Temperature and moisture both control net methane uptake in a temperate forest soil

Abstract

The role of well-aerated forest soils as sinks for atmospheric methane (CH₄) and their impact on mitigating climate warming have gained attention recently. However, there is a lack of continuous time series data on net soil CH₄ flux in these forest soils, making annual budget estimates uncertain. In this study, we investigated the spatiotemporal variations and driving factors of soil CH₄ uptake in a temperate forest ecosystem over 4 years using continuous automatic in-situ chamber measurements. Our results showed that the soil consistently acted as a CH₄ sink, averaging 5.24 kg CH₄-C ha⁻¹ yr⁻¹, with a peak uptake rate of 243.98 µg C m⁻² h⁻¹ in summer and minimum uptake rates of 0.82 µg C m⁻² h⁻¹ in winter. Soil CH₄ uptake was mainly influenced by soil temperature and moisture, with methanotroph abundance and soil organic carbon content also playing roles. A simple linear regression model indicated that soil temperature and moisture explained 36 % and 56 % of the variance in CH₄ uptake, respectively. Moreover, the Temp-WFPS model and diffusion-reaction equation model explained 86 % and 53 % of the annual CH₄ uptake variance, respectively. Through the provision of comprehensive measurements detailing daily, seasonal, and annual CH₄ uptake, along with their environmental determinants, our data aids in the advancement of more precise biogeochemical models, thereby enhancing the estimation of global CH₄ budgets.