Ecological Consequences of Climate Change on Rangelands

Climate change science predicts warming and greater climatic variability for the foreseeable future. These changes in climate, together with direct effects of increased atmospheric CO2 concentration on plant growth and transpiration, will influence factors such as soil water and nitrogen availability that regulate the provisioning of plant and animal products from rangelands. Ecological consequences of the major climate change drivers-warming, precipitation modification, and CO2 enrichment-will vary among rangelands partly because temperature and precipitation shifts will vary regionally, but also because driver effects frequently are nonadditive, contingent on current environment conditions, and interact synergistically with disturbance regimes and human interventions. Consequences of climate change that are of special relevance to rangelands are modification of forage quantity and quality, livestock metabolism, and plant community composition. Warming is anticipated to be accompanied by a decrease in precipitation in already arid to semiarid rangelands in the southwestern USA, Central America, and south and southwestern Australia. Higher temperatures combined with drought will significantly impair livestock production by negatively impacting animal physiological performance, increasing ectoparasite abundances, and reducing forage quality and quantity. Conversely, the warmer, wetter conditions anticipated in the northwestern USA, southern Canada, and northern Asia may increase animal productivity by moderating winter temperatures, lengthening the growing season, and increasing plant productivity. Synergist interactions between climate change drivers and other human impacts, including changes in land-use patterns, intensification of disturbances, and species introductions and movements, may further challenge ecosystem integrity and functionality. Evidence from decades of research in the animal and ecological sciences indicates that continued directional change in climate will substantially modify ecosystem services provisioned by the world's rangelands.