Stoichiometric homeostasis of wetland vegetation along a nutrient gradient in a subtropical wetland. Understanding stoichiometric mechanisms of nutrient retention in wetland macrophytes

Abstract

1 subtropical wetland. Understanding stoichiometric mechanisms of nutrient retention in wetland 2 macrophytes. Abstract (limit 250 words) 1 4 Nutrient homeostasis relates ambient stoichiometric conditions in an environment to the stoichiometry of 1 5 living entities of the ecosystem. In wetland ecosystems, vegetation can be a large, highly variable and 1 6 dynamic sink of nutrients. This study investigated stoichiometric homeostasis of dominant emergent and 1 7 submerged aquatic vegetation (EAV and SAV, respectively) within two treatment flow-ways (FW) of 1 8Everglades Stormwater Treatment Area 2 (STA-2). These FW encompass a large gradient in plant 1 9 nutrient availability. The hypotheses of this study is that wetland vegetation is non-homeostatic relative to 2 0 ambient nutrients and consequently nutrient resorption will not vary along the nutrient gradient. We 2 1 developed a framework to investigate how vegetation uptake and resorption of nutrients contribute 2 2 separately to homeostasis. Overall, the wetland vegetation in this study was non-homeostatic with respect 2 3 to differential uptake of nitrogen (N) vs. phosphorus (P). Resorption evaluated for EAV was high for P 2 4 and moderate for N, resorption efficiency did not significantly vary along the gradient and therefore did 2 5 not affect overall homeostatic status. Nutrient addition experiments may help to compensate for some of 2 6 the limitation of our study, especially with respect to resolving the primary nutrient source (organic vs. 2 7inorganic sources, water vs. soil compartment) and nutrient utilization rates. 2 8 2 9