Selective debarking by ungulates in temperate deciduous forests: preference towards tree species and stem girth

Abstract

Debarking by ungulates has various effects on stem development and forest tree composition. Selectivity for debarking may prevail based on tree species and stem girth. We investigated this selective utilization based on species and size composition of available and debarked stems. Measurements were taken on 2100 sampling points in different temperate deciduous forests of Mátra Mountains region, Hungary. We distinguished specific stem injuries from each other. Factors influencing debarking (stem density and diversity, understory browsing) were also studied. Frequency of debarking was very low (5 % of sampling points). It was the lowest in beech forests (0.2 %) and the highest in Turkey oak–sessile oak forests (6 %). The proportion of injured stems varied between 0.001 % in beech forests to 0.04 % in Turkey oak–sessile oak forests. Ash, linden and maple trees were the most utilized; ash was revealed as significantly preferred species. Most of the injured stems had a perimeter between 12 and 21 cm, proved as preferred stem size interval. Trunks larger than 50 cm girth were generally avoided. Bark stripping and antler rubbing occurred mainly on thinner ash stems, whereas bark rubbing on larger oak stems. Understory density and diversity was significantly higher at debarked sampling points than intact ones. Ungulate debarking is functioning as selective natural disturbance. As a driver of forest vegetation dynamics, its total elimination should not be targeted from forest ecosystems. We recommend maintaining a diverse forest composition to ensure selective stem utilization of ungulates and reduce damage on major tree species of economic importance.

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