Abiotic and biotic controls of soil moisture spatiotemporal variability and the occurrence of hysteresis

An expression that separates biotic and abiotic controls on the temporal dynamics of the soilmoisture spatial coefficient of variation C v(h) was explored via numerical simulations using a mechanisticecohydrological model, Tethys-Chloris. Continuous soil moisture spatiotemporal dynamics at an exemplaryhillslope domain were computed for six case studies characterized by different climate and vegetationcover and for three configurations of soil properties. It was shown that abiotic controls largely exceed theirbiotic counterparts in wet climates. Biotic controls on C v(h) were found to be more pronounced in Mediter-ranean climates. The relation between Cv(h) and spatial mean soil moisture h was found to be unique in wetlocations, regardless of the soil properties. For the case of homogeneous soil texture, hysteretic cyclesbetween C v(h) and h were observed in all Mediterranean climate locations considered here and to a lesserextent in a deciduous temperate forest. Heterogeneity in soil properties increased C v(h) to values commen-surate with field observations and weakened signatures of hysteresis at all of the studied locations. Thisfinding highlights the role of site-specific heterogeneities in hiding or even eliminating the signature ofclimatic and biotic controls on C v(h), thereby offering a new perspective on causes of confounding resultsreported across field experiments.