Long-term effects of supplementary feeding of moose on browsing impact at a landscape scale

Supplementary, or diversionary feeding of wildlife is a common management practice, increasingly used to reduce or divert herbivore impact from sensitive habitats, forestry or agriculture. The landscape-scale spatial distribution of herbivory in relation to diversionary feeding is relevant to wildlife and land management, yet has never been quantified. We considered multiple hypotheses, based on central-place foraging theory, to investigate how landscape-scale browsing impact changed as a function of distance from feeding stations and thereby test the effectiveness of diversionary feeding. We assessed the landscape-scale browsing impact of moose by quantifying browsing patterns and moose density in commercially-valuable young Scots pine stands in an area of South-East Norway with a long history of winter feeding. We also used positions from GPS-collared female moose to investigate the spatial distribution of individuals across the landscape. Moose density and browsing impact at the local spatial scale (<1 km) followed an exponential decrease with distance from diversionary feeding stations. However, at the landscape scale (1-10 km), browsing impact did not show any relationship with distance to feeding stations. Leader stem browsing on Scots pine trees was high at both the local (68 +/- 12%) and landscape (59 +/- 8%) scales. In addition, browsing on commercially valuable Norway spruce, which is normally avoided by moose, was locally high around feeding stations. Long-term diversionary feeding of moose is ineffective in diverting browsing impact from young pine stands at the landscape scale, as currently practiced. Browsing on commercially-important tree species was sufficiently high that economic consequences could be expected. To avoid further conflict, we suggest a combination of reducing moose density and increasing the availability of natural or higher quality supplementary forage. (C) 2013 Elsevier B.V. All rights reserved.