New methods and allelopathic considerations of riparian buffer zones using Phragmites australis (Cav.) Trin.

Recently, the riparian buffer zone using Phragmites australis (Cav.) Trin. has frequently been installed in the ecotone, and young shoots of P. australis have been produced worldwide using seeds and/or rhizomes. However, the expenditures of labor, time, and money related to this technique have been enormous. In this paper, therefore, a new method which enables the reduction of the above-mentioned expenditure is developed and proposed. Using this method, we were able to install an area where P. australis flourished without the production of young shoots, by simply placing segments of P. australis culms by the water, and were able to reduce the above-mentioned usual expenditure. On the other hand, hydrophytes such as Scirpus tabernaemontani Gmel., Zizania latifolia Turcz. and Typha latifolia L. have frequently been planted with P. australis as a riparian buffer zone material. In this study, therefore, the care required in the mix planting of the above-mentioned four hydrophytes was also examined on the basis of the allelopathic potential of the interspecies. As a result, the allelopathic inhibition of root elongation was observed between the interspecies. Therefore a sufficient planting interval is required in order to ensure the elongation of the roots of the above-mentioned hydrophytes in the case of mix planting.