Maintaining tree islands in the Florida Everglades: nutrient redistribution is the key

Authors

Paul R. Wetzel, Smith CollegeFollow
Asnold G. van der Valk, Iowa State University
Susan Newmand, South Florida Water Management DistrictFollow
Dale E. Gawlik, Florida Atlantic UniversityFollow
Tiffany Troxler-Gann, Florida International UniversityFollow
Carlos A. Coronado-Molina, South Florida Water Management DistrictFollow
Dan Childers, Florida International UniversityFollow
Fred H. Sklar, South Florida Water Management DistrictFollow

Abstract

The Florida Everglades is an oligotrophic wetland system with tree islands as one of its most prominent landscape features. Total soil phosphorus concentrations on tree islands can be 6 to 100 times greater than phosphorus levels in the surrounding marshes and sloughs, making tree islands nutrient hotspots. Several mechanisms are believed to redistribute phosphorus to tree islands: subsurface water flows generated by evapotranspiration of trees, higher deposition rates of dry fallout, deposition of guano by birds and other animals, groundwater upwelling, and bedrock mineralization by tree exudates. A conceptual model is proposed, in which the focused redistribution of limiting nutrients, especially phosphorus, onto tree islands controls their maintenance and expansion. Because of increased primary production and peat accretion rates, the redistribution of phosphorus can result in an increase in both tree island elevation and size. Human changes to hydrology have greatly decreased the number and size of tree islands in parts of the Everglades. The proposed model suggests that the preservation of existing tree islands, and ultimately of the Everglades landscape, requires the maintenance of these phosphorus redistribution mechanisms.

Comments

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Wetzel, P., A.G. van der Valk, S. Newman, D.E. Gawlik, T. Troxler-Gann, C. Coronado-Molina, D.L. Childers, F.H. Sklar. 2005. Maintaining tree islands in the Florida Everglades: nutrient redistribution is the key. Frontiers in Ecology 3(7): 370-376.