Wetland Ecology

Wetland ecosystems comprise only 3–5 percent of the world’s land surface, but their unique habitats and specialized and rare species have garnered the attention of biologists for centuries. The use of wetlands in Europe and Asia has a deep history, as draining peat bogs, marshes, mires, and swamps for fuel, timber, and agricultural crops was common practice. The first academic use of the word wetlands appears in Catesby’s 1754 book The Natural History of Carolina, Florida and the Bahamas Islands, and early studies of wetlands focused on the distinct flora and fauna found in these ecosystems, with a particular emphasis on waterfowl, fish, or other game. Illustrating this point is the first major assessment and classification of wetlands across the United States in 1956, which is solely based on waterfowl habitat value. Research on wetlands quickly evolved in the 1960s and 1970s to become a distinct subdiscipline of the burgeoning field of ecology. Fueled by the concept of wetlands as “Mother Nature’s kidneys,” and by their potential for cheap wastewater treatment, there was an initial focus on their biogeochemical and hydrologic functions on the landscape, as well as the nutrient removal or transformation services they provided. Research in both Europe and the United States also focused on how plants and animals survived the alternating wet/dry soil regimes wetlands possessed and demonstrated that wide-ranging soil redox conditions were microbial driven and produced either reduced or oxidized chemical ions, often with toxic or altered properties, depending on the presence or absence of oxygen and alternate electron acceptors like nitrate or iron. These findings led to a number of elegant studies focusing on the ecophysiology of how wetland plants and animals survived anaerobic conditions, the presence of toxic chemicals, and saline conditions found in coastal marshes. Since the 1990s, research has focused more on biogeochemical cycling in wetlands, especially nitrogen, phosphorus, and, more recently, carbon flux and storage as it relates to global climate change, as it became understood that wetland soils are globally important stores of carbon and sources of atmospheric methane, a potent greenhouse gas. Thus, global warming effects on boreal and tropical wetlands and continued drainage of these ecosystems worldwide have become a major area of concern, along with the effects of sea level rise on coastal wetland survival. To offset these losses, the fields of wetland restoration and ecologic economics have become increasing relevant.