Abstract: By the method of comparison and analysis, the evolution pattern of different forms of phosphorus and phosphatase activity in rhizosphere and non-rhizosphere soil at different development stages in Larch (Larix olgensis) plantations was revealed. The relationship between different forms of phosphorus content, phosphatase activity, and stand age was explained. Stepwise regression models among various forms of phosphorus, phosphatase activity, organic matter, rapidly available K, hydrolyzable N and tree growth were established. The results showed that there were apparent variation rule of different types of phosphorus and phosphatase activity in rhizosphere soil. When stand age increased, the content of available phosphorus, O-P, total P, organic P, acid phosphatase activity in rhizosphere soil presented notably or apparently decreasing tendency, the content of inorganic P, Ca-P and Fe-P in rhizosphere soil presented notably or apparently increasing tendency. Ca-P in non-rhizosphere soil presented very significantly increasing tendency, acid phosphatase activity in non-rhizosphere soil presented apparently decreasing tendency over stand ages. Except for acid phosphatase activity, neutral phosphatase activity, and Al-P in non-rhizosphere soil, the difference of other components in rhizosphere soil and non-rhizosphere soil reached greatly significant level or significant level between different development stages. 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 content of other components in rhizosphere soil was more than that in non-rhizosphere soil. Main types of phosphorus in soil affecting tree increment in different growth and development 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