Date of Award
5-2014
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Legacy Department
Wildlife and Fisheries Biology
Committee Chair/Advisor
Robert F. Baldwin
Committee Member
Elizabeth D. Baldwin
Committee Member
Hugh Hanlin
Committee Member
Michael Childress
Abstract
Throughout the world, wetlands are known to support a wide variety of taxa as well as high levels of biodiversity and species richness. Although the ecological significance of wetlands is well documented in the scientific literature, efforts to map and assess wetlands on regional or national scales (e.g., National Wetlands Inventory (NWI)) often overlook wetlands which are either very small (< 1 ha) or have ephemeral hydroperiods. While the vast majority of wetland research in the southeastern United States has focused on wetlands distributed across the coastal plain ecoregion, very little information exists on small and/or ephemeral wetlands in areas of southern Appalachia, although there are several notable exceptions. Despite the paucity of small wetland data in this region, the southeastern US is known as a hotspot for both aquatic biodiversity and species endemism. My goal with this project was to examine the biotic communities inhabiting small, ephemeral and geographically-isolated wetlands to identify the major environmental drivers that contribute to observed community patterns and species' distributions. I studied a set of small, mostly-ephemeral, mostly-isolated wetlands (N = 41) in the upper Piedmont and lower Blue Ridge ecoregions of South Carolina from January-June of 2010 and 2011 and focused my efforts on describing the structure, biotic communities and surrounding habitat characteristics of my study wetlands. I observed high levels of species richness and biodiversity in this previously-undocumented wetland system, despite the small size and ephemeral nature of study wetlands. My results indicated that the amphibian and benthic invertebrate communities of small, ephemeral wetlands responded to different environmental drivers (e.g., wetland depth, area, hydroperiod, canopy cover, surrounding land use types) occurring across multiple spatial and temporal scales. Additionally, the amphibian community was significantly influenced by a number of environmental variables occurring at both the within-pond scale and larger spatial scales (250 m, 500 m and 1 km surrounding land cover variables). By contrast, the benthic invertebrate community was significantly influenced primarily by variables occurring at the within-pond scale. This wetland system also served as both breeding and overwintering habitat for a variety of species such as wood frogs (Lithobates sylvatica), spotted salamanders (Ambystoma maculatum), bullfrogs (Lithobates catesbeiana), cricket frogs (Acris crepitans). This study highlights the ecological importance of small, ephemeral aquatic habitats in a region where little research exists regarding such systems; these often-unnoticed ecosystems are likely the result of a combination of historical anthropogenic and natural environmental process. These legacy wetlands (i.e., wetlands that are the unintended result of some human-induced environmental change in either the recent or long-term past) are found ubiquitously across the landscape and are often missed by coarse-filter mapping approaches (e.g., National Wetlands Inventory). I observed many study wetlands to be extremely small in size (< 0.05 ha) and that many wetlands were habitats of circumstance and opportunity rather than of permanence and predictability. The ephemerality of the majority of study wetlands demonstrates the biological significance of small, temporary habitats for many species requiring these habitats for breeding activity. Despite the small size and ephemeral nature of my study wetlands, I found that these wetlands represented a large proportion of amphibian biodiversity in the regional species pool and thus, are an important conservation feature at the local, landscape and regional scales. My study demonstrates that small, semi-isolated, mostly-ephemeral wetlands in southern Appalachia support high levels of biodiversity and are an important asset deserving of further study and conservation recognition.
Recommended Citation
Hawley, Joanna, "Isolated and Ephemeral Wetlands of Southern Appalachia: Biotic Communities and Environmental Drivers Across Multiple Temporal and Spatial Scales" (2014). All Dissertations. 1330.
https://tigerprints.clemson.edu/all_dissertations/1330