Structure and Growth of a Multistoried Forest of Japanese Larch (Larix leptolepis) and Keyaki (Zelkova serrata)

1990

S. 15-31

3 Tab., 12 Abb., 10 Lit. Ang.

Unselbständiges Werk

200034708

The purpose of this paper is to clarify the structural characteristics and growth of a multistoried forest of Japanese larch (Larix leptolepis) and Keyaki (Zelkova serrata) in the Takizawa Experimental Forest, Iwate University. Three plots (P1, P2 and P3) were set up there in 1988. The canopy was formed of the above two tree species and showed a typical multistoried structure in P1 and P2, while Japanese larch was hardly seen in P3 and it was close to a pure stand of Keyaki. In P1 and P2, the 1st layer of the canopy was occupied by Japanese larch exceeding 30 m in height and the 2nd was Keyaki. Some deciduous tree species including Keyaki were grown as the 3rd layer below the canopy. In P1, the ratio of the number of tree individuals were 65 % and 33 % for Keyaki and Japanese larch, respectively. However, Keyaki showed a rather lower volume than Japanese larch, 29 % for the former and 71 % for the latter. This is due to the higher height and larger DBH of Japanese larch. Almost the same results were obtained for P2. In P3, Keyaki accounted for 95 % and 85 % in terms of the number of trees and stem volume, respectively. From the results of stem analysis for the sample trees of P1 and P3, it was considered that the planting of tree seedling should be done two times in the early growing stage, the 1st one in 1919 and the 2nd one in 1929. The 2nd one would be that to fill up large gaps among tree crowns which were produced by poor development or death of the 1st planted seedlings. The latest annual increments of stem volume in P1 were calculated at 10.85 m3/ha for Japanese larch and 3.40 m3/ha for Keyaki. Those in P3 were 1.22 and 7.83 m3/ha for the former and latter, respectively. Comparing the total increments of stem volume between the two plots, P1, regarded as multistoried stands, showed a larger value than the P3 of the monostoried stand.