To What Extent Can Constructed Wetlands Enhance Biodiversity?

Abstract

We carried out a literature review to find evidence from empirical studies that constructed wetlands (CWs) can increase biodiversity at the site or landscape level. A set of criteria from general and theoretical ecology was developed that we found useful for defining ‘best practice’ in the construction of wetlands (e.g. landscape connectivity, area versus size, disturbance regime). Thereafter, we analyzed 21 original research papers where biodiversity development after wetland construction was documented. Wetland construction is a established routine procedure serving various purposes in environmental protection, such as waste water retention and treatment. ’Best practice’ criteria with respect to biodiversity protection were not regularly applied during the construction and monitoring process. The published records were substantially different as far as methodological approaches and aims are concerned. They contained short-term snapshot studies to long-term monitoring of biotic and abiotic conditions. Only a few case studies were published in international journals where biodiversity improvement in terms of specific biodiversity indicators was well-documented. A general conclusion whether or not biodiversity is enhanced by CWs cannot be drawn from the published record. As there are confirming results in some studies, we conclude that under certain circumstances constructed wetlands can be useful complements to other biodiversity conservation strategies.