Interaction of grazing with biodiversity and climate affects ecosystem services

Grazing is the most extensive type of land use worldwide, but how does it affect a region's ecosystem services? Fernando Maestre and colleagues now show in a global survey that grazing's impact depends on its interaction with other factors such as biodiversity, climate, and soil composition. Learning more about grazing's effect on ecosystem services is particularly critical for drylands, which make up 78% of global rangelands where grazing provides nutrition and income for one billion people. Maestre et al. studied grazing's impacts through a survey of plots ranging from low to high grazing pressure by livestock and some natural herbivores, at 98 dryland sites across six continents. They evaluated nine ecosystem services in these plots, including plant, animal, and soil organism diversity, water regulation, carbon storage, erosion, and provisioning of materials such as wood, among other services. The researchers found that, on average, increasing grazing pressure had positive impacts on ecosystem services in cold sites rich in plant species diversity, but negative effects in warmer sites with lower plant species diversity. Efforts to promote diverse grazing systems could limit some of these negative effects and increase soil carbon storage, according to the researchers. In a related Perspective, Amy Ganguli and Megan O'Rourke discuss how this grazing study and others need transdisciplinary context and cooperation so that their findings can be turned into actionable climate change policy.