Decepa de plantas jovens de eucalipto e manejo de brotações, em um sistema agroflorestal

Abstract

Resumo -O objetivo deste trabalho foi avaliar o uso de decepa de plantas jovens de eucalipto, para produção de árvores de menor diâmetro, com colheita facilitada por pequenos produtores; ou para recuperação de povoamentos jovens severamente danificados e produção de biomassa para energia em ciclos curtos. O experimento foi conduzido em sistema agroflorestal, com espaçamento entre plantas de 9,5x4 m. O crescimento de plantas intactas foi comparado ao de brotações de decepas realizadas aos nove ou doze meses após plantio. Aos seis ou nove meses após a decepa, realizou-se a desbrota, para deixar dois ou três brotos por cepa. Quando a desbrota foi realizada aos 12 meses após a decepa, todos os brotos dominantes foram deixados. Um tratamento sem desbrota também foi avaliado. Aos 42 meses após plantio, o tratamento sem desbrota apresentou o mesmo número de brotos por cepa que o de plantas desbrotadas para três brotos. O diâmetro das brotações foi equivalente a 69% do valor estimado para as plantas intactas. O valor assintótico de produção das brotações, da maioria dos tratamentos de decepa aos nove meses, foi igual ao das plantas intactas, o que evidencia a viabilidade da decepa sem a realização da desbrota, em sistemas agroflorestais.Termos para indexação: Eucalyptus, clone de eucalipto, desbrota, madeira para carvão, recuperação de povoamentos. Juvenile eucalypt plant coppicing and sprout management in agroforestry systemAbstract -This study aimed to evaluate juvenile eucalypt clone plant coppicing, in order to obtain small diameter logs, in the first rotation, which facilitates harvesting by small farmers; or to recover damaged young stands and to produce biomass for energy in short rotations. The experiment was carried out in an agroforestry system with 9.5x4 m spacing. Intact plant growth was compared to sprout growth from coppicing at nine and twelve months after planting. At six or nine months after coppicing, sprout thinning was carried out to leave two or three sprouts per stump. When thinning was done after 12 months of coppicing, all dominant sprouts were left. A treatment without thinning was also evaluated. Forty-two months after planting, treatment without thinning showed about the same amount of sprouts per stump as those thinned to three sprouts per stump. The estimated asymptotic value for sprout diameter was 69% of that for intact plants. The asymptotic value for sprout production, for most treatments of plants coppiced nine months after planting, was similar to that obtained for intact plants, which indicates that coppicing young eucalypt plants, without sprout thinning, can be used in agroforestry systems.

Growth of pruned eucalypt clone in an agroforestry system in southeastern Brazil

“…Recently, eucalypt trees have also been established in agroforestry systems (Andrade et al 2001;Dubè et al 2002;Vale et al 2004;Cacau et al 2008). The trees in such systems may improve or reduce yield and quality of crops and pasture, depending on the understorey requirements and the effects of trees on nutrient, water, light transmittance and others.…”

Growth of intact plants and coppice in short rotation eucalypt plantations

“…On the other hand, the studies on clonal coppice growth are quite recent and deal with few clones in agroforestry systems, for juvenile plant coppice (Cacau et al 2008;Oliveira et al 2008;Paula 2011;Oliveira 2014), and adult tree coppice (Lopes 2012); or in monoculture, for adult tree coppice (Silva 2013).…”

“…According to the Köppen classification, the climate of the region is ''Aw''. The annual average temperature is 26.5°C, with an annual average rainfall of 1350 mm, and an average water deficit of 480 mm (March-October) (Cacau et al 2008). The water deficit may reach values as high as 722 mm year -1 (Oliveira et al 2008).…”

“…Coppice management of young clonal eucalypt plantations has been studied recently for producing wood of reduced dimensions, in short rotations, which enables earlier financial return in agroforestry systems (Cacau et al 2008;Oliveira et al 2008). These studies indicate that, by harvesting eucalypt at very young ages, the coppice biomass production of unthinned sprouts treatment is similar to that of intact plants.…”

“…These studies indicate that, by harvesting eucalypt at very young ages, the coppice biomass production of unthinned sprouts treatment is similar to that of intact plants. The growth rate of coppice at young ages is usually higher than that of the intact plants, which may shorten the harvesting age of forests managed by coppice (Kauppi et al 1988;Harrington and Fownes 1993;Sims et al 2001;Luostarinen and Kauppi 2005;Cacau et al 2008).…”