Abstract
We examined growth performance of planted trees in the last 16 years in the multi-storied Japanese cedar (Cryptomeria japonica) plantations with the upper story trees being over 100 years old and the mid and lower story trees being 30 to 52 years in Kuma district, Ehime prefecture, Shikoku, Japan, to clarify if planted trees can grow soundly in the old-aged multi-storied conifer plantation under intensive forest management. The diameter growth rate showed more than 0.80 cm/year for the upper- and mid-story trees, which was similar or higher than that of trees in a single-storied plantation. It was 0.25 cm/year for the lower-story trees, which was lower than that of trees for the upper- and mid-story trees. The height growth rate showed more than 0.5 m/year for the mid-story trees. However, it appeared to reach a plateau for the upper story trees, 0.13 m/year, for the upper-story trees and 0.22 m/year for the lower-story trees. The height/diameter ratio was lower than about 60 for the upper story trees, whereas it was from 70 to 120 for the mid-story trees. Median height/diameter ratio showed over 100 in the lower-story trees. This multi-storied plantation can be mentioned as a rare example of good practice in terms of its high growth rate in terms of upper- and mid-story trees, owing to a long-term intensive tree density management by the owner. However, the high values of height/diameter ratio for a part of the mid-trees and most of the lower-story trees and low growth performance of the lower-story trees suggest high risk of snow accretion damage and the difficulty of maintaining the multi-storied plantation sound for a long time even under intensive forest management.
