Evaluación del efecto de regímenes de poda sobre el crecimiento y calidad de madera en Pinus taeda

This work was developed in a Pinus taeda´s pruning trial of 19.2 years located near Punta de Cinco Sauces, Department of Tacuarembó, Uruguay. The trial was installed in 2008 on a stand planted in 2003. The experimental design is Complete Random Blocks with three repetitions where five pruning schemes were evaluated. Those schemes comprised different intensity and number of interventions called Light prunning, Medium Light. Medium Severe, Severe, plus a Commercial witness. The objective was to evaluate the effect of different pruning schemes on individual growth, wood quality and compression wood. The variables studied were diameter at breast height, total height, basal area, individual volume, total volume per hectare, volume of the individual pruned cylinder, volume of the pruned cylinder per hectare, maximum diameter of the knotty cylinder, the percentage of wood free of defects and warping (bow, twist and cup). In addition, the impact of compression wood on wood quality and its correlation with deformations was analyzed. The results indicate that pruning intensity and frequency did not have significant effects on individual growth and tree quality for most variables, but did have an impact on individual volume of pruned cylinder and the percentage of wood free of defects. The Light, Medium Severe and Medium Light pruning schemes were the most effective for the production of individual volume of the pruned cylinder up to 9 m height, while the Commercial scheme was the most suitable for the production of wood free of defects considering a basal log of 3 m length. It was concluded that early pruning is important, but it should not exceed 50% of the extraction of the green crown. The study also determined that the presence of compression wood was lower in the Commercial and Medium Light pruning schemes. However, no relationship were found between the presence of compression wood and the deformation variables analyzed. The importance of managing the planted forest from an early age to achieve production objectives is highlighted. This implies to pay timely attention to both density management and pruning to obtain a production that quantitatively and qualitatively optimizes the yield and profitability at harvest.

Keywords: Pinus taeda; pruning severity; growth; crown reduction; clear wood; pruned volume; wood quality, compression wood.