摘要：The Mongolian Plateau is dominated by grassland ecosystems. It frequently
experiences drought and is underlain by permafrost in the north. Its complex
responses of plant carbon uptake and soil carbon release to climate change are
considered to have affected the global carbon cycle during the 21st century. Here
we combine spatially explicit information on vegetation, soils, topography and
climate with a process-based biogeochemistry model to assess the carbon responses
for the 20th and 21st centuries. We estimate the region acted as a C sink of 31 Tg C yr−1 in the 1990s, but that this sink will likely decline in both magnitude and extent under
future climate conditions. This change is due to the relatively larger enhancement of soil
organic matter decomposition, which releases carbon to the atmosphere, than the
corresponding enhancement of plant C uptake, by rising temperatures and atmospheric
CO2 concentrations. Future plant C uptake rates are expected to become more limited due to
drier soils caused by increasing evapotranspiration rates. Complex soil thermal and
moisture dynamics result in large interannual and spatial variability as a consequence of
the different rates of change of air temperature and precipitation in this region.
