Natural and Social Environments in a Large Old-Growth Japanese Horse-Chestnut Forest in Shiga Prefecture, Central Japan

There are many large old-growth Japanese horse-chestnut (Aesculus turbinata) trees growing in the Kutsuki region, Shiga prefecture, central Japan, with diameter at breast height (DBH) ≥1 m. Large old-growth trees are ecologically important as keystone structures in forests as they provide valuable habitats for many animal and plant species. In recent years, however, large old-growth trees have rapidly declined in many places around the world. In this study, we examined the characteristics of the growth environments of large old-growth Japanese horse-chestnut trees and analyzed the natural and social factors related to the establishment of these trees in a catchment area in the Kutsuki region. In our field survey, 230 Japanese horse-chestnut individuals including young trees were identified in the riparian zone, and 47 (20%) were large old-growth trees. These old-growth trees were mostly located in the upper parts of the catchment area and partly on the knick line of the side slope and upper part of the head hollow zone compared with the location of the small- and medium-sized individuals with DBH