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Separating overstory and understory leaf area indices for global needleleaf and deciduous broadleaf forests by fusion of MODIS and MISR data
Liu, Yang1; Liu, Ronggao1; Pisek, Jan2; Chen, Jing M.3,4,5
2017-03-08
Source PublicationBIOGEOSCIENCES
ISSN1726-4170
Volume14Issue:5Pages:1093-1110
Corresponding AuthorLiu, Ronggao(liurg@igsnrr.ac.cn)
AbstractForest overstory and understory layers differ in carbon and water cycle regimes and phenology, as well as ecosystem functions. Separate retrievals of leaf area index (LAI) for these two layers would help to improve modeling forest biogeochemical cycles, evaluating forest ecosystem functions and also remote sensing of forest canopies by inversion of canopy reflectance models. In this paper, overstory and understory LAI values were estimated separately for global needleleaf and deciduous broadleaf forests by fusing MISR and MODIS observations. Monthly forest understory LAI was retrieved from the forest understory reflectivity estimated using MISR data. After correcting for the background contribution using monthly mean forest understory reflectivities, the forest overstory LAI was estimated from MODIS observations. The results demonstrate that the largest extent of forest understory vegetation is present in the boreal forest zones at northern latitudes. Significant seasonal variations occur for understory vegetation in these zones with LAI values up to 2-3 from June to August. The mean proportion of understory LAI to total LAI is greater than 30 %. Higher understory LAI values are found in needleleaf forests (with a mean value of 1.06 for evergreen needleleaf forests and 1.04 for deciduous needleleaf forests) than in deciduous broadleaf forests (0.96) due to the more clumped foliage and easier penetration of light to the forest floor in needleleaf forests. Spatially and seasonally variable forest understory reflectivity helps to account for the effects of the forest background on LAI retrieval while compared with constant forest background. The retrieved forest overstory and understory LAI values were compared with an existing dataset for larch forests in eastern Siberia (40-75 degrees N, 45-180 degrees E). The retrieved overstory and understory LAI is close to that of the existing dataset, with an absolute error of 0.02 (0.06), relative error of 1.3% (14.3 %) and RMSE of 0.93 (0.29) for overstory (understory). The comparisons between our results and field measurements in eight forest sites show that the R-2 values are 0.52 and 0.62, and the RMSEs are 1.36 and 0.62 for overstory and understory LAI, respectively.
DOI10.5194/bg-14-1093-2017
WOS KeywordSEASONAL DYNAMICS ; BOREAL FORESTS ; BRDF DATA ; TERRESTRIAL ECOSYSTEMS ; REFLECTANCE MODEL ; SATELLITE IMAGERY ; UNITED-STATES ; LAI ; VEGETATION ; RETRIEVAL
Indexed BySCI
Language英语
Funding Projectkey research and development programs for global change and adaptation[2016YFA0600201] ; National Natural Science Foundation of China[41301354] ; Distinctive Institutes development program, CAS[TSYJS04] ; Youth Science Funds of LREIS, CAS[08R8B6G0YA] ; Estonian Science Foundation grants[PUT232] ; Estonian Science Foundation grants[PUT1355]
Funding Organizationkey research and development programs for global change and adaptation ; National Natural Science Foundation of China ; Distinctive Institutes development program, CAS ; Youth Science Funds of LREIS, CAS ; Estonian Science Foundation grants
WOS Research AreaEnvironmental Sciences & Ecology ; Geology
WOS SubjectEcology ; Geosciences, Multidisciplinary
WOS IDWOS:000396168100003
PublisherCOPERNICUS GESELLSCHAFT MBH
Citation statistics
Document Type期刊论文
Identifierhttp://ir.igsnrr.ac.cn/handle/311030/64760
Collection中国科学院地理科学与资源研究所
Corresponding AuthorLiu, Ronggao
Affiliation1.Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, State Key Lab Resources & Environm Informat Syst, Beijing, Peoples R China
2.Tartu Observ, Toravere, Estonia
3.Nanjing Univ, Nanjing, Jiangsu, Peoples R China
4.Univ Toronto, Dept Geog, Toronto, ON, Canada
5.Univ Toronto, Program Planning, Toronto, ON, Canada
Recommended Citation
GB/T 7714
Liu, Yang,Liu, Ronggao,Pisek, Jan,et al. Separating overstory and understory leaf area indices for global needleleaf and deciduous broadleaf forests by fusion of MODIS and MISR data[J]. BIOGEOSCIENCES,2017,14(5):1093-1110.
APA Liu, Yang,Liu, Ronggao,Pisek, Jan,&Chen, Jing M..(2017).Separating overstory and understory leaf area indices for global needleleaf and deciduous broadleaf forests by fusion of MODIS and MISR data.BIOGEOSCIENCES,14(5),1093-1110.
MLA Liu, Yang,et al."Separating overstory and understory leaf area indices for global needleleaf and deciduous broadleaf forests by fusion of MODIS and MISR data".BIOGEOSCIENCES 14.5(2017):1093-1110.
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