Dinâmica de copa, crescimento e viabilidade econômica de um povoamento de eucalipto submetido a desrama e desbaste

• Autor(a) principal: Stocks, Jonathan James
• Data de Publicação: 2007
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2963
• topic: Desrama; Desbaste; Viabilidade econômica; Clone; Eucalipto; Dinâmica de copa; Thinning; Prunning; Economic viability; Clone; Eucalyptus; Crown dynamics; CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::SILVICULTURA

Canopy structure and growth of pruned Eucalyptus grandis W. Hill ex Maiden clone plants submitted to thinning at different intensities and frequencies (0%, 35% at the age of 55 months and at 81 months, 70% at 81 months, with and without sprouts removal of the thinned plants) were evaluated between 81 and 102 months of age, in the cerrado region. The canopy coverage index (CCI) was obtained from digital photographs and the leaf area index (LAI) was obtained with a canopy analyzer. For the economical analysis, nine prescriptions were defined in a 21 year planning horizon, varying thinning age and intensity and, clearfell age. The income was determined according to the thinning and clearfell volume, using tax rates of 5, 8 and 12% a year. The CCI was significantly correlated to the LAI at all evaluation ages (81, 86, 93 and 102 months). At the age of 102 months, there was significant difference (p≤0.05) for LAI and CCI between thinning treatments. At the age of 102 months, the unthinned treatment presented LAI 22% smaller than at the age of 81 months due to a possible decrease in site quality, and a LAI mean increase of 30% during this period was observed for both 35% thinning treatments and of 19% and 56% for the 70% thinning at 81months without and with sprouts, respectively. The CCI did not vary between 81 and 102 months of age in the unthinned and in the 35% thinning at 81 months, and, there was an increase of 30 to 50% for the other treatments. The leaf area index was considered a more sensitive parameter to detect variation in the canopy structure. At 102 months, a significant difference (p≤0.05) was observed for the diameter at breast height, total height, volume outside bark, periodic annual increment after thinning (PAI) and mean annual increment (MAI) between thinning treatments. The PAI was superior (p≤0.05) in the treatment of 35% thinning, at 81months and the outside bark volume was larger (p≤0.05) in the unthinned area at the age of 102 months. At the end of a 21 year cycle, a larger volumetric production (416 m3.ha-1) was obtained in the unthinned prescription, involving clearfell every seven years. The wood volume for the other prescriptions varied from 265 to 392 m3.ha-1. The largest Net Present Value was obtained for the prescription that included a 70% thinning intensity at the age of 81 months (6.8 years), taking into account the sprouts and clearfell only at the age of 21 years.