Scale-dependent responses of predators and their prey to spruce plantations in subarctic birch forests in winter

Abstract

Planting of non-native spruce in subarctic birch forests introduces new habitats that change the landscape mosaic and increase the extent of artificial edges. This may alter the spatio-temporal predator—prey dynamics. In this study, we focused on small- to medium-sized ground-dwelling prey species and their mammalian predators in winter. In a spatially extensive snow-tracking study over 3 winters (2003–2005), we explored the spatial distribution of species at 3 spatial scales ranging from forest stands to landscape mosaics. We documented scale- and time-dependent responses to spruce plantations for red fox, stoat, mountain hare, and voles, which were the dominant species in the study. However, the responses to spruce plantations were mostly inconsistent across scales. A small-scale affinity for plantation edges, largely consistent over time, was found for all species. By contrast, habitat selection for and against spruce plantations at stand scale alternated profoundly among the different years, although in qualitatively similar patterns among the dominant species, which suggests a common cause. At the landscape scale only red fox was negatively related to proportion of spruce plantations, while mountain hares exhibited annual shifts in occurrence relative to the amount of spruce. Predators and prey were spatially and temporally related at the 2 smallest scales (i.e., within and among forest stands) in a manner that may be explained by year- and stand-specific snow conditions affecting the predator—prey interactions within the community.