Mass Mortality of Oak Trees in an Old Evergreen Broad-leaved Forest Dominated by Castanopsis sieboldii and C. cuspidata in Miyazaki.

Abstract

In the summer of 2015, mass mortality of oak trees by Platypus quercivorus occurred in an evergreen broad-leaved forest in Miyazaki, Japan. To reveal the characteristics of damage, we surveyed the damaged tree species, the diameter at breast height (DBH) and the micro topography in the old evergreen broad-leaved forest dominated by Castanopsis cuspidata and C. sieboldii. Attack by P. quercivorus was observed for all 7 fagaceous species occurring in the study site. The percentages of attacked trees were higher for C. cuspidata than for Quercus glauca and Q. salicina. Attack was more often observed for trees over 33 cm DBH. Frequency distribution of DBH was different between tree species, which mostly ranged larger than 33 cm for C. cuspidata. Micro topography did not influence the occurrence of damage. We conclude that DBH was the major factor in selection by beetles and that beetles preferred larger DBH trees over 33cm.