Spatial pattern in boreal shrub communities: effects of a peak in herbivore density

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Abstract
As part of a large-scale experiment on the dynamics of boreal forest communities, we examined the effects of experimental manipulations on the spatial pattern of two shrub species, Salix glauca and Betula glandulosa, before and after the population peak of the herbivore Lepus americanus, the snowshoe hare. Despite high rates of twig browsing during the peak, at most sites the basic characteristics of the spatial pattern recovered quickly. Only where food addition and predator exclosure enhanced and prolonged the hare density peak was there a sharp decline in the intensity of spatial pattern of the preferred winter food plant Betula. The spatial pattern of these shrubs is resilient to normal changes in herbivory and may persist, therefore, for decades through several hare population cycles. Key words: Betula glandulosa, Lepus americanus, Salix glauca, spatial pattern.