Abstract
In August 2003, we found new habitat of Salix hukaoana, a rare willow species that is endemic to Japan and designated as an endangered species Class IB, along the Ina River, in the Tadami River basin, Fukushima Prefecture, northern Japan. S. hukaoana is distributed from the confluence with the Tadami River for 45km along the Ina River and its branches and along the Kanoutsu River. The riparian forests containing S. hukaoana along the Ina and Kanoutsu Rivers were quite similar to the "Salicetum jessoensis Ohba 1973" and were classified into five types in a cluster analysis based on floristic composition. However, there were no significant relationships between the forest types, site condition, and stand age. All of the study stands were younger than 45 years old, and most showed a unimodal distribution of diameter at breast height (dbh), suggesting regeneration after a disturbance. S. hukaoana habitats have been lost with river engineering works. Therefore, countermeasures for the conservation of this species are urgently needed.
