Abstract:

Single Robinia pseudoacacia tree sap flow and its environmental factors were respectively measured by means of TDP (Thermal Dissipation Probe) and Portable-Meteorological Station in a 24-year-old pure forest and its mixed forest (Robinia pseudoacacia and Fraxinus velutina) in Coastal Alkali-saline Soil of the Yellow River Delta. The results showed that diurnal variation of sap flow of mixed forest displayed a narrow-peaked curve and that of pure forest displayed a wide-peaked curve, both peaks were occurred at 10:30 or so, and there were no obvious starting and stopping sign of the sap flow even over night; The peak height of mixed forest was higher than pure forest; The daily average sap flow of mixed forest was 145% of pure stands. Water content of mixed forest Soil surface is more than pure stands, and salt content is less than the soil of pure stands. Multiple regression analysis showed that the important factors effected sap flow of mixed forest were solar radiation, air humidity and the important factors affected pure forest were atmospheric temperature, solar radiation.

Key words: Robinia pseudoacacia; mixed stands; sap flow; thermal dissipation probe; coastal saline soil