Edge tree decline of hinoki (Chamaecyparis obtusa Endlicher) mature stands after typhoon damages

Abstract

Tree decline of hinoki (Chamaecyparis obtusa Endlicher) mature stands after typhoon (Typhoon13, 1993) damages was investigated in 1996 at the Miyazaki University Forests located in southern Kyushu. Our experiments indicated significant decline of trees facing large tree fall gaps. Most declined trees showed coloring and death of leaves in the lower crown. Frequency of tree decline was related to the exposure status of each tree in such a way that isolated trees have the largest decline followed by west-facing edge trees, south-facing edge trees, east-facing edge trees, north-facing edge trees and interior trees. Our experiments also showed that leaf water potential during the day time in autumn was significantly lower in the exposed lower part of crown of edge trees. Edge tree decline after the typhoon damages would be caused by increasing water stress in the lower crown induced by the environmental changes due to edge creation; larger water vapor demand, higher irradiance exposure and stronger wind environments.