Abstract:

Stem sap flow of Robinia pseudoacacia was continuously detected with the thermal dissipation probe (TDP) from April to August in 2006 Results showed that the diurnal variation of sap flow displayed a widepeaked curve. The sap flow started to increase about at 6:50, and reached to the peak about at 13:00, then declined quickly about at 19:30 There was no obvious stopping sign of the sap flow even over night. In summer, the starting time of increase in diurnal sap flow was about 10 minutes earlier than that in spring, and the peak was reached about an hour earlier than that in spring, and the rapidfalling time was about an hour later than that in spring. The duration of the peak lasted longer in summer than that in spring, however the peak height, the sap flow and daily average sap flow were lower than those in spring. There was no significant correlation between the stem sap flow and the stem diameter, whereas there existed significant correlations between the daily water consumption and the stem diameter (r=0.983)，and the sapwood area (r=0.999).

Key words: Robinia pseudoacacia, stem sap flow, water consumption, thermal dissipation probe