Studies On Water Consumption Of Two Major Landscape Tree Species In Beijing: Pinus Tabulaeformis And Platycladus Orientalis

The sap flow index and the elements that affect it has been studied in this paper by in situ measurements in the Pinus tabulaeformis and Platycladus orientalis which are the main garden tree species in the growth seasons under different water conditions so as to obtain water consumption rules which help further deduce the prognostic model related to the sap water consumption, and the SPAC has been used to analyze the importance and probability of vegetation construction on the basis of water balance, which provide theoretical foundation for vegetation construction and improving survival rate in the process of afforestation in semi-arid and arid regions.Study showed: The sap flow velocity is higher than other months in Jun to Sep, the maximum of Pinus tabulaeformis occurred in Jun, which is 0.00060 cm.s^-1; the maximum of Platycladus orientalis occurred in Jul, 0.00176 cm.s^-1, which is 2.9 times as much as Pinus tabulaeformis, The minimum of the two trees occurred in Jan, which are 0.00019 cm.s^-1 and 0.00020 cm.s^-1 respectively. The water consumptive period of Pinus tabulaeformis concentrate in May to Oct and the water consumption are 1380L that are 65 percentage of the all year, in which the Jun,Jul and Aug are better, and the average are 260L. The water consumptive period of Platycladus orientalis concentrate in Jun to Oct and the water consumption are 748L that are 76 percentage of the all year, in which the Jun and Jul are better, 198L and 201L respectively.In the environmental elements which affect the sap flow index, the soil water container determines the general level of the sap flow, while the meteorological factor affects the instantaneous variability. It is showed the distinct exponential correlation between soil water container and sap flow fluctuation. Pinus tabulaeformis :y₁ = 0.597e^25.154x(R² = 0.8999), Platycladus orientalis: y₂ = 3.8706e^15.855(xR² = 0.9574)Among the meteorological factors, the sun radiation,atmosphere temperature and the wind speed are positively related to the sap flow index, which are also belonged to the firstly primary component that almost affect the sap flow directly, while the air relative humidity and the soil temperature are negatively related to the sap flow index, which are also belonged to...