The Future Resiliency of Mangrove Forests to Sea-Level Rise in the Western Pacific: Initiating a National Assessment Approach

Abstract:

Mangrove forests provide habitat for wildlife and fish, as well as critical ecosystem services that support local communities. Mangrove forests are threatened by sea-level rise (SLR); however, in many areas we lack the tools necessary to inform management strategies and planning. For the Pacific island mangroves of Pohnpei, Federated States of Micronesia, we developed a generalizable modeling framework that accounts for both tree species interactions and the belowground processes that influence elevations. The model was calibrated with field datasets: soil cores, forest plots, water loggers, and elevation surveys. The responses of elevation and the mangrove community composition were analyzed under four global SLR scenarios (37, 52, 67, and 117 cm) by 2100 for seven regions of the island. The results showed that mangroves can build their elevations relative to moderate rates of SLR to prevent submergence, with limited changes on mangrove community composition through 2060. Under higher SLR, forest elevation decreased substantially with more drastic changes in the tree community composition and loss of mangroves by 2100. Variation in accretion rates, water levels, and initial forest elevation led to different vulnerabilities? around the island, with mangroves on the leeward side generally the most at-risk to higher rates of SLR. The successful co-production of this science-based mangrove SLR vulnerability assessment will inform island management on Pohnpei and is transferable to other areas in the Pacific.