Impact of wild ungulates on forest regeneration and tree composition of mountain forests in the Western Italian Alps

Abstract

The impact of ungulates on forest regeneration was observed in six localities of the Italian Western Alps recently colonized by deer and having different densities of ungulates. The selectivity of bark stripping, browsing and fraying damage was analysed. The incidence of damage on forest regeneration varies between 79.8% (class A, height 10–150 cm) in the most severely damaged area to 10.2% in the least affected area. The incidence of damage in each species varies considerably and the tree species most sensitive to browsing damage is the silver fir ( Abies alba). Browsing and bark stripping are always highly selective, whilst a difference between red and roe deer was found in relation to fraying damage. The lethality (dead trees/damaged trees) of damage resulting from fraying is important also with low densities, but increases slowly at high densities; the lethality of damage resulting from browsing is nil with low densities of ungulates, whereas it increases rapidly with good correlation when ungulate densities are high.