BARK STRIPPING BY MOOSE IN COMMERCIAL FORESTS OF FENNOSCANDIA - A REVIEW

Abstract

The stripping of bark from young timber trees by wild cervids is of commercial concern in many parts of Fennoscandia. we review the occurrence of this habit in moose (Alces alces) in relation to region, forestry practices, site productivity, and quality of available forage in the vicinity of areas with bark stripping. The greatest commercial loss from bark stripping is seen in Scots pine (Pinus sylvestris), with lesser impacts on Norway spruce (Picea abies). In stands of young Scots pine subject to bark stripping, generally less than 5% of trees are affected each year. In central Sweden the damage to pine is confined to sapling stands 1.5-4 m tall, but to the north older trees in ‘thinning-stage stands’ are also frequently barked. Bark stripping in central Sweden occurs primarily during spring, while in the north it occurs throughout the year with a higher frequency in mid- to late winter. Bark stripping of Norway spruce has previously occurred only to a small extent, but in the past decade it has increased in importance in parts of southern Fennoscandia. In these new occurrences there is an apparent association with areas of high acidification from anthropogenic sources. Various authors have suggested why cervids seek tree bark, particularly red deer (Cervus elaphus). For moose, however, no single hypothesis has been verified. Possible mechanisms inducing bark stripping are discussed here, including the role of nutrient deficiencies in moose. Finally, methods for reducing bark stripping damage by moose are discussed.