近20年黄河流域植被净初级生产力时空分布及其对极端天气变化的时空响应

为探究黄河流域植被净初级生产力(Net Primary Productivity, NPP)变化及对极端天气指数的响应情况，利用MODIS NPP数据和极端气候数据，辅以斜率法和偏相关分析法分析了2000—2019年黄河流域植被NPP时空动态及其对极端降水指数和极端温度指数的响应情况。结果表明：(1)近20 a黄河流域植被NPP呈从北向南增加的趋势，大面积上表现为增加趋势。(2) NPP与极端降水指标以显著和极显著正相关为主。其中，除最长连续湿润天数呈显著正相关和极显著正相关的像元占比为16.5%,其他几种指标均在25%以上。(3)极端降水事件的水量和强度呈显著增加趋势，极端温度事件中与偏冷相关指标总体呈下降趋势，与变暖有关的事件呈明显上升趋势，其变化存在显著空间异质性，年际差异大。(4)日最高气温的最大值、日最低气温的最大值、冷夜日数、冷昼日数、冰冻天数和霜冻天与植被NPP以负相关为主，日最高气温的最小值、日最低气温的最小值、暖夜日数、暖昼日数、气温日较差和暖期与植被NPP以正相关为主。近20 a黄河流域植被NPP时空变化存在显著地域性差异，其中在干旱和半干旱地区极端降水增多在一定程...

Spatiotemporal Variation of NPP and Its Response to Extreme Climate Indices in Yellow River Basin in Recent 20 Years

MODIS NPP data and extreme weather data are used in order to explore the changes of net primary productivity(NPP)of vegetation in this area and its response to extreme weather indexes. The spatial and temporal dynamics of NPP of vegetation in the Yellow River Basin from 2000 to 2019 and its response to extreme precipitation index and extreme temperature index were analyzed by using slope method and partial correlation analysis. Based on MODIS NPP and extreme climate data, the spatiotemporal variation characteristics and trend of vegetation NPP and its response to extreme climate change in Yellow River Basin from 2000 to 2019 were studied by using trend analysis and partial correlation analysis. The results showed that:(1)in the past 20 years, the vegetation NPP in the Yellow River Basin showed an increasing trend from north to south, and showed an increasing trend in a large area;(2)NPP was mainly positively correlated with extreme precipitation events; among them, except that the pixels with significant positive correlation and extremely significant positive correlation for the longest continuous wet days accounted for 16.5%, the other indicators were more than 25%, indicating that the increase of extreme precipitation events was conducive to the increase of vegetation NPP;(3)the water volume and intensity of extreme precipitation events showed a significant increasing trend, the indicators related to partial cooling in extreme temperature events generally showed a downward trend, and the events related to warming showed an obvious upward trend; there was significant spatial heterogeneity and large interannual difference in their changes;(4)the maximum value of daily maximum temperature, the maximum value of daily minimum temperature, cold night days, cold day days, freezing days and frost days were mainly negatively correlated with vegetation NPP, while the minimum value of daily maximum temperature, the minimum value of daily minimum temperature, warm night days, warm day days, daily temperature range and warm period were mainly positively correlated with vegetation NPP; there are significant regional differences in the spatial and temporal changes of NPP of vegetation in the Yellow River Basin in recent 20 years; in arid and semi-arid areas, the increase of extreme precipitation was beneficial to vegetation growth to a certain extent, but the increase of extreme temperature was very unfavorable to vegetation growth in this area; in addition, vegetation growth in humid areas had a negative effect on extreme climate. The above research results have guiding significance for the vegetation growth monitoring and climate change response in the Yellow River Basin to propose protection strategies, promote vegetation ecological recovery, formulate effective disaster prevention and mitigation measures, and build a stable ecological barrier.