Responses of aboveground biomass and soil organic carbon t o projected future climate change in Inner Mongolian grasslands

Understanding the impacts of future climate change on the grassland ecosystems of Inner Mongolia is important for adaptation of natural resource planning, livestock industries and livelihoods. The CENTURY model was validated against observed climate data from 1981 to 2010 for 16 sites. It simulated grass productivity and soil fertility with acceptable agreement, with the coefficient of the root-mean-square error calculated as 41.0% for biomass and 19.5% for soil organic carbon. The model was then used to assess changes to 2100 in aboveground biomass and soil organic carbon under two different climate-change scenarios that were developed for the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. The first scenario, RCP4.5 is an intermediate scenario for climate change, incorporating policies and technologies that stabilise growth in greenhouse-gas emissions. The second, RCP8.5, assumes continuing, high demand for energy and increasing greenhouse-gas emissions. Aboveground biomass of meadow and desert steppes responded positively to both scenarios, whereas the typical steppe showed a negative response to RCP4.5 but a positive response to RCP 8.5. Soil organic carbon showed a negative response for all steppe types. The simulations indicated that aboveground biomass and soil organic carbon of Inner Mongolian steppes were sensitive to projected emission scenarios. The CENTURY model predicted aboveground biomass to be 8.5% higher in the longer term (2081-2100) than baseline (1986-2005) under RCP4.5, and 24.3% higher under RCP8.5. Soil organic carbon was predicted to undergo small but significant decreases on average across all sites (1.2% for RCP4.5. 2.9% for RCP8.5). Our results could help decision makers to appreciate the consequences of climate change and plan adaptation strategies.