Estrutura do dossel e crescimento após desbaste em povoamento de clone de eucalipto desramado

• Autor(a) principal: Monte, Marco Antonio
• Data de Publicação: 2006
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3142
• topic: Desrama artificial; Desbaste; Estrutura do dossel; Artificial pruning; Thinning; Canopy structure; CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::SILVICULTURA

Canopy structure and plant growth of Eucalyptus grandis W. Hill ex Maiden clone, submitted to different intensity and frequency of artificial pruning starting at the ages of 16, 20 and 28 months and, to thinning (0 and 35% of the total planted seedlings) at the age of 55 months, were evaluated between the ages of 55 and 93 months, in the cerrado region. The Canopy Coverage Index (CCI) was obtained from digital photographs with the sizes 640x480 and 1280x960 pixels processed with the Erdas-imagine 8.5, Gap light analyser 2.0 and Sidelook 1.1 softwares. CCI was significantly correlated with LAI, independently of the photographs processing methods when they were taken with the size of 1280x960 pixels, while the Sidelook processing method was the best when 640x480 pixels photographs were taken. At the age of 93 months, there were no significant differences (p>0.05) between pruning treatments and the interaction between pruning and thinning, independently of the age of the first pruning intervention. However, there was significant difference (p≤0.05) between thinning treatment. LAI and CCI in thinned stands were, respectively, 28.0 and 16.9% smaller than in non-thinned one immediately after thinning while at the age of 93 months these values were 13.8 and 6.9 %. These results indicate that there was substantial canopy recovery in the thinned stands three years after thinning. At the age of 93 months, there were no significant differences (p>0,05) for the diameter at 1.3 m height (DBH), total height (Ht), volume outside bark, periodic annual increment after thinning (PAI) and mean annual increment (MAI) among artificial pruning treatments. By removing more than 60 % of total leaf area, a greater proportion of trees was allocated into lower diameter classes, according do Weibull distribution, even though there was no significant differences for average DBH. Total height was significantly (p≤0.05) higher in the non-thinned stand as compared to the thinned one, independently of the age pruning was first applied. The volume outside bark, PAI and MAI varied significantly (p≤0,05) with thinning only when pruning started at the age of 20 months, being, respectively, 7.9, 23.0 and 7.3 % greater in the thinned stand, in comparison to the non-thinned one. Growth had already been stagnated in the non-thinned stand, whereas, in the thinned stand, this stagnation may occur around the age of 100-110 months, when the second thinning intervention should be applied. The overall results indicated that digital photographs can be used for canopy coverage index estimation and that LAI and CCI obtained over an age sequence, in addition to growth data, can be helpful to define at which age thinning should be applied to forest stands.