Observations And Modeling Of ANPP Dynamics For Desert Steppe In Inner Mongolia And Its Responses To Global Climate Change Based On CENTURY Model

We analyzed the temporal and spatial variation of temperature and precipitation of desert steppe in Inner Mongolia according to the 11 automatic weather stations data from 1985 to 2014; calibrated and tested CENTURY model using seven sampling points include siziwang banner、damao banner、mandula、 dongsu banner、xisu banner、Erenhot and wulatehou banner. Then, simulated the temporal and spatial dynamic of aboveground net primary productivity (ANPP) of desert steppe in Inner Mongolia, also analyzed the correlations between ANPP and precipitation and moisture factors. The conclusions are as followed:(1) The annual average temperature and average temperature growing season show a significant warming trend in rate of 0.55℃/10a and 0.646℃/10a, respectively there is the significant increasing trend from 1985 to 2014.The largest extent of temperature increase mainly occurresin the wulate banner. Annual precipitation and growing season precipitation showe a weakly upward trend and fluctuate around the annual average value.The spatial distribution showes that annual average temperature had increased significantly in most parts of desert steppe in Inner Mongolia. Annual precipitation increases only in siziwang banner but in recent decade it was declined.(2) We verified the accuracy of CENTURY model. The results showed that the value of R is 0.7032, the value of RMSE is 35.79g/m2, and that of MAPE is 37.0%, which indicate that CENTURY model has the high credibility in desert steppe in Inner Mongolia and itis more suitable to simulate ANPP in this region.(3) ANPP decreases in desert grassland in Inner Mongolia from 1985 to 2014with the change rate of-0.921g/m2 ·10a.and has a low-high-low trend. The regional variation of ANPP is strong,and show a trend of decreasing from southeast to northwest in desert grassland in Inner Mongolia.(4) The correlation analysis between the meteorological factors and ANPP shows that ANPP has a extremely significant correlation with annual precipitation, growing season precipitation and available precipitation. The correlation between ANPP and annual average relative humidity is significant. The correlation between ANPP and extreme maximum temperature is extremely significant negative. ANPP has no significant correlation with mean annual temperature,annual maximum air temperatures, annual average minimum air temperatures, extreme minimum temperatures, sunshine Shi number, and annual average wind speed.(5) We established a climate-production model of grassland with temperature and precipitation. The model is:y=-48.849+0.571x1,-0.336x2, which means that if the mean annual precipitation increase or decreases by 1mm, the annual climatic productivity of desert grassland in Inner Mongolia will increaseor decrease with the rate of 0.751 g/m2 and if the mean annual temperature increased or decreased by 1℃, the annual productivity will decrease or increase with the rate of 0.336 g/m2.