Examples of natural (left) and constructed (right) ridge-top wetlands in the Daniel Boone National Forest
Male (dark-colored) and female (light-colored) wood frogs in amplexus at a natural ridge-top wetland in the Daniel Boone National Forest.
System overview: The broad, flat ridge-tops on the Appalachian Plateau in the Daniel Boone National Forest of eastern KY are home to a unique system of naturally occurring ephemeral wetlands (Brown and Richter 2012). These wetlands provide breeding habitat for wood frogs, marbled salamanders, American and Fowler’s toads, mountain chorus frogs, spring peepers, gray tree frogs, spotted salamanders, Jefferson salamanders, and four-toed salamanders (Denton and Richter, 2013; Drayer and Richter, 2016; McTaggart, 2016; Fedders, 2018). Multiple species of bats and other wildlife use the wetlands as a food and water source. These wetlands also provide habitat for wetland plants amidst the otherwise xeric-to-mesic ridges (Fedders, 2018).
Green frogs and floating aquatic vegetation are a few of the tell-tale signs of a permanent wetland.
Over the past several decades, many small depressional wetlands have been constructed on the ridge-tops with the goal of providing year-round water sources for deer, turkeys, and bats. Although these wetlands serve their intended management purpose as permanent water basins, research projects in our lab beginning in 2009 revealed that constructed wetlands have habitat characteristics that are dissimilar to those of natural ridge-top wetlands. Chief among these differences is that constructed wetlands tend to be permanent instead of ephemeral, which affects the amphibian community composition in these ridge-top systems .
This natural, ephemeral ridge-top wetland teems with newly-hatched wood frog larvae in the spring.
Along with hydroperiod, other factors driving amphibian community composition include canopy closure, water chemistry, and vegetative structure. The introduction of permanent-hydroperiod wetlands has allowed populations of green frogs, bullfrogs, and eastern newts, which require permanent or semi-permanent water sources, to become established in the ridge-top environment. These species, especially eastern newts, prey on wood frog eggs and larvae, making permanent constructed wetlands population sinks for wood frogs (Kross and Richter, 2016). There is also concern that green frogs, bullfrogs, and eastern newts, which may serve as disease reservoirs, will introduce and help spread emerging amphibian diseases such as Bd chytrid fungus and ranavirus (Richter et al. 2013). Hydroperiod, canopy closure, and disturbance history also affect plant communities. Natural wetlands tend to have a closed canopy and plants that are less tolerant of disturbance (high ecological conservatism). Constructed wetlands have greater richness of vascular plants than natural wetlands, but lower average ecological conservatism and more nonnative species (Fedders, 2018).
A toad metamorph found at a constructed wetland site.
Current research in this system seeks to continue elucidating mechanisms driving differences in habitat, amphibian communities, and plant assemblages at natural and constructed wetlands. Our goals are to inform management decisions that will improve ridge-top habitat for ephemeral-wetland obligate species and species of high ecological conservatism, minimize the risk of disease transmission, and manage invasive species.
Students: Graduate students who have contributed to research in this system include: Andrea Drayer, Robert Denton, Susan King, Chelsea Kross, Jennifer Skibbe, Audrey McTaggart, and Rachel Fedders. Undergraduates include Selsey Stribling, Ston Coles, and Sarah Phillips.
Collaborators: The Richter lab is collaborating with Dr. Kelly Watson (EKU Department of Geosciences), Dr. Luke Dodd (EKU Department of Biological Sciences) and graduate student Courtney Hayes to study wildlife usage of natural and constructed ridge-top wetland sites using bat detectors and trail cameras. The lab is also working with Dr. Watson and Matt McClure to carry out LiDAR detection of ridge-top wetland basins. LiDAR is being used to understand wetland geomorphology and distribution and to locate previously unknown natural wetlands and undocumented constructed wetlands. Undergraduate students who have contributed to this geospatial research include Raymond Patrick, Cody Click, and Cory Abrams. Dr. Jonathan Malzone (EKU Department of Geosciences) is leading hydrology research in the ridge-top wetland system to investigate surface water-groundwater interactions of natural and constructed wetlands. Dr. Malzone’s research elucidates the hydrologic connections of wetlands that have been previously thought to be ‘geographically isolated’. Undergraduate students who have contributed to this hydrology research include Addison Bell, Gilbert Minzenberger, Ethan Sweet, Selsey Stribling, James Thompson, Daniel Draper, Victoria Swisher, and William White.
