Beyond continental peatlands: A review of peat-influenced small island systems

Peatlands on small islands are often compared to peatlands found in larger terrestrial systems, although they have distinct characteristics. They are more vulnerable to sea-level rise, saltwater intrusion, freshwater scarcity, and coastal erosion. This article introduces Peat-Influenced Small Islands (PISI) as a framework for small islands in which peat deposits and peatland processes materially shape the island’s environmental function, given the spatial constraints imposed by island shape and marine-land interactions. Using a global peatland and island dataset, we identified 756 PISIs worldwide, representing 2.12% of the global peatland area. Despite their limited extent, these systems are distributed from high latitudes to the tropics, with North America dominating the peatland area and Indonesia having the largest tropical concentration. This article demonstrates that PISIs are not simply smaller versions of continental peatlands. Their distinctiveness lies in the interactions between peat deposits and small island properties, freshwater limitations, the marine-terrestrial interface, geomorphological exposure, and closely related socio-environmental vulnerabilities, such as climate vulnerability. The PISI framework provides a basis for integrating peat science, island hydrology, coastal change, adaptation-mitigation research, and guiding conservation and policy efforts in vulnerable peat-bearing island systems.