Tree browsing by mountain hares (Lepus timidus) in young Scotspine (Pinus sylvestris) and Birch (Betula pendula) woodland

Understanding the factors that influence the extent of mammalian browsing of young trees can facilitate the development of management strategies that permit successful woodland establishment. The effect of tree density, tree species, relative mountain hare (Lepus timidus L.) abundance and ground vegetation height on the extent and severity of browsing damage by mountain hares on Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula L.) saplings was investigated between May 1998 and May 2000. Browsing damage by mountain hares was recorded annually on 300 trees (<1.2 m height) within young woodland at eight sites across north and north-east Scotland, seven of which were fenced to exclude ungulates. Morphological measurements of browsed trees were also recorded to investigate relationships between tree morphology and both the extent of browsing and the response of trees to browsing. Seasonal utilisation of the sites and the relative abundance of hares across sites and between the young woodland and adjacent control areas of moorland within each site were assessed using faecal pellet-counts.

Utilisation of the study sites by mountain hares was highest in spring (May) and the young woodland at each site was utilised less than the adjacent control areas of moorland. A mean of 5.8% of trees were browsed annually per site, although the percentage of trees browsed at each site differed significantly between years. Tree density, relative hare abundance, tree species and ground vegetation height did not significantly influence the percentage of trees browsed. The extent of recorded browsing suggests that the impact of mountain hares on the establishment of Scots pine or birch woodlands in the uplands of Scotland would be minimal where hares occur at the moderate densities such as those indicated by pellet-counts in this study. (C) 2002 Elsevier Science B.V. All rights reserved.