Characteristics of Vegetation Response and Recovery and its Influencing Factors Under Summer Flash Drought in Northeast China

Global warming has led to the intensification of the water cycle and the frequent occurrence of flash drought, which in turn has an important impact on the terrestrial ecosystem. However, the research on the response and recovery of vegetation to flash drought in Northeast China is relatively limited. This paper uses soil moisture which from ERA5-Land reanalysis data to select flash drought events and identify the summer flash drought in Northeast China from 2000 to 2022 firstly, and the spatial distribution characteristics during onset and recovery stages are analyzed. On this basis, the characteristics of different vegetation types response and recovery to flash drought are analyzed by combining with the MODIS Leaf Area Index (LAI), and the spatial pattern of dominant factors is further discussed by using random forest model and partial correlation analysis. The results show that there are significant differences in response and recovery of different vegetation types to flash drought in Northeast China. Specifically, forest has the longest response time (28 days) but the shortest recovery time (12 days), while grasslands has the shortest response time (10 days) but the longest recovery time (30 days). In addition, the decrease and recovery rate of forests are both faster (0.99/pentads and 1.02/pentads), while that of grasslands are slower (0.31/pentads and 0.41/pentads). The results of dominant factors suggest that soil moisture and Vapor Pressure Deficit (VPD) are the main factors affecting the response time of vegetation, the onset rate of flash drought and temperature play a major role in the decrease rate, the recovery time of vegetation is mainly impacted by soil moisture and precipitation, and the recovery rate is primarily influenced by soil moisture and VPD. Moreover, temperature and VPD determined the decrease and recovery rate of more than 50% of forests, respectively, and are higher than that of grasslands and croplands, while soil moisture dominates the response and recovery time of more than 73% of forests, grasslands and croplands. This paper results can provide some reference for the possible effects of flash drought on different ecosystems, and deepen the understanding of ecosystem response and recovery after flash drought.