タクバツ ホウシキ ニヨル シラカシ シンタンリン ノ セイサン キコウ ニ カンスル ケンキュウ ダイ6ホウ シモヤマサ ダイ1 コテイ シケンチ ノ ダイ1 ダイ2 ケイリキ ニオケル セイチョウ
Studies on the Productive Structure of ”Shirakashi” (Cyclobalanopsis Myrsinaefolia Oerst.) Coppice-Forest Managed by Selection Method(6) : On the Growth in Two Circulation-Periods at the SHIMOYAMASA No.I Permanent Plot
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In February 1959, the authors established a permanent plot (area 332 m^2) of Shirakashi(Cyclobalanopsis mysinaeforia Oerst ) coppice selection forest at Shimoyamasa, Hirose cho, Shimane Prefecture. Even after they have studied a production structure of this forest. This paper reports change of forest structure and volume increment of this forest in two cutting cycles (during 7 years).
The results of this study are as follows.
1. Percentage of trees to be cut was 53.0 % at the first cutting (in February 1959) and 47.4. % at the second operation (in November 1962), and the choice of cutting trees was as follows.
Dominant class (D. b. h. 13 cm and over) : all trees were cut.
Intermediate class (D. b. h. 7-12 cm) : good trees were reserved and poor or injured trees were removed.
Overtopped class (D. b. h. 6 cm and under) : only injured trees were removed.
2. The diameter of trees was measured by tape (mm unit) at every inventory, and the volumes was calculated with the local volume table maked by following equation.
log V = 4^^￣.06887+ 2.427449・log D
3. After cutting, the sprouts rose from almost all stumps, and the regeneration succeeded. On the other hand, the change process of the structure of this stand were shown in table 5, 6 by the statistic method of the diameter distribution.
4. The current annual volume increment of this stand amounts to 13.3 m^3 per ha (rate of increment was about 20.7%) in the two cutting cycles from the inventory data. This net increment is wonderful amounts in the coppice forest in Japan.
About 60-70% trees of the intermediate class were reserved at each cutting and they have fulfiled the major part of the increment of this stand in each cutting cycles. Naturally, the increment of this intermediate class survivors took up approximately 61% of the total of the stand (shown in Table 11, 12).