| In order to characterize the variance in pioneer trees water ecophysiology and explore to theadaptation mechanisms of stress, whole tree sap flow responsed to local environmentalconditions were investigated in three degree restoring inhabits in Changting county of Fujianprovince,where is a granite mountainous area in subtropical regions. Pinus massoniana is one ofthe pioneer tree species of re-vegetation there.The results showed that water transport rate didn't increase as the degree of restoringincreased. The peak values and daily change range of sap flux density (SFD) were found inPinus massoniana pure forest. It was related to the difference in plant structure and physiology,and the community structure. The SFD values of Pinus massoniana were lower thanbroad-leaved trees which could regenerate naturally. The SFD would decrease as environmentalstress continued to increase. The leaf water potential (LWP,Ψ) decreased to a lower value in theday of drought stress. The results indicated that Pinus massoniana with high drought tolerantability could maintain lower LWP (leaf water potential,Ψ) (Ψdawn, of large tree was-4.92 Mpa,Ψdawn of small tree was -4.52 Mpa) and water deficit in large tree could be supplied by sap flowin night. The point that taking our attention was the value of SFD didn't increase, but decreasedafter the heavy rainfall (158.6mm).The results provided ecophysiology basis to reveal the adaptation and regulation mechanismsof pioneer species, in the restoring ecosystem of a granite mountainous area in subtropicalregions. They offered clews guiding the practices of tree species selection and ecosystemrestoration management, which are important during the process of restoring and reconstructingvegetation.
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