A Global Database of Soil Methane uptake (SMUD)

Abstract. Soil methane uptake (SMU), the second-largest and represents a biologically mediated sink for atmospheric methane (CH₄) in terrestrial ecosystems, plays a non-negligible role in regulating the global CH₄ budget. Field SMU observations have been conducted since the 1980s, but have not yet been systematically compiled within any unified and openly available framework. Here, we present the global Soil Methane Uptake Database (SMUD), which includes 2427 site-level records from 920 peer-reviewed publications spanning 1986 to 2025. SMUD contains SMU measurements at multiple temporal scales, including daily (n = 1425), monthly (n = 2001), seasonal (n = 1720), and annual (n = 1098), along with soil moisture and temperature data at daily and monthly scales. The collected datasets cover all major climatic zones and ecosystem types, across which SMU exhibits pronounced spatial and temporal variability. We found that seasonal- and biome-specific variations were key to understanding intra-annual changes in SMU. In particular, the effects of soil temperature and moisture on SMU are biome-specific: observations from Temperate Grassland are primarily associated with temperature changes, whereas those from Tropical Rainforest and Desert are mainly controlled by moisture, and other biomes show a mix of controlling factors. Overall, SMUD provides a comprehensive basis for understanding the global patterns of SMU, unraveling the underlying mechanisms, and estimating the global SMU budget. The database, associated data, and code to reproduce the results can be found at https://doi.org/10.5281/zenodo.18299391 (Jiang et al., 2026). We aim to establish SMUD maintenance as a collaborative, community-driven, shared, and user- managed database within the research community.