<Articles>The Resource Cycle of the Sato'umi and Satoyama in Southern Omi in Early Modern Times : A Study of Environmental History from the Viewpoint of the History of Fisheries

本稿では漁業史からの環境史研究へのアプローチを試み、近世琵琶湖における蜆漁と採藻業という二つの漁業史料の新たな読み解きによって、山地までを含む琵琶湖南部の集水域における近世の人間活動と生態系の変化を解明した。田上山地の荒廃とそれに対する土砂留政策が、一八世紀半ばに草肥に代わるものとして湖産の貝灰肥料の導入を促し、それまで里山に頼っていた村々を「里湖」の循環的システム内へ編入させる契機となった。また一九世紀には菜種の栽培技術の革新が湖岸の半湿田での裏作を可能にし、さらに京での菜種油の価格上昇がその栽培肥料としての藻取りを加速させたことが明らかとなった。水草肥料を自給できた当地は金肥高騰に悩む他産地を抑え、全国有数の菜種産地に成長しえたのである。藻取りは水域からの栄養塩の除去にもつながっており、このような「二次的自然」としての「里湖」の生態系には、近世後期に確立の画期があることがわかった。In this article, I attempt to approach environmental history form the perspective of the history of fisheries, and through a new interpretation of source materials on two varieties of fishery activities (harvesting shijimi clams (corbicula) and waterweeds) on Lake Biwa during the early modern period, I hope to illuminate changes in the ecosystem and human activities of early-modern people in this watershed, including mountainous areas, of the southern region of Lake Biwa. The southern portion of the Lake Biwa region is a single spatial unit of watershed extending from the mountains to the lakeshore and is relatively compact. As this is also a central location for the study of the history of early-modern fisheries as many written sources have been preserved in the region, it is the most appropriate area for the methodology used in this study. In this article, I make clear the fact that the mountains, plains, and lake that are linked by rivers are understood as part of a river basin in which early-modern human activity, employing fishing, agriculture and the use of the satoyama (a natural environment maintained and managed by humans) operated together to form a single ecosystem. Moreover, I examine the temporal periods and causes of changes in this ecosystem In the mountainous area of the southern Lake Biwa region, despoiling of the land and landslides spread due to the uprooting of pines that had been carried out from the beginning of the early-modern period and also due to the over harvesting of underbrush that was used as green manure and accompanied production of commercial crops thereafter. Furthermore, limitations on the use of the satoyama began to occur due to construction projects intended to halt the landslides. In response to the lack of underbrush manure in this region, shell-lime of corbicula japonica (shijimi clams) from Lake Biwa was introduced to compensate for the shortfall. Shell- lime of corbicula japonica was transported to farming villages in the foothills from the mid-18th century onward and used as fertilizer for the paddy fields. This meant that the villages that had previously depended on the satoyama were incorporated into the system of recycling the resources of the lake, Because in the following 19th century the improvements in cultivation technology of rapeseed made it possible to produce a second crop on the imperfectly drained paddy fields on the shore of Lake Biwa, the water plants used for compost began to be harvested in great quantities by the villages on the southern part of the lake. Rapeseed was commercialized as product that could be taken to the large market in the capital as lamp oil, and it has become clear that the rising price of rapeseed oil in 19th-century Kyoto caused the surface area devoted to rapeseed cultivation to expand on the southern shores of Lake Biwa and accelerated the harvesting of water plants for fertilizer. In this manner, the region that was self-sufficient in water plant fertilizer outstripped other regions that suffered from the rising cost of fertilizers (mainly dried sardine), and it grew to become one of the nation's leading producers of rapeseed. In recent years shijimi clam fishing and the harvesting of water plants, i.e. the varied use of resources along the shore by human beings, has been seen simultaneously as "maintenance" of the lakeshore environment, and thus it has been pointed out that "secondary nature, " similar to the satoyama, existed along the shore. These areas have been called sato'umi in contradistinction to satoyama. In the ecosystem of the sato'umi, due to the harvesting of water plants for fertilizer, the extraction of nutritive salts became a necessity in the resource cycle, but it is important to note that full-fledged implementation of this activity occurred in the period of the spread of commercial cultivation of crops during the late early-modern period. In other words, ultimately the establishment of the sato'umi ecosystem involved an aspect of the importation of commercial crops from other regions, a quintessentially artificial act. In previous research there has been tendency to imagine the ecosystem of the sato'umi as a "traditional regional system built up over a lengthy time, " but it cannot be claimed that this system was a natural outgrowth of the region. It highly likely that the sato'umi of the late early-modern period was instead directly linked to a large market outside the region and was an "artificial ecosystem" formed in a relatively short period of time