ZLV Online

Abstract

Proper design of skid racks is an important silviculture measure. However, optimal width of skid racks and its influence on possible production loss is still poorly understood. The objective of the study is to evaluate production differences related to width of skid racks in two unmixed even-aged Norway spruce stands within the two experiments: (i) IUFRO CZ 14 Machov, and (ii) IUFRO CZ 13 Vítkov that was established on a former agricultural land. The initial densities were 2 500 trees.ha-1 with top height 3.5 m, and 7 700 trees.ha-1 with the top height 1.2 m, respectively. Following the experimental program, both initial trees densities were reduced to 2 500 trees.ha-1. Mean stem diameter and height did not differ markedly between the treatments. Slenderness quotient showed favorable values varying from 79 to 84. Slenderness quotient of the 200 thickest trees per hectare ranged from 73 to 76. No substantial differences between productions related to the treatments were found. Total volume production varied from 570 to 620 m3 in the Machov locality, and from 750 m3 to 800 m3 in the Vítkov locality. We can conclude that both 3M (3.5m width) and 5M (5m width) treatments represent suitable thinning regimes for spruce stands investigated. The small losses of wood production (approximately 3%, not statistically significant) due to missing trees on wider skid racks are likely to be counterbalanced by less frequent stem damage due to skidding.