Modelling light obstruction in three conifer forests using hemispherical photography and fine tree architecture

Fournier, Richard; Landry, Robert J.; August, N.M.; Fedosejevs, G.; Gauthier, Robert P.

doi:10.1016/0168-1923(96)02345-3

Cited by 61 publications

(31 citation statements)

References 31 publications

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“…Nevertheless, large deviations were often observed between estimates and measurements of transmittance (often up to 20%) even for low light levels. Many authors argued that point-to-point variations beneath the forest canopy are rarely predicted with accuracy because minor errors in tree position and crown dimensions can lead to dramatic changes in simulations of transmittance (Da Silva et al, 2012;Fournier et al, 1996;Groot, 2004;Mariscal et al, 2004). On the other hand, site averages were better predicted (Da Silva et al, 2012;Mariscal et al, 2004;Pinno et al, 2001;Stadt and Lieffers, 2000).…”

Section: Model Evaluationmentioning

confidence: 99%

“…Nevertheless, the influence of this aggregation on FRTM predictions appeared weak (Bartelink, 1998b;Cescatti, 1997), probably because 3D models are used mostly for stands with rather open canopy where gaps between crowns are more important than gaps within crowns. Similarly, modeling trunk interception was reported without significant effects in the two sensitivity analyses studying this parameter (Brunner, 1998;Fournier et al, 1996). With 3D crown model, using the default values of k = 0.5 and Ω = 1 appeared therefore a reasonable simplification.…”

Section: D Crown Modelmentioning

confidence: 99%

“…Additional measurements such as crown radii measured in different directions, height of maximum crown extension, and shape coefficients might be required to construct more complex shapes. For 3D surface models, a geometric description of leaves, branches, and stems can be obtained by vectorization (Fournier et al, 1996), digitalization (Moulia and Sinoquet, 1993), or simulations of plant morphology (Leroy et al, 2009). …”

Section: Stand and Tree Measurementsmentioning

confidence: 99%

See 2 more Smart Citations

Forest radiative transfer models: which approach for which application?

Ligot

Balandier²,

Courbaud³

et al. 2014

Can. J. For. Res.

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Radiation is fundamental in forest ecosystem ecology as it drives plant photosynthesis, morphogenesis, and fluxes of carbon, water and energy between soil, vegetation, and the atmosphere. Though all approaches of forest radiative transfer models (FRTM) share general properties, they differ greatly in terms of calibration parameters, required assumptions, and model objectives. They use different precision levels of canopy description (from one to three dimensions) and different mathematical relationships to model the attenuation of radiation through the canopy. To date no general guideline has been given to help the modeler choose the approach that best suits his needs. We therefore reviewed evaluation, sensitivity, and performance of FRTMs recently reported in the literature. We quantified FRTM uncertainty and identified the most sensitive parameters relative to the modeling choices. Their advantages and drawbacks are discussed and recommendations are made relative to application potential.

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Section: Model Evaluationmentioning

confidence: 99%

Section: D Crown Modelmentioning

confidence: 99%

Section: Stand and Tree Measurementsmentioning

confidence: 99%

See 1 more Smart Citation

Forest radiative transfer models: which approach for which application?

Ligot

Balandier²,

Courbaud³

et al. 2014

Can. J. For. Res.

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show abstract

“…It has been proven useful in studies requiring fi ne details of canopy structure or the light penetration (Chen and Black 1991). In addition, it combines the advantages of relatively simple procedure for data acquisition, good spatial defi nition of imagery and the easily processing system for the image (Fournier et al 1996). Therefore, the hemispherical photographic silhouette was used for OSP estimation in this experiment.…”

Section: Defi Nition Of the Ospmentioning

confidence: 99%

“…It is fair to say that the relationships between wind speed and the optical porosity have been paid little attention in the coastal protective forests because of the diffi culty and peculiarity. Fortunately, there have been a number of efforts using hemispherical photographs to assess the effect of obstruction on irradiation (Anderson 1964, Koike 1985, Wang et al 1992, Fournier et al 1996, Saito 1996. These provide us a method using hemispherical photographic silhouette to estimate the optical porosity in a coastal protective forest, and further to assess the relationships between wind speed and optical porosity within the coastal protective forest (Zhu et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Modeling relative wind speed by optical stratification porosity within the canopy of a coastal protective forest at different stem densities

Zhu¹,

Gonda²,

Matsuyama³

et al. 2003

Silva Fenn.

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Wind speed and optical stratifi cation porosity (OSP) were measured at various heights inside a coastal protective forest thinned to different stem densities to assess whether any characteristics of the wind profi le in the coastal protective forest could be predicted from OSP. OSP was defi ned as vertical distribution of the proportion of sky hemisphere not obscured by tree elements inside a forest stand, and was determined for various heights using hemispherical photographic silhouettes on a computer processing system. The distribution of OSP in the coastal forest follows the Lambert-Beer's law with an extinction coeffi cient (ν). The relative wind speed within the canopy can be described using an exponential form with an attenuation coeffi cient (α). Variation in relative wind speed was very closely correlated with the distribution of OSP within the canopy. While below the canopy, i.e., in the trunk space, relative wind speed was little correlated with the distribution of OSP because the distribution of OSP was relatively constant there. Therefore, the linear relationships between relative wind speed and OSP and between the two coeffi cients ν and α were established within the canopy. The results suggest that OSP can be used to predict the wind profi le in case of the application within the canopy of the coastal forest.

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Boreal forests and snow in climate models

Essery¹

1998

Hydrol. Process.

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Modelling light obstruction in three conifer forests using hemispherical photography and fine tree architecture

Cited by 61 publications

References 31 publications

Forest radiative transfer models: which approach for which application?

Forest radiative transfer models: which approach for which application?

Modeling relative wind speed by optical stratification porosity within the canopy of a coastal protective forest at different stem densities

Boreal forests and snow in climate models

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