Pine afforestation improves the biological soil attributes linked to methane oxidation in a temperate zone of Argentina

ABSTRACT Background: Atmospheric methane (CH 4) is responsible for approximately 20% of global warming since the preindustrial era. Forests are land ecosystems whose role is crucial for mitigating the greenhouse effect due to their capacity to capture and store C and preserve other processes such as CH 4 oxidation in the soil. On the other hand, in the particular case of afforestation, there are contradictory results about the magnitude of CH 4 uptake variation due to changes in methanotrophic bacteria activity and its relationship with micro-environmental conditions. Results: The average potential CH 4 oxidation rate in the laboratory (MOL) of afforested soil was 186% greater than that of the grassland, which could be marginally attributed to differences in soil physicochemical parameters like bulk density, pH and organic matter. A seasonal pattern in MOL was observed in both land uses, with the highest values at the warm and rainy season. MOL magnitude increased with soil depth up to 10-15 cm, which corresponds with the mineral layer. Conclusion: Pine afforestation would improve the biological soil attributes linked to methane oxidising bacteria compared to the grassland systems.

摘要 背景：自前工业化时代以来，大气甲烷（CH₄）对全球变暖的贡献约占20%。森林作为陆地生态系统，凭借固碳能力以及维持土壤甲烷氧化等相关过程的功能，在缓解温室效应方面发挥着至关重要的作用。而就人工造林这一特定情形而言，关于甲烷氧化细菌活性变化所引发的甲烷吸收能力波动幅度，以及其与微环境条件之间的关联，目前已有的研究结论存在矛盾。结果：本研究中，人工造林土壤的实验室潜在甲烷氧化速率（MOL）平均值较草地土壤高出186%，该差异可部分归因于土壤理化参数（如容重、pH值与有机质含量）的不同。两种土地利用类型的MOL均呈现出季节性变化规律，在温暖多雨的季节达到峰值。MOL数值随土壤深度增加而升高，直至10~15 cm的矿质土层。结论：相较于草地生态系统，松树人工造林可改善与甲烷氧化细菌相关的土壤生物学属性。