Hiromi Yamagawa, Fumiaki Kitahara, Tatsuya Otani, Reiji Yoneda, Kei K Suzuki, Haruto Nomiya

Predicting the level of damage caused by deer browsing in young plantations is important for selecting appropriate damage control measures. In this study, we examined a method for assessing the level of deer damage in young Sugi (Cryptomeria japonica) plantations by observing field signs of deer. First, a questionnaire survey was conducted to obtain information about the damage caused by deer browsing on planted trees and the extent of field signs, such as browsing marks and deer fecal pellets in young plantations where deer-proof fences were installed. The extent of field signs was recorded as qualitative data (i.e., "None", "A few", and "Many"). A multiple correspondence analysis (MCA) of these relationships revealed a relationship between the extent of deer damage in young plantations and the presence of five field signs (browsing marks, bark stripping marks, fecal pellets, trails and tracks). Based on the coordinate values of each field sign obtained using the MCA, the extent of each field sign was scored, and the total value was calculated as the deer impact score (DISco). When the relationship between the DISco and the extent of deer damage to planted trees was subjected to a logistic regression analysis (LRA), the DISco was found to be a significant explanatory variable and the LRA was an effective model (AUC of 0.7122 and 0.7794, respectively) for predicting the probability of stand damage and High stand damage. Therefore, the DISco was shown to be an effective tool for assessing the impact of deer in young Sugi plantations.