Estimation of the distribution of cryptomeria japonica on yakushima island by using an old picture map

Abstract

An old picture map named “Yakushima kozu” which covered Yakushima Island was drawn around 1660. This old map was drawn in detail; therefore, we can distinguish the names of villages, mountain tops, rivers, famous points, the existence of dominant tree species in the forest (e.g. Japanese cedar (Cryptomeria japonica) and pine trees), and mountain trails. In this study, we geo-referenced this old map to match a present map on GIS, and estimated the distribution of Cryptomeria japonica at that time. Furtermore, we compared the distribution of Cryptomeria japonica at that time and the present, and considered the factors of change. We also considered the possibility of using this old picture map for academic research. In summary, we succeeded in geo-referencing an old picture map. The distribution of Cryptomeria japonica at that time was biased to the east of the island, especially to the basin of the Anbo River. In the basin of the Anbo River, the distribution of Cryptomeria japonica was down to 200 meters a.s.l. The currently lost distribution area of Cryptomeria japonica compared to that of around 1660 is concentrated in the lower elevation zone and the location near the rivers. In conclusion, this old picture map named “Yakushima zennzu” is worth using as valuable data describing the forest conditions of Yakushima Island around 1655.