1999-2019年西南喀斯特地区NDVI时空变化及其气候驱动

目的]西南喀斯特地区生态环境脆弱，对其植被覆盖变化及气候驱动机制进行研究具有重要意义。方法]基于1999—2019年SPOT NDVI数据和同期209个气象站点的气温和降水数据，采用Theil-Sen+Mann-Kendall趋势分析法、偏相关分析和复相关分析法，探讨西南喀斯特地区NDVI时空变化及其气候驱动。结果]1999—2019年西南喀斯特地区NDVI呈显著上升趋势，整体植被覆盖较好；NDVI变化主要以极显著上升趋势为主，仅5.73%的地区呈退化趋势。NDVI与气温和降水整体上均呈正偏相关关系，气温对NDVI的影响强于降水，且存在空间差异性。NDVI与气温和降水的复相关显著性通过0.05,0.01水平的面积分别占15.12%,5.68%;NDVI主要受气温驱动，占研究区面积的13.90%,其他气候因子驱动类型占比均未超过3%。结论]揭示了西南喀斯特地区植被覆盖的时空变化特征，明确了气候因子对植被覆盖变化的驱动机制。

Spatiotemporal Evolution of NDVI and Its Climatic Driving Factors in the Southwest Karst Area from 1999 to 2019

Objective]The ecological environment is fragile in the southwest karst area of China. It is of great significance to study its vegetation cover change and climate driving mechanism. Methods] Based on the SPOT NDVI, temperature and precipitation data at 209 meteorological stations during 1999—2019, we used trend analysis, Theil-Sen+Mann-Kendall test, partial correlation coefficient and multiple correlation coefficient to study the spatiotemporal evolution of NDVI and its climatic driving in the southwest karst area. Results] NDVI showed a significant upward trend during 1999—2019, and the overall vegetation coverage was relatively good in the southwest karst area. NDVI mainly showed an extremely significant upward trend, and only 5.73% of the areas showed a trend of degradation. NDVI had the positive partial correlation with temperature and precipitation on the whole. The influence of temperature on NDVI was stronger than that of precipitation, and there were spatial differences. The areas where the multiple correlation between NDVI and temperature and precipitation passed 0.05 and 0.01 significant levels accounted for 15.12%, 5.68%, respectively. NDVI was mainly driven by temperature, accounting for 13.90% of the study area, and the proportion driven by other climate factors was not more than 3%. Conclusion] The spatial and temporal variation characteristics of vegetation cover were revealed and the driving mechanism of climatic factors on vegetation cover changes had been clarified in the southwest karst areas of China.