由冠层孔隙度反演植被叶面积指数的算法比较

植被的叶面积指数（LAI）是植被最重要的生态参数之一，也是估算多种植被冠层功能过程的关键参数迄今已提出的LAI的获取方法可归纳为直接测定和间接估算两大类．本文以河北省黄骅市为研究区，从遥感光学模型建立机理及数量分析的角度，对由植被冠层孔隙度反演植被LAI的4种间接估算方法进行了试验和比较．研究结果表明，LAI与植被盖度之间呈明显的正相关关系，即随着LAI的增大，植被盖度也在增大．在这4种估算方法中，LAI-2000算法最适用于研究区植被LAI的估算．

A Comparison on the Algorithms for Retrieval of LAI Based on Gap Fraction of Vegetation Canopy

The leaf area index(LAI) of vegetation is one of the most important structure parameters used in the ecological system studies and one of the key parameters used in estimating the varied function process of vegetation canopy.At present,there are basically two kinds of method in obtaining LAI,i.e.the direct measurement and indirect estimation.In this paper,from the point of view of the mechanism of developing the optical models and through quantitative analysis,four indirect methods used for LAI retrieval based on the gap fraction of vegetation canopy are analyzed and compared.Through this way,it was found that among these algorithms the LAI-2000 algorithm is most suitable for estimating LAI in the study area.In addition,a nonlinear positive correlation exists in the relation between LAI and vegetation coverage.In other words,with the increase of LAI,vegetation coverage of the research area appears to nonlinearly go up.