Study On Transpiration And Water Consumption Of 4 Commonly Used Garden Trees

Garden plant as an important part of the landscape,can not only beautify the landscape to create a beautiful environment,but also has the pollution dust,bacteria and noise reduction,water conservation,nutrient cycling,maintaining biodiversity,ecological functions such as disaster prevention and mitigation,and to a great extent,helps to reduce the environmental pressure of the city.With the scarcity of water resources,the water use of garden plants has been paid more and more attention by urban ecological construction.Taking Pinus bungeana(Pinus bungeana Zucc),Salix willow(Salix matsudana Koidz),Platycladus orientalis(Platycladus orientalis(L.)Franco),Sophora japonica(Sophora japonica Linn.)as the research object,the application of thermal diffusion probe technique(TDP)combined with automatic meteorological observation system to study the water consumption of transpiration of the trees,Analyze various aspects of water consumption by tree transpiration.The research was carried out from three aspects: tree fluid flow,transpiration water consumption and its response to meteorological factors.The results of the study showed that:(1)Under the three typical weather conditions of sunny,cloudy,and rainy days,the flow of trunk sapwood showed different characteristics.The sap flow started at the earliest day in sunny days,and the average daily flow rate was the largest,and it was the latest in the low trough.In the rainy days,the sap flow started at the latest,and the average daily flow rate was the lowest,entering the low trough time was the earliest,and the cloudy days were middle.(2)Comparison of the velocity of trunk sap flow at the end of growing season and at the end of the growing season showed that the sap flow rate during the growth period was higher than that of the sapwood at the end of growth period.The sap flow was initiated during the growing season.The time earlier than the start of the sap flow at the end of the growing season,the sap flow into the trough during the growth season is later than the end of the growing season.(3)The water consumption of the 4 tree species in the 8/9/10 month is shown as the water consumption in August is greater than the water consumption in September is greater than the water consumption in October.(4)Analysis of the flow velocity and meteorological factors of trunk and sapwood shows that atmospheric temperature,solar radiation intensity and relative air humidityhave the most significant effect on the sap flow velocity and are the first principal component.The main reason is that the daily variation trend of the three meteorological factors is relatively fast and direct to the flow.The wind speed is the second principal component,and the influence on the sap flow is not particularly significant because the wind speed is not stable during daily changes.The effect of atmospheric pressure on sap flow is negligible.The transpiration water consumption of trees is closely related to the relationship between solar radiation and atmospheric temperature.The transpiration water consumption of trees is positively correlated with solar radiation and atmospheric temperature.With the increase of solar radiation and atmospheric temperature,the transpiration water consumption of trees also increases.On the contrary,the transpiration water consumption of trees is negatively correlated with the air humidity.As the air humidity increases,the transpiration water consumption of trees decreases gradually.