U.S. Department of Agriculture conservation program and practice effects on wetland ecosystem services: a synthesis

Ecosystem services provided by wetlands on agricultural landscapes include fish and wildlife habitat support, mitigation of pollution effects, water conservation, and climate change mitigation. Riparian buffer practices are also considered in this synthesis due to their implementation in wetlands or effects on wetland ecosystem service provisioning when implemented adjacent to wetlands. Conservation practices are most extensive in the first three of the following seven regions analyzed: Mississippi Alluvial Valley, Glaciated Interior Plains, Piedmont-Coastal Plain, Prairie Pothole Region, California Central Valley, Appalachia, and the High Plains. Of the eight dominant practices available to establish and manage wetlands, the three most prevalent are Wetland Establishment, Wetland Management, and Riparian Buffer establishment and management. Differences in physiography among regions strongly influence the types of practices commonly applied. Highly altered drainage patterns and nutrient loading common to agriculture can make wetland establishment difficult. Nutrient enrichment, especially with nitrogen, can create trade-offs between reduced export of nutrients downstream (e. g., nitrate) and enhanced greenhouse gas emissions (e. g., nitrous oxide). Guidance is needed that considers the full array of ecosystem functions and services of multiple practices across a range of spatial scales. Both positive and negative effects need to be addressed given the trade-offs between enhancement of ecosystem services and the lack of knowledge of thresholds at which ecosystem functions are no longer ecologically or economically sustainable. In many cases, data are not presently available, nor is there a suitable monitoring process in place to assess the long-term effects of agriculture on additional wetlands and the potential services they provide, and vice versa. This points to the need to better match practices with goals, to evaluate restoration costs and benefits, and to optimize how decision-making is distributed between national and local levels.