北部湾海岸带植被覆盖时空动态特征及未来趋势

分析北部湾海岸带植被覆盖动态变化趋势，能为开展海岸带植被生态环境监测提供决策。以2000―2011年SPOT-VEGETATION逐旬NDVI数据为基础，采用MVC（最大值合成法）、标准差、线性趋势分析（SLOPE）和Hurst指数等数理统计方法对研究区植被覆盖时空变化特征及未来趋势进行定量分析。结果表明：1）研究区植被覆盖整体上处于变好的状态，在年尺度上呈现出“波动―明显改善”的趋势，且海岸带东岸与西岸的植被变化趋势快于丘陵地区；在季节尺度上NDVI的增长速率为：秋季＞夏季＞春季＞冬季；在月尺度上NDVI在6―11月植被生长迅速，而在1―4月则生长缓慢；2）NDVI均值的空间分布规律自东北―西南中心线呈现出“两头高、中心地带低”的趋势，且NDVI均值自西向东的变化规律为-0.026/1N°，具有经向地带性特点；3）NDVI的Hurst指数值为0.306 5~0.995 3，平均值为0.777 4，反持续性序列（15.78%）＜持续性序列（84.22%），未来总体植被覆盖呈现出持续性改善趋势。未来需要重点进行保护的植被区域主要集中在十万大山的西南部、钦江流域的上游以及合浦县的西南部。

Temporal-Spatial Dynamic Differences and Future Trends of the Vegetation Cover in the Beibu Gulf Coastal Zone

Based on the 10-day SPOT-VEGETATION NDVI data during the period of 2000-2011, by using the mathematical-statistics methods of MVC (maximum synthesis), standard deviation, SLOPE (linear trend analysis) and Hurst index, this paper analyzes the characteristics of temporal-spatial change of vegetation cover and its future trend in the coastal zone around the Beibu Gulf. The results indicate that: 1) The vegetation cover in the study area has been changing better, showing a “volatility-significant improvement” trend on year scale. At the same time, the vegetation trends of the east and west coast grow faster than that of the hilly areas; On seasonal scale the growth rate of NDVI is autumn>summer>spring>winter; On monthly scale the NDVI grows faster from June to November, whereas slowly from January to April; 2)The spatial distribution of mean NDVI in northeast-southwest centerline shows the trend of “high at two ends and low in central” and the law of mean NDVI variation from west to east is -0.026 per 1Nº, which also shows a meridional zonality; 3)The NDVI value of Hurst index ranges from 0.306 5 to 0.995 3, with a mean of 0.777 4, anti-sustained sequence (15.78%)