Severe droughts in Mongolian Plateau during recent decade: Frequency, duration and impacts on terrestrial ecosystems
Mongolian Plateau is a typical region for advancing our understanding of climate extreme impacts owing to its diversified vegetation covers, climate warming three times faster than global average, and intensive human and animal disturbances in recent decades. Both tree-ring records and climate reanalysis data sets showed a severe dry period spanning from 1997-2010 across most area of Mongolian Plateau. Here we incorporate input data of multiple environmental changes into a process-based land ecosystem model, Dynamic Land Ecosystem Model (DLEM), to investigate how drought events affected terrestrial ecosystem production, evapotranspiration (ET) and water yield in terms of different drought frequency, timing, duration, and locations.
We find that, in most years of 2000s, over 80% of land area in Mongolian Plateau suffered from moderate to extreme drought events and their duration exceeds 10 months per year. Model simulations indicate reductions of 3%, 12% and 30% in grassland NPP, ET and water yield, respectively, caused by recent decade drought relative to 30-year (1961-2000) average. Largest NPP reduction and water shortage occurred in the eastern Mongolian Plateau. Precipitation, rather than temperature, is the major climate factor regulating Mongolian grassland productivity and hydrological dynamics. Drought frequency, severity, timing, duration, as well as vegetation covers being exposed are all important indices for evaluating drought impacts on terrestrial ecosystem functions. Given vulnerability of grassland ecosystem, rigorous strategy needs to be implemented for coping with extensive and long-lasting drought.