, Volume 13, Issue 1, pp 75–89 | Cite as

Biogeochemical Contributions of Tree Islands to Everglades Wetland Landscape Nitrogen Cycling During Seasonal Inundation

  • Tiffany G. Troxler
  • Daniel L. Childers


In the Florida Everglades, tree islands are conspicuous heterogeneous elements in the herbaceous wetland landscape. We characterized the biogeochemical role of a seasonally flooded tree island during wet season inundation, specifically examining hydrologically mediated flows of nitrogen (N) and N retention by the tree island. We estimated ecosystem N standing stocks and fluxes, soil and litter N transformation rates, and hydrologic fluxes of N to quantify the net ecosystem N mass flux. Results showed that hydrologic sources of N were dominated by surface water loads of nitrate (NO3) and ammonium (NH4). Nitrate immobilization by soils and surficial leaf litter was an important sink for surface water dissolved inorganic N (DIN). We estimated that the net annual DIN retention by a seasonally flooded tree island was 20.5 ± 5.0 g m−2 during wet season inundation. Based on the estimated tree island surface water DIN loading rate, a seasonally flooded tree island retained 76% of imported DIN. As such, seasonally flooded tree islands have the potential to retain 55% of DIN entering the marsh landscape via upstream canal overland flow in the wet season. By increasing reactive surface area and DOC availability, we suggest that tree islands promote convergence of elements that enhance DIN retention. Tree islands of this region are thus important components of landscape-scale restoration efforts that seek to reduce sources of anthropogenic DIN to downstream estuaries.


ecosystem budget gross mineralization gross nitrification denitrification nitrogen fixation plant uptake landscape heterogeneity 



This work would not have been possible without the contributions of several colleagues. I. Anderson and B. Neikirk of the Virginia Institute of Marine Sciences were patient and accommodating enough to share and demonstrate the techniques of isotope N pool dilution. L. Scinto of Florida International University greatly facilitated denitrification and N fixation studies. D. Rondeau, J. Mahoney, T. Grahl, G. Losada and A. Wood of the Wetland Ecosystem Ecology lab helped greatly with field and laboratory work. We also appreciate the thoughtful and detailed comments provided by two anonymous reviewers and Dr. Stephen Davis on an earlier draft of the manuscript. This work was also supported by a FIU University Graduate School Dissertation Year Award, the South Florida Water Management District and the National Science Foundation through its support of the FCE LTER Program (DEB-9910514).


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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.Southeast Environmental Research Center and Department of Biological SciencesFlorida International UniversityMiamiUSA
  2. 2.Global Institute of Sustainability and School for SustainabilityArizona State UniversityTempeUSA

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