Constructed wetlands and the rehabilitation of ecosystem services in freshwater ecosystems: A systematic review of influencing factors

Freshwater ecosystems have lost up to 75% of their area due to anthropogenic degradation. In this context, constructed wetlands (CWs) are emerging as technologies for the rehabilitation of multiple ecosystem services. Through a systematic review of 84 studies (2005–2023) following the ROSES protocol, this study identifies spatiotemporal trends and influencing factors that influence the rehabilitation of ecosystem services through CWs. Geographically, 62% of the studies were concentrated in the US and China, while South America and Africa remained underrepresented. Ecosystem service assessments focused predominantly on water quality (83%), while supporting (<15%), cultural (<10%), and provisioning (3%) services were less frequently evaluated. The influencing factors for rehabilitation encompassed multiple dimensions: (i) spatiotemporal: geographic concentration and ecosystem type biases; (ii) Contextual: multiple degradation pressures, combination of CWs with complementary interventions, and lack of long-term monitoring (>10 years); (iii) Design and operation: hydraulic parameters (hydraulic retention time, depth, flow rate), vegetation composition (emergent macrophytes), and substrate type (adsorbent materials such as zeolite, ceramsite); (iv) Performance: design-specific removal efficiencies for nutrients, organic matter, and solids; and (v) Assessment of ecosystem services: predominance of water quality regulation and limited representation of cultural, supporting, and provisioning services. Collaborative approaches (governance frameworks, community participation, and innovative financing) are crucial for the long-term sustainability of freshwater ecosystems. Also, maximizing the multifunctionality of CWs requires long-term monitoring, climate-adaptive designs, and participatory governance to enhance their value in the comprehensive rehabilitation of freshwater ecosystems.