科尔沁沙地胡枝子液流特征OA

Water is the main limiting factor for plant growth and survival in the southern edge of Horqin Sandy Land.Stem sap flow is an important basis for reflecting the physiological activities of trees and estimating water consumption per plant.This study investigated the sap flow rate of the sand-fixing shrub Lespedeza bicolor and its response mecha-nisms to environmental factors,aiming to provide a scientific basis and reference for formulating water use strategies and management measures for local Lespedeza bicolor populations.The experimental results showed that the average flow rate of L.bicolor during the observation period was 446.38 g/d.The diurnal variation pattern of sap flow in L.bicolor showed a bimodal"midday depression"phenomenon,with the timing of the midday depression advancing by 1 hour as the months progress from July to October.The average flow velocity at night was 0.045 g/h,and its contribution to the total daily flow was very low,at 0.077%.The flow velocity of the stem sap of L.bicolor was positively correlated with total solar ra-diation,temperature,wind speed,soil temperature,and vapor pressure deficit,and negatively correlated with relative humidity and precipitation.Among the above environmental factors,the vapor pressure deficit had the greatest impact on the sap flow of L.bicolor,with a contribution rate as high as 89.78%.There was an obvious threshold effect in the re-lationship between the two.The inflection point of the vapor pressure deficit liquid flow velocity relationship curve was 0.719 kPa,and the upper limit of the liquid flow velocity threshold was 111.85 g/h.Understanding the characteristics of transpiration water consumption and its response mechanisms to environmental factors in sandy-land L.bicolor can fa-cilitate the comprehension of eco-hydrological processes of sandy-land L.bicolor under climate change,and provide a sci-entific theoretical basis for optimizing stand structure and managing stand resources in the study area.