Abstract: From May to October 2005, the sap flow velocity of greening tree species Salix matsudana cv. ‘Pendula’ in Beijing Botanical Garden was measured with heat dissipation technique, and the photosynthetic active radiation, wind velcoity, air relative humidity, air temperature, were determined simultaneously. The results showed that the sap flow velocity of S. matsudana varied steadily, with a diurnal variation curve of wide unimodal type, and the difference between day and night on sunny days was larger than that on cloudy days. The monthly mean sap flow velocity of S. matsudana began to increase from May, with the maximum in August (0.0050 cm·s^-1), and then decreased, with the minimum in October (0.0013 cm·s^-1). Solar radiation and air temperature were the most important factors affecting the sap flow velocity, while wind velocity was the least important one. The per hour water consumption of S.matsudana was more correlated with the sap wood area and the diameter at breast height than with the tree height and crown projection area.

Key words: Artificial tending, P. tabulaeformis forest, Structural characteristics of forest, Forest management