Modelling Dynamics Of ANPP By Using CENTURY Model And Its Response To Climate Change In Hulun Buir, Inner Mongolia

Based on the CENTURY model, this study stimulates the ANPP of Hulun buir meadow and typical steppe in Inner Mongolia during 1985 and 2014, and also analyzes the spatial-temporal characteristics. Meanwhile, the spatial-temporal distribution pattern of temperature and precipitation in the past 30 years was showed, the correlations between ANPP and factors of temperature and precipitation had been figured out. According to the response of ANPP to the climate change,’climate-productivity’model of Hulun buir steppe had been established.(1) By adjusting parameters, it shows that the CENTURY model can be well applied in Hulun Buir Grassland area, and can well estimate the ANPP in the study area. The results showed that the value of R2, RMSE and MAPE are 0.7636, 32.69g/m2 and 14.02% respectively in the meadow steppe, while that of R2, RMSE and MAPE are 0.6246,37.13g/m2 and 30.55% respectively in the typical steppe.(2) Both in meadow and typical steppe, ANPP has increasing trend with the rate of 4.81 g/m2·10a and 0.94 g/m2·10a. The ANPP is smaller in typical steppe than that of in meadow steppe, with the trend of gradually decreasing from the east to the west.(3) In meadow steppe the annual mean temperature increases with a rate of 0.036℃/10a, while in the typical steppe the annual mean temperature shows a warming trend with a rate of 0.158℃/10a. The growing season mean temperature is more than the annual mean temperature. There is a significant increasing trend from the east to the west in both meadow and typical steppe.During the past 30 years the change of precipitation in meadow steppe increases, while in typical steppe it shows a decreasing trend. Precipitation in Hulun buir shows the significant zonel distribution trend which reflects it is the dryness in northeast and the wetness in southwest, and the downtrend from northeast to southwest.(4) Temperature in growing season is negatively correlated with ANPP, however, there is a high positive correlation between precipitation and ANPP. Therefore, precipitation plays a dominant role to promote the ANPP.(5) The two steppe " climate-productivity " models are as followed:in the meadow steppe:Z=0.544X-9.1317+10.901 (R2=0.694); in the typical steppe: Z=0.323X-0.582Y+24.028 (R2=0.7831). Z stands for ANPP estimated value; X and Y stand for the annual temperature and precipitation respectively. The model fits well by verifying.