Abstract
This paper aims to propose the adequate buffer widths for preserving the ecological functions of riparian forests by reviewing both Japanese and international literatures and guidelines. The result of our review indicates the wide variations in the proposed buffer widths probably due to the differences in environmental backgrounds at each study site. The recommendation for the adequate buffer width for the conservation of each function is, thus, made considering Japanese landscape and vegetations. Approximately 30 m is required for maintaining shading effects and the provision of organic litter and woody debris which are especially important in the headwater to 3rd order mountainous streams. Water quality control is, on the other hand, more crucial in larger floodplain rivers with high potential of contaminations associated with urban development and agriculture. Regarding this function, 10-20m buffer width is proposed as the minimum value in the literatures reviewed. The buffer width for aquatic habitat conservation should be determined by linking with other ecological functions, such as shading and organic litter input, thus about 30m is recommended in mountainous streams. Riparian forest functioning as habitat and corridor for terrestrial animals has different requirement for its width depending on the targeted species. Most of the recommended widths fall into the ranges up to 100 m and 200 m for the conservation of amphibians, reptiles and mammals and that of birds, respectively. Although this review focused mainly on the width of riparian forest, the future studies should put an emphasis on the longitudinal continuity along river or the whole stream net-works for the establishment of more appropriate guidelines.
