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The 2011 National Wetland Condition Assessment: Overview and an Invitation
Citation:
Kentula, M. AND Steve Paulsen. The 2011 National Wetland Condition Assessment: Overview and an Invitation. ENVIRONMENTAL MONITORING AND ASSESSMENT. Springer, New York, NY, , 325, (2019). https://doi.org/10.1007/s10661-019-7316-4
Impact/Purpose:
The first National Wetland Condition Assessment (NWCA) was completed by EPA in 2011. A team of scientists from ORD played a major role in designing the survey, analyzing the data, and reporting on the results of the assessment in cooperation with the Office of Water. This paper provides an overview of the major themes in a collection of papers to be published in the peer-reviewed journal, Environmental Monitoring and Assessment to document the technical underpinnings of the NWCA, present a summary of the major results, and provide examples of how the methods and results from the NWCA could be used to support wetland protection and management. For example, reporting on the extent and condition of the resource can be used to track effectiveness of regulation and management practices by geographic region and/or wetland type. Alternatively, the estimates of the extent of stressor indicators could identify the emergence of new threats to wetland condition, while the use of relative and attributable risk helps to prioritize management actions by stressor, geographic region, and/or wetland type. Moreover, the NWCA data provide an opportunity to explore patterns in wetland functioning at a continental scale. The insights that will emerge from such independent analyses of the NWCA data will strengthen the science of wetland ecology. Finally, this research contributes to work being done under SSWR task 3.01A, subtask 1.1.
Description:
The first National Wetland Condition Assessment (NWCA) was conducted in 2011 by the US Environmental Protection Agency (USEPA) and its federal and state partners, using a survey design that allowed inference of results to national and regional scales. Vegetation, algae, soil, water chemistry, and hydrologic data were collected at each of 1138 locations across the conterminous United States (US). Ecological condition was assessed in relation to a disturbance gradient anchored by least disturbed (reference) and most disturbed sites identified using chemical, physical, and biological disturbance indices based on site-level data. A vegetation multimetric index (VMMI) was developed as an indicator of condition, and included four metrics: a floristic quality assessment index, relative importance of native plants, number of disturbance-tolerant plant species, and relative cover of native monocots. Potential stressors to wetland condition were identified and incorporated into two indicators of vegetation alteration, four indicators of hydrologic alteration, a soil heavy metal index, and a nonnative plant indicator and were used to quantify national and regional stressor extent, and the associated relative and attributable risk. Approximately 48±6% of the national wetland area was found to be in good condition and 32±6% in poor condition as defined by the VMMI. Across the conterminous US, approximately 20% of wetland area had high or very high stressor levels related to nonnative plants. Vegetation removal, hardening, and ditching stressor indicators were found on the greatest extent of wetland area with high stressor levels, affecting 23-27% of the wetland area in the NWCA sampled population. The results from future NWCA assessments will build on those from 2011 and will enable the ability to report on trends in addition to status. The data and tools produced by the NWCA can be used by others to further our knowledge of wetlands in the conterminous US.
