Sap Flow Velocity in Fraxinus pennsylvanica in Response to Water Stress and Microclimatic Variables

作者：Su Yu, Xinyu Wang, Yiqiu Sun, Hailong Wu · 发表于：Frontiers in Plant Science · 年份：2022 · DOI：10.3389/fpls.2022.884526 · 被引用次数：18 · 研究领域：Plant Water Relations and Carbon Dynamics、Tree-ring climate responses、Hydrology and Sediment Transport Processes

In arid and semiarid regions with water shortage, forestry development is limited by water availability. Understanding how tree sap flow responds to water stress and microclimatic variables is essential for the management of trees and the understanding of the eco-physiological properties of trees in arid areas. In the city of Tianjin in northern China, we measured the sap flow of Fraxinus pennsylvanica , a widely distributed urban greening tree species in semiarid regions of China. We measured the sap flow in four F. pennsylvanica trees over 6 months (April–September 2021), using a thermal diffusion probe method, and simultaneously monitored microclimatic variables and soil moisture. Results indicated that high nighttime sap flow velocity might be produced under the water stress condition. In addition, the nighttime sap flow velocity under the water stress condition was more susceptible to the combined effects of meteorological factors at night. The daytime sap flow velocity exerted a highly significant positive effect on the nighttime sap flow velocity during the whole research period, and the model fit was higher in the early growing season than that in the late growing season (early growing season: R 2 = 0.51, P < 0.01; late growing season: R 2 = 0.36, P < 0.01). Vapor pressure deficit had a positive effect on daytime sap flow. However, net vapor pressure deficit restrained daytime sap flow velocity when the intercorrelation between the microclimatic variable...