Introduction Wetlands comprise about 6% of the Earth’s surface, but their ecological importance may be disproportionately higher (Batzer and Sharitz, 2006). Existing at the interface between terrestrial and aquatic landscapes, wetlands can support more species and greater productivity than adjacent communities because they are at the confluence of species pools and resources (Gopal et al., 2000; Wetzel, 2006). They are, therefore, important contributors to global biodiversity and their highly active biological communities modify nutrient and gas concentrations and soil-forming processes at a variety of scales. Organic wetlands (peatlands) store an estimated 450 gigatonnes of carbon (Gt C), equivalent to ∼20% of carbon in the terrestrial biosphere (Gorham, 1991; Maltby and Immirzi, 1993; Roulet, 2000) and almost equivalent to the entire global atmospheric carbon pool (Charman, 2002). The economic value of services that all wetland types provide to humans are reported to be higher than other ecosystems (Costanza et al., 1997) because they can be harvested for food, regulate availability and quality of fresh water, and protect neighboring landscapes from flooding. Despite their importance, wetlands are being lost at an alarming rate. Almost half of the wetlands in the United States were drained or filled by 1970 (Tiner, 1984) and globally they are amongst the most threatened ecosystems on the planet. Threats come in the form of land loss and habitat degradation resulting from drainage for agricultural purposes, conversion for urban expansion, and flooding to create reservoirs for water storage or power generation.
