Ranniku Reti, Kazmi Fahad Ali, Espenberg Mikk, Truupõld Joosep, Escuer-Gatius Jordi, Mander Ülo, Soosaar Kaido
Department of Geography, Institute of Ecology & Earth Sciences, University of Tartu, 46 Vanemuise, EST-51014 Tartu, Estonia.
Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 5 Fr.R. Kreutzwaldi, EST-51006 Tartu, Estonia.
Biogeochemistry. 2025;168(3):48. doi: 10.1007/s10533-025-01238-3. Epub 2025 May 7.
Spring can be a critical time of year for stem and soil methane (CH), nitrous oxide (NO) and carbon dioxide (CO) emissions as soil freeze-thaw events can be hot moments of gas release. Greenhouse gas fluxes from soil, Downy birch () and Norway spruce () stems were quantified using chamber systems and gas analysers in spring 2023 in a northern drained peatland forest. Dissolved gas concentrations in birch sap and soil water, environmental parameters, soil chemistry, and functional gene abundances in the soil were determined. During spring, initially low soil and stem CH, NO, and CO emissions increased towards late April. Temperature emerged as the primary driver of soil and stem fluxes, alongside photosynthetically active radiation influencing stem fluxes. Soil hydrologic conditions had minimal short-term impact. No clear evidence linked stem CH emissions to birch sap gas concentrations, while relationships existed for CO. Functional gene abundances of the N and CH-cycles changed between measurement days. Potential for methanogenesis and complete denitrification was higher under elevated soil water content, shifting to methanotrophy and incomplete denitrification as the study progressed. However, our results highlight the need for further analysis of relationships between microbial cycles and GHG fluxes under different environmental conditions, including identifying soil microbial processes in soil layers where tree roots absorb water.
The online version contains supplementary material available at 10.1007/s10533-025-01238-3.
春季可能是一年中茎干和土壤中甲烷（CH）、一氧化二氮（NO）和二氧化碳（CO）排放的关键时期，因为土壤冻融事件可能是气体释放的活跃时刻。2023年春季，在北方排水泥炭地森林中，使用箱式系统和气体分析仪对来自土壤、柔毛桦（）和挪威云杉（）茎干的温室气体通量进行了量化。测定了桦树汁液和土壤水中的溶解气体浓度、环境参数、土壤化学性质以及土壤中的功能基因丰度。在春季，土壤和茎干最初较低的CH、NO和CO排放到4月下旬有所增加。温度是土壤和茎干通量的主要驱动因素，光合有效辐射也影响茎干通量。土壤水文条件的短期影响最小。没有明确证据表明茎干CH排放与桦树汁液气体浓度有关，而CO排放存在这种关系。测量日之间，氮和CH循环的功能基因丰度发生了变化。在土壤含水量升高的情况下，甲烷生成和完全反硝化的潜力较高，随着研究进展，转变为甲烷氧化和不完全反硝化。然而，我们的结果强调需要进一步分析不同环境条件下微生物循环与温室气体通量之间的关系，包括确定树木根系吸水土壤层中的土壤微生物过程。
在线版本包含可在10.1007/s10533-025-01238-3获取的补充材料。
