Carbon and nutrient (N, P) cycling of created and restored wetlands

Abstract

Wetlands are created or restored for a number of purposes, including flood control, water purification, sediment and nutrient retention, and biodiversity. Restoration of wetlands is the process of recreating former conditions at a site that once contained a wetland. Restoration and creation of wetlands involve the creation or restoration of hydrology, but may also include activities that alter soil composition, manipulate vegetative communities, or promote target wetland functions. Carbon accumulation in restored and created wetlands is dependent on hydrology, vascular vegetation, and microbial communities. Once hydrology is restored, consistent periods of soil inundation reduce rates of microbial decomposition by creating anoxic soils. Wetlands prior to restoration and terrestrial soils prior to development of wetland hydrology are usually carbon poor, and created wetlands often retain soil properties from the soils from which they are created, potentially taking tens of decades to build up carbon reserves similar to natural wetlands. Initial nitrogen pools reflect past land use. Agricultural sites are increasingly being converted into wetlands, resulting in many restored or created wetlands with large initial nitrogen pools due to legacy effects of fertilizer use.