Performance of Four Optical Methods in Estimating Leaf Area Index at Elementary Sampling Unit of Larix principis-rupprechtii Forests

doi:10.3390/f11010030

	Performance of Four Optical Methods in Estimating Leaf Area Index at Elementary Sampling Unit of Larix principis-rupprechtii Forests
	Zou, Jie 2,3; Zuo, Yong 2,3; Zhong, Peihong 2,3; Hou, Wei 2,3; Leng, Peng 2,3; Chen, Bin 1
刊名	FORESTS
	2020
卷号	11 期号:1 页码:28
关键词	leaf area index clumping effects inversion model woody components correction method Larix-dominated forest plots optical method elementary sampling unit
DOI	10.3390/f11010030
通讯作者	Zou, Jie(zoujie@fzu.edu.cn)
英文摘要	Optical methods are frequently used as a routine method to obtain the elementary sampling unit (ESU) leaf area index (LAI) of forests. However, few studies have attempted to evaluate whether the ESU LAI obtained from optical methods matches the accuracy required by the LAI map product validation community. In this study, four commonly used optical methods, including digital hemispherical photography (DHP), digital cover photography (DCP), tracing radiation of canopy and architecture (TRAC) and multispectral canopy imager (MCI), were adopted to estimate the ESU (25 m x 25 m) LAI of five Larix principis-rupprechtii forests with contrasting structural characteristics. The impacts of three factors, namely, inversion model, canopy element or woody components clumping index (Omega(e) or Omega(w)) algorithm, and the woody components correction method, on the ESU LAI estimation of the four optical methods were analyzed. Then, the LAI derived from the four optical methods was evaluated using the LAI obtained from litter collection measurements. Results show that the performance of the four optical methods in estimating the ESU LAI of the five forests was largely affected by the three factors. The accuracy of the LAI obtained from the DHP and MCI strongly relied on the inversion model, the Omega(e) or Omega(w) algorithm, and the woody components correction method adopted in the estimation. Then the best Omega(e) or Omega(w) algorithm, inversion model and woody components correction method to be used to obtain the ESU LAI of L. principis-rupprechtii forests with the smallest root mean square error (RMSE) and mean absolute error (MAE) were identified. Amongst the three typical woody components correction methods evaluated in this study, the woody-to-total area ratio obtained from the destructive measurements is the most effective method for DHP to derive the ESU LAI with the smallest RMSE and MAE. In contrast, using the woody area index obtained from the leaf-off DHP or DCP images as the woody components correction method would result in a large LAI underestimation. TRAC and MCI outperformed DHP and DCP in the ESU LAI estimation of the five forests, with the smallest RMSE and MAE. All the optical methods, except DCP, are qualified to obtain the ESU LAI of L. principis-rupprechtii forests with an MAE of <20% that is required by the global climate observation system. None of the optical methods, except TRAC, show the potential to obtain the ESU LAI of L. principis-rupprechtii forests with an MAE of <5%.
资助项目	National Key Research and Development Program from Ministry of Science and Technology of China[2016YFB0501501] ; National Natural Science Foundation of China[41871233] ; National Natural Science Foundation of China[41371330] ; National Natural Science Foundation of China[41001203]
WOS关键词	INCLINATION ANGLE DISTRIBUTION ; ESSENTIAL CLIMATE VARIABLES ; GROUND-BASED MEASUREMENTS ; SIZE ANALYSIS THEORY ; HEMISPHERICAL PHOTOGRAPHY ; CLUMPING INDEXES ; SLOPE CORRECTION ; CANOPY STRUCTURE ; GROWING-SEASON ; GEOV1 LAI
WOS研究方向	Forestry
语种	英语
出版者	MDPI
WOS记录号	WOS:000513184500030
资助机构	National Key Research and Development Program from Ministry of Science and Technology of China ; National Natural Science Foundation of China
内容类型	期刊论文
源URL	[http://ir.igsnrr.ac.cn/handle/311030/132495]
专题	中国科学院地理科学与资源研究所
通讯作者	Zou, Jie
作者单位	1.Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, Key Lab Ecosyst Network Observat & Modeling, Beijing 100101, Peoples R China 2.Minist Educ, Key Lab Spatial Data Min & Informat Sharing, Fuzhou 350116, Peoples R China 3.Fuzhou Univ, Spatial Informat Res Ctr Fujian Prov, Fuzhou 350116, Peoples R China
推荐引用方式 GB/T 7714	Zou, Jie,Zuo, Yong,Zhong, Peihong,et al. Performance of Four Optical Methods in Estimating Leaf Area Index at Elementary Sampling Unit of Larix principis-rupprechtii Forests[J]. FORESTS,2020,11(1):28.
APA	Zou, Jie,Zuo, Yong,Zhong, Peihong,Hou, Wei,Leng, Peng,&Chen, Bin.(2020).Performance of Four Optical Methods in Estimating Leaf Area Index at Elementary Sampling Unit of Larix principis-rupprechtii Forests.FORESTS,11(1),28.
MLA	Zou, Jie,et al."Performance of Four Optical Methods in Estimating Leaf Area Index at Elementary Sampling Unit of Larix principis-rupprechtii Forests".FORESTS 11.1(2020):28.