Scholars from the Institute of Surface-Earth System Science at Tianjin University in collaboration with the Joint Global Change Research Institute at the University of Maryland have made progress on earth system models of soil heterotrophic respiration. Their research results have recently been published in Nature Communications: “A Moisture Function of Soil Heterotrophic Respiration that Incorporates Microscale Processes”.

Soil heterotrophic respiration (HR) is an important source of soil-to-atmosphere CO2 flux, but its response to changes in soil water content (θ) is poorly understood. Earth system models commonly use empirical moisture functions to describe the HR–θ relationship, introducing significant uncertainty in predicting CO2 flux from soils. Generalized, mechanistic models that address this uncertainty are thus urgently needed. Researchers from Tianjin University and the University of Maryland derived, tested, and calibrated a novel moisture function, fm, that encapsulates primary physiochemical and biological processes controlling soil HR. They validated fm using simulation results and published experimental data and established the quantitative relationships between parameters of fm and measurable soil properties, which enables fm to predict the HR–θ relationships for different soils across spatial scales. The fm function predicted comparable HR–θ relationships with laboratory and field measurements and may reduce the uncertainty in predicting the response of soil organic carbon stocks to climate change compared with the empirical moisture functions currently used in Earth system models.

Figure: Establishing macroscale process-based models from microscale mechanics of soil heterotrophic respiration.