Geographically Isolated Wetlands: Rethinking a Misnomer

David M Mushet,Mark C Rains,Matthew J Cohen,Laurie C Alexander,Edward S Dekeyser,Susan C Walls,Aram J K Calhoun,Charles R Lane,Laurie Fowler,Megan W Lang

doi:10.1007/s13157-015-0631-9

Abstract

We explore the category Bgeographically isolated wetlands^ (GIWs; i.e., wetlands completely surrounded by uplands at the local scale) as used in the wetland sciences. As currently used, the GIW category (1) hampers scientific efforts by obscuring important hydrological and ecological differences among multiple wetland functional types, (2) aggregates wetlands in a manner not reflective of regulatory and management information needs, (3) implies wetlands so described are in some way Bisolated,^ an often incorrect implication, (4) is inconsistent with more broadly used and accepted concepts of Bgeographic isolation,^ and (5) has injected unnecessary confusion into scientific investigations and discussions. Instead, we suggest other wetland classifi- cation systems offer more informative alternatives. For example, hydrogeomorphic (HGM) classes based on well- established scientific definitions account for wetland func- tional diversity thereby facilitating explorations into questions of connectivity without an a priori designation of Bisolation.^ Additionally, an HGM-type approach could be used in combination with terms reflective of current regula- tory or policymaking needs. For those rare cases in which the condition of being surrounded by uplands is the relevant distinguishing characteristic, use of terminology that does not unnecessarily imply isolation (e.g., Bupland embedded wetlands^) would help alleviate much confusion caused by the Bgeographically isolated wetlands^ misnomer.

Highlights

It has been over a decade since the state of scientific understanding of isolated wetlands was synthesized in a specialA
Justice Kennedy stated that wetlands can be covered under the Clean Water Act (CWA) Bif the wetlands, alone or in combination with situated lands in the region, significantly affect the chemical, physical, and biological integrity of other covered waters.^ it has become increasingly clear that while the original intent was well-founded, referring to wetlands as Bgeographically isolated^ has done little to alleviate the implications of functional isolation that accompany the GIW terminology, as we present from an analysis of the recent literature in a later section
We suggest that classification systems that account for functional differences among diverse wetland types offer less ambiguous and more scientifically defensible alternatives that are less prone to misunderstanding

Summary

Introduction

Even the generalization that GIWs are surrounded by uplands has been questioned as field surveys (e.g., Leibowitz and Vining 2003; Wilcox et al 2011) and new, high resolution, remote sensing techniques (e.g., LiDAR; Lang et al 2012) reveal surface connections among wetlands previously considered to be Bgeographically isolated^ (Fig. 1).

Results

Conclusion