Simulation of the effect of root distribution on hydraulic redistribution in a desert riparian forest

Abstract

AbstractHydraulic redistribution (HR) of roots plays an important role in the water relations of desert riparian plants. In order to estimate the effect of vertical root distribution on the HR process of Populus euphratica Oliv. during the entire growth season, we performed simulation and scenario analyses based on the observed soil water potential and root distribution data. The results showed that our simulation model achieved a good accuracy. The initial value of soil water content could significantly affect the simulated soil water content at soil depths of >90 cm, but had only limited effect on soil water content in the 0‐ to 90‐cm soil layers. Scenario analysis revealed that with increase in root distribution depth, the HR process extended from the upper and middle soil layers downward toward the middle and deeper soil layers: the deeper the root distribution, the more likely it was to trigger the HR process in deep soil layers. However, a deeper rooting system led to a decrease in the total amount of hydraulically redistributed water over the entire soil column. Redistributed water also significantly increased the soil water depletion and the soil water storage. However, the effects of redistributed water (HR vs. without HR) on water depletion and soil water storage were reduced with the deepening of root distribution. These results indicate that HR can obviously affect the moisture of the upper soil layers, while vertical root distribution significantly changes the spatial and quantitative characteristics of HR within soil columns.