基于NOAA/AVHRR数据的西部植被覆盖变化监测

Monitoring of changes in land vegetation covers using NOAA/ AVHRR NDVI datasets

应用图像差分技术、生物量变化线性方程斜率和主成分分析方法 ,对 1 981～ 2 0 0 1年间西部植被的变化状况进行时间序列分析 ,并讨论了影响变化监测的因素 .结果显示 ,1 981～ 2 0 0 1年的 2 0年间 ,四川盆地和西部塔里木盆地周缘的耕地以及具有高 NDVI的南方林区的生物量处于较好的持续增加状态 ;而内蒙古以及西藏东北部的草地出现大面积的退化现象 .总体分析来看 ,西部的林地、草地都发生了高比例、大面积的退化 ,只有很小比例的植被得以改善 ,表现出局部改善。

In this paper the long- sequence time series NDVI datasets are analyzed and statistic results separately obtained,using Simple Differencing,Slope Map of Biomass,and Principle Component Analysis techniques.Based on the discussion of the exotic factors affecting the NDVI,such as satellite shiftor sen- sor degradation,the statistics indicate that the majority of the pixels of different vegetation covers have experienced almost the same changes in direction and magnitude during the same period,and the slope image of biomass shows higher correlation with the4th principle components than the simple differenc- ing image.The slicing slope images of biomass ( no change occurs in desert areas) indicate that most of the vegetation covers that are continuously increasing in NDVI are the cultivated land around Sichuan Basin,Tarim Basin and the forest areas in Southern China,while the vegetation covers that are continu- ously decreasing in NDVI are the grassland in Inner- Mongolia and northeastof Tibet.In conclusion,the vegetation in the western partof China in the past2 0 years ( 1 981～ 2 0 0 1 ) has been suffering from an ex- tensive deterioration and only a little improvement in some regions.