モウソウチク（Phyllostachys pubescens Mazel ex Houzeau de Lehaie）を中心とする竹林の拡大が全国各地で報告され，社会的な問題となっている．竹林拡大を抑止するためには，竹林所有者のみならず市民参加を促し，協働の枠組みを構築しながら継続性を担保できる計画を策定することが肝要である．本研究では，産民学官からなる協議会「みなみから届ける環づくり会議」が，徳島県阿南市において，竹林の拡大抑制に取り組むにあたり，その活動方針決定にいかすために行った竹林所有者と地域住民を対象とした意識調査を通じて，竹林所有者と地域住民の竹林に対する認識とニーズを明らかにした．その結果，たけのこ生産が盛んであった当地域では，竹林はたけのこ生産の場であると強く認識がされていた．一方，主に竹林所有者にしか竹林の拡大は認識されておらず，竹林を所有していない住民との間で認識に差異があった．また，竹林は所有者の資産であるという考え方が強く，地域全体の問題として竹林拡大抑制策に取り組もうとする意識は低かった．これらのことから，本地域では，竹林の拡大に係る課題を地域内で共有する努力を行って，所有者と地域住民の双方が現状を認識し，合意形成を図る必要がある．
In this study, the differences in maintenance and management of an urban section of the Uzuma River (Tochigi City, Tochigi Prefecture, Japan) was investigated for influences that cause the growth of hydrophytes such as Sparganium L., which is described in the red data books of the Ministry of the Environment (2000) and Tochigi prefecture (2005). The investigated sections consisted of the three types of the two-plane concrete protection, the hydrophilicity shore protection and the natural type river. In the two-plane concrete protection, the hydrophytes of Potamogeton subfuscus and Sparganium japonicum were growing in places where the water springs flowed, however, Sparganium japonicum, which was located downstream of a diversion weir for agriculture, showed local distribution. We considered that a rapid flow was caused, sand was removed, and establishment of Sparganium japonicum was difficult when the diversion weir for agriculture was opened by the rising of the river. In the hydrophilicity shore protection, only Sparganium erectum was found. We considered that this was because the flow of the river became slower due to a widening of the river channel, the fine sand and silt soil piled up, and the growth of Sparganium erectum was promoted. In the natural type river, the range of growth of Sparganium japonicum was reduced in places where the riverbed was dug. We considered that this was because the rhizome of Sparganium japonicum was removed by the digging up of the riverbed. Therefore, as for the growth factors of hydrophytes, we consider stream management with a diversion weir for agriculture and an artificial riverbed excavation and river channel widening to have had a great influence.
In this study, the different land uses in the valley bottom and the basin of Yatsu were investigated for their influences on benthic fauna, which grows in the river in Yatsu. The valley bottom of Yatsu has a natural type land use and is an over-marsh and hydrophyte communities, and the rate of wooded area in the basin is high. The semi-natural land use type of Yatsu at the valley bottom is marshland, however, the rate of residential and farmland areas in the basin are considerably higher than that of wooded area. In the natural type, the ratio of the number of species and individuals with a low water pollution series was high, such as Perlodidae sp., Simulium sp. etc, in case of the semi-natural type, the ratio of the number of species and individuals with a high water pollution series was high, such as Rhantus pulverosus, Gerris paludum japonicus, etc. The similarity index between the investigation points was different in a natural type and semi-natural type. As for the water quality value of the natural type, DO was high, the water temperature, TP, TN, and Cl were low in comparison with those in the semi-natural type. We considered that the natural type may have a high water-holding capacity and water purification ability due to the presence of hygrophytes, and that an abundant supply of spring water into the river may enhance the water quality, the species of low water pollution series has increased. In the correlation coefficient between the individuals of the main benthos species and the water quality, Asellus hilgendorfi was 0.967 (P=0.007) with TP, Chironomidae sp. was 0.964 (P=0.008) with Cl and was 0.913 (P=0.03) with EC. We considered that water pollution has progressed, and species of a high water pollution series has increased as the residential and the farmland development in the basin has advanced.