Our paper on the landscape pattern of cypress dome wetlands in Big Cypress National Preserve, led by Adam Watts, is available online at Earth Surface Processes and Landforms. Using a variety of lines of evidence, we show that cypress domes are regularly distributed, and that this pattern is more strongly reflected in the bedrock and vegetation than in soil elevations. We also expand on and refine our conceptual model of how this pattern arises. In brief, we propose that cypress domes are drilling into the limestone bedrock via the acidity of organic matter and CO2 production by vegetation. This local positive feedback expands wetland basins vertically and laterally. As wetlands expand, they essentially come into competition for runoff from the adjacent uplands, which ultimately limits the size and density of wetlands on the landscape. Patterns of soil phosphorus suggest that P mobilization by this dissolution may amplify this biogeomorphic feedback. This paper lays the foundation for our new NSF grant, which will support more mechanistic study of the processes that create these wetland basins and control their distribution on the landscape.
We've just heard from NSF that our proposal to study the wetlands of Big Cypress National Preserve will be funded! The Big Cypress landscape is a mosaic of isolated wetlands, grasslands, and pine forests. The core observation that motivates our proposal is that the Cypress wetlands appear to be regularly spaced. This sort of regular pattern occurs in dryland vegetation, in peatlands (including the nearby Everglades) and elsewhere, and is thought to arise from feedbacks that are spatially-dependent. Basically, organisms improve the environment in their immediate vicinity, but that has the effect of making more distant locations unsuitable. In Big Cypress, we think that cypress trees essentially capture water from the surrounding landscape by dissolving the limestone bedrock and creating wetland depressions. Pretty smart! Testing this core hypothesis, and all of its pieces, requires an interdisciplinary team. My colleagues at UF, who are going to do most of the field work, include ecohydrologists, soil scientists, and organic and inorganic geochemists. Brad Murray and I are in charge of developing a model of this landscape. It's gonna be fun.
This is the homepage of the Heffernan Lab at Duke University. Here you can find all sorts of information about our research, teaching, and outreach. If you have any questions, contact Dr. Heffernan.
Dr. Jim Heffernan
I am an Assistant Professor in the Nicholas School of the Environment at Duke University. My research is focused on the causes and consequences of major changes in ecosystem structure, mostly in streams and wetlands.
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