Damage caused by cattle to Eucalyptus benthamii trees in pruned and unpruned silvopastoral systems

Abstract: The objective of this work was to evaluate the effect of tree pruning on the incidence and intensity of the damages caused by cattle to 26-month-old Eucalyptus benthamii, in a silvopastoral system, in the municipality of Pinhais, in the state Paraná, Brazil. The experiment was performed in a randomized complete block design, with two treatments - livestock and forest with pruned eucalyptus (WP), and livestock and forest with unpruned eucalyptus (UP) - and three replicates, characterizing six types of damages and five damage intensities. There were significant differences between the WP and UP treatments for the different types of damages. Cattle entry in the silvopastoral system at 26 months after the planting of eucalyptus causes low-intensity damages to the trees, in the treatment with pruning, and medium-intensity damages to the trees in the treatment without pruning. Damages of stronger intensities were detected in the UP treatment, in which class-two damages (d2 = average damage) were verified in approximately 91% of the trees. The silvicultural practice of pruning E. benthamii trees does not affect the diameter at breast height or the total height of trees. Pruning can be recommended, as it does not affect tree development; moreover, this practice enables the production of knot-free, better-quality wood.摘要：本研究旨在评估树木修剪对巴西巴拉那州皮奈斯市林牧复合系统（silvopastoral system）中26月龄本哈姆桉（Eucalyptus benthamii）受牛只侵害的发生率与损害程度的影响。本实验采用完全随机区组设计，设置两组处理：经修剪桉树的林牧复合系统（WP）与未修剪桉树的林牧复合系统（UP），每组设置3次重复，共涵盖6类损害类型与5级损害程度。两组处理在不同损害类型上均存在显著差异。在桉树种植26个月后将牛只引入林牧复合系统的场景下，修剪组树木仅遭受低强度损害，未修剪组树木则出现中等强度损害。未修剪组（UP）中检测到强度更高的损害，其中约91%的树木出现二级损害（d2=中度损害）。对本哈姆桉实施修剪的营林措施，不会影响树木的胸径（Diameter at Breast Height）与总树高。因此推荐采用修剪措施，其既不会影响树木生长发育，还可产出无节良材，提升木材品质。