Mangrove species’ response to sea-level rise across Pohnpei, Federated States of Micronesia
Mangrove forests are likely vulnerable to accelerating sea-level rise; however, we lack the tools necessary to understand their future resilience. On the Pacific island of Pohnpei, Federated States of Micronesia, mangroves are habitat to endangered species and provide critical ecosystem services that support local communities. We developed a generalizable modeling framework for mangroves that accounts for species interactions and the belowground processes that dictate soil elevation. The modeling framework was calibrated with extensive field datasets, including accretion rates derived from thirty 1-meter-deep soil cores dated with lead-210, more than 300 forest inventory plots, water-level monitoring, and differential leveling elevation surveys. We applied the model using a community of five mangrove species and across seven regions around Pohnpei to identify which regions are most vulnerable to sea-level rise. The responses of mean elevation and the mangrove community composition were analyzed under four global sea-level rise scenarios: an increase of 37, 52, 67, or 117 centimeters by 2100. The model was validated against a 20-year surface elevation table record (1999–2019) and showed good agreement when driven by observed water levels.
The model projected that mangroves around Pohnpei can build their elevations relative to moderate rates of sea-level rise to prevent submergence, with limited changes in mangrove community composition through 2060. By 2100, however, the model projected a decreasing abundance of high-elevation mangrove species and an increasing abundance of lower elevation species adapted to more persistent flooding. Under higher sea-level rise scenarios, forest elevation decreased substantially relative to mean sea level and there were more drastic changes in the tree community composition and loss of suitable mangrove habitat by 2100. Variation in accretion rates, water levels, and initial forest elevation led to differential vulnerability around the island, such that mangroves on the leeward side of the island generally were the most at-risk to higher rates of sea-level rise. Our findings indicate that the relatively undisturbed state of the mangrove forests and the surrounding landscape is an important factor in their ability to keep pace with sea-level rise.
Citation Information
| Publication Year | 2021 |
|---|---|
| Title | Mangrove species’ response to sea-level rise across Pohnpei, Federated States of Micronesia |
| DOI | 10.3133/ofr20211002 |
| Authors | Kevin J. Buffington, Richard A. MacKenzie, Joel A. Carr, Maybeleen Apwong, Ken W. Krauss, Karen M. Thorne |
| Publication Type | Report |
| Publication Subtype | USGS Numbered Series |
| Series Title | Open-File Report |
| Series Number | 2021-1002 |
| Index ID | ofr20211002 |
| Record Source | USGS Publications Warehouse |
| USGS Organization | Western Ecological Research Center |
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Future sea-level rise poses a risk to mangrove forests. To better understand potential vulnerability, we developed a new numerical model of soil elevation for mangrove forests. We used the model to generate projections of elevation and mangrove forest composition change under four sea-level rise scenarios through 2100 (37, 52, 67, and 117 cm by 2100). We employed a data-driven modeling approach, uPohnpei, Federated States of Micronesia Mangrove Elevation Survey Data
U.S. Geological Survey (USGS) scientists conducted field work efforts during February 15-23, 2017 and April 10-25, 2019 in the mangrove forests of Pohnpei, Federated States of Micronesia (FSM) with logistical assistance from the Micronesia Conservation Trust (MCT) and field assistance from the Conservation Society of Pohnpei and the Pohnpei Department of Forestry. The field team combined the surve - Connect
Karen Thorne, Ph.D.
Research EcologistEmailPhone