Field-Scale Floating Treatment Wetlands: Quantifying Ecosystem Service Provision from Monoculture vs. Polyculture Macrophyte Communities

Abstract

Global water security is critical for human health, well-being, and economic stability. However, freshwater environments are under increasing anthropogenic pressure and now, more than ever, there is an urgent need for integrated approaches that couple issues of water security and the remediation of degraded aquatic environments. One such strategy is the use of floating treatment wetlands (FTW), which are artificial floating mats that sustain and support the growth of macrophytes capable of removing nutrients from over-enriched waterbodies. In this study, we quantify a range of indicators associated with FTWs, planted with different vegetation community types (i.e., monocultures and polycultures) over the course of a three-year field-scale study. The composition of the two different types of FTWs changed significantly with a convergence in diversity and community composition between the two types of FTWs. Phytoremediation potential of the two FTW communities, in terms of nutrient standing stocks, were also similar but did compare favourably to comparable wild-growing plant communities. There were few substantial differences in invertebrate habitat provision under the FTWs, although the high incidence of predators demonstrated that FTWs can support diverse macroinvertebrate communities. This field-scale study provides important practical insights for environmental managers and demonstrates the potential for enhanced ecosystem service provision from employing nature-based solutions, such as FTWs, in freshwater restoration projects.