DISTRIBUTION OF WINTER BROWSING BY MOOSE: EVIDENCE OF LONG-TERM STABILITY IN NORTHERN SWEDEN

Abstract

Predicting spatial distribution of large herbivore foraging is important for successful management, but accurate predictions remain elusive against a background of multiple causes modified by environmental stochasticity. Moose (Alces alces) might prefer to browse areas with high plant density, but if snow depth co-varies with plant density, this could restrict access to these sites and force use of sites with lower plant density and snow depth. Moose browsing was measured in 72 plots distributed within the subarctic birch (Betula spp.) forest landscape at Abisko in northern Sweden in 1996. In 2010, the same plots were revisited and the measurements repeated. A generalized linear model predicted moose browsing on birch in 2010 from the browsing pattern on birch measured in 1996. The model suggested that neither total density of willow and birch stems nor snow depth were influential of foraging distribution of birch at multiple spatial scales. The spatial scale at which clustering of browsing on birch occurred, coincided with the scale of clustering of birch and willow (Salix spp.) stems at distances of 1000-2500 m; at lesser distance browsing was distributed randomly. We concluded that moose demonstrate stability in spatial browsing patterns after 14 years which corresponds to 3-4 generations of moose, and that plant density represents a cue for moose only at certain scales. Predictability of feeding sites is valuable for long-term moose and forest management, and conservation planning.