Dual function of root systems in balancing soil water flow behavior

A limitation in characterizing three-dimensional (3D) soil water flow from dye-stained images hinders further insights into the role of 3D root systems. Here we used X-ray computed microtomography, dye-tracing experiments, and 3D soil water flow modeling software to imply the dual function of 3D root systems. Our results revealed that soil water flow traits exhibited depth-dependent changes at the mixed forest stands with loam soils. We also concluded that root systems under loam soil conditions could promote both preferential flow- and soil matrix flow behavior. Preferential flow will dominate soil water flow behavior when the key indicators of root systems traits were less than a critical value; otherwise, soil matrix flow will dominate. Critical values of the indicators inducing the transfer of soil water flow behavior varied for different soil water flow traits. Our study provides an insight into the dual function of root systems from a 3D perspective. Root systems under loam soil conditions promote both preferential flow and soil matrix flow behavior, according to X-ray computed microtomography, dye-tracing experiments, and 3-dimensional soil-water flow modelling software at the mixed forest stands, eastern China.