Macroelemental Cycling in Subtropical Wetland Ecosystems: The Everglades As a Case Example.

Wetland ecosystems provide a unique opportunity for understanding and responding to the challenges imposed by climate variability and change, land use, and human activity, and the effects of these changes on macroelemental cycles.   Wetlands serve as a major ecosystem “hub” for coupled macroelemental cycles and play a significant role as a critical regulator and integrator of global impacts.  Macroelemental cycles in wetlands impact inter-related processes at the local level (e.g., microbial processes, plant growth and soil accretion), regional level (water storage and water quality), and global level (greenhouse gas emissions and carbon storage). Eutrophication of wetlands resulting from increased nutrient loads from urban and agricultural land uses can enhance primary productivity which in turn can result in increased rates of organic matter accumulation providing a significant sink for macroelements.  However, high rates of macroelemental accumulation can enhance microbial activities and increase the production of greenhouse gases.  Thus, wetlands may be a net sink or source of greenhouse gases.  These feedbacks are often not recognized because of the complexity and lag time of biotic and abiotic responses to anthropogenic and natural drivers (i.e. changes in land use, water use, temperature and precipitation patterns, atmospheric CO₂ concentrations and sea level rise).  In this presentation I will review the inter-relationships between and within carbon, nitrogen, and phosphorus cycles as influenced by both external and internal forcing functions.  The review will identify critical research needs for better understanding of elemental cycles in wetlands as related to water quality, carbon sequestration, and global climate change.