Diversity loss and changes in saproxylic beetle assemblages following a high-severity fire in Araucaria–Nothofagus forests

Abstract

Forest fires have increased in frequency worldwide due to global warming, drought, and land-use change. These fire-regime changes have altered the dynamics of deadwood accumulation in forests, which can affect biological communities dependent on this resource. We analyzed the effect of high-severity fire events on saproxylic beetle assemblages, which specialize in using deadwood that accumulates after disturbances. We compared assemblages in sites severely burned in 2002 to those in unburned sites in Chilean Araucaria–Nothofagus forests. Insects were collected using window-interception traps from spring 2017 to summer 2018. Rarefaction–interpolation curves revealed a significant decrease in diversity as a result of fire. Permutational multivariate analysis of variance showed a significant effect of fire on insect community structure. In addition, we observed that species turnover contributing most, and nestedness to a lesser extent, to differences in s-diversity between burned and unburned sites. Species replacement was associated with an increase in abundance of xylophagous (deadwood feeders) and a decrease in abundance of mycophagous (fungivorous) insects with fire. Therefore, our results suggest that fire causes a reduction in diversity while benefiting the abundance of xylophagous beetles in Araucaria–Nothofagus forests. We recommend the use of these insects as an evaluation tool in conservation planning, management practices, and ecological restoration efforts in burned forests in southern Chile.