The floristic composition of paddy fields and their levees under different weed management techniques
2006
Otsuka, H.(Unshouen Co. Ltd., Hokuto, Yamanashi (Japan)) | Nemoto, M. | Masuda, S.
To clarify the characteristics of the floristic composition, three different weed management techniques, namely (1) the herbicide application at paddy fields and their levees, (2) hand weeding with rice bran application at paddy and (3) mowing by machine at levees, were investigated. The vegetational survey was carried out on the paddy fields and their levees in a vally in hill land at Sousa, Chiba prefecture. According to TWlNSPAN analysis, the vegetation in surveyed area on the whole can be divided into paddy field and levee, and the former was subdivided corresponding the seasonal variation. The mean number of species at quadrates in herbicide non-application paddy was significantly bigger than that in the herbicide application paddy. Not only perennial species i.e. Equisetum arvense, Artemisia princeps, but annual species such as Alopecurus aequalis, Digitaria ciliaris. Cyperus microiria were conspicuous in the levees in herbicide application sites. While in the levees in herbicide non-application, the representative species of traditional levee flora like Imperata cylindrica, Rumex acetosa, and Ixeris debilis were patchily distributed, and threatened plant of Ricciocarpus natans was recognized in paddy in herbicide non-application. These results indicate that the introduction of paddy management by hand weeding or mowing machine, may contribute to the vegetation restoration like traditional paddy landscape.
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