Soil and tree-stem co₂ and ch₄ fluxes from living and dead mangrove forests in se Brazil
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Data
2026-03-17
Autores
Lima, Layza Roxanne Santana de
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Universidade Federal do Espírito Santo
Resumo
Although mangrove forests are essential to blue carbon dynamics in coastal zones, relatively little is known about the greenhouse gas (GHG) fluxes emitted by these ecosystems. In this study, we investigated soil- and tree-mediated GHG fluxes in living and dead mangrove forests within a polyhaline estuary in southeastern Brazil, with the aim of assessing the effects of forest mortality on soil and tree-stem CO₂ and CH₄ fluxes. Because CO₂ fluxes are partially mediated by aerobic plant respiration, and methane fluxes from soils and tree stems are influenced by the balance between microbial production and oxidation, we expected lower GHG fluxes in dead mangrove forests. However, our results showed that living and dead mangroves exhibited comparable mean soil CO₂ fluxes, with mean annual values of 70.8 ± 25.0 and 74.0 ± 27.1 mmol m⁻² d⁻¹, respectively. Mean soil CH₄ fluxes were also similar between live and dead mangrove forests, ranging from 205 ± 238 to 244 ± 130 µmol m⁻² d⁻¹, with methane contributing only 2–3% of total CO₂-equivalent emissions. We further observed a seasonal effect on soil CO₂ fluxes, with higher emissions during summer compared to winter, whereas soil CH₄ fluxes showed no consistent seasonal variation. Water column height, used as a daily-integrated proxy of inundation conditions, influenced soil CO₂ and CH₄ flux variability, regardless of forest condition.. Tree-stem CO₂ fluxes decreased along the vertical gradient of the stem, indicating diffusion-dominated passive transport, while tree-stem CH₄ fluxes were negligible. When integrated and extrapolated to the studied estuarine region, ecosystem-scale GHG emissions were overwhelmingly dominated by soil processes (>99%) under both mangrove conditions.
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Gases efeito estufa , Manguezais , Carbono azul