摘要
To assess the effects of savanna afforestation on soil phosphorus （P） transformations in eastern Horqin Sandy Land, China, P fractions and phosphomonoesterase activities were examined in two soil horizons （0-5 cm and 5-20 cm） under a savanna and an adjacent 30-year-old Mongolian pine （Pinus sylvestris L. vat. mongolica Litv.） plantation on a P-deficient semi arid sandy soil. The results showed that all soil P fractions and phosphomonoestcrase activities decreased with soil depth at both sites except that labile organic P under the plantation was constant with soil depth, In contrast to savanna, soils trader Mongolian pine plantation had lower phosphomonoesterase activities and concentrations of all P fractions （with an exception of Al-P）, lower proportions of organic P and Ca-P in total P, and higher proportions of labile P, Al-P and Fe-P in total P. These results suggested that P transformations mainly occurred in surface soils, and P recycled through litterfall was the most important source of plant available P. Mongolian pine afforestation enhanced the bioavailability of both organic P and Ca-P. simultaneously reduced soil P pools. indicating that protection of forest floor and P fertilization are necessary to maintain the sustainable functioning of Mongolian pine plantations.
To assess the effects of savanna afforestation on soil phosphorus （P） transformations in eastern Horqin Sandy Land, China, P fractions and phosphomonoesterase activities were examined in two soil horizons （0-5 cm and 5-20 cm） under a savanna and an adjacent 30-year-old Mongolian pine （Pinus sylvestris L. vat. mongolica Litv.） plantation on a P-deficient semi arid sandy soil. The results showed that all soil P fractions and phosphomonoestcrase activities decreased with soil depth at both sites except that labile organic P under the plantation was constant with soil depth, In contrast to savanna, soils trader Mongolian pine plantation had lower phosphomonoesterase activities and concentrations of all P fractions （with an exception of Al-P）, lower proportions of organic P and Ca-P in total P, and higher proportions of labile P, Al-P and Fe-P in total P. These results suggested that P transformations mainly occurred in surface soils, and P recycled through litterfall was the most important source of plant available P. Mongolian pine afforestation enhanced the bioavailability of both organic P and Ca-P. simultaneously reduced soil P pools. indicating that protection of forest floor and P fertilization are necessary to maintain the sustainable functioning of Mongolian pine plantations.
基金
This work was supported by Innovation Research Project of Chinese Academy of Sciences （KZCX3-SW-418）, National Natural Science Foundation of China （30471377） and sustentation project of the Institute of Applied Ecology of Chinese Academy of Sciences （SLYQY0409）.
