Improving the ability of the photochemical reflectance index to track canopy light use efficiency through differentiating sunlit and shaded leaves

doi:10.1016/j.rse.2017.03.012

	Improving the ability of the photochemical reflectance index to track canopy light use efficiency through differentiating sunlit and shaded leaves
	Zhang, Qian 1,2; Chen, Jing M.1,2,3; Ju, Weimin 1,2; Wang, Huimin 4; Qiu, Feng 1,2; Yang, Fengting 4; Fan, Weiliang 5; Huang, Qing 1,2; Wang, Ying-ping 6; Feng, Yongkang 1,2
刊名	REMOTE SENSING OF ENVIRONMENT
	2017-06-01
卷号	194 页码:1-15
关键词	Photochemical reflectance index (PRI) Light use efficiency (LUE) Sunlit and shaded leaves Half-hourly or daily time steps Light stress
ISSN号	0034-4257
DOI	10.1016/j.rse.2017.03.012
通讯作者	Ju, Weimin(juweimin@nju.edu.cn)
英文摘要	Accurate estimation of light use efficiency (LUE) of plant canopies is essential for calculating gross primary productivity (GPP) using LUE models and is also useful for calibrating process-based models for regional and global applications. A promising method for estimating LUE is through remote sensing of the photochemical reflectance index (PRI). However, there are internal (e.g. pigment concentrations) and external factors (e.g. environmental conditions and sun-target-view geometry) that affect PRI signals. Considering the reflectance difference between sunlit and shaded leaves, the ratio of observed canopy reflectance to leaf reflectance is used to represent the observed fraction of sunlit leaves, and the observed fraction of shaded leaves is calculated with a geometrical optical model. Thus, a canopy-level PRI observation is separated into sunlit and shaded PRI values, and a two-leaf canopy PRI (PRIt) is calculated as sum of these two values weighted by their respective sunlit and shaded leaf area indices. The usefulness of PRIt in assessing the canopy-level. LUE is evaluated with automated multi-angle PRI observations acquired on a flux tower from April to September 2013 over a sub-tropical coniferous forest in southern China. In each 15-minute observation cycle, PRI is observed at four view zenith angles fixed at (37 degrees, 47 degrees, 57 degrees) or (42 degrees, 52 degrees, 62 degrees) and the instantaneous solar zenith angle in the azimuth angle range from 45 degrees to 325 degrees (from the geodetic north). In both the half-hourly and daily time steps, PRIt can effectively improve (>50% and >35% increases in R-2, respectively) the ability as a proxy of LUE derived from the tower flux measurements over the big-leaf PRI taken as the arithmetic average of the multi-angle measurements in a given time interval. In the dry season from July to September, correlations of PRI with LUE at daily time steps are much stronger in the two-leaf case than in the big-leaf case. The correlation between PRIt and LUE is the strongest (R-2 = 0.785, p < 0.001) in July. PRIt is very effective in detecting the light and low-moderate drought stress on LUE at half-hourly time steps, while ineffective in detecting severe atmospheric water and heat stress, which is probably due to alternative radiative energy sink, i.e. photorespiration. Overall, the two-leaf approach well overcomes some external effects (e.g. sun-target-view geometry) that interfere with PRI signals. (C) 2017 Elsevier Inc. All rights reserved.
资助项目	Key Research and Development Programs for Global Change and Adaptation[2016YFA0600202] ; National Natural Science Foundation of China[41671343] ; National Natural Science Foundation of China[41401418] ; National Natural Science Foundation of China[31300420]
WOS关键词	GROSS PRIMARY PRODUCTION ; NET PRIMARY PRODUCTION ; PHOTOSYNTHETIC DOWN-REGULATION ; SUBTROPICAL PINUS PLANTATION ; THERMAL-ENERGY DISSIPATION ; LEAF PIGMENT CONTENT ; CHLOROPHYLL FLUORESCENCE ; TERRESTRIAL ECOSYSTEM ; PRIMARY PRODUCTIVITY ; VEGETATION INDEXES
WOS研究方向	Environmental Sciences & Ecology ; Remote Sensing ; Imaging Science & Photographic Technology
语种	英语
出版者	ELSEVIER SCIENCE INC
WOS记录号	WOS:000401888600001
资助机构	Key Research and Development Programs for Global Change and Adaptation ; National Natural Science Foundation of China
内容类型	期刊论文
源URL	[http://ir.igsnrr.ac.cn/handle/311030/64496]
专题	中国科学院地理科学与资源研究所
通讯作者	Ju, Weimin
作者单位	1.Nanjing Univ, Jiangsu Prov Key Lab Geog Informat Sci & Technol, Int Inst Earth Syst Sci, Nanjing 210023, Jiangsu, Peoples R China 2.Jiangsu Ctr Collaborat Innovat Geog Informat Reso, Nanjing 210023, Jiangsu, Peoples R China 3.Univ Toronto, Dept Geog & Program Planning, Toronto, ON M5S 3G3, Canada 4.Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, Beijing 100101, Peoples R China 5.Zhejiang A & F Univ, Sch Environm & Resources Sci, Linan 311300, Peoples R China 6.CSIRO Ocean & Atmosphere Flagship, PMB 1, Aspendale, Vic 3195, Australia 7.Chinese Acad Sci, Inst Soil Sci, Nanjing 210008, Jiangsu, Peoples R China 8.Nanjing Univ Informat Sci & Technol, Coll Appl Meteorol, Nanjing 210044, Jiangsu, Peoples R China
推荐引用方式 GB/T 7714	Zhang, Qian,Chen, Jing M.,Ju, Weimin,et al. Improving the ability of the photochemical reflectance index to track canopy light use efficiency through differentiating sunlit and shaded leaves[J]. REMOTE SENSING OF ENVIRONMENT,2017,194:1-15.
APA	Zhang, Qian.,Chen, Jing M..,Ju, Weimin.,Wang, Huimin.,Qiu, Feng.,...&Zhang, Fangmin.(2017).Improving the ability of the photochemical reflectance index to track canopy light use efficiency through differentiating sunlit and shaded leaves.REMOTE SENSING OF ENVIRONMENT,194,1-15.
MLA	Zhang, Qian,et al."Improving the ability of the photochemical reflectance index to track canopy light use efficiency through differentiating sunlit and shaded leaves".REMOTE SENSING OF ENVIRONMENT 194(2017):1-15.