Factors influencing deer browsing damage to red spruce ( Picea rubens) seedlings in coastal red spruce–balsam fir stands of southwestern Nova Scotia

Abstract

The impact of deer browsing on the distribution and growth of naturally regenerating red spruce seedlings established within recently harvested and mature, coastal red spruce–balsam fir stands was evaluated. More specifically, we examined browsing frequency and severity in relation to distance from forest cover, stand age, and seedling height. Relative height increment and condition of browsed (20% removal of total biomass) and non-browsed seedlings after one growing season were also compared. A significant distance×stand age interaction was observed for browsing frequency, largely the result of differences among recently harvested stands. Browsing damage within mature stands was negligible, but when occurring, was restricted to taller seedlings within 20 m of the forest edge. Eleven percent of all seedlings within harvested stands were browsed, with seedlings between 50 and 100 cm tall being preferred. Most of the seedlings (92%) sustained less than 30% biomass removal. Fifty-two percent of these seedlings experienced less than 10% biomass loss. Relative height increase of browsed seedlings was significantly reduced. Most seedlings were able to recover from clipping damage, regaining much of the initial height and biomass originally lost by the end of summer. Seedling condition was not detrimentally affected by the clipping rate, although overall biomass gain of affected seedlings was lower. If no further browsing damage is sustained, biomass increment may be delayed by approximately one growing season, relative to undamaged seedlings of equal size and established under similar micro-environmental conditions. Current population densities of deer appear to have minimal impacts on re-establishment of coastal red spruce–balsam fir stands in southwestern Nova Scotia. Low impacts may be due to high seedling densities, as more than adequate numbers of seedlings remained untouched throughout the harvested stands.