2001年至2010年三峡库区重庆段植被活动时空特征及其影响因素

The Temporal and Spatial Characteristics of Vegetation Activity in Three Gorges Reservoir Area (Chongqing ) from 2001 to 2010 and Its Influencing Factors

利用2001年-2010年的MODIS陆地产品MOD13A3 NDVI数据对三峡库区重庆段近10年来的植被生长状况及其影响因素进行分析,结果表明:①三峡库区重庆段东部、中南部中高山区NDVI较高,西部川东平行岭谷区,长江干流及其支流谷地NDVI较低;地形和人类建设活动成为主要的影响因素;②近10年来三峡库区重庆段植被活动总体上呈逐渐增强的趋势;③研究区植被活动出现极化的趋势,植被稀疏的区域植被活动进一步减小,植被茂密的区域植被活动保持稳定或增强,夏季最为明显;④研究区6种植被类型中,阔叶林的NDVI最高,为0.6904;水生植被的NDVI最低,为0.5710。草甸和灌丛、灌草丛两种植被类型增长最为迅速,分别为0.6%和0.48%;⑤地形、坡度和地形起伏度是影响三峡库区重庆段植被生长状况最为重要的因素,三个因素从根本上决定了植被的空间分布与变化轨迹。其中,地形起伏是坡度与地形起伏度形成的充分条件,成为最根本的决定性影响因素,同时,人类活动已经成为该区植被退化的主要因素。

Three Gorges Reservoir Area （Chongqing） is a significant ecological barrier and vegetation resource pool in southwest China. The growth condition and trend of vegetation in Three Gorges Reservoir Area （Chongqing） play a very important role in maintaining Three Gorges Reservoir Area sustainable and stable as well as studying the carbon cycle and balance. This paper has investigated the vegetation change and its influencing factors in Three gorges Reservoir area （Chongqing） from 2001 to 2010 based on multi-temporal MODIS NDVI dataset. The results show that： 1 ）The middle and high mountain areas in the east and middle-south part of Three Gorges reservoir area （Chongqing） have high NDVI value, while the paralleled ridge-valley areas in the east of Sichuan and the valley areas in west of Yangtze River and its tributary have low NDVI value. It is of great significance to strengthen the protection and construction of vegetation in the middle and high mountain areas in the east and middle-south part of Three Gorges reservoir area （Chongqing）; 2）The vegetation activities in Three Gorges Reservoir Area （Chongqing） have gradually displayed an increasing trend on the whole over the past decade; 3）The vegetation activities within the study area present a polarized trend. The vegetation activities decrease further in the region with sparse vegetation, but keep stable or increasing in the region with thick vegetation, which is especially obvious in summer. The main reason is the further decrease of minimum value caused by human activities in sparse vegetation area; 4） The NDVI of the broadleaf forest is the highest （0.6904） among six vegetation types in the study area, but the NDVI of the aquatic vegetation is the lowest （0.5710）. Meanwhile, meadow, shrub and shrub-grassland all maintain a rapid growth with rates of 0.6% and 0.48% respectively, while the growth rate of aquatic vegetation is only 0.2%. The NDVI values of other vegetation types are all increasing, with 0.47% for coniferous forest type, 0.46% for cultivated vegetation type and 0.38% for broadleaf forest type; 5） Terrain （DEM）, slope and terrain amplitude are the most important factors that affect the status of vegetation growth in the study area, and they fundamentally determine the spatial distribution of vegetation and change trend. Terrain （DEM） is a sufficient condition to shape slope and amplitude, thus becoming a fundamentally decisive factor for the vegetation distribution in this area. Simultaneously, human activities have been becoming a main factor that brings about the degradation of vegetation coverage.