ZLV Online

Abstract

Monospecific stands of spruce and pine have manifested health worsening over the last two decades in the Czech Republic. Given the ongoing climate changes, one can expect a further loss of these coniferous forest stands in near future. Therefore foresters are interested in the use of pioneer species to restore a woody-species cover within large clearings. The most promising pioneer is silver birch that can perform well at many sites. The study deals with thinning of naturally-regenerated birch stand following a salvage clear-cutting of spruce. Three thinning treatments such as no thinning (K), 1,100 trees left on site (Z3), and 400 crop trees released from competitors with all others left on site (Z5) were established in the 16-year-old stand. The experiment was measured 4 years after thinning. Both thinned treatments affected the diameter increment of the released trees positively. Slenderness ratio responded significantly to Z3 thinning, and insignificantly it is very likely to have a similar effect at Z5 treatment though. The live crown length was also significantly affected at Z3 whereas at Z5 was observed only a minor effect, which was attributable to completion with a part of understory left on site. Early response to thinning highlights the importance of a density reduction for stabilization and vigour of birch stands.