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|Title:||The Effects of Environmental Complexity on Community Structure in Woodland Centipedes|
|Author(s):||Summers, Gerald Frederick|
|Department / Program:||Zoology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Woodland centipedes occur in both log/fallen deadwood and leaf-litter microhabitats in temperate forests. The variation in centipede diversity among similar sites in the Great Smoky Mountains National Park of eastern Tennessee and the Nantahala National Forest of western North Carolina is related to the structural complexity of these microhabitats.
Mean litter depth, mean litter volume per unit area, and absolute estimates of interstitial space in leaf litter are shown to be inappropriate measures of litter complexity due to the patchy distribution of leaf litter. The amount of interstitial space in a volume of litter (relative habitat space), however, is significantly correlated with both species richness and species diversity in litter-centipede communities in these sites.
Twenty-two species were collected in 9 study areas of the southern Appalachians. Four species were significantly associated with log/fallen deadwood microhabitats, while 14 species showed significant concentrations in leaf-litter microhabitats. A group of four species occurred equally often in either microhabitat. These distinctions support the importance of habitat in the structure of centipede communities.
Centipede life-cycles do not permit seasonal segregation, and the diurnal activity patterns of coexisting woodland species are found to be random with respect to time. Body size among coexisting species generally shows an increasing trend, but the trophic apparatus of these species does not follow the same pattern. Instead, two broad categories of mouthpart sizes occur among the coexisting species. These data indicate asymmetries in prey utilization based on food size and are consistent with expectations that ecological segregation based on food size will be rare among arthropod predators.
The distribution of centipedes among log/fallen deadwood and leaf-litter microhabitats is summarized in Levins' "niche breadth" index which is tested for significance by a multinomial exact test. Significant values of this index which are not related to sample size occur. Mean values of microhabitat utilization for species in either microhabitat at each site are not related to species richness for each site. Likewise, average overlap in microhabitat utilization among coexisting species does not vary with species richness. In contrast, species richness in leaf-litter microhabitats is significantly correlated with relative habitat space and centipede diversity in log/fallen deadwood microhabitats is significantly correlated with log dispersion. These findings support the relationship between species diversity and structural complexity of the environment.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1982.
|Date Available in IDEALS:||2014-12-16|