滇东南喀斯特地区植被覆盖变化及其影响因素

利用MODIS NDVI数据资料集、标准气象站点的气候数据及社会经济统计数据，辅以叠置分析、空间统计分析和相关分析等方法，探讨了滇东南喀斯特地区植被覆盖的时空变化特征及其与气候因子、人类活动的关系。结果表明:滇东南喀斯特地区植被4月上旬进入生长季而9月中旬结束，2001—2010年植被覆盖呈现出上升的趋势，NDVI增加速率为0.03/10 a；滇东南喀斯特地区植被覆盖呈增加和减少趋势的面积分别占总面积的70.03%和29.97%，植被NDVI减少最为突出的区域主要集中在人口聚集的城镇周围及河流沿线，而增加的区域主要集中在高海拔山区；气候影响因素中的水分类因素即平均相对湿度、最小相对湿度和降水是滇东南喀斯特地区植被NDVI年内变化主要的影响因素，其影响有2个月左右的滞后期，温度类气候因子的滞后期为3个月左右，其他类型的气候因子滞后期约为2个月；滇东南喀斯特地区实施的退耕还林工程，极大地提升了植被覆盖度，而城镇化过程则使得城镇周边的极低、低植被覆盖度区面积增加。

Temporal and Spatial Evolution Characteristics of Vegetation NDVI and Its Driving Factors in Karst Area of Southeast Yunnan,China

Based on the MODIS NDVI(Normal Difference Vegetation Index, NDVI) data sets, climate data from standard meteorological stations and socio-economic statistical data, overlay analysis, spatial statistical analysis methods and correlation analysis were employed to study the characteristics of temporal and spatial variation of vegetation NDVI, and the relationship between NDVI, climatic factors and human activity in Karst area of southeast Yunnan. The results show that growing season in Karst area of southeast Yunnan starts from early May and ends around mid-term September, vegetation NDVI presented a rising trend from 2001 to 2010, the rate was 0.03/10 a, the vegetation coverage area demonstrated an increasing trend. With respect to the change in vegetation coverage in Karst area of southeast Yunnan, the areas of increase and decrease of vegetation coverage were 70.03%, 29.97% of the total area of Karst area of southeast Yunnan, respectively. The most prominent areas of vegetation NDVI decrease are mainly around the cities and towns which have a large population, and the increased areas mainly concentrated in the high-altitude areas. The average relative humidity, minimum relative humidity and precipitation are the main factors affecting annual change of the vegetation NDVI, their impaction has about two months lag phase, the temperature factor has about for three months lag phase, and the other types of climatic factors have about two months period of lag phase. The implementation of returning land for farming to forestry plays a key role in the enhancement of the vegetation coverage in Karst area of southeast Yunnan, while the process of urbanization leads to vegetation degradation.