Study On The Characteristics Of Transpiration And Water Consumption Of Typical Plants By Using Liquid Flow Density Method

Shortage of water resources and changes in precipitation are the main factors influencing the service function of the ecosystem.It is of great significance to study the characteristics of transpiration of different types of vegetation for vegetation restoration and selection.Transpiration water consumption is a complex physiological process of plants,and also an important way of water conduction in the soil-plant-atmosphere?SPAC?continuum.Therefore,accurate measurement of the transpiration intensity of plants has always attracted attention.In order to evaluate the accuracy and operability of the external heat ratio method to measure the flow of tissues such as small stems,this paper newly designed an external heat ratio stem flow meter to determine the stem and rose?Posa chinensis Jacq?of potted pomegranate?Punica granatum L?Stems,pedicels,sap flow.Subsequently,the newly designed external heat ratio stem flow meter was used to measure the sap flow of Caragana,a typical shrub of the Loess Plateau,to study the water utilization strategies of Caragana and its response to rainfall with different root distribution depth treatments.The needle method was used to measure the difference in transpiration water consumption of typical forest trees Willow and Populus simonii in different slope positions in the northern loess plateau.The effects of meteorological elements,soil moisture and topography on vegetation transpiration were studied.The main conclusions are as follows:?1?The external heat ratio probe dynamically monitors the sap flow of pomegranate stems,rose stems,and pedicels and compares it with the artificial water conduction test of isolated stem segments.The results showed that during the flowering period of the potted rose,the changes of the sap flow density of the stem,pedicel and pomegranate stem of the rose had a similar trend.The flow density measured by the external heat ratio method and the results of artificial water conduction were both Significant linear correlation?R²=0.820?0.938?,external heat ratio method can be used as an effective means to accurately measure the flow rate of small stems and plant tissues and organs.?2?The typical shrub Caragana in the Loess Plateau was selected for field seepage pond tests with 60 cm,100 cm,and 140 cm back cover and no back cover,to simulate the different distribution depths of Caragana root in the soil,and the external heat ratio method was used to determine different tests The stem sap flow of Caragana microphylla.The results show that the flow density changes of Caragana intermedia in the field seepage tanks of different treatments are consistent.During the observation period,the liquid densities of Caragana intermedia in 60 cm and non-bottomed leakage pools are higher than those in 100 cm and 140 cm,Mainly due to the deep processing of different root distributions.In contrast,the root system of Caragana korshinskii can be freely pierced in the non-bottomed seepage pool.After the root system of Caragana korshinskii in the bottom-sealed leakage pool is restricted,the growth of Caragana korshinskii depends mainly on shallow soil moisture and growth is inhibited.The horizontal root system in the 60 cm seepage pond is more developed than the 100 cm and140 cm Caragana horizontal root systems.At the same time,the change of rainfall has a great influence on the liquid density of Caragana korshinskii in different treatments.Carbohydrates in bottom-sealed seepage tanks use rainfall as the main source of water;Carbohydrates in non-bottomed seepage tanks mainly rely on deep soil moisture.?3?The liquid density changes of Willow and Populus simonii in different slope positions in the Liudaogou small watershed in the northern Loess Plateau are consistent.The sap flow density of Willow in Huangmian soil dam land is about 4 times that of Willow in wind-sand soil slopes,but there is no significant difference in sap flow between Populus simonii in dam land and Populus simonii in sandy land.According to the linear regression analysis of the liquid density of Willow and Populus simonii and meteorological elements ET₀,VPD and R_s,there was a significant positive correlation?P<0.001?.The Huangmian earth dam land and the wind-sand soil slope are different soil and topographic conditions,and the detected soil water content is significantly different.The Willow and Populus simonii in the dam area make use of shallow groundwater as a main source of water,and the sandy land is high in terrain without shallow groundwater recharge.Therefore,meteorological factors and soil moisture conditions are the main factors affecting vegetation transpiration.