Natural regeneration of chamaecyparis obtusa for 36 years by strip logging in relation to dwarf bamboo elimination, examined by aerial photographs, in Kiso, Japan

In order to clarify the effect of dwarf bamboo (Sasa palmata) elimination on regeneration of hinoki cypress (Chamaecyparis obtusa), changes in the coverages of dwarf bamboo and regenerating trees were examined by aerial photographs taken from 1969 to 2005. Strip logging took place in 1967̃1969. In three of six logged strips, the dwarf bamboo was eliminated with herbicide (sodium chlorate) in 1969, weeded manually every year from 1977 to 1979 and herbicide (tetrapion) was applied again in 1980. The effect of herbicide which decreased dwarf bamboo was estimated lasting for approximately three years. In the remaining three strips dwarf bamboo was undisturbed (control treatment), and the control area has been covered with thick dwarf bamboo till 2005 except for the short term after the logging. In 2005, the regenerating trees covered about 24 (of the control area, while they covered more than 70) of the treated area. There was a negative correlation between the coverages of dwarf bamboo in 1979 and regenerated trees in 2005. These results suggest that the elimination treatment of dwarf bamboo promotes the regeneration of hinoki cypress.