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

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.