Insect Conservation Within the Severely Fragmented Eastern Tallgrass Prairie Landscape

136 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1998.This dissertation reports the results of three studies which address issues related to the conservation of insects within the severely fragmented tallgrass prairie ecosystem. In one study, insects were surveyed within natural area remnants and developed habitats in an attempt to gauge levels of remnant-dependence for 17 prairie and savanna-inhabiting taxa. In a second study, plant and insect data were used to assess the extent to which reliance on plant criteria for conservation planning might result in the conservation of insect biodiversity within the tallgrass prairie ecosystem. Both experimental and comparative approaches were used in a third study to examine the role of fire as a determinant of insect species richness and abundance within isolated prairie remnants. Remnant-dependence among 17 taxa was found to range from lows of 0% for grouse locusts, carrion beetles, and treehoppers, to highs of 75% and 83% for flower and root-boring moths. Plant community richness, plant species richness, and plant genus richness were found to explain significant levels of variation in insect species richness, suggesting that plants are a useful surrogate for insect species diversity. Remnant-dependent insect species were found to be well represented within the botanically-selected Chicago-area reserve system, providing additional support for a vegetation-based, preserve selection approach. Post-fire responses ranged from fire-positive (26%) to fire-negative (40%) for 151 species representing 33 families and seven orders. All fire-negative species recovered in two years or earlier, suggesting that the judicious use of rotational cool season burning is compatible with the conservation of insect biodiversity within fragmented reserve systems. Comparative studies of leafhopper and butterfly population density and species richness among fire-managed and fire-excluded sites provided additional support for this conclusion. The frequent fire hypothesis predicts that annual fires will lower insect mortality by minimizing fuel availability and, hence, fire intensity. Data from consecutive bums on six sites failed to support this prediction for most populations and species studied.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD