Decline of Fagus crenata in the Tanzawa Mountains, Japan

Abstract

The Tanzawa Mountains are located in the southwestern part of the Kanto District of Japan, and many hikers and climbers visit the area from several gateways, leading to the overuse of trails and the retreat of vegetation. Siebold's beech (Fagus crenata) forests are distributed in the high-elevation areas. Beech growth on the southern slopes, along the ridgeline, and around peaks has declined significantly. Recent ozone monitoring data suggest that high ozone concentrations may be a possible chronic cause of the loss of beech vitality. Outbreaks of sawfly and repeated sawfly attacks are fatal for the weakened beech trees. Another indirect biotic factor is the increased population of sika deer (Cervus nippon), which destroy ground vegetation and the related community balance. The factors affecting beech decline in the Tanzawa Mountains are complicated, and further scientific research activities in various fields are required to understand the phenomena and to recover the beech forest vegetation.