Peatlands are recognized as crucial greenhouse gas sources and sinks and have been extensively studied. Their emissions exhibit high spatial heterogeneity when measured on site using flux chambers. However, the mechanism by which this spatial variability behaves on a very fine scale remains unclear. This study investigates the fine-scale spatial variability of greenhouse gas emissions from a subantarctic Sphagnum peatland bog. Using a recently developed skirt chamber, methane emissions and ecosystem respiration (as carbon dioxide) were measured at a submeter scale resolution, at five specific 3 x 3 m plots, which were examined across the site throughout a single campaign during the Austral summer season. The results indicated that methane fluxes were significantly less homogeneously distributed compared with ecosystem respiration. Furthermore, we established that the spatial variation scale, i.e., the minimum spatial domain over which notable changes in methane emissions and ecosystem respiration occur, was <0.56 m(2). Factors such as ground height relative to the water table and vegetation coverage were analyzed. It was observed that Tetroncium magellanicum exhibited a notable correlation with higher methane fluxes, likely because of the aerenchymatous nature of this species, facilitating gas transport. This study advances understanding of gas exchange patterns in peatlands but also emphasizes the need for further efforts for characterizing spatial dynamics at a very fine scale for precise greenhouse gas budget assessment.

Scrub mangrove forests, dominated by Rhizophora mangle L., are characterized by high porewater salinity, which might compromise individual sap flow rates (SF) due to seasonal and diurnal microenvironmental variations. We tested the functional, anatomical, and SF responses of 12 individuals to microenvironmental variables such as solar radiation, photosynthetic photon flux, wind speed, evaporative demand, and porewater salinity, measured using an in situ weather station. Measurements were made in the dry and rainy seasons in the Yucatan Peninsula, using Granier heat dissipation sensors, installed on tree branches. During the rainy season, SF was twice as high as that during the dry season (0.22 ± 0.00 L h⁻¹ and 0.11 ± 0.00 L h⁻¹, respectively), despite lower evaporative demand. In both seasons, negative relationships between SF with vapor pressure deficit (VPD; dry τ = −0.54; rainy τ = −0.56) and with photosynthetic photon flux (PPF; dry τ = −0.97; rainy τ = −0.98) were found, indicating a strong hydraulic coupling to atmospheric conditions. Sap flow and transpiration rates of this R. mangle scrub mangrove forest exceeded those of some tropical dry deciduous forests, suggesting adaptations that support water transport in saline environments. The clustered xylem vessels of R. mangle ensure safe sap flow year-round. As an evergreen species, it contributes water to the atmosphere all year-round, underscoring its critical role in the tropical ecohydrological environment.

Peatlands play a crucial role in the global carbon cycle, and among several key processes, it is essential to characterize photosynthesis-irradiance (PI) curves, which describe the relationship between light availability and carbon assimilation through photosynthetic activity. Traditional methods, such as Eddy Covariance and portable photosynthesis measurement systems, provide valuable data at the ecosystem and leaf scales, respectively. However, these approaches leave a gap in capturing carbon dynamics at intermediate scales, where complex plant assemblages and microhabitat variability influence photosynthetic activity in ways that cannot be fully resolved at broader or finer spatial resolutions. In a previous companion paper, we introduced a skirt-chamber method for measuring greenhouse gas emissions in peatlands. Building on that work, we further developed a second version, specifically designed to determine photosynthetic activity at multiple light intensities. This improved modulated-light skirt-chamber enables in situ characterization of photosynthetic responses under natural light conditions by using adjustable screens to regulate light intensity. The chamber is particularly suited for generating PI curves in peatlands and other low-stature ecosystems with diverse microhabitats. Field tests conducted in a subantarctic peatland bog demonstrated the method’s reliability. The generated PI curves fit well with existing models and closely matched measurements from an EC station at the study site, accurately capturing photosynthetic responses to light. The modulated-light skirt-chamber offers a portable, cost-effective, and flexible solution for studying carbon dynamics at an intermediate scale, bridging leaf-level measurements and ecosystem-scale observations. This method holds significant promise for advancing our understanding of carbon fluxes in complex and heterogeneous ecosystems.

Peatlands play a crucial role in the global carbon cycle, and among several key processes, it is essential to characterize photosynthesis-irradiance (PI) curves, which describe the relationship between light availability and carbon assimilation through photosynthetic activity. Traditional methods, such as Eddy Covariance and portable photosynthesis measurement systems, provide valuable data at the ecosystem and leaf scales, respectively. However, these approaches leave a gap in capturing carbon dynamics at intermediate scales, where complex plant assemblages and microhabitat variability influence photosynthetic activity in ways that cannot be fully resolved at broader or finer spatial resolutions. In a previous companion paper, we introduced a skirt-chamber method for measuring greenhouse gas emissions in peatlands. Building on that work, we further developed a second version, specifically designed to determine photosynthetic activity at multiple light intensities. This improved modulated-light skirt-chamber enables in situ characterization of photosynthetic responses under natural light conditions by using adjustable screens to regulate light intensity. The chamber is particularly suited for generating PI curves in peatlands and other low-stature ecosystems with diverse microhabitats. Field tests conducted in a subantarctic peatland bog demonstrated the method’s reliability. The generated PI curves fit well with existing models and closely matched measurements from an EC station at the study site, accurately capturing photosynthetic responses to light. The modulated-light skirt-chamber offers a portable, cost-effective, and flexible solution for studying carbon dynamics at an intermediate scale, bridging leaf-level measurements and ecosystem-scale observations. This method holds significant promise for advancing our understanding of carbon fluxes in complex and heterogeneous ecosystems.

Tropical wetlands are the largest natural source of methane (CH4) globally. While soils are the primary CH4 emitters, recent studies reveal that trees mediate soil-produced methane, highlighting potential underestimations in current methane and carbon budgets. In mangrove forests, the contribution of trees to local, regional, and global CH4 emissions remains uncertain, despite their significant role as blue carbon reservoirs. Mangrove species exhibit unique physiological and morpho-anatomical adaptations—such as extensive aerenchyma tissues and lenticels—that facilitate gas exchange through their bark and roots. In this study, we assessed the spatiotemporal variation of CH4 emissions from tree stems and stilt roots of three mangrove species (Rhizophora mangle, Avicennia germinans, and Laguncularia racemosa) across distinct ecological types (i.e., scrub, basin and hammock) during the rainy and dry seasons in the Ría Celestún Biosphere Reserve (Mexico). We also investigated the relationship between bark anatomical traits, aerenchyma development, and CH4 fluxes. Our findings revealed that CH4 emissions varied by species, tissue type, and season. Scrub R. mangle showed the highest CH4 emission rates from both tree stems and stilt roots, particularly in near-ground tissues like third-order stilt roots with abundant bark aerenchyma, whereas basin mangrove forests had the lowest emissions, particularly in A. germinans and L. racemosa. Methane emissions increased during the rainy season and were positively correlated with bark (aerenchyma) proportion, lenticel density but negatively with wood density. To date, tree stem CH4 emissions have been documented in eleven mangrove species globally. Our results underscore the need to refine local-to-global carbon models by integrating bark anatomy and tree-mediated CH4 emissions. Moreover, mangrove trees can act as either CH4 sources or sinks, depending on physicochemical and microenvironmental conditions. Understanding these dynamics requires a comprehensive approach rooted in plant physiology and anatomy.