Indicators of vegetation development in restored wetlands

Significant wetland losses across the globe have motivated large-scale restoration efforts to improve the quality of wetland habitats. However, previous studies have shown a high variability in the outcomes of restoration treatments. Post-restoration monitoring is critical to identifying factors constraining wetland recovery and diverting sites away from restoration goals but is often limited by a lack of funding. To circumvent limitations to the large-scale monitoring of wetlands, it is pivotal to identify metrics that can be implemented at low cost yet provide a reliable signal of restoration progress. We review scientific literature on methods to appraise post-restoration progress in wetland ecosystems, focusing on vegetation-based indicators. We present a synthesis of demonstrated relationships between these indicators, site conditions, landscape context, and key ecosystem functions to highlight benefits and potential limitations to the widespread applications of these indicators to post-restoration monitoring. Based on this literature synthesis, we suggest adopting a multi-metric approach to fully measure ecosystem recovery. Potential solutions identified in this review to reduce costs associated with large-scale monitoring include: identifying correlation among indicators, focusing on the most widespread species, and using remote sensing to expand the spatiotemporal scope of monitoring and inform monitoring efforts.