PS 45-193 - Coastal grassland plant community shifts along a grazing management continuum

Abstract: Rangelands cover the majority of the land area in California – approximately 60%. California rangelands represent a multi-billion dollar industry and are of vital importance from both an economic and ecological standpoint. Rangelands are comprised of a variety of habitats, but the habitat type with both the highest concentration of grazing and highest output of forage are grasslands. Along with their economic importance, California grasslands are reservoirs of biodiversity – grasslands alone support about 40% of California’s total native plant species. Further, 90% of California’s rare and endangered plant species are found in grasslands. California grasslands face challenges from non-native species invasion, drought, and land degradation. Restoration of this critical plant community and working landscape is needed to continue to support its vital ecological and economic functions. We conducted an observational study along a grazing management continuum to assess management impacts on plant community composition. Our study compared plant and soil responses of three ranches: one under continuous grazing management, one under rotational conservation grazing management, and a county park that has been ungrazed for 4 years. We hypothesize that rangelands managed under conservation grazing will have greater cover of native species and lower cover of nonnative species, and that the rangelands managed under conservation grazing will have plant communities more similar in structure and composition to intact native grasslands. We quantified plant communities by assessing cover and several aspects of the surface soil environment. We found significantly higher plant species richness under rotational conservation grazing compared to the other two sites. We found significantly higher diversity under continuous grazing compared to the other two sites. Average cover of native taxa did not differ between the sites. Naturalized plant cover was lowest at the county park with no recent grazing, and not different between the other two sites. We will evaluate whether soil properties or management are stronger drivers of these community shifts. Our results indicate that it is possible to support biodiversity and conservation goals in working landscapes.