LAUSR

Grazing represents the most extensive use of land worldwide. Yet its impacts on ecosystem services remain uncertain because pervasive interactions between grazing pressure, climate, soil properties, and biodiversity may occur but have never been addressed simultaneously. Using a standardized survey at 98 sites across six continents, we show that interactions between grazing pressure, climate, soil, and biodiversity are critical to explain the delivery of fundamental ecosystem services across drylands worldwide. Increasing grazing pressure reduced ecosystem service delivery in warmer and species-poor drylands, whereas positive effects of grazing were observed in colder and species-rich areas. Considering interactions between grazing and local abiotic and biotic factors is key for understanding the fate of dryland ecosystems under climate change and increasing human pressure. Description Complex effects of livestock Livestock grazing provides food and livelihoods for billions of people but at the cost of ecosystem degradation in many places. Maestre et al. investigated how grazing by livestock and native herbivores affects ecosystem functions and services and how these effects vary with climate, soil properties, and biodiversity (see the Perspective by Ganguli and O’Rourke). Using a replicated survey at 98 dryland sites spanning six continents, the authors found that grazing effects on ecosystem services often depend on other factors. Interactions between grazing and climate were especially important; warmer sites had lower rates of carbon storage, organic matter deposition, and erosion control under high (but not low) grazing pressure. —BEL Interactions among grazing pressure, climate, soil properties, and biodiversity affect ecosystem services provided by drylands.