Biogeochemical Processes on Tree Islands in the Greater Everglades: Initiating a New Paradigm

Abstract

Scientists’ understanding of the role of tree islands in the Everglades has evolved from a plant community of minor biogeochemical importance to a plant community recognized as the driving force for localized phosphorus accumulation within the landscape. Results from this review suggest that tree transpiration, nutrient infiltration from the soil surface, and groundwater flow create a soil zone of confluence where nutrients and salts accumulate under the head of a tree island during dry periods. Results also suggest accumulated salts and nutrients are flushed downstream by regional water flows during wet periods. That trees modulate their environment to create biogeochemical hot spots and strong nutrient gradients is a significant ecological paradigm shift in the understanding of the biogeochemical processes in the Everglades. In terms of island sustainability, this new paradigm suggests the need for distinct dry-wet cycles as well as a hydrologic regime that supports tree survival. Restoration of historic tree islands needs further investigation but the creation of functional tree islands is promising.

KEYWORDS:

• Everglades restoration
• Focused Nutrient Redistribution model
• Florida Everglades
• groundwater flows
• landscape modulation
• nitrogen
• phosphorus
• sap flow
• tree patches
• tree transpiration
• zone of confluence

ACKNOWLEDGMENTS

Research on tree islands in the Everglades requires the efforts of many people and the authors express their appreciation for the hard work of their colleagues. The water chemistry analysis was improved with the comments of Robert Newton. The authors also appreciate the comments of three anonymous reviewers. Work at the Loxahatchee Impoundment Landscape Assessment described in this paper was funded by the South Florida Water Management District. The authors are grateful for the help of Eric Cline and Ryan Desilu at LILA. A portion of R.M. Price's contribution to this research was supported by the National Science Foundation under Grant No. DBI-0620409. This paper is contribution No. 506 of the Southeast Environmental Research Center (SERC).

Notes

^aEwe, 2008.

^bCorstanje et al., 2006.

^cBruland et al., 2006.

^dOsborne et al., 2011.