The Sap Flow Of Hippophae Rhamnoides Trunk And Its Influencing Factors In Arsenic Sandstone Area

Chestnut soil developed with arsenic sandstone as its parent material was used as the test soil,and Hippophae rhamnoides was taken as the test tree species and placed in the greenhouse of Inner Mongolia Agricultural University in order to explore the water dissipation characteristics and supply-demand relationship of adaptable plants in arsenic sandstone area.The fluid flow rates of Hippophae rhamnoides under different irrigation gradients T1(field moisture capacity θFc25%),T2(θFC40%)and T3(θFC55%)during the whole growing season were monitored based on the stem heat balance(SHB)method,and environmental factors were monitored by AGWS100 agrometeorological observation system,which aimed to investigate the response of the fluid flow rate of Hippophae rhamnoides to environmental factors and provide data support and theoretical basis for the management of forest stands and the sustainable development of ecological construction in arsenic sandstone area.The main conclusions are as follows:(1)While showing significant day-night changes,the fluid flow rate of Hippophae rhamnoides was accompanied by the phenomenon of "heat dormancy".Fluid flow presented a "bimodal" changing curve and maintained "non-zero" steady changes at night.Soil moisture content was positively proportional to the fluid flow rate of Hippophae rhamnoides.The changes of the fluid flow characteristics of Hippophae rhamnoides under different irrigation gradients were T3>T2>T1.The inter-monthly variation of the fluid flow rate of Hippophae rhamnoides was:Fluid flow rate presented the trend of increasing first and then decreasing over time.Meanwhile,Hippophae rhamnoides has certain self-regulation mechanism in the face of drought stress.(2)Under different irrigation gradients,the dynamic change characteristics of growth rhythm and fluid flow rates were almost unaffected by water stress and expressed as T3>T2>T1.The fitting degree of leaf area index and fluid flow dissipation was T2>T3>T1.Moderate water stress was beneficial to increasing the tolerance of vegetation.(3)Under different irrigation gradients,the fluid flow rate of Hippophae rhamnoides was positively correlated with photosynthetically active radiation,air temperature and water vapor pressure,and negatively correlated with air humidity.The absolute value of correlation between fluid flow rate and environmental factors under different irrigation gradients was T2<T3<T1.Among all meteorological factors in each month,air temperature was the leading factor affecting the fluid flow rate of Hippophae rhamnoides.(4)The results of the prediction model for the transpiration water cons umption of Hippophae rhamnoides showed that the fitting precision of T2 gradient was good.Transpiration dissipation model of seabuckthorn during g rowing season:T=-21.58+0.002*X1+0.336*X2+9.077*X3+0.003X4-1.362*X5-0.087*X6+172.83*X7;Among them,atmospheric·temperature X1;℃,air relati ve humidity X2;%,water vapor pressure X3;kpa,photosynthetically active radiation X4;W/m2,10cm ground temperature X5;℃,soil water potent ial X6;kpa,soil moisture X7;%.Besides,the average error rate of water consumption predicted by the model and measured in the field was within 10%.The model constructed has certain application and promotion value in arsenic sandstone area.