Livestock grazing is a major land use in California. While grazing converts grass and other plants into meat, leather, wool, and other products, it also affects biota and their associated ecological systems in varied and complex ways. Through consumption, physical impact, and nutrient redistribution, grazing livestock can change vegetation, soils, and habitats. Although grazing effects are known, whether they are beneficial or detrimental to a specific species depends on the species, the ecosystem, the current environmental conditions, as well as the management of the livestock and grazing. In implementing the United States’ Endangered Species Act (ESA) of 1973, the United States Fish and Wildlife Service identifies plants and animals vulnerable to extinction and develops information about their recovery that includes recognizing specific threats to individuals and their habitats. Past studies have used ESA data to quantify threats to threatened and endangered species, including impacts to species and habitat from livestock grazing. In this study, we analyze ESA data to quantify and describe impacts of livestock grazing, threats as well as benefits, on the conservation of all federally-listed threatened and endangered species in California.
Results/Conclusions
Based on ESA listing documents, recovery plans, and species status reviews, approximately 75% of the 283 federally-listed plant and animal species in California have some nexus with grazing. While 42% are said to be threatened by livestock grazing, trampling, or overgrazing, impacts of grazing vary. Livestock grazing, among other factors, has contributed to the spread of non-native species and habitat loss, and livestock consume and trample plants or parts of plants. However, grazing and ranching also provide conservation benefits; at least 43% of the listed species or 90 species in California may be positively impacted by grazing. Grazing is credited for reducing competition from invasive species, and for providing and maintaining specific environments and habitats for some flowering plants, mammals, insects, reptiles, amphibians, fish, crustaceans, and birds. Benefits from grazing are found across all of California’s terrestrial and aquatic habitats except for those in alpine and marine locations. This assessment of grazing impacts on federally-listed species in California documents a critical role for livestock in species conservation in combating impacts of invasive species and other anthropomorphic threats such as nitrogen deposition and land-use change.