Abstract

CAMPOS, José; GOMES, Susana  and  TAVARES, Mário. Maritime Pine Stand Canopy Evaluation by Fish-Eye Imaging System: Dendrometric Variables Its Relationship with the. Silva Lus. [online]. 2007, vol.15, n.1, pp.1-12. ISSN 0870-6352.

Light that hits forest stands soil depends on the canopy thickness and density, which is responsible for wood growth and production. So, functional relationships between its quantity and quality, and some maritime pine stand dendrometric variables, can be expected. This study was settled out on 45 plots taken from 2002 Leiria National Forest inventory. Plot densities ranged from 160 to 1240 trees/hectare. The photographs, with 640x480 pixels, were obtained in the centre of each plot, and analyzed by CI-100 on a 50% threshold. The plots dendrometric evaluation followed a Draudt method variation, while Generalized Linear Models (GLM) of Statistica 6 was used for modeling process. Significant current dendrometric variables estimation models are presented by the jointly utilization of canopy structure variables and the number of trees per hectare. Most of the models have a good fitting to data and manage to explain the most part of dendrometric variables variability. The available Wilson factor analysis model allows realizing that 67% of the plots are in pre thinning situation and 24% are unbalanced or very unbalanced, because of under occupation or misfit between its dominant height and the number of stand trees. Only the remainders 9% do not require thinning. The Leiria National Forest maritime pine stand canopy, sampled in 2002, is characterized by a mean leaf area index of 0.93, in which the needles occupy about the half of the forestry vault horizontal projection and about 53% of crossing radiation is done by transmission.

Keywords : Leiria National Forest; maritime pine stand; hemispheric photos; leaf area; Generalized Linear Models.

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