The 2011 National Wetland Condition Assessment: overview and an invitation

Mary E Kentula,Steven G Paulsen

doi:10.1007/s10661-019-7316-4

Abstract

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 stressors had 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 the 2016 NWCA will build on those from the 2011 assessment and initiate 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.

Highlights

From the time of the Lewis and Clark expedition (180406), the United States (US) has a long and rich history of exploring and cataloging our natural resources
Is a brief overview of the methods used in the National Wetland Condition Assessment (NWCA) abstracted from the 2011 the Site Evaluation Guidelines (USEPA 2011d), Field Operations Manual (USEPA 2011b), Laboratory Methods Manual (USEPA 2011c), and Technical Report (USEPA 2016b)
The 2011 NWCA found 48% of the national wetland area was in good condition, 20% in fair condition, and 32% in poor condition (Fig. 5) (USEPA 2016a)

Summary

Introduction

From the time of the Lewis and Clark expedition (180406), the United States (US) has a long and rich history of exploring and cataloging our natural resources. Lewis and Clark kept extensive journals on the flora and fauna encountered throughout their expedition, sparking the imagination of others with the rich biological diversity in the American West. Others followed in their footsteps—Wilkes, Pickering, Pike, Whipple, Beckwith, and Fremont, to mention just a few. 325 Page 2 of 18 sponsored numerous surveys and expeditions, as did the Smithsonian Institute’s newly formed National Museum of Natural History. These various surveys and expeditions provided an enormous amount of information on the biological and geological wealth across the US. These uses began to border on over use or misuse and required a national response and collaborative effort to protect and restore the quantity and quality of these resources

Objectives

Methods

Results