Date of Award

January 2011

Degree Type

Open Access Thesis

Document Type

Master Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

First Advisor

David R. Brown

Department Affiliation

Biological Sciences

Abstract

Land snails are cornerstone organisms that contribute to properly functioning ecosystems. However, habitat loss and destruction have led to these organisms being one of the most imperiled groups on the planet. Due to their relatively sedentary nature, land snails can be susceptible to anthropogenic disturbance and habitat fragmentation. Because of this, old-growth forests have the potential for being premiere habitat for these organisms, and snails have the potential to be good indicators of old-growth habitats. This study compared land snail species diversity and community composition in old-growth and second-growth forests in the Inner Bluegrass, Cumberland Plateau, and Pine Mountain ecoregions of Kentucky. Study areas were selected in central and eastern Kentucky based on disturbance histories. Within each study area, data regarding species diversity, richness, and abundance between disturbance classes was collected and analyzed using a random effects analysis of variance as well as non-metric multidimensional scaling to compare community structures. Habitat data was analyzed using canonical correspondence analysis. In the Inner Bluegrass Region, the snail diversity was high, and had low variability between sampling plots, but community composition differed significantly between the disturbance classes. In the Cumberland Plateau and Pine Mountains sites, species diversity and abundance was higher in the undisturbed forests compared to disturbed forests. There was also high variability in species composition among the sampling plots within these sites. Non-metric Multidimensional Scaling highlighted variation in community structure across all study sites. In the Inner Bluegrass, two distinct communities emerged with complete separation based on disturbance, whereas sites on the Cumberland Plateau and Pine Mountain showed more overlap between disturbance regimes. Canonical correspondence analysis showed that relationships between land snails and environmental factors were variable across all study sites as well. Coarse woody debris, pH, soil moisture, aspect, duff accumulations, herbaceous cover and shrub height all had strong environmental relationships with the snail communities present, but differed in terms of what disturbance class they were correlated with across the study areas. Eighteen species were shown to be statistically significant indicators of undisturbed forests. However, these species were not found at all sites, so the utility of using these species as indicators across a broad geographical region may be limited. However, on an ecoregional scale, micro-snails showed more affinity for the undisturbed habitat than macro-snails. These findings highlight the complexity of snail communities across ecoregions and disturbance classes, as well as the potential utility of land snails as indicators of ecological conditions on regional levels. These results also reinforce evidence of the effects of anthropogenic disturbances on community composition. These findings support efforts to maintain ecological integrity by protecting areas with minimal historical human disturbance.

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