Abstract: In this experiment, the effect of different grazing time but fixed length on vegetation in the different rotational grazing paddocks was studied. The result showed that the structure of the vegetation, grazed in early time, apt to be changed comparatively to that grazed in later time and the ungrazed paddocks. The use ratio of herbage was higher in the early grazed paddocks than that in the later grazed ones, but the productivity of the vegetation showed an opposite trend. In practice the grazing time should be flexible considering both the sustainable use of the vegetation and animal productivity.

Key words: Arundo donax, Phytoremediation, Wetland, Bio-concentration