Abstract:

Mechanisms behind phosphorus buffering by riparian zone are inadequately studied.In this paper,contents of different phosphorus forms and its sorption behaviours of rhizosphere soils for several native plants were analyzed in the riparian zone of Lake Chaohu from April to July，2011，and the phosphorus sorption behaviour of the study soils was well described by the Langmuir equation.Compared to the control,the rhizosphere soils of Artemisia argyi and Conyza canadensis (Linn.) Cronq.had significantly lower total phosphorus content and higher the maximum sorption capacity (Qmax).On the other hand,Cephalanoplos segetum Bge.Kitam.and Setaira viridis(L.)Beauv corresponded to the significantly higher OlsenP content,together with the significantly lower Qmax and sorption strength.In the rhizosphere soils,the length of roots and stems of the study plants significantly increased along the growing seasons,which was companied by a gradual decrease in degree of phosphorus saturation in the soils.Thus,plant uptake and soil sorption were the major mechanisms behind phosphorus buffering in the riparian zone.Soil organic matter simultaneously enhanced the OlsenP content and the Qmax,thereby adjusted the equilibrium phosphorus concentration (EPC0).The rhizosphere soils of Artemisia argyi and Conyza canadensis (Linn.) Cronq had significantly lower EPC0 Values and a stronger P sorption capacity,while,Cephalanoplos segetum Bge.Kitam. and Poa pratensis Linn.var.Pratensis corresponded to significantly higher EPC0 values,which tended to act as a P source diffusion towards the lake