红壤丘陵区LAI与土壤侵蚀分布特征的关系

叶面积指数(LAI)是常用的一个用于描述植被覆盖的方面指数,土壤侵蚀的分布又与植被的覆盖状况息息相关,这就意味着LAI与土壤侵蚀有一定的相关性,目前有关这二者的相关性研究还鲜有文献报道。基于这此,本研究首先利用2000年的遥感影像(TM)解释出该年度的土壤侵蚀强度图,再利用该遥感影像通过图像的代数运算得出该地区的NDVI栅格图,通过实测该县不同典型植被条件的LAI值,得出实测的LAI与图像NDVI值之间的函数关系式,由图像的代数运算把NDVI图转换成LAI图,即实现了遥感图像的实测LAI纠正。在GIS软件的帮助下,通过将LAI栅格图与土壤侵蚀强度图的空间叠加分析,得到不同LAI条件下的土壤侵蚀分布。结果表明,LAI与土壤侵蚀的分布表现为:大致以LAI=2为分界线,当LAI<2时,土壤侵蚀并未随LAI的增加而迅速减少,LAI>2时,土壤侵蚀的分布随植被指数的增加而减少,当LAI=2左右时,土壤侵蚀的面积最大。这种情况对于轻度、中度及强度土壤侵蚀的影响是类似的,都呈类正态分布的曲线形式,但在曲线的两侧土壤侵蚀类型是有本质区别的,在曲线的左侧土壤侵蚀类型的分布是中度和强度为主,而在曲线右侧则以轻度为主。表明LAI这个指标与土壤侵蚀有很好的相关性,可以用于土壤侵蚀方面的相关研究工作。

Relationship between LAI and distributional character of soil erosion in hilly red soil regions

Leaf area index(LAI)is a parameter often used to describe vegetation coverage, while, soil erosion have a close relation with vegetation coverage. From this case, some relationship between LAI and soil erosion should be existed. But related article about this relation is little at present. Based on the idea, soil erosion intensity map was produced from interpreting the remote sensing im- age (TM) in Xingguo County in 2000 year, which was also use to calculate NDVI map through algebra operation by itself. Field investigations were carried out to determine the LAI value in different vegetation types. By using the linear relationship between LAI and NDVI, LAI distribution map was gotten through image calculation. By the overlaying analysis of LAI and soil erosion intensity map in GIS circumstance, distribution of soil erosion at different LAI territory was hence gotten. The results show there is close rela- tion between LAI and soil erosion, that is, LAI=2 can be consider of a turning point, in circumstance of LAI<2, soil erosion is not decrease with LAI increase, when LAI>2, soil erosion does rapidly decrease with LAI values increase, and LAI=2, all types of soil erosion intensity present the largest distribution in area. This case are same to light, moderate and severe erosion type, which turn out to be a curve similar to Gaussian distribution, but soil erosion types at the two sides of the curve are totally different, in the left side of the curve, soil erosion are dominated by moderate and severe erosion type, and in the right side of the curve, mainly soil erosion type is light erosion. From the results, we conclude that LAI can be used as a vegetation index to evaluate soil erosion in red soil regions.