Abstract: Inner Mongolia grassland is one of the most important grazing lands in China. Grassland area of Inner Mongolia is about 87 million hm², accounts for 67.5% of land area of Inner Mongolia and 25% of national grassland area of China. It is very important for sustainable utilization of grassland and the prevention of grassland desertification to study the impact of climate changes on grassland ecosystem. Grassland ecosystem models have been widely used as tools to analyze the impact of climate change on grassland productivity. At present, grassland ecosystem model (CENTURY) has been validated in a single grassland type of Inner Mongolia. However, few studies evaluated the adaptability of CENTURY model in different grassland types within Inner Mongolia. Therefore, there is lack of parameters for applying CENTURY model over different grassland types of Inner Mongolia. In this paper, Ergun Right Banner (N50.25?,E120.18?), Xianghuang Banner (N42.23?,E113.83?), Wushen Banner (N38.60?,E108.83?) and Sunit Left Banner (N43.85?,E113.72?) were selected to represent four main grassland types including meadow steppe, typical steppe, desert steppe and steppe desert in Inner Mongolia. The long-term observation data of grassland biomass from the livestock meteorological experiment stations were used to calibrate and validate the grassland ecosystem model (CENTURY 4.6). CENTURY model was a process-based ecosystem model comprising the sub-models of plant production, soil organic matter and soil water movement. Monthly meteorological data (maximum temperature, minimum temperature, and precipitation) for the study sites were used as the driving variables of CENTURY model. Management measures and soil data were also used as the inputs of the model. The calibration and validation results showed that there was a close consistency between the simulated and measured aboveground biomass of meadow steppe, typical steppe, desert steppe and steppe desert. The determination coefficients (R²) were 0.60, 0.60, 0.65 and 0.59 (P<0.05). Relative mean square roots (RMSE) were 29.65, 31.45, 25.51 and 7.90 g C穖^-2. CENTURY model could be used to simulate the response of aboveground biomass of different grassland types to climate change and climate variability and thereafter study the impact of climate change on grass productivity. Sensitivity analyses showed that the sensitive parameters of grassland aboveground biomass were the optimum growth temperature, the maximum growth temperature and the coefficient for calculating potential grassland productivity. Accurate determinations of these parameters are the key in applying CENTURY model. The sensitivity analysis of CENTURY model to driving variables showed that grassland aboveground biomass was more sensitive to monthly precipitation and monthly maximal temperature than monthly minimum temperature. The changes of accumulated aboveground biomass of four main grassland types was simulated during the past 50 years (1961-2010) based on CENTURY model. The simulation results displayed that the accumulated aboveground biomass during the last 50 years increased in Ergun Right Banner and Wushen Banner and decreased in Xianghuang Banner and Sunit Left Banner, but there was no significant difference at 95% level. These results were consistent with existing studies.

Key words: Grassland ecosystem model, Climate change, Suitability, Validation

摘要： 基于草地生态系统模型评估气候变化对草地的影响及其适应对于草地的可持续利用和草地荒漠化的防治具有重要意义。本研究选择内蒙古草甸草原、典型草原、荒漠草原及草原化荒漠4种主要草地类型的代表性站点-额尔古纳右旗、镶黄旗、乌审旗和苏尼特左旗,基于牧业气象试验站的长期围封草地生物量观测资料,对草地生态系统模型(CENTURY)进行了校正和验证。结果表明:CENTURY模型模拟的草甸草原、典型草原、荒漠草原和草原化荒漠生长季地上部分生物量的模拟值与实测值变化趋势比较一致,决定系数(R²)分别为0.60, 0.60, 0.65和0.59,均方根误差(RMSE)分别为29.65, 31.45, 25.51和7.90 g C·m^-2,CENTURY模型能够模拟草地地上部分生物量对气候因子的响应,适用于气候变化对内蒙古草地生态系统的影响研究。模型参数敏感性分析表明:草地地上部分生物量敏感的生理参数是草地生长最适温度、最高温度及潜在生产力系数。对过去50年草地地上部分生物量的变化模拟显示:额尔古纳右旗与乌审旗的草地年累积地上部分生物量在近50年间呈现波动增加,镶黄旗与苏尼特左旗呈现波动减少,但统计上均不显著。

关键词: 草地生态系统模型, 气候变化, 适应性, 验证