Abstract:

By the method of comparison and analysis, the succession pattern of phosphorus and phosphatase activity in rhizosphere and non|rhizosphere soil in larch (Larix olgensis) plantations was revealed. The relationship between phosphorus forms, phosphatase activity, and stand age was explained. Stepwise regression models among phosphorus forms, organic matter, rapidly available K, hydrolyzable N and tree growth were established. The results showed: when stand age increased, the content of available phosphorus, O-P, total P, organic P, acid phosphatase activity in rhizosphere soil decreased significantly,the content of inorganic P, Ca-P and Fe-P in rhizosphere soil increased significantly. The content of Ca-P and the acid phosphatase activity in non-rhizosphere soil increased and decreased respectively with stand growing.Except for acid phosphatase activity, neutral phosphatase activity, and the content of Al-P in non-rhizosphere soil, the difference of other components in rhizosphere and non-rhizosphere soil reached greatly significant level and significant level between different development stages. The content of Fe-P in half-mature stand, available P, Fe-P, and acid phosphatase activity in near mature stand, available P, Ca-P, and acid phosphatase activity in mature stand in non|rhizosphere soil was more than that in rhizosphere soil, the contents of other components in rhizosphere soil were more than those in non|rhizosphere soil. Main types of phosphorus which affecting tree increment in different stages were total P, organic P, available P, total inorganic P, Ca-P and Fe-P.

Key words: Larch plantations, Rhizosphere soil, Phosphatase activity, Phosphorus availability, Tree growth