The influence of accelerated aspen-dominated forest senescence on local invertebrate populations.

Abstract

An increase in plant diversity following aspen senescence should impact animal diversity, but the exact nature of such changes is not known. The present study, set in an aspen-dominated forest, focuses on the response of a food chain to induced acceleration of plant senescence. Invertebrate primary consumers, specifically insects, have repeatedly been demonstrated to respond rapidly to such changes. Thus, to answer the question of how a transitioning aspen-dominated forest ecosystem affects local insect assemblages, we sampled insects in an aspen- and birch-dominated forest at the University of Michigan Biological Station, on control sites and on similar sites where senescence has been induced by the girdling of aspens and birches in spring 2008. At this time, approximately one year after girdling, chisquare tests yield significant differences in guild densities between girdled and ungirdled areas. Regression tests, however, yield no statistically significant correlations between guild density and girdled / total tree density, indicating that more time may be necessary before the effects of aspen and birch senescence on higher trophic levels will be made manifest. Introduction