Harvest retention patches are insufficient as stand analogues of fire residuals for litter-dwelling beetles in northern coniferous forests

Abstract

We compared litter-dwelling beetle assemblages of <1- to 2-ha unharvested coniferous patches embedded in 1-year-old clearcuts with beetle assemblages from <1- to 10-ha unburned fire residuals within 15- and 37-year-old burned forests. Our primary objective was to determine whether unharvested patches retain biotic elements that are similar to those of the surrounding uncut forests and to those of patches of forest skipped by wildfires. Beetle assemblages of the harvest residuals were similar to those of the uncut forest, suggesting that harvest residuals retain elements of the mature forest. However, beetle assemblages of harvest residuals differed from those of fire residuals. Thus, harvest residuals sited without regard to microhabitat characteristics or stand structure in fire residuals are insufficient analogues for the late successional habitats provided by fire residuals. There was no relationship between size of harvest residuals and either beetle catch or diversity. Beetle catches were higher in round harvest residuals, and a number of forest species also appeared to be aggregated in round residuals. Forest managers may preserve biotic elements of young uncut forest by leaving round harvest residuals in clearcuts; however, a closer habitat match between harvest and fire residuals is likely required to preserve and maintain landscape-level forest biodiversity.