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Abstract Mangroves play a crucial role in mitigating hurricane impacts in coastal ecosystems, and their adaptive traits enable regeneration and forest recovery following these disturbances. Yet, how species‐specific regeneration varies across life stages and interacts with environmental conditions is poorly understood. We quantified regeneration rates of three dominant species of mangrove seedlings and saplings (Avicennia germinans,Laguncularia racemosa, andRhizophora mangle) recovering from a major hurricane. We selected forests with varying light availability and phosphorus (P) gradients in the Everglades (Florida, USA). From 2020 to 2022, we measured biannual stem elongation, height, and density of seedlings and saplings, and collected porewater variables (salinity, sulfide, and inorganic nutrients) and continuous light intensity to assess species‐specific drivers of regeneration. Species‐specific growth rates, total height, and density varied across sites, driven by differences in porewater P and light. Growth rates ofR. mangleseedlings and bothR. mangleandL. racemosasaplings were influenced by light, whileA. germinansgrowth rates were unaffected. OnlyR. mangleandL. racemosasaplings were influenced by porewater P, while growth of both seedlings and saplings was unaffected by porewater salinity and sulfide. Mangrove regeneration post‐disturbance is explained by spatial differences in subsidies and stressors and the composition of species and life stages, underscoring complex regeneration strategies in mixed‐species forests.
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Hydrodynamic Limitations to Mangrove Seedling Retention in Subtropical Estuaries
Mangrove-forest sustainability hinges upon propagule recruitment and seedling retention. This study evaluates biophysical limitations to mangrove-seedling persistence by measuring anchoring force of two mangrove species (Rhizophora mangle L. and Avicennia germinans (L.) L.). Anchoring force was measured in 362 seedlings via lateral pull tests administered in mangrove forests of two subtropical estuaries and in laboratory-based experiments. Removal mechanism varied with seedling age: newly established seedlings failed due to root pull-out while seedlings older than 3 months failed by root breakage. The anchoring force of R. mangle seedlings was consistently and significantly greater than A. germinans (p = 0.002); however, force to remove A. germinans seedlings increased with growth at a faster rate (p < 0.001; A. germinans: 0.20–0.23 N/g biomass; R. mangle: 0.04–0.07 N/g biomass). Increasing density of surrounding vegetation had a positive effect (p = 0.04) on anchoring force of both species. Critical velocities at which seedlings become susceptible to instantaneous uprooting estimated from anchoring forces measured in the field were 1.20 m/s and 1.50 m/s, respectively, for R. mangle and A. germinans. As estimated critical velocities exceed typical flow magnitudes observed in field sites, removal of established seedlings likely occurs following erosion of sediments from the seedling base.
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- Award ID(s):
- 1944880
- PAR ID:
- 10431667
- Date Published:
- Journal Name:
- Sustainability
- Volume:
- 14
- Issue:
- 14
- ISSN:
- 2071-1050
- Page Range / eLocation ID:
- 8605
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/su14148605