Spring peepers are one of the many amphibians that breed in ridge-top wetlands
Acknowledgements: Ridge-top wetland research has been made possible through support and funding by the US Forest Service, with special thanks to Cumberland Ranger District Biologist, Christy Wampler. Additional funding has been provided through EPA Wetland Program Development funds, National Science Foundation Research Experience for Undergraduates grant, EKU University Funded Scholarship grant, EKU Division of Natural Areas, EKU Department of Biological Sciences, the Kentucky Division of Water, and various other grants and funding sources. Student funding sources have included the Society for the Study of Amphibians and Reptiles, Sigma Xi Grants in Aid of Research, The American Society of Ichthyologists and Herpetologists' Gaige Award, The Northern Kentucky Fly Fisher’s Association Red Barrington Scholarship, Kentucky Society of Natural History Research Grant, The Kentucky Native Plant Society, and the Kentucky Academy of Science.
__________________________________________________________________________________________________________________________ Publications from Research System (* = student coauthor)
PDFs of publications are available via ResearchGate.
Skibbe, J.R.*, J. Farrar*, K. Watson, and S.C. Richter. Accepted, pending revisions. Population genetics of wood frogs (Lithobates sylvaticus) in a forested ridge-top wetland ecosystem. Herpetological Conservation and Biology.
Richter, S.C., M.L. Guidugli, and D.R. Brown. 2017. Wetlands of Kentucky: connecting landscapes and waterways. In: B.D. Lee, A.L. Jones, D. Carey, and S. McSpirit (eds.), Water in Kentucky: Shaping Landscapes, People, and Communities.
Calhoun, A.J.K., D.M. Mushet, L.C. Alexander, E.S. DeKeyser, L. Fowler, C.R. Lane, M.W. Lang, M.C. Rains, S.C. Richter, and S.C. Walls. 2017. The significant surface-water connectivity of "geographically isolated wetlands". Wetlands 37:801-806.
Drayer, A.N.*, and S.C. Richter. 2016. Physical wetland characteristics influence amphibian community composition differently in constructed wetlands and natural wetlands. Ecological Engineering 93:166–174.
Kross, C.S.*, and S.C. Richter. 2016. Species interactions in constructed wetlands result in population sinks for wood frogs (Lithobates sylvaticus) while benefitting eastern newts (Notophthalmus viridescens). Wetlands 36:385-393.
Calhoun, A.J.K., J. Arrigoni, R.P. Brooks, M.L. Hunter, and S.C. Richter. 2014. Creating successful vernal pools: a literature review and advice for practitioners. Wetlands 34:1027–1038.
Richter, S.C., A.N. Drayer*, J.R. Strong*, C.S. Kross*, D.L. Miller, and M.J. Gray. 2013. High prevalence of ranavirus infection in permanent constructed wetlands in eastern Kentucky, USA. Herpetological Review 44:464-466.
Denton, R.D.*, and S.C. Richter. 2013. Amphibian communities in natural and constructed ridge top wetlands with implications for wetland construction. Journal of Wildlife Management 77:886-889.
Denton, R.D.*, and S.C. Richter. 2012. A quantitative comparison of two common amphibian sampling techniques for wetlands. Herpetological Review 43:44-47.
Brown, D.R., and S.C. Richter. 2012. Meeting the challenges to preserving Kentucky's biodiversity. Sustain 25:22-33.