Abstract
We assessed the decline in deciduous hardwood forests due to sika deer in 835 stands in the Kansai region (Hyogo Pref., Kyoto Pref., Shiga Pref. and Fukui Pref.) by using the shrub-layer decline rank (SDR), determined by combining the shrub-layer vegetation cover and the presence of signs of grazing by sika deer in a stand. The results showed a SDR rise in with an increase in an index of density of sika deer and declines in several components in forests in most of the prefectures. We estimated the spatial distribution of deciduous hardwood forests with each SDR in the Kansai region, based on the collected data, using a spatial interpolation method in the Geographic Information System. By checking the estimation by leave-one-out cross validation, it was confirmed that most of the errors are within one rank in SDR. From these results, we conclude that the approach using SDR would be applicable not only to the prefectures adjacent to Hyogo Pref. in the Kansai Region but also to multiple prefectures in the other regions. The results of the spatial estimation in the Kansai region showed that there are three areas in the region in which forest decline is very severe. The these area are the inland area of Hyogo Pref. and Tango Mountains excluding Tango Peninsula, Tanba Highland centered on Ashiu Forest Research Station, Kyoto University, and Suzuka Mountains.
