Spatio-temporal patterns of meteorological drought and impact on vegetation in karst region and non-karst region of Southwest China
Based on the monthly self-correcting Palmer index(sc_PDSI)and normalized difference vegetation index(NDVI)data sets from 1982 to 2020,the ensemble empirical mode decomposition(EEMD),Mann-Kendall trend test and correlation analysis were applied to analyzing the temporal and spatial variation charac-teristics of meteorological drought in karst and non-karst regions of Southwest China.And the response rela-tionship of vegetation to meteorological drought at multiple time scales was discussed.The results are follow-ing.1)Both karst and non-karst regions in Southwest China presented the process of"dry-humid-dry".There was a cyclical pattern of seasonal,interannual and interdecadal scales in sc_PDSI after decomposition by EEMD,in which interannual scale change was predominant with maximum variance contribution rate.The sc_PDSI of non-karst and karst regions changed abruptly in 2014 and 2015 in turn,and the changes in karst areas occurred after non-karst areas.In general,the dryness and humidity in karst region were superior to those in non-karst region.2)In the karst region of Southwest China,the proportions of aridification and significant aridification were 42.47％and 12.75％,both were lower than those in non-karst region with proportions of 50.69％and 27.79％,respectively.And the proportion of significant humidified area in karst area was 48.81％,outclassing that in non-karst area with proportion of 36.23％.And the area of significant aridification in karst region was much smaller than in non-karst region.This indicated that both aridification and humidification were better in karst areas than in non-karst areas.3)Vegetation NDVI presented negative correlation with sc_PDSI in both karst and non-karst areas at monthly,annual and multi-year scales.The correlation between vegetation NDVI and sc_PDSI increased with time.There was a time lag in the response of NDVI to sc_PDSI in Southwest China and the percentage of lagging area is 78.87％.The proportion of lagging area in karst and non-karst regions was 76.43％and 68.75％,respectively.And the lag time scales were dominated by 1～3 months(34.33％of karst area)and 3～6 months(25.81％of non-karst area),respectively.The shorter the lag time,the more sensitive the response of the vegetation to the drought.This is an indication that the vegetation in karst areas is more sensitive to the response to drought.
sc_PDSIEEMDmulti-timescale responsekarst regionnon-karst regionSouthwest China
万方数据
维普
