基于多尺度遥感数据的塔里木河干流地区植被覆盖动态

利用地面观测数据，Landsat TM和MODIS数据，基于尺度上推的研究思路，采用修正的三波段最大梯度差模型反演植被覆盖度，分析了塔里木河干流地区2000-2013年植被覆盖度时空分布及其动态变化特征。结果表明：（1）地面观测数据、Landsat TM与MODIS数据相结合进行尺度上推，尺度转换相对误差控制在4%以内，可以实现分析大范围长时间序列植被变化；（2）塔里木河干流区域植被覆盖度年内最大值出现在7、8月，2000-2013年平均植被覆盖度变化整体上呈现增长的趋势，上游年均植被覆盖度18.67%~23.67%，中游10.6%~12.44%，下游4.7%~6%，但呈现两段式发展（2000-2006年显著提高，2006-2013年小伏波动变化）；（3）塔里木河干流区域植被覆盖度空间差异明显，上游植被覆盖度增长速率最高，中游次之，下游增长速率最小。上游植被覆盖度年增长速率为0.37%，且增长趋势显著；中游年增长速率为0.06%，没有显著的变化趋势；下游年增长速率为0.05%，增长变化显著区域位于河道或稍远离河道附近及台特玛湖附近。

Dynamic Changes of Fractional Vegetation Cover along the Mainstream of the Tarim River

This paper, by using ground observation data with Landsat TM data and MODIS data, based on upscaling method,employing the modified three-band maximal gradient difference model which reverses vegetation fractional cover, analyzed the spatial-tempo change characters as well as dynamic changes of vegetation fractional cover on the mainstream of the Tarim River during 2000-2013. The result indicated that:(1) The method of upscaling combined with ground observation data, Landsat TM and MODIS data could realize the analysis of vegetation changes of a wide range during long time series, scale conversion error controlled within 4%; (2) The maximum value of vegetation fractional cover appeared in July and August within a year on the mainstream of the river, the annual average vegetation fractional cover changes overall showed a positive trends where the range of vegetation fractional cover between 18.67%-23.67% on the upper reaches, 10.6%-12.44% on the middle reaches, 4.7%-6% on the lower reaches. There was a remarkable increase during 2000-2006 and a small fluctuation during 2006-2013; (3) The fractional vegetation cover on the mainstream had a significant spatial variation. The upper reaches had a highest growth rate, followed by the middle reaches, the lower reaches had a minimum growth rate. The growth rate of upper reaches was 0.37%, the growth rate of the middle reaches was 0.06%, but there is no significant change trend in it, the growth rate of lower reaches wass 0.05%.