Freshwater wetlands of the south Florida Everglades have experienced significant environmental changes over the past 70 years due to natural variability and human management of hydrology, fire regimes, and nutrient loading. These changes have significantly altered the diversity, community structure, and ecosystem processes in the Everglades. The most common plant species in the Everglades, Cladium jamaicense, increased in percent cover since 1960, reducing overall aquatic productivity, and potentially the feeding habitat of wading birds. In some areas, Cladium abundance has been reduced, due to increased phosphorus loading which has favored the dominance of Typha dominguensis (Jensen et al., 1995). Restoration efforts under the Comprehensive Everglades Restoration Plan (CERP) are currently aimed at restoring the hydrology to historic conditions (i.e., before construction of the Tamiami Trail in the 1930?s). However, predicting ecosystem responses to restoration efforts is daunting due to the limited number of well-replicated, factorial experiments on Cladium and competing species, the short-term nature of ecological data, and the complexity of wetland ecosystems which generate short- and long-term dynamics at varying spatial scales (e.g, Day et al., 1999; Simas et al., 2001).
The goals of our research are to (1) integrate modeling and ongoing field research in the Florida Coastal Everglades Long-Term Ecological Research (FCE LTER) program to infer historic changes in the long-term dynamics (i.e., decadal to century) of Cladium ecosystems from <1900 to present in Shark River Slough, Everglades National Park; and (2) understand potential effects of future restoration efforts in those systems. Our research complements the Water Conservation Area 3 Decompartmentalization (DECOMP) project under CERP?in which the purpose is to re-establish natural hydroperiods and hydropatterns that sustain ecosystem processes in Shark River Slough (URL: www.evergladesplan.org). Our proposed research will extend over a 3 year period and will entail (1) developing a simulation model predicting Cladium biomass, a critical performance measure for ecosystem structure, on a decade to century time scale; (2) using Cladium seeds buried in peat and marl sediments to test model simulations and ultimately to infer past Cladium dynamics from 1900 to present; (3) reconstructing historic changes in hydrology, fire, and available phosphorus; and (4) conducting ?modeling experiments? to quantify potential changes in Cladium biomass in response to water management scenarios.
Key to Everglades restoration is the need to understand the past as a prerequisite for predicting the future. Our research does both. Importantly, our modeling and empirical work will provide a mechanistic understanding of how Cladium dynamics are regulated by environmental change as well as processes of plant growth, allocation, and plant-soil feedbacks. Additionally, our model will refine our knowledge of the extent to which more ?natural? hydroperiods and water flow, as planned in the DECOMP project, may alter or reduce Cladium biomass, and consequently promote wet prairie and slough species in its place.