An Experimental Investigation of Precipitation Utilization of plants in Arid Regions
Abstract. What is the water source for ecological restoration plants in arid region is still up to debate. To address this issue, we conducted an in-situ experiment in the Ulan Buh Desert of China. We selected Tamarisk, a common drought-salt-tolerance species in the desert for ecological restoration as our research subject, used a new designed lysimeter to monitor precipitation infiltration, a sap flow system to track reverse sap flow that occurred in shoot, branch, and stem during the precipitation event, and observed the precipitation redistribution process of the Tamarisk plot. The results showed that Tamarisk indeed directly absorb precipitation water, when precipitation occurs, the main stem, lateral branch, and shoot all show the signs of reversed sap flow, and the reversed sap flow accounted for 21.5 % of the annual sap flow in the shoot and branch, and 13.6 % in the stem. Precipitation event in desert was dominated by light precipitation events, which accounted for 81 % of the annual precipitation events. It was found that light precipitation can be directly absorbed by the Tamarisk leaves, especially in nighttime or cloudy days. Even when the precipitation is absent, it was found that desert plants can still absorb unsaturated atmospheric vapor, as reversed sap flow was observed when the atmospheric relative humidity reached 75 %. This study indicated that the effect of light precipitation on desert plants was significant and should not be overlooked in terms of managing the ecological and hydrological systems in arid regions.
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