Modeling the dynamics of Cladium jamaicense biomass over the last century in Everglades National Park.
Saunders, Colin*,1, Childers, Daniel1, Lynch, Jason2, Jaffe, Rudolf1, Gao, Min1, 1 Southeast Environmental Research Center, Miami, FL, USA2 North Central College, Naperville, IL, USA
ABSTRACT- Freshwater wetlands of the Florida Everglades experienced significant environmental changes over the past 70 years due to natural variability and human management. These changes have significantly altered community structure and ecosystem processes, including increased aerial cover of the dominant plant species, Cladium jamaicense. While restoration efforts under the Comprehensive Everglades Restoration Plan are aimed at restoring the hydrology to historic conditions, predicting how the current system will respond to these efforts requires an integrative approach coupling long-term data within a modeling framework. The goals of this study are (1) to develop a simulation model predicting historic Cladium biomass and (2) to use seed profiles to test model simulations of Cladium dynamics at an upstream, middle, and downstream site in Shark River Slough. The potential for Cladium seed profiles as a proxy for biomass is demonstrated by a significant correlation between Cladium biomass and seed abundance (R2 = 0.57), obtained from measurements along a 50 m transect. In our model, we used existing literature on Cladium biomass as a function of water depth and seed production as a function of biomass. We used historic rainfall records (1895-present) to reconstruct water levels, with additional assumptions to account for human alterations to water levels after 1930 and 1960. Despite its simplicity, the model agrees in magnitude and correlates strongly (R2 = 0.74) with observed seed profiles at the upstream site. Larger deviations between predictions and observed values at the downstream site suggest factors other than water level influenced Cladium at this site. For both sites, the model successfully predicts an increase in seed abundance, and by inference Cladium biomass, since 1930. While our research suggests the importance of past water management on Cladium dynamics, including additional mechanisms such as fire, nutrient load, biotic interactions and accretion/erosion may refine these efforts to understand and predict ecosystem changes due to water management and restoration.
Key words: Everglades, modeling, Cladium jamaicense, seed profile
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