Abstract: Field experiments show that reed community and ditches in Baiyangdian Lake ecotonescan effectively retain nutrient elements from land sources.Under moderate hydrologicalcondition, water flows through the ditches and the root zone of reed community.The retention of total nitrogen (TN) and total phosphorus (TP) by a 300m ditch is measured tobe 42 and 65 % respectively, and that by a 4m distance of reed community soil is respectively 64 and 92%.The retention by reed community mainly happens at the rhizosphere,while the removal of organic matter is less in comparison with inorganic nutrients.Thecomponents retained at the largest ratio are ammonia nitrogen and ortho-phosphate phosphorus.These retention effects play an important role in stabilizing the adjacent ecosystems and reducing the eutrophication of waters.

Key words: Land/inland water ecotone, Reed, Nutrient, Baiyangdian Lake, Retention, particulate orga-nic carbon, microbial biomass carbon, tillage erosion, spatial distribution, dissolved organic carbon