@article{oai:u-ryukyu.repo.nii.ac.jp:02005831,
 author = {砂川, 季昭 and Sunakawa, Sueaki},
 issue = {11},
 journal = {琉球大学農家政工学部学術報告, The science bulletin of the Division of Agriculture, Home Economics & Engineering, University of the Ryukyus},
 note = {1. To compare rentability of the broad-leaved forest and the Ryukyu-matsu (Pinus luchuensis Mayr) forest, the author calculated the expectation value of forest land and index percent. Necessary factors are decided as follows: 1) The least diameter of the breast height of log is 12 cm. 2) Lumber percentage are 50％ in 30 years and 60％ in 35 years in the broad-leaved tree, and the percentage of other age prescribed accordingly. The percentage of the Ryukyu-matsu added 10％ to the broad-leaved tree. 3) The percentage to be utilized for fuel is the remainder of 90％, the value of the tree for utilization. 4) Price of Ryukyu-matsu per 1 m^3 in the lumber is $ 5.00 of 20 years of age and $ 9.00 of 40 years, and as to the broad-leaved tree, $ 4.50 in 20 years and $ 6.50 in 40 years. The price of tree of other ages are prescribed accordingly. The price of the both kinds. of trees for fuelwood are $ 0.15. 5) The expenditure per 1 ha of Ryukyu-matsu as $134.50 and that of the broad-leaved tree is $18.00. 6) Forest management expence is $ 3.00. 7) The rate of interrest is 6％. 8) The value of land is considered from both the net value of forest soil and the estimated land value, $150.00. 2. The suitable final age of the Ryukyu-matsu is 25 to 35 years, and that of the broad-leaved tree, 25 to 30 years. 3. The economical maximum utilization period of land for the Ryukyu-matsu is 35 years and 30 years for the broad-leaved tree. The return from final cutting in these periods are $1620.25 for the Ryukyu-matsu, $703.80 for the broad-leaved tree when tendered and $535.50 when untendered. The expectation value of land is $197.22, $76.57 and $62.88 respectively. The Ryukyu-matsu is better than the broad-leaved tree for rentability. However, when the management of the Ryukyu-matsu is unproper, the return from final cuttings of it is greater than that of the broad-leaved trees, the rentability may be smaller. Therefore, it is necessary to consider whether to plant the Ryukyu-matsu or not in the remote land., 紀要論文},
 pages = {102--108},
 title = {壮令広葉樹林分と壮令リュウキュウマツ林分との収益性試算}
}