| In the paper, the heat-pulse technique was applied to measure the stem sap flow of Populus alba var. pyramidalis in shelter belt of Hetao-irrigated region At the same time, meteorological factors were monitored. The daily change and the diurnal fluctuation of sap flow, the diurnal variation of stem sap flow velocity and whole tree water consumption off. alba var. pyramidalis under the different conditions were studied. The results show that the velocity of sap flow at different depths below the cambium showed the same temporal changes of P. alba var. pyramidalis. Around the noon they reached the maximum, and their differences did so. At the different soil moisture content conditions, the velocity of sap flow of the tree was higher at non-irrigated than irrigated condition, in the different seasons, the velocity of sap flow of the plant was higher at summer than spring and autumn, in the different weather condition, the velocity of sap flow of the tree was higher at sunny days than at the cloudy days, and that at the cloudy days was higher than that at the somber days. The mathematic model of the meteorological factors and transpiration water consumption was established by qualitative analysis, the result shows that the principal factors influencing the transpiration water consumption were solar radiation intensity and meteoric temperature. Annually average water consumptions of individual tree and whole shelter belt were provided as basic data for planning water use of Hetao-irrigated region. |
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