Influence of harvest gaps and coarse woody material on click beetles (Coleoptera: Elateridae) in Maine’s Acadian forest
In order to maintain biodiversity in forests, it has been recommended that harvests be designed after patterns of natural disturbance. Using a long-term study that includes harvest treatments designed to emulate tree-fall gap disturbances in Maine’s Acadian forest, we examined how the species richness, abundance, diversity, and assemblage similarity of click beetles inhabiting coarse woody material (CWM) were affected by gap harvesting and CWM characteristics (diameter, degree of decay, and type of wood). There were few differences in beetle assemblages between 0.07 and 0.12 ha harvest gap treatments. Four of the most common species had higher abundances under a closed forest canopy than within harvest gaps. Species richness and total abundance were higher in CWM that had larger diameters and were more decayed. Species assemblages also differed with the degree of wood decomposition. Diversity was higher in CWM from softwood trees than hardwood trees. Results from this study suggest that small (<0.2 ha) harvest gaps with living trees retained throughout the gap can maintain click beetle assemblages similar to that of an unharvested forest. Forest managers also need to address the temporal continuity of CWM, including different types of wood (hardwood and softwood), a range of decay conditions, and a range of diameter classes, especially larger diameters (>35 cm).