PARENT SESSION
Poster Session # 17: Aquatic Systems.

Thursday, August 7 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Phosphorus biogeochemistry of the Everglades National Park tree island soils.

Jayachandran, Krish^*,1, Sah, Seema¹, Sah, Jay¹, Ross, Mike¹, ¹ Florida International University, Miami, FL, USA

ABSTRACT- Soils serve as a media for plant growth, exchange and storage of nutrients. Also, their structural profiles provide a record of soil formation and site history. Tree Island soils biogeochemistry and nutrient cycling, primarily phosphorus (P) in the Everglades National Park, FL is of particular interest to us. The objectives of the soils component of the project as follows: How are the recent changes in hydrology affecting the vegetation mosaic and soils? Are these soils functioning similarly to the adjacent marsh soils? Are these soils nutrient sinks or sources? Do they differ in their elemental composition? And how does this elemental composition affect vegetation? With these questions, we describe physical and chemical properties of soils from three tree islands - Black, Gumbo Limbo, and Satinleaf Hammocks. Composite surface soil samples at 0 to 10 cm depth were collected from three tree islands in November 2001. By using a 10 cm diameter soil auger, several 0-10 cm deep cores were taken at each sampling spot, composited in a sampling bag, and transported to the laboratory for physicochemical analysis. Soils were homogenized in the bag and refrigerated until further analysis. Sub-samples from each bag were transferred to a plastic sample cup, weighed wet (g), and measured for sample volume (cm3). Later, these samples were analyzed for dry weight (80 C), sample bulk density (g dry cm-3), fractional water content, pH, EC, total C, carbonate content, inorganic and organic C, organic matter content, total N, and total P. We have established baseline physicochemical properties of soils on three tree islands, Black Hammock, Gumbo Limbo, and Satin Leaf. Gumbo Limbo Hammock seems to be different from Black and Satinleaf Hammocks in several soil properties. In general, soils in the hardwood hammock communities, particularly the raised part of the community, have alkaline pH, low organic matter, abundant carbonate minerals, and low N. The P content seems to be very high in all three tree islands, especially in the hammock portions. Based on the high levels of total P in these soils, we postulate several theories on P retention, transport, cycling, and biogeochemistry that are being tested in our research, with field and laboratory data.

Key words: Phosphorus, Nutrient Cycling, Biogeochemistry, Soils