气候变化和人类活动对西南喀斯特地貌区植被NDVI变化相对作用

定量厘定气候变化和人类活动对西南喀斯特地貌区植被NDVI变化的相对作用,可为揭示喀斯特地貌区植被NDVI时空演变特征及其驱动机制提供依据。以MODIS NDVI、SRTM DEM、基于站点的气象数据为数据源,建立Theil-Sen Median斜率估计、残差分析、相对作用分析等多数学模型,分析了2001—2019年西南喀斯特地貌区气候变化和人类活动对植被NDVI变化的相对作用,揭示植被NDVI与降水、气温、相对湿度和日照时数的相关性。结果表明:研究时段内西南喀斯特地貌区植被NDVI总体上呈上升态势,植被NDVI变化趋势呈现明显的空间异质性,植被NDVI增加的区域面积远大于减少的区域面积; 研究区植被改善和植被退化均受人类活动的主导。研究时段内西南喀斯特地貌区植被NDVI与降水、气温以及相对湿度整体呈正相关,相关程度依次递减,与日照时数呈负相关。综上可知,研究时段内西南喀斯特地貌区植被覆盖呈改善态势,人类活动可被认为是影响西南喀斯特地貌区植被NDVI变化的主要驱动力,植被NDVI与降水、气温、相对湿度和日照时数的相关系数在空间上呈现明显的异质性。

Vegetation Cover Change and the Relative Role of Climate Change and Human Activities in Southwest Karst Areas

Studying on vegetation cover change and the relative role of climate change and human activities can provide a better understanding for spatiotemporal vegetation variation and the driving mechanism of climate change and human activities to vegetation variation in southwest karst areas, China. Based on the moderate resolution imaging spectroradiometer(MODIS)normalized difference vegetation index(NDVI)time series, digital elevation model data(DEM), in situ climate data using Theil-Sen Median analysis, Mann-Kendall significance test, relative analysis, and so on, we analyzed the relative role of climate change and human activities on vegetation variation, explored the correlation coefficients between NDVI and climate variables in southwest karst areas, China from 2001 to 2019. The results showed that from 2001 to 2019, the vegetation cover presented an upward trend in southwest karst areas. The spatial pattern of vegetation variation exhibited obvious spatial heterogeneity and the areas with vegetation improvement were greater than the areas with vegetation degradation. Furthermore, the relative role of human activities on vegetation improvement and vegetation degradation was higher than the relative role of climate change on vegetation variation. The vegetation cover was positively and most significantly associated with precipitation, followed by temperature and relative humidity but negatively associated with sunshine duration in southwest karst areas from 2001 to 2019. These results indicated that both the vegetation improvement and vegetation degradation were dominated by human activities, and the correlation coefficient between NDVI and climate variables exhibited significant regional differences in southwest karst areas in the study period.