David A. Kaplan
Michael Osland
Yiyang Kang
2025
<ol class=""><li>Freeze events govern the distribution and structure of mangrove ecosystems, especially in tropical-temperate transitional zones. Understanding mangrove responses to freezing is crucial for predicting their poleward expansion under climate change. However, there is a need for field-based measurements of mangrove freeze resistance and resilience.</li><li>After an extreme winter storm in December 2022, we measured mangrove post-freeze damage and recovery (January and November 2023), building on a pre-freeze baseline assessment conducted in July 2022 across 12 sites along the temperature gradient of Florida's Gulf of Mexico coast (USA).</li><li>Low-temperature thresholds for leaf damage to<span> </span><i>Avicennia germinans</i>,<span> </span><i>Rhizophora mangle</i><span> </span>and<span> </span><i>Laguncularia racemosa</i><span> </span>were quantified near −6, −4 and − 4°C, respectively. Thresholds for mortality were found to be near −6 to −7°C for<span> </span><i>A. germinans</i><span> </span>and −4 to −5°C for<span> </span><i>R. mangle</i>. A threshold for loss of reproductivity in<span> </span><i>A. germinans</i><span> </span>was identified near −6 to −7°C. Resprouting was observed in all three species but limited to just one individual for<span> </span><i>R. mangle</i>. Surviving<span> </span><i>A. germinans</i><span> </span>resprouted vigorously and had the greatest number of resprout branches, which was proportional to leaf damage. Tall<span> </span><i>A. germinans</i><span> </span>had a higher resprout percentage than short trees.</li><li>Strata-specific differences in freeze damage were most pronounced for<span> </span><i>R. mangle</i>, with higher damage in tall versus short trees, while no difference was found between<span> </span><i>A. germinans</i><span> </span>strata. These results suggest that<span> </span><i>R. mangle</i><span> </span>population recovery may depend on the growth of short trees, while<span> </span><i>A. germinans</i><span> </span>can recover from all strata.</li><li>Minimum air temperature was strongly correlated with mangrove height and above-ground biomass. Projections of future minimum temperature and species-specific freeze degree days predict warming winters, suggesting further mangrove development and range expansion under climate change.</li><li><i>Synthesis</i>: Collectively, our study advances understanding of mangrove responses to freezing and identifies low-temperature thresholds for each species, aiding predictions of mangrove range expansion.</li></ol>
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10.1111/1365-2745.14440
en
British Ecological Society
Mangrove freeze resistance and resilience across a tropical-temperate transitional zone
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