Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Droughts and other extreme precipitation events are predicted to increase in intensity, duration, and extent, with uncertain implications for terrestrial carbon C sequestration.
Soil wetting from above precipitation results in a characteristically different pattern of pore-filling than wetting from below groundwater , with larger, well-connected pores filling before finer pore spaces, unlike groundwater rise in which capillary forces saturate the finest pores first.
Here we demonstrate that pore-scale wetting patterns interact with antecedent soil moisture conditions to alter pore-scale, core-scale, and field-scale C dynamics. Drought legacy and wetting direction are perhaps more important determinants of short-term C mineralization than current soil moisture content in these soils. Our results highlight that microbial access to C is not solely limited by physical protection, but also by drought or wetting-induced shifts in hydrologic connectivity.
We argue that models should treat soil moisture within a three-dimensional framework emphasizing hydrologic conduits for C and resource diffusion. Climate change is altering global precipitation patterns: droughts are predicted to increase in intensity, duration, and geographic coverage, with major implications for soil carbon C storage at ecosystem and global scales 1 , 2 , 3.
Precipitation events are becoming less common but more intense in the majority of warm, humid environments in the contiguous United States 4 , 5. Laboratory and field studies indicate drought-affected soils produce a CO 2 pulse when rewet 8 , 9 , 10 , but models do a poor job of reproducing these moisture-related patterns of greenhouse gas GHG emissions in soils 7 , limiting our ability to predict how drying and rewetting will influence soil C source or sink capacity under scenarios of altered precipitation 6.
