Abstract
The effects of human activity on the formation and maintenance of seepage marshes, which are small oligotrophic wetlands formed by seepage water, were examined. The study site was Yanami marsh in Toyota city, central Japan. The distribution of the grassland community in the marsh and its relationships to groundwater level, changes in land use and vegetation surrounding the marsh, and characteristics and stratigraphy of the marsh sediment were surveyed.
Human activity in the form of construction of a sand-trap dam or creation of rice paddies influenced the process of formation of Yanami marsh. Human activity also affected the succession of the grassland community in the marsh. The type of grassland community present was mainly determined by the groundwater level, which likely varied with changes in the state of the vegetation surrounding the marsh; this vegetation was maintained and used by local people. In addition, disturbances caused by frequent mudslides and by mowing of wetland grass for fertilizer or forage likely also affected the vegetation succession in the marsh. It is concluded that seepage marshes can be formed under the influence of human activity and maintain their characteristic vegetation.
