Growth and survivorship, occurrence of cankers on old dense artificial stands of Chamaecyparis pisifera

Abstract

There are many questions on management method of old artificial sawara cypress (Chamaecyparis pisifera) stands whose age are almost 100 years old because they are rare compared with sugi (Cryptomeria japonica) and hinoki (Chamaecyparis obtusa) stands. Three plots, Shakujo1, Shakujo2, and Tsukino-ore, were selected in 2005 and total cruises were conducted three times in 8 years to analyze survival and growth. Thinning records could not be found for Shakujo1 and Shakujo2. The density of sawara cypress in Shakujo1, Shakujo2, and Tsukino-ore was 586 ha^-1, 1,067 ha^-1, and 450 ha^-1, respectively, and mean diameter at breast height were 35.5 cm, 30.4 cm, and 47.8 cm, respectively. All sawara cypress trees were classified into five grades. Although the lowest grade class ratio was high in Shakujo1 and Shakujo2 (35% and 47%), it was low in Tsukino-ore (18%) because cleaning cutting was conducted. The death rate in 8 years was 2.4%－4.5%. Dead trees were found only in the lowest grade class in the three plots. Tree cankers were found on 69.5% and 48.7% of sawara cypress trees in Shakujo1 and Shakujo2 but 4.2% in Tsukino-ore. Thus, it should be concluded that thinning might urge growth of diameter, prevent canker damage from spreading, and effectively maintain stand soundness.