1998—2012年中国西南岩溶区植被覆盖时空变化分析

基于1998—2012年长时间序列SPOT-VEGETATION植被指数数据集，采用最大值合成法、变化矢量分析法、一元线性回归变化斜率法和Mann-Kendall非参数检验法对我国西南岩溶区植被覆盖的时空变化进行了分析。结果表明:（1）SPOT-VEGETATION植被指数数据可以较好地在宏观尺度上监测西南岩溶区的植被覆盖状况；（2）1998—2012年，西南岩溶区NDVI年均最大值呈上升趋势，整体上植被覆盖情况得到改善，约71.85%的区域植被覆盖情况得到不同程度的改善，主要集中分布在贵州、云南和广西；局部地区植被覆盖情况恶化，主要分布在四川、云南；基本不变的区域约占总面积的27.62%；（3）近14 a的变化矢量分析结果显示高变化和中变化的区域合计占54.17%，两个7 a相比，1999—2005年的变化大于2006—2012年，前者是后者的1.82倍；（4）变化斜率法和Mann-Kendall非参数检验法对西南岩溶区植被覆盖状况的分析结果基本一致。

Temporal and Spatial Variation of Vegetation Cover in Southwest China Karst Area during 1998-2012

Temporal and spatial variation of vegetation cover in southwest China karst area during 1998—2012 has been studied based on the SPOT-VEGETATION data set by using the methods of the maximum value composite (MVC), change vector analysis (CVA), slope of the linear regression and Mann-Kendall non-parametric test. Results show that: (1) the SPOT-VEGETATION index time series data can monitor the vegetation coverage changes in southwest China karst area on a large scale; (2) during the period of 1998—2012 the maximum annual NDVI rose, the whole vegetation conditions were improved, about 71.85% of the total area had different degrees of improvement, mainly distributed in Guizhou province, Yunnan province and Guangxi Zhuang Autonomous Region. There were areas where vegetation cover had degenerated markedly, mainly distributed in Sichuan and Yunnan province, vegetation conditions accounting for 27.62% of the total area remained essentially invariant; (3) the CVA for the 14 a scale showed that areas with mid-high to high degree of vegetation type change accounted for 54.17% of the study area, the comparison of CVA for the two 7 a periods showed that the density and extent of vegetation cover change between 1999 and 2005 was much acute than that between 2006 and 2012, the former is 1.82 times of the latter; (4) results of change slope method are basically identical to Mann-Kendall non-parametric test.