The moisture response of soil heterotrophic respiration: interaction with soil properties

Soil moisture is of primary importance for predicting the evolution of soil carbon stocks and fluxes, both because it strongly controls organic matter decomposition and because it is predicted to change at global scales in the following decades.  However, the soil functions used to model the heterotrophic respiration response to moisture have limited empirical support and introduce an uncertainty of at least 4 % in global soil carbon stock predictions by 2100. The necessity of improving the representation of this relationship in models has been highlighted in recent studies.  Here we present a datadriven analysis of soil moisture respiration relations based on 90 soils.  With the use of linear models we show  how  the  relationship  between  soil  heterotrophic  respiration  and  different  measures  of  soil  moisture  is  consistently affected by soil properties.  The empirical models derived include main effects and moisture interaction effects of soil texture, organic carbon content and bulk density.  When compared to other functions currently used in different soil biogeochemical models, we observe that our results can correct biases and reconcile differences within and between such functions.  Ultimately,  accurate predictions of the response of  soil  carbon  to  future  climate  scenarios  will  require  the integration of soildependent moisture respiration functions coupled with realistic representations of soil water dynamics.