Diurnal hysteresis between soil CO2 and soil temperature is controlled by soil water content

Abstract

Recent years have seen a growing interest in measuring and modeling soil CO2 efflux, as this flux represents a large component of ecosystem respiration and is a key determinant of ecosystem carbon balance. Process-based models of soil CO2 production and efflux, commonly based on soil temperature, are limited by nonlinearities such as the observed diurnal hysteresis between soil CO2 concentration ([CO2]) and temperature. Here we quantify the degree to which hysteresis between soil [CO2] and soil temperature is controlled by soil water content in a montane conifer forest, and how this nonlinearity impacts estimates of soil CO2 efflux. A representative model that does not consider hysteresis overestimated soil CO2 efflux for the entire growing season by 19%. At high levels of soil water content, hysteresis imposes organized, daily variability in the relationship between soil [CO2] and soil temperature, and at low levels of soil water content, hysteresis is minimized.

Citation

Riveros-Iregui, Diego A.; Emanuel, Ryan E.; Muth, Daniel J.; McGlynn Brian, L.; Epstein, Howard E.; Welsch, Daniel L.; Pacific, Vincent J.; Wraith, Jon M. 2007. Diurnal hysteresis between soil CO2 and soil temperature is controlled by soil water content. Geophysical Research Letters. 34: L17404.