Physical effects of weather events on the abundance and diversity of insects in North American forests

Abstract

We summarize the effects of major weather events such as ice storms, wind storms, and flooding on the abundance and diversity of terrestrial forest insects and their allies. This synthesis indicates that weather events influence both spatial and temporal patterns of forests and insect communities in North American landscapes. The Atlantic and Pacific oceanic sides of the continent are relatively more susceptible to ice and wind storms, respectively. There have been more studies and reports on the responses of forest insects to wind storms, and on economically important subcortical insects than on gall-forming, foliage-feeding, fungal-feeding, litter-dwelling, pollinating, parasitizing, predaceous, root-feeding, and sap-feeding insects. Weather events positively affect populations of subcortical insect species, and impact their colonization patterns and dynamics. Species belonging to genera such as Dendroctonus (Scolytidae) and Monochamus (Cerambycidae) may sometimes cause economic damage by colonizing residual live tree, and dead trees, rendering the wood unsalvageable. Subsequent outbreaks of spruce beetle, Dendroctonus rufipennis (Kirby) and Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, have been frequently documented in western North American forests following wind events. Wind disturbances have also been observed to accelerate the life-cycles of D. rufipennis and Semanotus litigiosus (Casey) (Cerambycidae), and in rare instances, have caused Monochamus spp. to become primary colonizers. Populations of other important subcortical species have not always increased dramatically following weather events. Foliage- and pollen-feeding insects may experience mortality directly from a weather event or indirectly through habitat alteration. In some cases, forest insects may use storms to migrate to new habitats. Populations of open-habitat and forest specialist litter-dwelling species have increased and decreased, respectively, subsequent to weather events. Forest specialist species generally rebound within a short period of time, suggesting that they are adapted to these periodic weather events. Little is known about the combined effects of post-weather-disturbance management practices such as salvage-logging and prescribed-burning on insects in North American forests.