THINNING RESIDUES AS A SOURCE OF BROWSE FOR MOOSE IN MANAGED FORESTS IN FINLAND

Abstract

Moose (Alces alces) browsing causes considerable damage in young Scots pine (Pinus sylvestris) stands in Finland. In this study, we examined the possibility of increasing moose browse in managed forests by providing cutting residues (i.e., the tops of different tree species) from commercial thinnings made in early or midwinter. The study was carried out in 24 thinned stands in southern and central Finland during 1993-98. Moose browsing on cut tree tops was measured on circular plots, as well as at feeding sites with salt (Na⁺) stones and on plots where the cut tree tops were raised up from the ground. The biomass of tree tops consumed in the thinned stands was even greater than that measured in young pine stands. The biomass consumption was increased by propping the tree tops against standing trees or rocks. Placing salt stones to attract moose had no effect on browsing on the pine tops raised up at the feeding sites. The phenolic acid concentrations were generally higher in the cut pine tops than in the side twigs of standing trees or in young pines, indicating that the high consumption by moose was not explained by low phenolic acid concentrations. According to the fecal pellet groups, 19-23 moose days/ha were spent in the thinned stands. We estimate that a 10 ha cutting area would provide food during 2 winter months for moose at a density of 1 animal/km². We conclude that more accessible winter food can be provided by timing the cuttings in early and midwinter.