Pruning of Eucalyptus grandis x Eucalyptus urophylla planted at low density in Southeastern Brazil

Tree pruning is a silvicultural operation that aims to improve wood quality, but care must be taken regarding the timing and height of the lift to ensure that tree growth is not negatively affected. The objective of this work was to evaluate the effects of different pruning heights on height and diameter growth of Eucalyptus grandis × Eucalyptus urophylla. The experiment was done in a one year old stand which was planted at 9 × 3 m spacing, managed under a silvopastoral regime, and located in Joao Pinheiro, Minas Gerais, Brazil. Pruning treatments removed branches carrying the lower green crown as follows: 0% (unpruned), 20, 40, and 60% of total tree height. Diameter at breast height (DBH at 1.3 m) and total height of all trees in the sample plots were measured prior to pruning and one year after pruning. Compared to the unpruned control, pruning significantly reduced mean DBH and total height in the 40 and 60% treatments but not in the 20% treatment. Thus, it was concluded that when pruning operation is done before canopy closure not more than 20% of lower green crow should be removed to avoid tree growth reduction. Key words: Silvopastoral regime, silvicultural intervention, forest management.