Studies on tree CH4 exchange in boreal forests regarding seasonality and role of tree canopies are rare. We aimed to quantify the contribution of boreal trees to the forest CH4 budget during spring leaf-out and to reveal the role of microbes in the CH4 exchange.
MethodsMethane fluxes of downy birch and Norway spruce (Betula pubescens and Picea abies) growing on fen and upland sites were measured together with soil CH4 flux, environmental variables and microbial abundances involved in the CH4 cycle. Tree CH4 fluxes were studied from three stem heights and from shoots.
ResultsThe trees emitted CH4 with higher stem emissions detected from birch and higher shoot emissions from spruce. The stem CH4 emissions from birches at the fen were high (mean 45\uffc2\uffa0\uffc2\uffb5g\uffc2\uffa0m\uffe2\uff88\uff922\uffc2\uffa0h\uffe2\uff88\uff921), decreasing with stem height. Their dynamics followed soil temperature, suggesting the emitted CH4 originated from methanogenic activity, manifested in high mcrA gene copy numbers, in the peat soil. Methanogens were below the quantification limit in the tree tissues. Upscaled tree CH4 emissions accounted for 22% of the total CH4 emissions at the fen.
ConclusionsThe variation in stem CH4 flux between the trees and habitats is high, and the emissions from high-emitting birches increase as the spring proceeds. The lack of detection of methanogens or methanotrophs in the aboveground plant tissues suggests that these microbes did not have a significant role in the observed tree-derived fluxes. The stem-emitted CH4 from birches at the fen is presumably produced microbially in the soil.
", "keywords": ["0301 basic medicine", "570", "550", "Methanogens", "LIVING TREES", "Trees", "03 medical and health sciences", "Methanotrophs", "METHANE EMISSIONS", "SAP FLOW", "Boreal forest", "Waterlogging", "PRECURSOR", "0303 health sciences", "BIOMASS EQUATIONS", "NORWAY SPRUCE", "Forestry", "Methane fux", "15. Life on land", "Environmental sciences", "METHANOTROPHS", "13. Climate action", "RADIATION", "Methane flux", "VEGETATION", "COMMUNITIES"]}, "links": [{"href": "https://link.springer.com/content/pdf/10.1007/s11104-022-05447-9.pdf"}, {"href": "https://doi.org/10.1007/s11104-022-05447-9"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Plant%20and%20Soil", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1007/s11104-022-05447-9", "name": "item", "description": "10.1007/s11104-022-05447-9", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1007/s11104-022-05447-9"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2022-05-24T00:00:00Z"}}, {"id": "10.1111/nph.20401", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-27T16:19:49Z", "type": "Journal Article", "created": "2025-01-17", "title": "Insights into the subdaily variations in methane, nitrous oxide and carbon dioxide fluxes from upland tropical tree stems", "description": "Summary
Recent studies have shown that stem fluxes, although highly variable among trees, can alter the strength of the methane (CH4) sink or nitrous oxide (N2O) source in some forests, but the patterns and magnitudes of these fluxes remain unclear. This study investigated the drivers of subdaily and seasonal variations in stem and soil CH4, N2O and carbon dioxide (CO2) fluxes.
CH4, N2O and CO2 fluxes were measured continuously for 19\uffe2\uff80\uff89months in individual stems of two tree species, Eperua falcata (Aubl.) and Lecythis poiteaui (O. Berg), and surrounding soils using an automated chamber system in an upland tropical forest. Subdaily variations in these fluxes were related to environmental and stem physiological (sap flow and stem diameter variations) measurements under contrasting soil water conditions.
The results showed that physiological and climatic drivers only partially explained the subdaily flux variations. Stem CH4 and CO2 emissions and N2O uptake varied with soil water content, time of day and between individuals. Stem fluxes decoupled from soil fluxes.
Our study contributes to understanding the regulation of stem greenhouse gas fluxes. It suggests that additional variables (e.g. internal gas concentrations, wood\uffe2\uff80\uff90colonising microorganisms, wood density and anatomy) may account for the remaining unexplained variability in stem fluxes, highlighting the need for further studies.
Recent studies have shown that stem fluxes, although highly variable among trees, can alter the strength of the methane (CH4) sink or nitrous oxide (N2O) source in some forests, but the patterns and magnitudes of these fluxes remain unclear. This study investigated the drivers of subdaily and seasonal variations in stem and soil CH4, N2O and carbon dioxide (CO2) fluxes.
CH4, N2O and CO2 fluxes were measured continuously for 19\uffe2\uff80\uff89months in individual stems of two tree species, Eperua falcata (Aubl.) and Lecythis poiteaui (O. Berg), and surrounding soils using an automated chamber system in an upland tropical forest. Subdaily variations in these fluxes were related to environmental and stem physiological (sap flow and stem diameter variations) measurements under contrasting soil water conditions.
The results showed that physiological and climatic drivers only partially explained the subdaily flux variations. Stem CH4 and CO2 emissions and N2O uptake varied with soil water content, time of day and between individuals. Stem fluxes decoupled from soil fluxes.
Our study contributes to understanding the regulation of stem greenhouse gas fluxes. It suggests that additional variables (e.g. internal gas concentrations, wood\uffe2\uff80\uff90colonising microorganisms, wood density and anatomy) may account for the remaining unexplained variability in stem fluxes, highlighting the need for further studies.