Piboule, Alexandre (2005) Influence of stand structure on understory light distribution. Case of a heterogeneous broadleaved forest on limestones. PhD thesis Sciences forestières, LERFOB, ENGREF.
Abstract
Light models simulate the distribution of understory lighting from a characterisation of crowns geometry. Our goal was to reduce the quantity of data required. We measured the data set necessary to a light model (tRAYci) in a heterogeneous broadleaved stand. We established relationships between the variables characteristic of the crown and the diameter of the trees at 1.30 m. We developed an algorithm taking competition between crowns for space occupation into account, given only the species of the tree, its diameter at a height of 1.30 m and its position. We compared this reconstruction method (anisotropic) to a simpler method (isotropic), considering the simulation quality of the light distribution obtained. Only the anisotropic approach allowed us to obtain an unbiased simulation of light distribution at the level of the plot. We also tested indices based on the spatial distribution of the basal area, which proved incapable of predicting the light distribution in an unbiased way.
| Item Type: | PhD Thesis (PhD) |
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| Thesis Supervisor: | Dhote, Jean-François |
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| Date: | April 2005 |
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| Board of examiners: | Berbigier, Paul and Messier, Christian and Collet, Catherine and Cordonnier, Thomas and Epron, Daniel |
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| Ecole Doctorale: | ENGREF |
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| Discipline: | Sciences forestières |
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| Collection (Fonds): | ENGREF |
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| Institution: | ENGREF |
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| Department: | LERFOB |
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| Subjects: | 7. Life Sciences and Engineering |
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| Uncontrolled Keywords: | Modélisation, Houppier, éclairement relatif, Modèle de lumière, Forêt hétérogène, tRAYci |
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