Prediction of PPFD variance at forest floor in a thinned Japanese cypress plantation

Mizunaga, Hiromi

doi:10.1016/s0378-1127(99)00102-4

Cited by 19 publications

(15 citation statements)

References 12 publications

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“…It is becoming easier to obtain detailed information, because of developments in optical measurements of leaf distributions at a canopy scale ) and in terrestrial LiDAR techniques for 3D distributions of leaves in a tree crown (Beland et al 2014). A model estimating the effect of silvicultural operations on leaf distributions within individual crowns has also been developed (Mizunaga 1996(Mizunaga , 2000. We expect that linking leaf distribution patterns and drag relations will contribute to mechanistic models that are based on the stand property (such as stand age, site productivity, and history of silvicultural operations), because of the higher accessibility to leaf distribution data.…”

Section: K Kitagawamentioning

confidence: 99%

Effects of components of the leaf area distribution on drag relations for Cryptomeria japonica and Chamaecyparis obtusa

et al. 2015

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The objectives of this study were to clarify the effects of components of the leaf area distribution on the drag coefficient of crowns and streamlining (e.g., leaf area index; LAI, outline of the crown shape, and clumpiness) and to contribute to the accumulation of data on drag relations by quantifying data for Chamaecyparis obtusa and Cryptomeria japonica. We conducted drag experiments while simultaneously capturing dynamic crown images for 28 Ch. obtusa crowns and 13 Cr. japonica crowns to analyze the relationships between the leaf area distribution components and drag coefficient or streamlining. The static drag coefficient increased with the LAI for Ch. obtusa and with decreasing clumpiness for Cr. japonica. The reduction rate of the static drag coefficient decreased with increasing clumpiness for Ch. obtusa and with a combination of increasing LAI and decreasing clumpiness for Cr. japonica. The reduction rate of the static drag coefficient had a clear relationship with the decreasing rate of the dynamic crown projected area of obstacles (foliage elements, branches, and stems) calculated from captured video images under windy conditions for Cr. japonica, while Ch. obtusa did not show clear relationship between them. The drag coefficients assuming non-porous crown; C max estimated by simple model combining LAI and clumpiness were approximately 1.0 in Ch. obtusa and 0.5 in Cr. japonica and were equivalent to the dynamic drag coefficients from video image under windy condition. The combination of LAI and clumpiness provided simple estimation for drag relations and enable to link crown structure to wind damage easier.

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Section: K Kitagawamentioning

confidence: 99%

Effects of components of the leaf area distribution on drag relations for Cryptomeria japonica and Chamaecyparis obtusa

et al. 2015

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“…Rich, 1990;Chen et al, 1991;Fournier et al, 1996;Frazer et al, 2000), and to predict daily and seasonal understory photosynthetic photon flux density (PPFD) (e.g. Canham, 1988;Rich, 1990;Clearwater and Gould, 1995;Mizunaga, 2000). The recent advancement in digital cameras may have brought us a needed tool at a reasonable cost to estimate quantities such as the plant area and clumping index.…”

Section: Introductionmentioning

confidence: 99%

Methodology comparison for canopy structure parameters extraction from digital hemispherical photography in boreal forests

Leblanc

Chen

Fernandes

et al. 2005

Agricultural and Forest Meteorology

386

245

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The retrieval of canopy architectural parameters using off-the-shelf digital cameras with fish-eye lens is investigated. The technique used takes advantage of the sensor's linear response to light of these cameras to improve the estimation of gap fraction using:(1) the digital numbers of mixed sky-canopy pixels to estimate the within-pixel gap fraction; and (2) this process is done considering the variation in view zenith angle to take into account the sky radiance distribution and the canopy multiple scattering effects.The foliage element clumping index is retrieved over a wide range of view zenith angles using:(1) the accumulated gap size distribution theory developed for the TRAC by Chen and Cihlar (1995a); (2) This article is a U.S. government work, and is not subject to copyright in the United States.Using data from Canadian and Russian boreal forests, comparisons of gap fraction, clumping index and plant area index measured with the tracing radiation and architecture of canopies (TRAC) and digital hemispherical photography are presented. Evaluation of the LAI estimated from digital hemispherical photography with allometric LAI of two boreal forest stands suggest that that the clumping index combined method may be more accurate. # 2005 Published by Elsevier B.V.

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“…Based on individual crown structures, the daily understory photosynthetic photon flux density and its spatial variance can be estimated (Mizunaga 2000). Silbernagel and Moeur (2001) calculated canopy openness (CO) by the computerized three-dimensional model of stem-mapped data using computer-aided design.…”

Section: Introductionmentioning

confidence: 99%

Methods for estimating understory light conditions using crown projection maps and topographic data

Takashima

Kume

Yoshida

2006

Ecological Research

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Four types of indices of canopy characteristics were compared to estimate understory light conditions using crown projection maps and topographic data. Crown area (CA) was formulated from the crowns in a focal sub-block (20 m·20 m). Canopy shade index (CSI) was formulated from the crowns in a focal sub-block and the surrounding sub-blocks with topographic effect. Site shade index (SSI) incorporated the shade of the slopes into CSI and represented the total physical closure of the site. Site light index (SLI) incorporated the azimuth of the site into SSI and evaluated the light condition of the understory. We tested the methods using the data on steep old-growth Cryptomeria japonica forests on Yakushima Island and the three-dimensional canopy structures of the forests were digitized on a geographic information system. The results were validated by the basic indices obtained by hemispherical photographs: canopy openness (CO) and gap light index (GLI). The three-dimensional structure of the surrounding canopies and topography had significant effects on the understory light conditions. CA had no significant correlation with CO, whereas CSI and SSI had significant negative correlations with CO. Although SLI had the highest negative correlation with GLI (R 2 =0.69), CSI had practical utility in the estimation of GLI (R 2 = 0.65). Our method is applicable to past crown projection maps that have been recorded at many forest research sites, thus making it possible to reconstruct past understory light conditions and to compare them with present conditions.

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Prediction of PPFD variance at forest floor in a thinned Japanese cypress plantation

Cited by 19 publications

References 12 publications

Effects of components of the leaf area distribution on drag relations for Cryptomeria japonica and Chamaecyparis obtusa

Effects of components of the leaf area distribution on drag relations for Cryptomeria japonica and Chamaecyparis obtusa

Methodology comparison for canopy structure parameters extraction from digital hemispherical photography in boreal forests

Methods for estimating understory light conditions using crown projection maps and topographic data

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