Rehabilitation method of plant community in the damaged reverside of subtropical waterhead

To explore the principles and techniques of ecological rehabilitation of the rivers,the ecological engineering principle and technology were used to study the rehabilitation methods of damaged riverside plant communities in subtropical waterhead of Tian-xia River.The authors validated the rehabilitation effects by the structure of species,coverage and biodiversity of plant communities.Results showed that native plant community was rehabilitated successfully and the structure of plant community was optimized in the experimental zone,which had been rehabilitated after two years' naural succession(the subtropical plant growth period was longer than that of the temperate and cool temperate zones).Through the natural invasion of native plant species,the plant community was rehabilitated in upstream plant community rehabilitation zone((A-1 zone));through the competition mechanism between the dominant species and invaded plant species,riverside plant zone dominated by Zizania aquatica was constructed in midstream plant community rehabilitation zone(A-2 zone);through increasing the planting density of Phragmites australis and Z.aquatica to accelerate their outspread,the plant community having the ability to decontaminate water was constructed in downstream plant community rehabilitation zone(A-3 zone).Compared with the contrast zone(zone B),the improvement of species and biodeverisity was obvious in zones A-1,A-2 and A-3.In 2006,the species of bottom riverside in the three above experimental zones had been increased to 24,26,23,and 16,17,14 in the top riverside,but in contrast zone,the species of the bottom riverside was only 14,and that of the top riverside was 12 only. The coverage was over 95% in all experimental zones,but that in contrast zone was only about 55%.This research transforms the design principle of the traditional hydraulic engineering,makes the river renovated not only considering the traditional project safety and economic properties,but also promoting the design principles of the hydraulic engineering based on the ecological principle,and provides a new angle of view for exploring the new principle of the river renovation.