Abstract: In order to explore the relationship between net primary productivity (NPP) change and drought in grassland growing season in Inner Mongolia Autonomous Region,this paper studies the interannual and spatial change characteristics of NPP and standardized precipitation evapotranspiration index (SPEI) in Inner Mongolia Autonomous Region from 2001 to 2015 based on the change rate analysis,correlation analysis and one-way linear regression analysis of SPEI and NPP simulated by Boreal Ecosystem Productivity Simulator (BEPS) model. At the same time,using SPEI data of different scales and grassland growth season NPP data simulated by BEPS model,the response analysis of grassland growth season NPP to drought in Inner Mongolia was realized.The results showed that the average growth rate of NPP was 2.20 g C·m^-2·a^-1 from 2001 to 2015,among which the average growth rate of NPP in meadow steppe was 3.73 g C·m^-2·a^-1,the fastest growth rate;the average growth rate of NPP in typical steppe was 1.69 g C·m^-2·a^-1,the second growth rate;the average growth rate of NPP in desert steppe was 0.30 g C·m^-2·a^-1,the slowest growth rate. In the aspect of spatial change,NPP increased gradually from southwest to northeast. Among them,meadow steppe was the highest,with an average annual unit area of 387.90 g C·m^-2·a^-1;typical steppe was the second,with an average of 291.26 g C·m^-2·a^-1;desert steppe was the lowest,with an average of 133.70 g C·m^-2·a^-1. The correlation between NPP and SPEI showed that NPP during grassland growth season had the strongest correlation with SPEI at one month scale. Meadow steppe had the strongest correlation with SPEI at one month scale,and typical steppe,desert steppe had the strongest correlation with SPEI in three months scale. The study also showed that NPP of grassland in Inner Mongolia had a strong response to short-term surface water anomalies and drought changes on a seasonal scale,while it had a poor response to medium and long-term drought changes,especially on the annual scale. The results of NPP response to SPEI showed that drought had the greatest impact on desert steppe,followed by typical steppe,and the least impact on meadow steppe.

Key words: BEPS, Grassland NPP, SPEI, Spatio-temporal change, Drought response

摘要： 为探究内蒙古草地生长季净初级生产力（Net primary productivity，NPP）的变化及其与干旱的关系，本文通过趋势变化和相关性计算对2001-2015年内蒙古草地NPP和标准化降水蒸散指数（Standardized precipitation evapotranspiration index，SPEI）的时空变化进行研究。结果表明：内蒙古草地生长季NPP平均增长率为2.20 g C·m^-2·a^-1，其中草甸草原为3.73 g C·m^-2·a^-1，典型草原为1.69 g C·m^-2·a^-1，荒漠草原为0.30 g C·m^-2·a^-1。NPP均值整体上自西南向东北逐渐增加，其中草甸草原最高，其次为典型草原，荒漠草原最低，年均NPP分别为387.90 g C·m^-2·a^-1，291.26 g C·m^-2·a^-1，133.70 g C·m^-2·a^-1。NPP整体上与SPEI-1相关性最强，其中，草甸草原与SPEI-1最强相关性最强，典型草原、荒漠草原与SPEI-3相关性最强。干旱对荒漠草原的影响最大，对典型草原的影响次之，对草甸草原的影响最小。

关键词: BEPS模型, 草地NPP, SPEI, 时空变化, 干旱响应