Bark-stripping damage by red deer in a Sitka spruce forest in western Scotland IV. Survival and performance of wounded trees

Abstract

Summary In Glenbranter Forest, Argyll, 29 sites were monitored for bark-stripping damage for 10-18 years, and the 495 damaged trees were compared in survival and subsequent performance with the other trees present. Performance was assessed by measuring at 1-2 year intervals the girth of all trees on permanent plots within the sites. At sites initially <8 years old, none of the 185 trees later bark stripped has yet died. At older sites 40 of the 310 bark-stripped trees have died. For sites initially of pre-thicket age, there was apparently better survival of bark-stripped trees than undamaged ones, but this arose entirely from differential survival of the many trees initially <10 cm in girth; in this class only the larger trees could readily be bark stripped and they were less likely than smaller trees to succumb to competition from stronger neighbours in later years. For thicket and pole-stage sites, the barkstripped trees had identical survival rates to the other trees present. Subsequent performance of bark-stripped trees was reduced by 0.2 cm 1 for the sites initially pre-thicket, and by 0.1 cm 1 for the sites initially thicket and pole-stage, in comparison to undamaged trees. The numbers of bark-stripped trees having less increment than expected for their size were significantly greater in sign tests than the numbers having greater increment than expected, which suggests that bark stripping causes a small check in growth. However, these losses will cause negligible reductions in timber yield, and may diminish once the wounds have healed.