One emphasis in our lab is the study of patterns and processes in coastal ecosystems. West-central Florida lies at the latitudinal transition between mangrove forests and salt marshes as the dominant biome of low-energy coastlines. Along with broad open salt flats, these two ecosystem types intermix to form patchy mosaic landscapes (top photo). This heterogeneity in plant form and physical environment at the land-ocean interface offers many research opportunities in all areas of ecology and biogeochemistry. Much of this habitat is threatened by extensive coastal urban development (lower photo). Below we describe one of our current coastal ecology projects.
Nutrient immobilization in mangrove forests and salt marshes
Human activities have nearly tripled the input of nitrogen (N) to the biosphere. Because N is an essential element for life, this acceleration of the N cycle has pervasive ecological and biogeochemical effects, many of them undesirable. It has also galvanized interest in the ability of ecosystems to retain N. Large quantities of N are stored by the decaying remnants of vegetation, animals, and microorganisms—collectively known as soil organic matter, or SOM.
This project uses isotopic tracers (15N) to test the hypotheses (1) that SOM quickly immobilizes N in the stable fraction, which is the subset of SOM that takes years and even decades to decompose, and (2) that immobilization rates vary with plant species composition owing to differences in SOM quality. This research is currently funded by a National Science Foundation RAPID award, and is being conducted in intertidal mangrove forests and salt marshes along the coast of west-central Florida near Tampa Bay. To help investigate how N immobilization differs among vegetation types, we have teamed up with foresters and remote sensing experts to quantify vegetation structure and composition. By investigating baseline mangrove and salt marsh ecosystem function with this mix of expertise, we hope to develop remote sensing tools for rapidly quantifying the impacts of disturbance (such as from oil spills) and targeting restoration efforts across west-central Florida’s vast and otherwise intractable mangrove forest inventory.
Of course, every good project starts with a well-conceived process of site selection. A big thanks to Mark Butler and our friends at the Pasco County School District for letting us work from the Energy Marine Center, their coastal environmental education facility. Here are Mark and Kristine hard at work scouting potential field sites!