巢湖陆向湖滨带常见野生植物对磷缓冲能力的影响

湖泊陆向湖滨带缓冲磷扩散的机制尚未得到充分地研究。系统分析了2011年4~7月巢湖陆向湖滨带5种野生植物的生长状况与根际土不同形态磷的含量和吸附行为。结果表明土壤磷的吸附行为可用Langmuir方程加以描述。与对照相比，艾草和小飞蓬根际土总磷含量明显较低，磷的最大吸附量（Qmax）明显较高，而小蓟和狗尾巴草根际土速效磷含量明显较高，Qmax与磷吸附强度明显较低。植物根与茎长均随季节增加，相应的土壤磷饱和度下降。因此，植物吸收与土壤吸附是陆向湖滨带缓冲磷扩散的重要机制。有机质可通过增加速效磷含量和Qmax值调节土壤磷平衡浓度（EPC0）。小飞蓬和艾草根际土的EPC0值明显较低，磷吸附能力较强。而小蓟和早熟禾根际土的EPC0值明显较高，故易成为向湖泊扩散的磷源

EFFECTS OF NATIVE PLANTS ON PHOSPHORUS BUFFERING CAPACITY IN THE RIPARIAN ZONE OF LAKE CHAOHU

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