ZLV Online

Abstract

European larch is a promising tree species for the creation of mixed forest stands in the Czech Republic. Due to its deciduous needles, it is relatively resistant to immission, and therefore it was used to establish substitute forest stands. Substitute forest stands were established in the 1970s and 1980s in heavily immissioned mountain and foothill areas with the intention of preserving the continuity of the forest environment and, in the case of larch, to partially replace the timber production of declining spruce stands. The aim of the study is to evaluate the effect of thinning on growth of a non-mixed larch stand in specific conditions of substitute forest stands at the age of 11–29 years. Thinning resulted in acceleration of the diameter growth of the released trees and improvement of their static stability in terms of reduction of the height-diameter ratio (HDR). The treatment where thinning at the age of 11 years was applied (treatment 3) showed a more favourable HDR of individual trees compared to the control, but the results were less satisfactory in terms of crown ratio (CR). The treatment with two thinning interventions at the age 11 and 20 years (treatment 2) produced satisfactory results both in terms of HDR and CR. However, the strong thinning at the age 20, when the stand was curtailed to only 320 trees per hectare, drastically reduced the basal area and is likely to result in a loss of production compared to the more moderate thinning options. However, in substitute forest stands, volume production is not the primary goal.