Impacts Of Climate Change And Grazing On Grassland In Inner Mongolia And Adaptation Strategies

Inner Mongolian grassland is not only an important part of the agricultural resource, but also an important natural resource and natural ecological barrier in Northern China. However, getting warmer and drier global climate inhibits the growth of grass and causes grass degradation, which restricts the sustainable development of grass stockbreeding. The study of grassland vulnerability in Inner Mongolia under the context of climate change is of considerable realistic significance for the rational using of Inner Mongolia grassland resources, promoting long-term healthy and stable development of grass stockbreeding. In this paper, we utilized the regional CENTURY model to simulate aboveground biomass and soil organic carbon in Inner Mongolia and analyzed their temporal and spatial distribution characteristics. We anlysed the effects of different grazing intensity and different grazing patterns on grassland biomass and soil organic carbon, and proposed proper adaptation strategies for local herders and policy maders to achieve the sustainable development of grassland. We tried to establish the vulnerability assessment system of Inner Mongolian grassland to evaluate its variable and vulnerable characteristics. The main conclusions are as follows:(1) The single point verification of CENTURY model simulation for aboveground biomass,0-20cm soil organic carbon and total nitrogen in Inner Mongolia indicated that:the simulation of0-20cm soil organic carbon performed the best consistency with observed data, followed by the simulation of soil total nitrogen. The linear regression determination coefficient (R2) of simulated and observed aboveground biomass was greater than0.5except at June. The simulations of CENTURY model were in good agreement with observed values. The spatial validation of simulation by using2006-2008data in Inner Mongolia showed that:when observed values were less than150g/m2, simulations were slightly higher, while simulations were slightly lower with observed values were greater than150g/m2.(2) Based on the CENTURY model simulations, aboveground biomass and0-20cm soil organic carbon in Inner Mongolia illustrated zonal distribution:decreasing from northeast region to southwest region. Among them, the aboveground biomass reduced from higher than350g/m2to less than50g/m2, and0-20cm soil organic carbon reduced from8000g C/m2to500g C/m2. The trends of aboveground biomass and0-20cm soil organic carbon showed obvious spatial differences during1961to2010. Aboveground biomass increased in most of region under the context of climate change, especially at meadow steppe and desert steppe under the RCP8.5scenario. Soil organic carbon under the context of climate change showed a decreasing trend due to the increasing temperature and pericipitation.(3) Under the background of future climate change, meadow grassland biomass was likely to increase obviously and the local government would have opportunity to increase grazing intensity accordingly to improve grassland utilization efficiency and realize the unification of ecological and economic benefits. Typical grassland biomass decreased under the RCP4.5scenarios, and it would be a big challenge for local government to control the livestock stocking rates in order to maintain the stability of grassland ecosystems. Rotational grazing strategies are better than traditional continuous grazing. Under future context of climate change, grazing-enclosed way with lightly grazing intensity could keep the quality of herbage, but also improve livestock production performance in order to maintain the grass "healthy" state and realize the unification of ecological and economic benefits.(4) Taking the sensitivity, adaptability and exposure of grassland into consideration, we tried to establish the vulnerability index of grassland in Inner Mongolia, and to anlyze the vulnerability of grassland in Inner Mongolia under climate change. As a whole, the vulnerable degree gradually decreased from east to west in Inner Mongolia. Meadow grassland was extremely at severely vulnerable or extremely vulnerable state. Typical steppe and the western border region of agro-pastoral ecotone were at moderate vulnerable state. Desert grassland was in lightly vulnerable state. And Alxa League was in potential vulnerable state. Under the background of future climate change, meadow steppe and typical steppe vulnerability varied obviously, restoring from moderate or severely vulnerable state in2030s to potential vulnerable state in2090s, and vulnerability in desert grasslands and Alxa League stayed unchanged.