Reestablishing the health of secondary forests Satoyama endangered by Japanese oak wilt: A preliminary report

Abstract

Japanese oak wilt caused by the fungus Raffaelea quercivora is increasing in secondary forests known as Satoyama that are surrounding rural communities. Oak wilt is occurring in stands that are 40 to 70 years old that have been used for fuel wood and charcoal production and then left unmanaged because those wood fuels were replaced with gas and kerosene since 1950s. An ambrosia beetle, Platypus quercivorus, which vectors the pathogen, can propagate effectively in thicker trunks. Due to the extensive population growth of this beetle in aged “Satoyama” forests, the infested areas are increasing annually. A drastic change occurs in the vegetation after the mass mortality of oak trees. Deterioration of biodiversity and soil erosion are of concern. To reduce oak mortality, rejuvenation of trees will be effective because the vector beetle cannot propagate in thin trunks. We are conducting an experiment to reestablish the health of “Satoyama” forests that are slightly affected by this disease. In this experiment, aged forests were clear-cut to promote sprouting from the oak stumps. This is a coordinated effort among the local governments and researchers. The management of the “Satoyama” combined with the utilization of biomass as fuel wood in the local area is essential for the success of this project. Key words: Oak, wilt, Raffaelea quercivora, biomass, management.