Growth, crown dynamic and wood quality for sawmill of Eucalyptus grandis [HILL EX MAIDEN] clone submitted to artificial pruning / Crescimento, dinâmica de copa e qualidade da madeira para serraria de clone de Eucalyptus grandis [HILL EX MAIDEN] submetido à desrama artificial

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

Plants of the clone 24504 of Eucalyptus grandis [HILL ex-MAIDEN] established at 3.0 x 3.0 m spacing, in Southeastern Brazil, were submitted to different artificial pruning intensities starting at two seasons: dry season, with the first pruning intervention occurring in July 2000 in plants aged 20 months and, wet season, with the first pruning intervention occurring in March 2001 in plants aged 28 months. Branches were removed up to 1.0, 1.5 and 2.0 m height in this first intervention. The second pruning intervention for both seasons was performed in plants aged 33 months to obtain a three meters log pruned. Total height, diameter at breast height (DBH) and horizontal and vertical external wound closure were measured from the first pruning intervention up to the age of 40 months. Tree trunk diameter was also measured at 0.30 m, 1.30 m, 2.30 m and 3.30 m height to evaluate the effect of pruning on taper. The internal wound closure was evaluated by taking bole discs at different tree heights at branch intersection point. Leaf area index (LAI), photossintetically active radiation (PAR) and canopy radius were measured at regular intervals to evaluate crown dynamic after artificial pruning. Artificial pruning starting at 20 months old plants (dry season) had no significant effect on DBH, height and volume while pruning starting at 28 months old plants affected significantly plant growth (p>.05). Significant reduction in LAI (p>.05) was observed after pruning at age 20 months (dry season) with plants recovering rapidly their crown in the subsequent rainy season. When plants were first pruned at age 28 months there was no significant reduction in LAI (p>.05) once it was observed partial leaf senescence up to the pruning height. Even though there was no significant effect on taper when pruning started at age of 20 months , it was observed a tendency of taper reduction with pruning up to the age of 40 months. When first pruning intervention occurred at age 28 months, it was observed significant taper reduction in the trunk segments of 1.30-2.30 m and 1.30- 3.30 m height. This effect may have happened because branches diameter increased, promoting reduction in trunk diameter at the position above branch insertion. This indicates that pruning of this clone plants should be applied at younger ages. The external analysis of pruning wound indicated that horizontal is faster than vertical closure and, that wound closure located at the base of the bole, where the bark was already brown, is slower than at higher heights in the trunk where the bark is still greenish. The overall results of this study indicate that pruning intensities adopted for 24504 Eucalyptus grandis clone did not affect growth and, that the first pruning intervention should be applied as earlier as possible when plants may have greater recovery capacity and the branches are still thin, reducing taper and wound size.

ASSUNTO(S)

Índice de área foliar growth leaf area index lumber eucalyptus grandis qualidade madeira serrada efeito da desrama silvicultura eucalyptus grandis effect of artificial pruning quality clonagem crescimento clone

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