关岭-贞丰石漠化治理示范区植被覆盖变化及其对气候因子的响应

为揭示喀斯特石漠化治理示范区植被覆盖变化以及气候因子对植被覆盖变化的影响，利用2006—2015年Landsat 30 m/16 d分辨率影像数据，采用最大合成法、NDVI差值指数和相关、偏相关分析法，系统分析示范区归一化植被指数的时空变化特征及其与气候因子的关系。结果表明:(1)2006—2015年最大NDVI平均值为0.39，NDVI较高覆盖区域在示范区南北边界，而较低覆区域以花江南岸为主；(2)2006年以来示范区极低(-1.210)、低(-0.669)和中等(-0.729)植被覆盖度呈减少趋势，高(1.359)和极高(1.247)植被覆盖度增加，整体上呈显著增加趋势；(3)本月NDVI与本月、上月、上上月降雨量和气温的相关性均通过显著水平0.05检验，且本月NDVI与本月降雨量相关性高于本月气温(RNDVI降雨 =0.782)，本月NDVI与上月气温相关性高于上月降雨量(RNDVI气温 =0.771)；(4)在月尺度上，示范区植被生长对降雨量无滞后期，而对气温存在1个月的滞后期。 

Change of vegetation coverage and its response to climatic factors in the Guanling-Zhenfeng demonstration area for reduction and control of rock desertification

This paper studies the variation of vegetation coverage and the effect of climatic factors on the vegetation coverage in a demonstration area for reduction and control of karst rocky desertification. Based on the 30 m(16 d) resolution Landsat images during 2006-2015, using the method of maximum value composite (MVC), normalized difference vegetation index (NDVI), and correlation and partial correlation analyses, we systematically examine the spatial and temporal variation characteristics and the trend of vegetation index of the demonstration area and its relationship with climate factors. The results show that, (1) the annual maximum average value of NDVI between 2006 and 2015 is 0.39, which is higher in the north and south boundary regions of the demonstration area and lower in the south bank of the Huajiang river; (2) Since 2006, the places with extremely low(-1.210), low(-0.669) and moderate(-0.729) NDVI values exhibited a falling trend, those with high(1.359) and extremely high(1.247) increased overall significantly; (3) On the monthly scale, the NDVI of this month and the rainfall and temperature of this month, last month and month before the last one all pass the correlation coefficient test(P<0.05), and the correlation between NDVI and rainfall this month is higher than that between NDVI and temperature(RNDVI rainfall =0.782), the correlation between NDVI of this month and temperature of last month is higher than that between NDVI of this month and rainfall of last month(RNDVI temperature =0.771). (4) The vegetation growth of the demonstration area has no lag phase to rainfall, but a month lag to air temperature.