Continuous estimation of leaf area index and the woody-to-total area ratio of two deciduous shrub canopies using fisheye webcams in a semiarid loessial region of China

doi:10.1016/j.ecolind.2021.107549

	Continuous estimation of leaf area index and the woody-to-total area ratio of two deciduous shrub canopies using fisheye webcams in a semiarid loessial region of China
	Niu, Xiaotao 1,2; Fan, Jun 2,3; Luo, Ruihua 3; Fu, Wei 3; Yuan, Hongyou 3; Du, Mengge 3
刊名	ECOLOGICAL INDICATORS
	2021-06-01
卷号	125 页码:11
关键词	Leaf area index Woody-to-total area ratio Fisheye webcam LAI-2200 Direct measurement Shrubs
ISSN号	1470-160X
DOI	10.1016/j.ecolind.2021.107549
通讯作者	Fan, Jun(fanjun@ms.iswc.ac.cn)
英文摘要	Automatic and accurate measurements of the leaf area index (LAI) can provide information about key parameters of vegetation structure in an ecosystem. Little attention, however, has been paid to LAI dynamics for shrub canopies in both arid and semiarid regions compared to forests and crops. One of the main sources of error when measuring shrub LAI from the indirect method is the woody part. The influence of woody parts on LAI estimations can be expressed as the woody-to-total area ratio, a; there are also relatively few studies on a value of shrubs, especially the dynamic changes of a. This study used a new cost-effective tool, the fisheye webcam, to derive daily LAI and a in the fields of Caragana korshinskii and Salix psammophila on the Loess Plateau in China. The LAI data were compared with measurements acquired by an LAI-2200 Plant Canopy Analyzer and direct methods. The LAI-2200 data were consistent with the effective plant area index (PAIeff) estimated using upwardpointing webcams (UPWs) (R-2 = 0.89, root mean square error (RMSE) = 0.21) but not downward-pointing webcams (DPWs) (R-2 = 0.52, RMSE = 0.68). Shrub PAIeff derived from the DPWs was much smaller than PAIeff derived from the UPWs over the season (y = 0.48x-0.03, R-2 = 0.79, RMSE = 0.85). LAI derived from the direct methods was strongly linearly correlated with the PAI minus WAI obtained from upward digital hemispherical photography (R-2 = 0.94, RMSE = 0.62 for C. korshinskii and R-2 = 0.99, RMSE = 0.31 for S. psammophila). This result indicates that the upward digital hemispherical photography for deriving PAI and WAI performs good, which can be utilized to calculate LAI accurately. The woody-to-total area ratio (a) of deciduous shrub canopies was a dynamic parameter that varied throughout the season, decreasing as the canopy leaves developed and increasing when they fell. alpha = 1 for the leaf-off season and < 0.1 when the foliage peaked. a differed little between the two shrub canopies (R-2 = 0.95, RMSE = 0.07), and it could be used to convert PAI to LAI for C. korshinskii and S. psammophila. The UPWs demonstrated excellent potential for continuous LAI measurement for the two shrub canopies, but the DPWs should be further tested before use. The fisheye-webcam is inexpensive and can easily monitor LAI at field scale and can be used to evaluate LAI products derived from remote sensing.
资助项目	Strategic Priority Research Program of the Chinese Academy of Sciences[XDA23070202] ; National Natural Science Foundation of China[41977016] ; National Natural Science Foundation of China[41830754]
WOS研究方向	Biodiversity & Conservation ; Environmental Sciences & Ecology
语种	英语
出版者	ELSEVIER
WOS记录号	WOS:000637785800003
资助机构	Strategic Priority Research Program of the Chinese Academy of Sciences ; National Natural Science Foundation of China
内容类型	期刊论文
源URL	[http://ir.igsnrr.ac.cn/handle/311030/161796]
专题	中国科学院地理科学与资源研究所
通讯作者	Fan, Jun
作者单位	1.Univ Chinese Acad Sci, Beijing 100049, Peoples R China 2.Chinese Acad Sci & Minist Water Resources, State Key Lab Soil Eros & Dryland Farming Loess P, Inst Soil & Water Conservat, Yangling 712100, Shaanxi, Peoples R China 3.Northwest A&F Univ, Inst Soil & Water Conservat, Yangling 712100, Shaanxi, Peoples R China
推荐引用方式 GB/T 7714	Niu, Xiaotao,Fan, Jun,Luo, Ruihua,et al. Continuous estimation of leaf area index and the woody-to-total area ratio of two deciduous shrub canopies using fisheye webcams in a semiarid loessial region of China[J]. ECOLOGICAL INDICATORS,2021,125:11.
APA	Niu, Xiaotao,Fan, Jun,Luo, Ruihua,Fu, Wei,Yuan, Hongyou,&Du, Mengge.(2021).Continuous estimation of leaf area index and the woody-to-total area ratio of two deciduous shrub canopies using fisheye webcams in a semiarid loessial region of China.ECOLOGICAL INDICATORS,125,11.
MLA	Niu, Xiaotao,et al."Continuous estimation of leaf area index and the woody-to-total area ratio of two deciduous shrub canopies using fisheye webcams in a semiarid loessial region of China".ECOLOGICAL INDICATORS 125(2021):11.