Abstract:Phosphorus has generally been assumed to be the limiting or co-limiting factor for plant growth in alpine ecosystems. This study examined the concentration of inorganic and organic phosphorus in surface soils (0—20 cm) under different vegetation types (alpine shrub-meadow, Rhododendron oganniphum and Abies faxoniana) near timberline on upper Min River, using a modified Hedley fraction method. The results showed that the total Phosphorus (TP) in the soil with three vegetation types was on average high (857.32 mg?kg-1). Only about 10% of TP was labile P, however; and organic P comprised over 60% of the TP pool. This suggested that surface soil phosphorus cycling and availability were mainly influenced by biological processes. Most soil inorganic P was found in the forms of D.HCl-Pi and C.HCl-Pi. The soil under different vegetation types had similar amount of labile inorganic phosphorus (labile Pi) and NaOH-Pi, while alpine shrub-meadow had more D.HCl-Pi and C.HCl-Pi than Rhododendron oganniphum and Abies faxoniana, which indicated that the soil under alpine shrub-meadow had more inorganic P combined with calcium. In addition, a significant positive correlation was found between soil organic forms P and the total organic carbon. NaOH-Po was found to be the major form of the soil organic P, ranging from 39.39% to 53.69% of TP. The soil of Abies faxoniana had higher level of NaHCO3-Po and NaOH-Po than alpine shrub-meadow and Rhododendron oganniphum. On the contrary, there was higher C.HCl-Po in alpine shrub-meadow and least in Abies faxoniana. The high level of soil organic P was attributed to low temperature and litters accumulation.