INSTYTUT DENDROLOGII

Igor Štefančík, Zdeněk Vacek, Ram P. Sharma, Stanislav Vacek, Michaela Rösslová

Effect of thinning regimes on growth and development of crop trees in Fagus sylvatica stands of Central Europe over fifty years

Dendrobiology 2018, vol. 79: 141-155

http://dx.doi.org/10.12657/denbio.079.013

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Abstract: 

Crop trees are the main component of the qualitative and value production of forest stands. Therefore, stand density of crop trees is one of the most important information items for comparing different management strategies in forestry. Although the number of crop trees per hectare and their productivity are influenced by various factors, thinning can be one of the most important among them. This article aims to compare the growth and development of crop trees in European beech (Fagus sylvatica L.) stands, which have been managed by three different thinning types over 50 years: heavy thinning from below, free-crown thinning and without thinning (or control). The measurements and assessments of crop trees were made using three essential criteria (best stem quality, diameter and height dimensions, regularity of spacing) every four or five years during 50 years. More than 9,000 assessments of crop trees with stand ages ranging from 30 to 105 years on 23 sample plots across Slovakia were analyzed. The highest number of crop trees was reached in a stand where free-crown thinning was applied. The proportion of crop trees on the subplots managed by crown thinning was 61% of the stand basal area and 66% of the merchantable volume at stand age of 100 years. However, much lower proportions of crop trees were found on the subplots managed by thinning from below (32% and 32%) and control (20% and 21%), respectively. The subplots, where free-crown thinning was applied, showed significantly higher values of other quantitative characteristics (e.g., diameter increment, height-diameter ratio, crown width) than those on the subplots managed with the other two thinning types (low thinning and control). Based on the results from a systematic investigation after 50 years, free-crown thinning is recommended for selective thinning in beech forests.

Keywords: European beech, crown thinning, low thinning, basal area proportion, stand skeleton, stand stability