長江下流低濕地における水生植物利用の變遷史

Abstract

This paper focuses on aquatic plants in the Lower Yangtze River region and analyzes the changes in their utilization and cultivation based on books of agronomy, materia medica, and local gazetteers in an effort to investigate new aspects of developmental history of the Lower Yangtze River region. Analysis of plant remains from the Neolithic Tianluoshan 田螺山 site in Yuyao, Zhejiang province indicates that aquatic plants, such as water chestnuts (菱) and gordon euryale (芡), were important components of the diets of waterside residents from the Neolithic Age onward. It can be surmised from the Huozhi Liezhuan 貨殖列傳 of the Shiji 史記 that food strategies were chosen based on various aquatic resources in addition to rice in south China in the Former Han era. The 6th century agronomy book, Qiminyaoshu 齊民耍術, recorded five types of aquatic plants as byproducts from fish ponds, and later books on agronomy state that they came to be cultivated independently and that the variety of these plants also increased. Full-fledged cultivation of aquatic plants in the Lower Yangtze River region occurred after the Tang era. During the Song and Yuan eras, the varieties of water chestnuts and gordon euryale increased, and water bamboo (茭白) became popular as a food source, while the lotus was also cultivated for its blossoms. It is therefore clear that aquatic plants became commercial crops, which resulted in the large-scale cultivation of aquatic vegetables bringing with it new problems due to decreases in lake surface area and lack of water supply. In the Ming era, the development of commercial farming was accompanied by intensive farming, which required increased labor and expenditures for such activities as transplanting, applying fertilizer, and weeding. The cultivation of Chinese arrowhead (慈姑), Chinese water chestnut (荸薺), and water taro (水芋) also appeared at this time. These changes in the cultivation of aquatic plants were closely associated with the development of irrigation and drainage projects. From the Song era onward, low-lying land was cultivated by diked enclosures (weitian 圍田) or polders (yutian 圩田), while aquatic plants were cultivated in underdeveloped sunken areas (dang 蕩). Aquatic plants have been important resources for waterside peasants in China, and were useful in relieving the effects of grain (稻) shortages that occurred for various reasons.