Features of planted cypress trees vulnerable to damage by Japanese black bears

The Japanese black bear (Ursus thibetanus japonicus) causes serious and persistent damage to conifer plantations in some areas of Japan. From 2006-08, we examined bear damage and tree characteristics (diameter at breast height [DBH], width of growth rings, and amount and nutritional content of newly-developing vascular tissues) in 7 even-aged stands of Japanese cypress (Chamaecyparis obtusa) growing at similar elevations in a university forest. Larger-diameter trees were more likely than smaller trees to be damaged by bears in each stand. The major nutritional component of vascular tissues was sugar, mainly sucrose. Sugar concentration of vascular tissues showed little variation, and was correlated with neither DBH nor stand age. Mass of vascular tissues was highly variable and was positively correlated with DBH, but not with stand age. To reduce bear damage, foresters should concentrate direct protection efforts on larger-diameter trees.