Electron accepting capacity of soil dissolved organic matter increases while electron donating capacity decreases along a temperature gradient

The electron transfer of soil-derived dissolved organic matter (DOM) plays a key role in the biogeochemical redox processes of redox-active substances. Yet the effect of temperature on soil DOM’s electron transfer capacity (ETC) remains poorly unexplored. This study investigates the temperature response of the ETC of soil DOM through an examination of soils collected from sites along a temperature gradient with 400 mm of annual precipitation in China. Our results demonstrate that increasing temperature enhances soil DOM’s electron-accepting capacity (EAC) while reducing its electron-donating capacity (EDC). For every 1 °C increase, EAC rises by 0.034 mmol e⁻ (g soil DOM)⁻¹ while EDC decreases by 0.014 mmol e⁻ (g soil DOM)⁻¹. This reduces the efficiency of electron transfer to redox-active substances, potentially weakening soil DOM’s role in biogeochemical redox processes under warming conditions. The influence of temperature on soil DOM’s ETC was achieved indirectly through modulating soil properties and plant litter composition affecting the traits of soil DOM. These findings provide crucial insights for predicting soil DOM’s response to climate warming.