2013 Volume 55 Issue 1 Pages 1-8
In this study, we aimed to obtain evidence of forest fires that had occurred in the mountainous region of Nikko, Tochigi, by using an analysis for detecting charcoal particles on the soil surface of Sasa grasslands on a historical topographic map drawn in 1915, in which there were no historical documents of forest fire. To test the efficacy of the charcoal particle analysis, we first conducted the analysis in places where forest fires had occurred in the past; we located these places by using old photographs of burnt forests, taken in 1905 in the Meiji era; literature survey for forest fires; and surveys for tree age structure. We found that these places are situated in the Sasa grasslands and the adjacent broad-leaved forest near the Yu-no-ko Lake on the map in 1915. The literature survey showed that the forest fires had occurred near these places about 120 years ago (1890s); this information corresponded with the tree age structure of birch and oak forests around these places that consisted of trees less than 120 years of age. Charcoal analysis used in these forests detected charcoal particles in all the forests, indicating the efficacy of the analysis. Then, charcoal particle analysis and surveys in other oak-white birch forests in the area where the Sasa grasslands were located in 1915 revealed the presence of charcoal particles in all the forests, and tree age structure showed that the forests consisted of trees that were, at most, 101 years of age. Therefore, we collected evidence that forest fires had occurred across the region in the Meiji era and that the existing forest vegetation on the Sasa grasslands and adjacent broad-leaved forests would have been established after the fires.