Early colonization of Populus wood by saproxylic beetles (Coleoptera)

The early colonization of newly created coarse woody material (CWM) by beetles was studied in aspen mixedwood forests at two locations in north-central Alberta. Healthy trembling aspen (Populus tremuloides Michx.) trees, in old (>100 years) and mature (40-80 years) stands, were cut to provide three types of CWM: stumps, bolts on the ground (logs), and bolts suspended above the ground to simulate snags. Over 2 years, 1049 Coleoptera, representing 49 taxa, were collected. Faunal structure differed little between the two locations. Species diversity was higher in old than in mature stands, and higher in stumps and logs than in suspended bolts; however, these "snags" tended to have higher abundance when compared with stumps and logs. Overall beetle abundance and the catch of wood-boring beetles was significantly higher in the first year posttreatment, mainly because of the ambrosia beetle (Trypodendron retusum (LeConte)) and one of its predators, Rhizophagus remotus LeConte; however, beetle diversity was higher in the second year, suggesting that early wood-boring species may "precondition" the wood for a number of succeeding species. The high turnover rate of taxa and spatial or temporal variation in faunal structure suggests that effort focused on habitat classification of CWM will facilitate management to conserve saproxylic faunal diversity.