Effects of Vegetation Management on Species Richness of Stream and its Riparian Zone

Abstract

Experimental vegetation management along a stream was done to clarify its effects on species richness of the stream and its riparian zone in Michinoku Lakewood National Government Park, Miyagi prefecture, northeast Japan. The research site was established along the stream and was divided into two sections with the same area size (10m (length)×6m (width)). Experimental mowing was performed in one section twice a year (experimental section) from 1995 to 1997 while the other (control section) was left alone. Data describing the stream ecosystem, such as abiotic conditions, vegetation (horizontal cover and vertical structure), flora, butterfly, dragonfly and benthos as biotic conditions were gathered in 1996 and 1997.Consequently, following results were obtained.(1) Vertical structure of vegetation between the two section became quite different. Herb layer of the experimental section became open due to the mowing.(2) Plant species diversity in the experimental section became richer than the control section, especially in the herb layer. Most species found only in the experimental section were annual plants and perennial plants.(3) Species diversity of butterfly, dragonfly and benthos were richer in the experimental section.(4) Shannon-Wiener's diversity index of plant, butterfly, dragonfly and benthos were compared. Effects of vegetation management on species richness were remarkable for plant, moderate for flying insects and not so remarkable for benthos.(5) Vegetation management of stream and its riparian zone were effective for enhancement of biodiversity due to not only increasing a diversity but also β diversity