Wetland Ecosystem Processes

By definition, the water table of wetlands is near, at, or above the hydrosoil (sediment) surface. These changing hydrologic conditions are primary drivers of nutrient fluxes in the sediments and all aspects of plant biology: physiology, growth, and productivity. Because of the very nature of low elevational gradients within wetlands, there is a tendency for these regions of the whole ecosystem to retain organic matter either produced there by wetland plants or organic matter imported there from upland areas. The accumulated organic matter and associated nutrients promote two basic features of wetland ecosystems: an anoxic, reducing habitat of vigorously growing microbial communities on and within the sediments and organic debris, and very actively growing aquatic plants that are adapted to these growth conditions. This chapter discusses wetland ecosystem processes, focusing on periphyton as a critical metabolic component of aquatic ecosystems, nutrient retention and nutrient cycling in wetlands, modulation of periphyton by light availability, modulation of macrophytes and periphyton by mortality and losses, and potential effects of global climate change and related environmental conditions on ecosystem processes.