Development of wood decay in bark-stripped Sugi (Cryptomeria japonica (Thunb. ex L.f.) D. Don) stem by Japanese black bear (Ursus thibetanus japonicus Schlegel).

Abstract

We analyzed forms and wood decay conditions of bark-stripped trees by Japanese black bear (Ursus thibetanus japonicus Schlegel) in Sugi plantations (Cryptomeria japonica (Thunb. ex L.f.) D. Don) of Utsunomiya University Forest and discussed development of wood decay in bark-stripped stem. Distribution in percentage of bark-stripped area was occupied 22.5% in 100% (all bark-stripped stem) with high mortality rate of trees. Percentage of high degree of wood decay increased with elapsed years after bark-stripping. Pilodyn penetration increased with elapsed years, while stress-wave velocity decreased. Moisture content on surface decreased rapidly until third year after bark-stripping. Development of wood decay depended on forms of bark-stripping.