Evaluating the progress of engineered tidal wetlands

New terminology is needed for the assessment of wetland restoration project s, focusing on progress towards ecological goals rather than the yes/no alt ernative of success versus failure. Mitigation projects should be evaluated based on 'compliance' of specific mitigation criteria. Peer-reviewed asses sments of wetland restoration projects have focused on appropriate paramete rs (topographic, hydrologic, soil, vegetation, and animal components); howe ver, for the most part, they have evaluated small, newly restored wetlands over the short-term with little repeated sampling. Future assessments shoul d focus on understanding problems at a particular site by identifying cause -effect mechanisms. We review a case study from San Diego Bay where detaile d assessments led to the identification of problems and subsequent manageme nt alternatives. We also recommend the use of two novel approaches: experim entation and the evaluation of ecosystem resiliency to unplanned disturbanc es. These assessments will provide a better understanding of ecosystem func tioning and enhance current comparisons of natural and restored systems. A stronger science base for wetland restoration and adaptive management do no t guarantee that restoration targets will be reached; however, these approa ches will identify the causes of problems and allow us to predict whether o r not restoration targets can be leached in a timely manner. (C) 2000 Elsev ier Science B.V. All rights reserved.