Ecology and biogeography of Odonata in a northern Minnesota mosaic forest landscape: The impact of anthropogenic disturbance on dragonfly communities in the Mississippi River headwaters region.

摘要

The Odonata of the western Great Lakes forests have not been well studied. In particular, relatively little is known about the ecology and biogeography of dragonflies in northern Minnesota. This region is ecologically diverse due to a major confluence of biomes (prairie, mixed hardwood-pine forest, and hardwood savanna) and watersheds (Mississippi River, Hudson Bay, and Great Lakes). Aquatic and wetland habitats constitute an important part of the region's complex forest landscape mosaic, and the likelihood of finding rare and threatened dragonfly species in such an area is high, especially where habitat is relatively undisturbed.; The purpose of my study was to provide greater understanding of the odonate fauna of northern Minnesota's forest wetlands; to locate habitats and populations of rare or uncommon species; and to assess the ecological and biogeographic impact of timber management and forest fragmentation on dragonfly species in the Mississippi River headwaters region. A total of 45 dragonfly (Anisoptera) species was found in the region, and stenotypic species preferred undisturbed mature forest sites. Several species appear to be sensitive to decline in water quality, and some species respond to vegetation structural changes or habitat fragmentation in disturbed areas where logging or shoreline development has occurred.; I also investigated the role of the Mississippi River headwaters as a habitat corridor linking undisturbed forest "islands" at Itasca State Park and the Chippewa National Forest within the larger disturbed forest landscape of the region. Gaps in the corridor habitat were noted, and several sites were identified as having significant conservation potential. Forest management practices that could aid in odonate conservation in particular, and forest wetland conservation in general, were identified. Continued investigation may provide new insights into biogeography and ecology of northern Minnesota's dragonflies, and may be undertaken as part of a larger survey of the Great Lakes dragonfly fauna. In addition, this study may add to our overall understanding of disturbance in temperate forest landscapes, and may stimulate similar investigations in other regions.