Global Wetland Ecological Restoration in the 21st Century: A Systematic Mapping Review of Research Patterns, System-Specific Pathways, and Priorities for Durable Ecological Recovery

Wetland restoration has become increasingly important for biodiversity conservation, ecosystem-function recovery, and climate resilience. However, global restoration evidence remains fragmented across geographical regions, wetland systems, restoration approaches, and ecological response domains, limiting the identification of broadly transferable restoration principles. This review conducted a systematic mapping review of global wetland ecological restoration research published between 2000 and 2024 by integrating evidence mapping, bibliometric analysis, and ecological interpretation of representative restoration studies. The global literature expanded substantially during the study period, but the evidence base remained unevenly distributed among regions, institutions, and wetland contexts. Differences among research participation, research leadership, and study locations indicated that patterns of scientific output were shaped not only by wetland distribution and restoration needs but also by research capacity, monitoring infrastructure, and institutional networks. Thematic development revealed a transition from intervention-oriented studies focusing on hydrological modification, habitat reconstruction, and pollution control toward broader consideration of biodiversity recovery, ecosystem functions, carbon dynamics, microbial processes, and nature-based solutions. Across wetland systems, restoration pathways varied according to ecological processes and degradation contexts, but common challenges emerged regarding the translation of structural improvements into durable ecological recovery. Improvements in habitat structure, vegetation, hydrological conditions, or physicochemical indicators did not necessarily indicate equivalent recovery of biodiversity, ecosystem functions, or resilience. These findings highlight the need for long-term, multidimensional restoration assessment, stronger evidence generation in underrepresented regions, and adaptive approaches that integrate ecological processes, monitoring, and local contexts to support durable wetland recovery.