Abstract. Forest soils, as crucial sinks for atmospheric methane in terrestrial ecosystems, are significantly impacted by changes in ecosystem dynamics due to deforestation and agricultural practices. This study investigated the methane oxidation potential of rubber plantation soils in Thailand, focusing on the effect of fertilization. The methane oxidation activity of the top soils (0–10 cm) in the dry season was found to be extremely low and slightly increased in the wet season, with lower activity for higher fertilization levels. The potential methane oxidation potential of the topsoil was too low to explain the in-situ methane uptake. Soils below 10 cm depth in unfertilized rubber plantations showed higher activity than the surface soils, and methane oxidation was detected at least down to 60 cm depth. In contrast, soils under the high-fertilization treatment exhibited similarly low activity of methane oxidation up to 60 cm depth as surface soils both in dry and wet seasons, indicating that fertilization of para rubber plantation negatively impacts the methane oxidation potential of the soils over the deep profile without recovery in the off-season with no fertilization. Methane uptake per area estimated by integrating the methane oxidation potentials of soil layers was comparable to the field flux data, suggesting that methane oxidation in the soil predominantly occurs in depths below the surface layer. These findings have significant implications for understanding the environmental impacts of tropical forest land uses on methane dynamics and underscore the importance of understanding methane oxidation processes in soils.

中文翻译：

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受施肥影响的泰国橡胶种植园土壤的甲烷氧化电位


摘要。森林土壤作为陆地生态系统中大气甲烷的重要汇，由于森林砍伐和农业实践，受到生态系统动态变化的显著影响。本研究调查了泰国橡胶种植园土壤的甲烷氧化电位，重点是施肥的影响。发现旱季表层土壤 （0-10 cm） 的甲烷氧化活性极低，在雨季略有增加，施肥水平越高，活性越低。表土的潜在甲烷氧化电位太低，无法解释原位甲烷吸收。在未施肥的橡胶种植园中，10 cm 深度以下的土壤显示出比表层土壤更高的活性，并且至少在 60 cm 深处检测到甲烷氧化。相比之下，在旱季和湿季，高施肥处理下的土壤在 60 cm 深处表现出与表层土壤类似的低甲烷氧化活性，这表明对位橡胶种植园的施肥对土壤在深层剖面上的甲烷氧化电位产生负面影响，在淡季没有施肥的情况下没有恢复。通过整合土壤层的甲烷氧化电位来估计的单位面积甲烷吸收量与现场通量数据相当，这表明土壤中的甲烷氧化主要发生在表层以下的深处。这些发现对于了解热带森林土地利用对甲烷动态的环境影响具有重要意义，并强调了了解土壤中甲烷氧化过程的重要性。