摘要:干旱对全球陆地生态系统影响广泛，中国东北地区干湿分异典型，干旱面积有逐步增大趋势，为了解东北地区自然植被生产力对干旱的响应，基于MODIS公开的数据产品、降水数据和scPDSI，采用统计学方法，在明确2002-2013年东北地区干旱分布特征的基础上，分析自然植被NPP、LAI和CUE的时空变化规律，探究自然植被对独立干旱事件和持续干旱的响应，结果表明：①从2002-2013年平均水平上看，森林的NPP和LAI年平均值明显高于草地，CUE年平均值略低于草地；②森林和草地均通过降低NPP和LAI来应对独立干旱事件，森林的NPP在干旱年过后第3年显著低于干旱前，LAI在干旱年过后第2年显著高于干旱前，而且这种变化效应至少持续到干旱年过后第4年；草地的NPP和LAI仅在独立干旱年当年有显著变化；③随着干旱的持续，森林NPP增加的比例有扩大趋势，LAI_Baseline较低的森林在持续干旱时ΔLAI_Dryn增加的可能性越大；草地对持续干旱也具有一定的适用能力，而且NPP_Baseline、LAI_Baseline和CUE_Baseline较低的草地，在持续干旱时ΔNPP_Dryn、ΔLAI_Dryn和ΔCUE_Dryn增加的可能性越大；④无论是独立干旱事件还是持续干旱，森林或草地的CUE变化很少达到显著性水平，变化规律的显著性也低于NPP和LAI。该项研究将为提高干旱对自然生态系统影响的评估能力做出贡献。



Abstract:Drought has a far-reaching influence on global terrestrial ecosystems. There is a typical difference between dry and wet areas, and a trend of a gradual increase in dry areas toward northeast China. This study was conducted to determine the response of natural vegetation productivity to drought in northeast China. Using the data published by MODIS, precipitation data, scPDSI, and statistical methods, characteristics of drought distribution and precipitation distribution in northeast China (including Heilongjiang Province, Jilin Province, Liaoning Province, and the eastern region of Inner Mongolia) were investigated and the spatio-temporal evolution law of NPP (Net Primary Productivity), LAI (Leaf Area Index), and CUE (Carbon Use Efficiency) of natural vegetation were analyzed. The response of natural vegetation to independent drought events and persistent drought were investigated based on the above research results. The results showed that:① From the average level in 2002-2013, the annual average of NPP and LAI of forests was significantly higher than that of grasslands, and the annual average of CUE was slightly lower than that of grasslands; ② Forests and grasslands responded to independent droughts by lowering NPP and LAI, which were significantly lower in the third year after the drought than before, LAI was significantly higher in the second year after the drought year than before, and the change lasted at least four years after the drought year. NPP and LAI of grassland had significant changes only in the year of independent drought; ③With the persistence of drought, the proportion of NPP in forests increased, and the increasing likelihood of ΔLAI_Dryn in the forests with lower LAI_Baseline was greater with the duration of drought. Grasslands also had a certain ability to be suitable for persistent drought, and the increasing likelihood of ΔNPP_Dryn, ΔLAI_Dryn, and ΔCUE_Dryn in the grasslands with lower NPP_Baseline, LAI_Baseline, and CUE_Baseline was respectively greater with the duration of drought; ④ The level of CUE change in the forest or grassland was rarely significant, and the law of change was less significant than NPP and LAI regardless of the independent drought event or the persistent drought. This study contributes to improving the evaluation of the influence of drought on natural ecosystems.





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