基于CENTURY模型的荒漠草原ANPP对气候变化响应的模拟

Simulation of ANPP in response to climate change in China's desert steppe based on CENTURY model

荒漠草原是内蒙古草原主要类型之一,生态系统脆弱,对气候变化响应敏感。利用四子王旗生态气象观测试验站50年的气候数据、近5年的土壤调查资料和7年草地样方资料对CENTURY模型适用性进行检验;分析了过去50年地上净初级生产力(ANPP)与26个气象因子之间的相互关系;最后基于区域气候模式系统PRECIS输出的2021—2050年SRES B2、A2和A1B气候排放情景数据,分析未来50年研究区ANPP的可能变化趋势。结果表明:CENTURY模型能够成功模拟这类荒漠草原的季节动态和年际变化;生长季内逐月地上生物量模拟值与观测值之间具有较好的相关性(R2=0.66,P<0.01);在过去50年中,四子王旗荒漠草原温度增加,降水略增,ANPP增加;模拟的ANPP随气温和降水的变化呈现出明显的变化规律;相关分析表明,ANPP与降水量呈显著正相关,与年极端最高气温和年蒸发量呈显著负相关,与其余气象因子相关性不显著;在SRES B2、A2和A1B情景下,未来四子王旗荒漠草原平均最高气温、最低气温和降水量均呈现增加趋势,ANPP年际间波动较大,但总体增加趋势明显,分别较基准时段增加了2.55%、4.19%和9.44%;3种情景下,未来四子王旗气候变化均对ANPP产生正面影响。本研究实现了CENTURY模型在内蒙古荒漠草原上的应用,弥补了由于西部荒漠草原区缺乏连续长期野外试验数据及生态系统异质性而导致无法对草地生产力进行准确动态评估的不足。

Desert steppe is one of the major community types of Inner Mongolia grassland, which becomes sensitive in response to climate change. CENTURY model applicability was tested using 50-year climate data, recent 5-year soil investigation information, and 7-year quadrat data on ecological meteorological observation experimental station of Siziwang County. The correlations of aboveground net primary production （ANPP） simulation values and 26 meteorological factors in the past 50 years were analyzed. Based on the output data of climate emissions scenarios of SRES B2, A2 and A1B from the regional climate system of PRECIS, possible variation trends of ANPP were analyzed under three kinds of climate scenarios over the future 50 years in the study area. The results showed that CENTURY model can successfully simulate the seasonal dynamics and inter-annual variability in Siziwang County desert steppe. The correlation of monthly aboveground biomass between the simulated and observed values was good in growing season （R2 =0.66, P〈 0.01 ）. Increased air temperature, slightly increased precipitation, and increased ANPP were found in Siziwang County desert steppe in the past 50 years. With changes of temperature and precipitation, simulated ANPP presented obvious change patterns. Correlation analysis showed that ANPP was significantly positively correlated with precipitation, negatively correlated with an- nual extreme maximum temperature and annual evaporation, and not remarkably correlated with the other meteorological factors. Under the climate scenarios of SRES B2, A2 and A1B, the mean maximum temperature, minimum temperature and precipitation were all of increasing trends. The overall increasing trend of ANPP was evident though its inter-annual fluctuation was stronger. The increases of future ANPP under the three scenarios were 2.55% , 4. 19% and 9.44% over the baseline period, respectively. Under the three climate scenarios, impact of cli- mate change on ANPP would be positive in Siziwang County desert steppe in future. This re- search realized the application of CENTURY model on desert steppe in Inner Mongolia, and made up the lack of unrealizable dynamical evaluation and estimation for grassland productivity due to the shortage of continuous long-term field experiment data and the heterogeneity of ecosystem.