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    陕西省丹江流域NDVI 分布及其与土地利用的关系

    NDVI spatial distribution and its correlation with land-use in Dan River Watershed of Shaanxi Province

    • 摘要: 植被覆盖是陆地生态系统的主体,研究植被空间分布格局与土地利用之间的关系,对于生态环境保护和水土流失防治具有积极意义。以南水北调中线工程水源地,丹江流域为研究对象,利用MODIS 250 m NDVI 数据,结合地理信息系统技术,对丹江流域NDVI 等级分布图和DEM 图叠加,得到NDVI 不同海拔、坡度和坡向等地形因子的分布情况,并且与土地利用进行相关分析。结果表明:1)丹江流域NDVI 平均值为0.84,表明流域植被覆盖较好。高植被覆盖分布于流域边缘高山区,东北和东南较集中;中植被覆盖分布于丹江流域河道两侧川塬区和低山区,西北和南部较集中;低植被覆盖位于丹江流域川道区,呈点和线状分布。2)不同海拔和坡度,植被覆盖面积呈单峰分布,平地的植被覆盖面积接近0;不同坡向植被覆盖面积差异不明显。3)除坡向外,不同海拔和坡度,高、中植被覆盖与耕地、林地和草地显著相关;不同地形因子下,低植被覆盖与建设用地和水域显著相关。丹江流域植被覆盖度与人类活动范围呈逆向分布,说明人类活动对植被分布影响较大;优化土地利用,适当增加林地覆盖面积,有利于提高丹江流域的水土保持功能。

       

      Abstract: Background Vegetation coverage is the main body of terrestrial ecosystem. Detecting the spatial distribution pattern of vegetation and its correlation with land-use will benefit the regional ecological environment protection and soil erosion control. Methods In this study, taking the Dan River Watershed, the water source of the middle route of the South to North Water Diversion Project, as the research area, MODIS 250-m NDVI data and GIS technology were used to obtain spatial distribution features of the different NDVI degree in the case of elevation, slope-degree and slope-direction via overlap of distribution maps of NDVI and topographic factors maps extracted from digital elevation model. Finally, the correlation between NDVI and land-use types was analyzed. Results The results showed that: 1) The average NDVI value was 0.85, which indicated that the ecological environment was fine in Dan River Watershed. The high vegetation coverage distributed in marginal areas of watershed, and relatively concentrated in northeast and southeast; while the middle vegetation coverage distributed in low mountain, and relatively concentrated in northwest and south. Low vegetation coverage distributed in the Dan River valley as point and linear way, especially in city area. 2) At the different elevation and slope- degree, the distribution of area percent of high and middle vegetation coverage was assumed as single peak. The vegetation coverage area percent was proximal zero in the flat. The vegetation coverage area in the case of different slope-directions was not different dramatically. 3) Except different slope-direction, at different elevation and slope-degree, the high and middle vegetation coverages were significantly correlated with farmland, forestland and grassland. Moreover, low vegetation coverage was significantly in correlation with construction land and waters in the different topographic factors. Conclusions Some conclusions have been obtained that the degree of vegetation coverage showed obvious revese distribution characteristics with human activities range in Dan River Watershed, which indicated that human activities had a great impact on vegetation distribution Optimization of land use structure and appropriate increase of area were beneficial to improve the soil and water conservation function of Dan River Watershed.

       

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