformation from native flora to exotic annual grasses. Grasslands along the coast are less degraded than inland ones, but are still in need of management activities to reduce the dominance of exotics and to promote natives. Grazing by domestic livestock such as cattle may be an effective tool for mitigating these invasions, but results to date have been complex and often come from correlative rather than experimental studies. Here, we summarize results from a cattle exclosure experiment that evaluates the effects of grazing on species richness and cover of both native and exotic plant groups in a coastal grassland in central California.
Results/Conclusions
After three years, we have found that grazing significantly reduced the cover of exotic annual grasses and increased native plant species richness. Additionally, we have found that variations in aboveground plant biomass was positively correlated with changes in exotic species cover, which suggests that increased intensity of grazing leads to greater reduction in exotics. In summary, our results indicate that cattle grazing may be an effective tool for the sustainable management of coastal grasslands.
