林下植被对遥感估算马尾松LAI的影响  

Impact of the understory on estimation of leaf area index of Pinus massoniana using remote sensing technology

作　　者：耿君[1,2] 王磊[1,2] 田庆久[1,2] 涂丽丽[1,2] 黄彦[1,2] 王龑[1,2] 吕春光[1,2] 杨冉冉[1,2] 杨闫君[1,2] 

机构地区：[1]南京大学国际地球系统科学研究所,南京210046 [2]南京大学江苏省地理信息技术重点实验室,南京210046

出　　处：《生态学报》2015年第18期6007-6015,共9页Acta Ecologica Sinica

基　　金：国家科技重大专项(30-Y20A01-9003-12/13)

摘　　要：叶面积指数是一项极其重要的描述植被冠层结构的植被特征参量。根据植被物候规律,利用中国环境卫星CCD多光谱影像和野外马尾松样区调查数据,通过建立不同季节和不同郁闭度样区马尾松LAI和影像NDVI经验回归模型,并利用一个新的LAI观测方式定量比较乔木层LAI和生态系统总LAI(包括草本层、灌木层和乔木层)的差异,研究林下植被对马尾松反演的影响程度。结果表明:(1)由于林下植被的物候变化,冬季林下植被对马尾松LAI反演影响最小,马尾松NDVI和LAI线性关系R2维持在0.65;夏季林下植被影响最大,线性关系R2只有0.25;春季和秋季影响居中,NDVI和LAI线性关系R2在0.47附近。但是,受林下植被影响较小的A类样区4个季节内NDVI和LAI线性关系基本都在0.60以上(夏季略低于0.60);(2)乔木层LAI和总LAI差距非常大,最大差距达到2.93,相差的比例最大达到了2.45倍;(3)总LAI和NDVI相关关系显著,其中线性关系R2达到0.66,对数关系R2可达到0.68,而乔木层LAI和NDVI相关关系较差,线性关系R2只有0.30。分别建立冬季和其它季节实测总LAI和NDVI的关系,可以估算出林下植被对马尾松LAI反演的影响程度。Leaf area index （LAI） , defined as half the total developed area of green leaves per unit ground horizontal area, is an extremely important vegetation characteristic parameter that describes the construction of vegetation canopy. For the past few years, LAI has been estimated operationally at a regional or even global scale by means of various retrieval methods using remotely sensed optical imagery. Understory vegetation （e.g., grasses, herbs, shrubs, etc. ） is the layer of foliage below the forest canopy. As a background signal source in remote sensing, understory has had a serious impact on estimating many forest canopy parameters by remote sensing techniques for two reasons, on the one hand, it has very similar characteristics with those of the forest eanopy because they are all vegetation, on the other hand, it has greater spatialtemporal heterogeneity than other backgrounds in remote sensing, e.g., soil, water, rock and litter, etc. The purpose of this paper is to determine the impact of understory on LAI inversion of forests with different canopy closures in different seasons. In this study, data from five field investigations and corresponding Chinese I-IJ- 1 CCD remote sensing images were collected and analyzed to study the impact of understory on LAI inversion of Pinus massoniana during the period September 2012 to October 2013 in Chuzhou, Anhui province. By building empirical models of LAI of Pinus massoniana with different canopy closures and Normalized Difference Vegetation Indices （NDVI） in different seasons based on the phenology of the understory and comparing the difference of LAI of tree layers and the LAI of all layers of the ecosystem using a new way of LAI measurement, the impact of understory on the calculation of LAI of Pinus massoniana with different canopy closures and in different seasons was found. The results show that： （ 1 ） Understory had minimal impact on LAI inversion of Pinus massoniana in winter; R2of the linear relationship between NDVI and LAI was 0.65. Underst

关 键 词：林下植被 马尾松 叶面积指数(LAI) 遥感 郁闭度 物候期 不确定性 

分 类 号：S771.8[农业科学—森林工程]