东亚五国气象干旱时空变化特征及其对植被的影响

Temporal and spatial variation of drought and the effect of drought on vegetation in East Asia

【目的】分析气象干旱对植被生长的胁迫作用。【方法】研究东亚五国多时间尺度标准化降水指数(SPI)、标准化降水蒸散发指数(SPEI)对叶面积指数(LAI)和归一化植被指数(NDVI)的影响。【结果】对比多时间尺度的气象干旱指数发现,在短时间尺度东亚五国的气象干旱波动幅度和频率较强,长时间尺度变化趋势更为明显,SPI和SPEI呈现相反的变化趋势,且在重合的3次气象干旱事件中SPEI具有更长的干旱历时;2001—2021年东亚五国的LAI、NDVI均呈现波动增加的变化趋势,且LAI的增加率要大于NDVI的增加率;对LAI、NDVI及SPI、SPEI进行相关性分析可知,SPI-12和SPEI-12对LAI的胁迫作用最强,NDVI对SPI-3和SPEI-3最为敏感。【结论】植被生长状态最好的地区集中在中国东北部、东部及南部地区、外蒙古国北部、朝鲜、韩国日本;3个月时间尺度的气象干旱对植被绿度影响最大,而12个月时间尺度的气象干旱对植被生理状态影响最大;此外,根据最大相关系数可知盛夏时期的气象干旱对植被生长的胁迫作用最强。研究结果以期为东亚五国植物群落的生态预警和生态修复提供理论参考。

[Objective]Analyzed the stress of meteorological drought on vegetation growth.[Methods]Studied the effects of multi-time scale Standardized Precipitation Index(SPI)and Standardized Precipitation Evapotranspiration Index(SPEI)on Leaf Area Index(LAI)and Normalized Vegetation Index(NDVI)in five East Asian countries.[Results]Compared the meteorological drought indexes of multi-time scale,it is found that the fluctuation amplitude and frequency of meteorological drought in the five East Asian countries are strong in the short time scale,the change trend in the long time scale is more obvious,SPI and SPEI show the opposite change trend,and SPEI has a longer drought duration in the three overlapping meteorological drought events.From 2001 to 2021,LAI and NDVI in the five East Asian countries showed a trend of fluctuating increase,and the increase rate of LAI was greater than that of NDVI;Through the correlation analysis of LAI,NDVI,SPI and SPEI,it can be seen that SPI-12 and SPEI-12 have the strongest stress effect on LAI,and NDVI is the most sensitive to SPI-3 and SPEI-3.[Conclusion]The regions with the best vegetation growth status were concentrated in Northeast China,East and South China,northern Outer Mongolia,North Korea,South Korea and Japan;The meteorological drought at the 3-month time scale has the greatest impact on vegetation greenness,while the meteorological drought at the 12-month time scale has the greatest impact on vegetation physiological status;In addition,according to the maximum correlation coefficient,the meteorological drought in midsummer has the strongest stress on vegetation growth.The results are expected to provide a theoretical reference for the ecological early warning and ecological restoration of plant communities in East Asia.We make the study on the effects of multi-time scale Standardized Precipitation Index(SPI)and Standardized Precipitation Evapotranspiration Index(SPEI)on Leaf Area Index(LAI)and Normalized Vegetation Index(NDVI)in five East Asian countries,and analyze the stress of meteorological drought on vegetation growth.The results show that:comparing the meteorological drought indexes of multi-time scale,it is found that the fluctuation amplitude and frequency of meteorological drought in the five East Asian countries are strong in the short time scale,the change trend in the long time scale is more obvious,SPI and SPEI show the opposite change trend,and SPEI has a longer drought duration in the three overlapping meteorological drought events.From 2001 to 2021,LAI and NDVI in the five East Asian countries show a trend of fluctuating increase,and the increase rate of LAI was greater than that of NDVI.The regions with the best vegetation growth status are concentrated in Northeast China,East and South China,northern Outer Mongolia,North Korea,South Korea and Japan.Through the correlation analysis of LAI,NDVI,SPI and SPEI,it can be seen that SPI-12 and SPEI-12 have the strongest stress effect on LAI,and NDVI is the most sensitive to SPI-3 and SPEI-3,indicating that the meteorological drought at the 3-month time scale has the greatest impact on vegetation greenness,while the meteorological drought at the 12-month time scale has the greatest impact on vegetation physiological status.In addition,according to the maximum correlation coefficient,the meteorological drought in midsummer has the strongest stress on vegetation growth.The results are expected to provide a theoretical reference for the ecological early warning and ecological restoration of plant communities in East Asia.