The effects of scarification and shelterwood treatments on naturally regenerated seedlings in southern Sweden

Abstract

This study investigated the effects and interaction effects of scarification versus no scarification and shelterwood versus clearcut on natural regeneration in southern Sweden. Focus was placed on the most common tree species, i.e. Scots pine ( Pinus sylvestris L.), Norway spruce ( Picea abies (L.) Karst.) downy birch ( Betula pubescens Ehrh.) and silver birch ( Betula pendula Roth), which are intended to form future stands. In addition, less common tree species were investigated, which would provide greater biodiversity in the future stands. The study was conducted on eight sites well distributed over southern Sweden. The shelterwoods were dominated by pine. Both the scarification and shelterwood treatments favoured the establishment of pine while spruce establishment was less affected. For birch, the scarification increased the density of seedlings in the shelterwood while it decreased the density of seedlings in the clearcut. In general, the less common tree species were not affected by the treatments. Instead, seed supply appeared to be a more important factor for regeneration success. However, the total density of the animal-dispersed tree species was favoured by a shelterwood and the total density of wind-dispersed tree species was favoured by scarification. The grass cover was reduced by the shelterwoods and hence the clearcuts were more grass-dominated. Furthermore, scarification increased the occurrence of herbs. The study showed that scarification and cutting treatments are efficient tools to steer the natural regeneration.