Influence of tree size and dominance on incidence of bark stripping by grey squirrels to oak and impact on tree growth

Grey squirrel damage was monitored annually in a stand of naturally regenerating oak in the Forest of Dean, UK, between 1998 and 2003. Incidences of damage and wound size were significantly related to tree size, with dominant oak trees and those above 7.5 cm diameter at breast height, most at risk of damage on the main stem. Fresh damage occurred on 9-38 per cent of trees each year, with 2-17 per cent of trees ring barked in any year. Damage was concentrated above 4 m up the main stem and for some trees led to dieback and loss of apical dominance accompanied by a reduction in top height increment. Continuing damage is likely to lead to a general reduction in yield of the stand. As with other species, tree diameter and dominance appear to be useful predictors of bark-stripping damage risk on oak.