内蒙古不同类型草地叶面积指数遥感估算  

Retrieval of leaf area index for different grasslands in Inner Mongolia prairie using remote sensing data

作　　者：柳艺博[1] 居为民[1] 朱高龙[1,2] 陈镜明[1] 邢白灵[1] 朱敬芳[1] 周艳莲[3] 

机构地区：[1]南京大学国际地球系统科学研究所,南京210093 [2]闽江学院地理科学系,福州350108 [3]南京大学地理与海洋科学学院,南京210093

出　　处：《生态学报》2011年第18期5159-5170,共12页Acta Ecologica Sinica

基　　金：国家863项目(2009AA12Z134);国家973项目(2010CB833503);江苏高校优势学科建设工程资助项目

摘　　要：叶面积指数(Leaf Area Index,LAI)是重要的植被结构参数,反演LAI是植被遥感的重要研究内容之一。根据在内蒙古呼伦贝尔和锡林浩特草原利用LAI 2000观测的草地LAI,比较了不同植被指数(SR、RSR、EVI、NDVI、SAVI和ARVI)估算不同类型草地LAI的能力,建立了基于Landsat-5 TM遥感数据的LAI估算模型,并利用LAI观测数据对模型进行了检验,生成了研究区内草地LAI分布图,据此对MODIS LAI产品一致性进行了评价。结果表明,在呼伦贝尔和锡林浩特两个研究区,RSR与LAI的相关性最高(R2分别为0.628、0.728,RMSE分别为0.512、0.490),在低密度草地,RSR的优势更为明显;验证表明,根据RSR建立的LAI估算模型的精度可达70%;利用TM数据生成的两个地区的LAI(TM LAI)空间变化明显,锡林浩特草地的LAI值整体上低于呼伦贝尔草地;在呼伦贝尔和锡林浩特,MODIS LAI产品与TM LAI一致性分别为0.566,0.323,MODIS LAI产品高估了呼伦贝尔草地LAI值,而在锡林浩特研究区则存在低估现象。Leaf area index（LAI）,defined as one half of the total green leaf area per unit ground surface area,is a crucial parameter of vegetation structure.It provides key quantitative information on the exchange of mass,energy,and momentum between the atmosphere and the land surface.Its retrieval is an important research focus in remote sensing of vegetation.LAI of grasslands in Hulunbuir prairie and Xilinhot prairie in Inner Mongolia was acquired using the LAI 2000 instrument from June 21 to 26 and June 28 to July 3,2010,respectively.Six vegetation indices including Simple Ratio（SR）,Reduced Simple Ratio（RSR）,Normalized Difference Vegetation Index（NDVI）,Soil Adjusted Vegetation Index（SAVI）,Atmospherically Resistant Vegetation Index（ARVI）,and Enhanced Vegetation Index（EVI） obtained from Landsat-5 TM data were correlated with measured LAI.LAI retrieved from TM data was then used as a benchmark for assessing the accuracy of MODIS LAI products.The measured LAI values of grasslands over the two study areas range from 0.46 to 4.06 in Hulunbuir and from 0.65 to 4.70 in Xilinhot.The average LAI value in Hulunbuir is 1.81,11% higher than that in Xilinhot（1.63）.Since grasses in these areas are short,we dug a small trench at each measurement location to place the LAI 2000 sensor head at the same level as the soil surface to ensure the total LAI is included in the measurement.Results show that RSR has the highest correlation with LAI in the two grasslands,with R2 equal to 0.628 and 0.728,respectively.The Root Mean Square Error（RMSE） values of estimated LAI from RSR are 0.512 and 0.490,respectively.RSR outperforms other VIs more obviously at lower LAI.Validation using 15 measured LAI values（not used in algorithm development） in both Hulunbuir and Xilinhot shows that RSR-derived LAI can capture 70% of LAI variations.Combined with the surface reflectance images of the grassland,the formulae LAI = 0.764×RSR0.675 and LAI= 0.462×RSR＋0.582 were developed to generate LAI maps at 30 m resolution for

关 键 词：草地叶面积指数 植被指数 LAI2000 内蒙古草原 

分 类 号：S812[农业科学—草业科学]