Crown and Low Thinning of 52-Year-Old Picea abies Stand in Oji Company Owned Forest at Yubari

1985

S. 25-27

1 Abb., 4 Tab., 5 Lit. Ang.

Unselbständiges Werk

200014138

Crown and low thinning were carried out experimentally in the 52 yrs. old Picea abies stand, which was already thinned practically at 35 yrs. old, at Yubari Company owned forest. 5-year results after thinning were as follows: 1) Accelerative effects on growth by thinning. Contents of stand at the time of thinning were 820 - 1067 stocks/ha in the number of stocks, 224 cm 23.1 cm in average diameter at D.B.H., and 333.6 m3 - 406.9 m3/ha in volume. This stand was thinned at the rate of 18% in stock number and 33% in volume at the crown thinning plot, on the other hand, 51% in number and 31% in volume at the lower thinning plot. Growth of crown thinning plot, low thinning plot and control plot during 5 years after thinning was average 3.2 cm, 4.2 cm and 3.5 cm in diameter growth at D.B.H. and 87.7 m3, 88.7 m3, 72.1 m3 in volume/ha (periodic annual increment 17.5 m3, 17.7 m3, 14.4 m3) respectively. From these results, diameter growth was best in low thinning plot, because of containing relatively more larger size stocks than other two plots. And volume growth in the thinned plots was more pretty accelerated by thinning than unthinned plot. 2) Economical effects of thinning. Income was (Formel) in the crown thinning, while (Formel) in the low thinning, because of more production of higher cost timber in the crown thinning plot than low thinning plots produced mainyl pulp wood. On the other hand, logging cost was (Formel) in the crown thinning, being relatively cheaper, and (Formel) in the low thinning, therefore the revenue of two thinnings was as follows: (Formel).