基于NDVI的广西近十年植被变化特征分析

[目的]掌握广西的归一化植被指数(NDVI)变化及分布规律,为广西的生态保护和建设提供科学依据.[方法]采用1999~2011年SPOT VEGETATION数据分析广西近十年的NDVI时空变化特征.[结果]1999~2011年NDVI月最小值主要出现在2、3月,其中2月6次,3月5次,另外1月和4月分别各有1次;NDVI月最大值主要出现在9月,13年中共有9次出现在9月,两次出现在10月,两次出现在11月;1999~2011年平均NDVI值与年份间呈正相关,相关系数为0.692;2011年广西全区有94.55%面积的年平均NDVI比1999年高,5.45%的面积比1999年低;1999~2011年平均NDVI最高的地级市是梧州,为0.503;平均NDVI最低的地级市是北海,为0.405.[结论]广西NDVI通常在2、3月出现最低值,在9月出现最高值;环绕广西周边地区的NDVI值相对较高,桂中地区的NDVI值相对较低;1999~2011年广西NDVI年际间有较明显的上升趋势.

Analysis of Guangxi vegetation variation characteristics during recent decade based on NDVI

【Objective】This research aimed to understand the changes and distribution of the Guangxi Normalized Difference Vegetation Index （NDVI） in order to provide scientific references to improve ecological protection and construction in Guangxi. 【Method】SPOT VEGETATION data from 1999 to 2011 were used to analyze the Guangxi NDVI spatial and temporal variation characteristics during the recent decade. 【Result】The monthly minimum NDVI values during 1999-2011 mostly existed in February and March； there were 6 minimums observed in February and 5 minimums observed in March. On the rare occasions， one minimum was observed in January and one minimum was observed in April. The monthly maximum NDVI， on the other hand， mostly existed in September. Out of the 13 maximums， 9 were observed in September， two were observed in October， and two were observed in November. There was a positive correlation between the average NDVI value and corresponding year during 1999-2011， with the correlation coefficient being 0.692. The average NDVI value during 2011 was higher than that during 1999 in 94.55% of Guangxi areas， but lower in the other 5.45% Guangxi areas. The maximum average NDVI value observed in Wuzhou from 1999-2011 was 0.503. In contrast， the minimum average NDVI value observed in Beihai from 1999-2011 was 0.405. 【Conclusion】The minimum monthly NDVI value in Guangxi was usually observed in February and March， while the maximum was usually observed in September. Regions surrounding Guangxi have relatively high NDVI， but regions in the center of Guangxi have relatively low NDVI. There were obvious increases in the NDVI values from 1999-2011.