PARENT SESSION
Oral Session # 15: Wetland Ecology I: The Everglades and Southern Wetlands.
Presiding: J Chick
Tuesday, August 5. 8:00 AM to 11:30 AM, SITCC Meeting Room 101.
Responses of vegetation in the Big Cypress Swamp to increased inputs of phosphorus and other potentially limiting nutrients.
Jacobs, Alyssa*,1, Volin, John1, Kruger, Eric2, 1 Florida Atlantic University, Davie, FL2 University of Wisconsin-Madison, Madison, WI
ABSTRACT- The Big Cypress Swamp and the Everglades of South Florida are inherently oligotrophic ecosystems that in recent decades have been subjected to increasing agricultural inputs of phosphorus and other nutrients. Inputs of phosphorus in particular are thought to have resulted in widespread and deleterious changes in the structure and function of these ecosystems. This tenet is supported by extensive research in the herb-dominated Everglades, but there is a lack of comparable data about the impacts of phosphorus within the adjacent Big Cypress Swamp. In a 12-month field study we assessed the responsiveness of Big Cypress vegetation to increased inputs of phosphorus and/or other nutrients, including potassium and nitrogen. The study focused on two major tree species, Taxodium distichum and Fraxinus caroliniana, as well as understory herbaceous vegetation, in the Kissimmee Billie Slough on the Big Cypress Seminole Indian Reservation. One of six different nutrient amendments (nitrogen, phosphorus, potassium, 2 x potassium, phosphorus + potassium or control) was applied to the soil around each of 210 randomly selected trees located throughout the 1,600-ha slough. During the 12 months following nutrient application, we measured leaf photosynthesis and nutrient status, as well as stem diameter growth, on trees. Additionally, we monitored changes in composition, growth and nutrient content of understory herbaceous communities. Nutrient concentrations in groundwater and/or surface water were also measured at monthly intervals throughout the year. In general, treatment responses indicated that the constraint on ecosystem productivity imposed by phosphorus availability may not be as important in the Big Cypress Swamp as it is in herbaceous ecosystems of the Everglades.
Key words: nutrient limitation, Everglades, Big Cypress Swamp, wetland