Simulation of the Effect of Root Distribution on Hydraulic Redistribution in a Desert Riparian Forest
2013-09-26
The general phenomena of water transfer from soil via the root system have often been referred to as hydraulic redistribution (HR). HR can improve the quantity of available water in soils, delay embolism formation in plant roots and enhance the nutritional status of deeply rooted plants during dry periods.
The main driving force of HR is the soil water potential gradient, which not only determines the occurrence of HR but also controls the amount of hydraulically redistributed water. Furthermore, roots are the most active participants in HR. However, very few studies have assessed the amount of hydraulically redistributed water and the effect of factors such as root distribution on HR remains unknown.
In order to estimate the effect of vertical root distribution on the HR process of Populus euphratica during the entire growth season, HAO Xingming et al. performed simulation and scenario analyses based on the observed soil water potential and root distribution data.
The results showed that the 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. The result was published in Ecological Research in July 2013.
The main driving force of HR is the soil water potential gradient, which not only determines the occurrence of HR but also controls the amount of hydraulically redistributed water. Furthermore, roots are the most active participants in HR. However, very few studies have assessed the amount of hydraulically redistributed water and the effect of factors such as root distribution on HR remains unknown.
In order to estimate the effect of vertical root distribution on the HR process of Populus euphratica during the entire growth season, HAO Xingming et al. performed simulation and scenario analyses based on the observed soil water potential and root distribution data.
The results showed that the 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. The result was published in Ecological Research in July 2013.