The responses of sub-boreal forest insects to a catastrophic wind-disturbance event and subsequent fuel-reduction practices in northeastern Minnesota.

摘要

I assessed the impacts of a catastrophic wind storm and subsequent fuel-reduction activities (salvaging and prescribed-burning) on litter-dwelling (Coleoptera: Carabidae) and subcortical (Coleoptera: Buprestidae, Cerambycidae, Cleridae, Cucujidae, Curculionidae, Histeridae, Scolytidae, Salpingidae, Tenebrionidae; Hymenoptera: Siricidae) insects in two sub-boreal forest cover types in Minnesota. In 2000-2003, a total of 136,996 insects represented by 216 species were trapped in the aspen/birch/conifer and jack pine, Pinus banksiana, cover types. Museum and field surveys revealed new state records for 13 genera and 100 species of ground beetles, and 24 species of subcortical insects. One-third more ground beetles were caught in the aspen/birch/conifer forests, whereas slightly greater species diversity was found in the jack pine forests. Trap catches of ground beetles were two-times greater in undisturbed than in wind-disturbed forests, but species diversity was one-fourth greater in wind-disturbed forests. Trap catches in burned forests were two- to six-times greater with one-third greater species diversity than in the other land-area treatments. Pterostichus melanarius, a European species, was the most abundant ground beetle in the study, and was caught in two- to eight-times greater numbers in burned forests. In 2001 and 2002, trap catches of subcortical insects were two- to three-times greater in wind-disturbed, salvaged, and burned jack pine areas than they were in 2003. Subcortical insect species diversity was greatest in wind-disturbed and burned forests. Both ground beetle and subcortical insect species composition of the salvaged and burned forests differed from that of the undisturbed and wind-disturbed forests. Semiochemicals were effective tools to monitor subcortical insect species in these forests, however, the insect responses varied strongly with the year of sampling and the land-area treatment. In wind-disturbed forests, more than one-third of leaning and standing live trees died between 2001 and 2003. Subcortical insects were generally more associated with dead than live trees, and their activity on the trees also declined in 2003. Monochamus spp. (Cerambycidae) became primary colonizers of standing live trees in the wind-disturbed forests. There was limited evidence for within-tree partitioning among the scolytid beetle species on fallen jack pine.