DOI: 10.1016/j.foreco.2014.12.026
Scopus记录号: 2-s2.0-84921059300
论文题名: Influence of woody tissue and leaf clumping on vertically resolved leaf area index and angular gap probability estimates
作者: Piayda A. ; Dubbert M. ; Werner C. ; Vaz Correia A. ; Pereira J.S. ; Cuntz M.
刊名: Forest Ecology and Management
ISSN: 0378-1127
出版年: 2015
卷: 340 起始页码: 103
结束页码: 113
语种: 英语
英文关键词: Clumping index
; Digital cover photography
; Gap fraction
; LAI-2000
; Leaf area index
; Woody tissue
Scopus关键词: Ecology
; Ecosystems
; Forestry
; Image analysis
; Photography
; Probability
; Tissue
; Vegetation
; Clumping index
; Gap fraction
; Ground-based observations
; Image analysis algorithms
; LAI-2000
; Leaf Area Index
; Object based image analysis
; Soil vegetation atmospheres
; Probability distributions
; algorithm
; data quality
; deciduous tree
; digital image
; ground-based measurement
; height determination
; image analysis
; leaf area index
; photography
; semiarid region
; wood
; Portugal
; Quercus suber
英文摘要: Leaf area index L is a key vegetation parameter that can be used in soil-vegetation-atmosphere exchange modeling. To represent the structure of ecosystems in vertically distributed modeling, vertically resolved L distributions as well as vertical and angular gap probability Pgap distributions are needed, but they are rarely available. On the experimental side, studies often neglect woody plant components when using indirect methods for L or Pgap observations. This can lead to significantly biased results, particularly in semi-arid savannah-type ecosystems with low L values.The objective of this study is to compare three non-destructive leaf area index measurement techniques in a sparse savannah-type cork oak canopy in central Portugal in order to derive vertically resolved L as well as vertically and angularly resolved Pgap. We used the established LAI-2000 device as well as fast digital cover photography (DCP), which was vertically and angularly distributed. We applied object-based image analysis to DCP to exclude woody plant components. We compared the results with vertically distributed LAI-2000 measurements and with vertical estimates based on easily measurable crown parameters.Height and angularly distributed DCP was successfully applied here for the first time. It delivers gap probability Pgap and effective leaf area index Le measurements that are comparable to the established LAI-2000. The height and angularly dependent leaf clumping index Ω could be determined with DCP, which led to a 30% higher total leaf area index L for DCP compared to LAI-2000. The exclusion of woody tissue from DCP yields on average a 6.9% lower leaf area index L. Including Ω and excluding woody tissue, the L of DCP matched precisely with direct measurements using litter traps. However, the set-up and site-specific adjustment of the image analysis algorithm remains challenging. We propose a special filter for LAI-2000 to enhance data quality when used in open canopies. Finally, if height-dependent observations are not feasible, ground-based observations of crown parameters can be used to derive very reasonable L height distributions from a single, ground-based L observation. © 2015 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/65553
Appears in Collections: 影响、适应和脆弱性
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作者单位: Deptartment Computational Hydrosystems, UFZ Helmholtz Centre for Environmental Research, Permoserstr. 15, Leipzig, Germany; Agroecosystem Research Department, BayCEER Center, University of Bayreuth, Universitätsstr. 30, Bayreuth, Germany; Department of Forestry, Instituto Superior de Agronomia, Technical University of Lisbon, Tapada da Ajuda, Lisbon, Portugal
Recommended Citation:
Piayda A.,Dubbert M.,Werner C.,et al. Influence of woody tissue and leaf clumping on vertically resolved leaf area index and angular gap probability estimates[J]. Forest Ecology and Management,2015-01-01,340