Soil moisture is of primary importance for predicting the evolution of soilcarbon stocks and fluxes, both because it strongly controls organic matterdecomposition and because it is predicted to change at global scales in thefollowing decades. However, the soil functions used to model theheterotrophic respiration response to moisture have limited empiricalsupport and introduce an uncertainty of at least 4% in global soilcarbon stock predictions by 2100. The necessity of improving therepresentation of this relationship in models has been highlighted in recentstudies. Here we present a data-driven analysis of soil moisture-respirationrelations based on 90 soils. With the use of linear models we show how therelationship between soil heterotrophic respiration and different measuresof soil moisture is consistently affected by soil properties. The empiricalmodels derived include main effects and moisture interaction effects of soiltexture, organic carbon content and bulk density. When compared to otherfunctions currently used in different soil biogeochemical models, we observethat our results can correct biases and reconcile differences within andbetween such functions. Ultimately, accurate predictions of the response ofsoil carbon to future climate scenarios will require the integration ofsoil-dependent moisture-respiration functions coupled with realisticrepresentations of soil water dynamics.
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