近55 a新疆净生态系统生产力对气候变化的响应

新疆地处干旱和半干旱气候区，明确其生态系统的碳汇大小及其对气候变化的响应对研究中国干旱区植被碳汇及其对陆地碳平衡的贡献具有重要意义。基于最新地面气象观测数据，利用大气植被相互作用模型AVIM2（Atmosphere-Vegetation Interaction Model 2），在0.05°×0.05°经纬度空间网格上估算分析了1961-2015年新疆净生态系统生产力（NEP）的时空分布特征及其对气候变化的响应。研究结果表明：近55 a新疆NEP平均值为14.4 gC·m^-2，没有明显变化趋势。空间上看，约40%地区的NEP呈下降趋势，主要分布在天山两麓的城市人口聚集区；而60%地区NEP呈上升走势，其主要分布在新疆昆仑山脉、天山山区和人烟稀少的荒漠地区。新疆NEP对降水量变化更为敏感，气温的变化对NEP的影响并不显著。虽然新疆平均碳汇随着年降水量的变化而在源与汇之间波动，但是从多年平均来看，新疆仍然为碳汇区。

Responses of net ecosystem productivity to climate change in Xinjiang in recent 55 years

Xinjiang is located in arid and semiarid areas. Understanding Xingjiang's ecosystems carbon budget and their responses to climate change is important for studying the dryland vegetation carbon sink in China and its contribution to terrestrial carbon balance. Based on the latest meteorological observations and the atmosphere-vegetation interaction model(AVIM2), the net ecosystem productivity(NEP)of Xinjiang from 1961 to 2015, with the spatial resolution of 0.05°×0.05° grids, were simulated and its responses to climate change were analyzed. The results show that the mean NEP of Xinjiang over the 55 years was 14.4 g C·m^-2, and the NEP has no significant trend during the studying periods. NEP decreased in about 40% areas of Xinjiang, and these areas were mainly distributed in the plain areas of the northern and southern sides of the Tianshan Mountains, where with dense population. The other 60% areas in Xinjiang experienced NEP increased. These areas are distributed in Kunlun and Tianshan Mountains and those sparse vegetated areas. NEP in Xingjiang was more sensitive to precipitation than to temperature. Although Xinjiang's averaged NEP fluctuated from sources to sinks as the yearly precipitation changed, the multiyear averaged NEP was positive, implying Xinjiang was the carbon sink area.