邕江流域植被时空分布及演变研究

Research of Vegetation Spatial-temporal Variation and Evolution in Yongjiang Basin

以250m分辨率的MOD13Q1数据为数据源，通过最大值合成法和均值法分别获得2000--2010年邕江流域年均NDVI时间序列，采用回归分析、相关系数分析和变异系数等方法，研究邕江流域植被状况的时空分布特征。结果表明，在空间分布上，邕江流域植被覆盖呈四周高，中部低的分布特征。在时间变化上，2000--2010年邕江流域植被覆盖区域年均NDVI波动为0．42～0．54，其中2000--2004年植被覆盖区域NDVI波动较大，不存在明显的趋势特征，但2004年以后植被覆盖区域NDVI呈波动性缓慢增长趋势；在年际波动上，邕江流域92．87％的植被覆盖区域NDVI呈中低波动，而高波动区域仅占植被覆盖区域总面积的7．13％，植被覆盖状况总体稳定性较好。在变化趋势上，2000--2010年邕江流域地表植被覆盖改善的区域远大于植被退化的区域，其中，改善的区域占植被覆盖区域总面积的56．02％，退化的区域占13．36％，30．62％的区域呈稳定不变的状态。

The annual mean NDVI time series in Yongjiang Basin in 2000-2010 were obtained by maximum value composite （MVC） method and average value method based on MOD13Q1 data with resolution of 250m, and the spatial-temporal variations of the vegetation status in the river basin analyzed using the methods of simple linear regression ＆ F test, correlation coefficient and variation coefficient. The results showed that： The average values of NDVI in Yongjiang Basin were high in the ambient, but were low in the middle. The values of NDVI in vegetation coverage area in Yongjiang Basin fluctuated in the range of 0.42-0.54. NDVI in Yongjiang Basin showed high fluctuations from 2000 to 2004, but with relatively slow and stable growth trend since 2004. 92.87% of vegetation covered area presented a medium-low variability, and only 7.13% area showed high fluctuations. During the period of 2000-2010, the area with an increase of NDVI value was much larger than the area with a decrease of NDVI value. The improved area occupied 56.02% of vegetation covered area, the depraved area accounted for 13.36%, and the rest 30.62% remained unchanged.