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No.18 (1971/12) >

 
Title :リュウキュウマツに対するソウシジュの混交効果試験 I (林学科)
Title alternative :Studies on mixed effect of Soshiju (Acasia confusa Merr.) in the Ryukyumatsu (Pinus luchuensis Mayr) forest. I(Department of Forestry)
Authors :大山, 保表
砂川, 季昭
山盛, 直
平田, 永二
高江洲, 重一
Authors alternative :Oyama, Hehyo
Sunakawa, Sueaki
Yamamori, Naoshi
Hirata, Eiji
Takaesu, Juichi
Issue Date :1-Dec-1971
Abstract :1 リュウキュウマツ林分施業の基礎資料を得るため, 9年生のリュウキュウマツとソウシジュの混植林の調査をおこない, ソウシジュの混植がリュウキュウマツの生長へおよぼす効果や広葉樹類の侵入混交状況および地床草本類の質的相違などについて検討し, 地力の改善効果を予測した。2 リュウキュウマツの生育本数は600∿11,600本/haであって, またソウシジュは100∿3,100本/haであって, 調査区間に生育本数の差異が大きく, 生育途中での枯損も大きい。リュウキュウマツの生育本数は, 対照区でもっとも大きく, 混植歩合の低い区がこれにつぎ, 混植の高い区がもっとも小さい。広葉樹の発生生育本数は, 200∿4,400本/haで, 混植区で大きい。3 樹種別樹高生長は, 混植区において常にソウシジュが大きく, リュウキュウマツは小さい。リュウキュウマツの樹高生長は, 混植区で大きく対照区で小さい。広葉樹類の生長は, リュウキュウマツの生長に匹敵し良好である。4 リュウキュウマツの平均胸高直径は, 立木密度8,000本/ha以上の区では, 立木密度に逆比例し, 8,000本/ha以下の区では密度との関係は認められない。ソウシジュ, 広葉樹類の平均胸高直径は, 立木密度の関係は見られず, 地力に応じた胸高直径生長量をしめしている。リュウキュウマツの胸高直径は, 混植の高い区でもっとも大きく, 混植の低い区がこれにつぎ, 対照区でもっとも小さい。5 各調査区における総胸高断面積およびリュウキュウマツの胸高断面積計は, それぞれの立木本数にほゞ比例し, また混植区において大きく, 対照区において小さい。リュウキュウマツ単木の胸高断面積は, 8,000本/ha以上の区では, 立木本数に逆比例し, 8,000本/ha以下の区間では, 立木本数の影響は認められない。また混植区において大きく, 対照区で小さい。6 各調査区の総材積およびリュウキュウマツの木積は, それぞれの立木本数に比例し, また混植区において大きく, 対照区で小さい。リュウキュウマツの単木の材積は, 8,000本/ha以上では, 立木本数に逆比例し, 8,000本/ha以下の区間では, 立木本数の影響は認められない。また混植区において大きく, 対照区で小さい。7 下層植生の中で, コシダの被度は, 対照区で大きく, 混植区で小さいか或は出現しない, 木本類では, ヒメツバキ, およびアカメガシワの両樹種計の本数歩合は, 全体の71%で主体をなし, その生育本数は混植区で多く, 対照区で少ない。8 以上の調査結果に基き, リュウキュウマツの林分施業は, 単純林の造成をさけて, ソウシジュの混交をはかり, かつ広葉樹類および草本類の発生本数を高めて, 腐植の良質化と地力の改善効果を促進し, リュウキュウマツおよびソウシジュ稚苗木の枯損本の減少と生育本数の増加をはかり, 除伐によってリュウキュウマツ, ソウシジュおよび広葉樹の適正な立木本数の混交をはかって, リュウキュウマツおよび林分の材積生長量を増大せしめるようにこころがける。
1. A mixed forest of nine years old Ryukyumatsu (Pinus luchuensis Mayr) and Soshiju (Acasia confusa Merr.) was investigated in Nakijin, Okinawa, in order to obtain basic data for management of Ryukyumatsu. In the investigation, estimatep were effects of Soshiju on soil fertility by measuring growth of Ryukyumatsu, and condition of broad leaved trees and ground floor plants in the forest. 2. The standing number of Ryukyumatsu and Soshiju ranged from 600 to 11,600 and from 100 to 3,100 per hectare in the experimental plots, respectively. The wide range of the standing was considered to be due to accurance of dead tree at different rate. Ryukyumatsu grew successfully as Soshiju was introduced to the forest at lesser rate. Broad leaved tree ranged from 200 to 4,400 per hectare in the mixed planting plot of Ryukyumatsu and Soshiju. The broad leaved tree was found incneasing as the rate of Soshiju to Ryukyumatsu increased. 3. Height growth of Soshiju was greater than that of Ryukyumatsu in mixed planting plots. The height growth of Ryukyumatsu was greater in the mixed planting plots than in the pure plots of Ryukyumatsu. 4. The brest height diameter of Ryukyumatsu was inverse proportion to stand density of the plots with more than 8,000 standing per hectare but no relation was recognized in the plots with less than 8,000 standing. 5. The total basal area of all tree species and Ryukyumatsu in the exprimental plots was slightly proportional to the number of the trees, and it was greater in the mixed planting plots than in the pure plots of Ryukyumatsu. However, it was found that the basal area of Ryukyumatsu was in inverse proportion to standing density over 8,000 standings per hectare. The basal area of Ryukyumatsu was not affected by the standing density with less than 8,000 standings, and it was greater in the mixed plots than in the pure planting plots of Ryukyumatsu.
6. The volume of all tree species and Ryukyumatsu in the exprimental plots was slightly proportional to the standing number of the trees, and it was greater in the mixed planting plots than in the pure plots of Ryukyumatsu. However. it was found that the volume of Ryukyumatsu was in inverse proportion to standing density over 8,000 standing per hectare. The volume of Ryukyumatsu was not affected by the standing density with less than 8,000 standings, and it was greater in the mixed plots than in the pure planting plots of Ryukyumatsu. 7. The cover degree of Koshida (Dicrauopteris dichotoma Bernk.) in under vegitation was greater in the pure plots and smaller in the mixed plots. The number of under floor tree was greater in the mixed plots than in the pure plots. The standing number of broad leaved trees was in a range of 200 to 4,400 per hecter, which was predominated by Himetsubaki (Schima superba Gord. et Champ.) and Akamegashiwa (Mallotus japonicus Muell. -Arg.) occuping 71 percent of whole broad leaved trees. 8. According to the result of the present investigation, improved management of Ryukyumatsu would be suggested as follows; It is better to plant Soshiju with Ryukyumatsu to establish Ryukyumatsu forest. Soil fertility of the Ryukyumatsu forest should be improved by accumulation of good humus from Soshiju and other broad leaved trees. Seedlings of Ryukyumatsu should be grown under enough care. It is necessary to keep a proper proportion of Ryukyumatsu seedlings and broad leaved trees in the mixed forest by improvement cutting. And it ought to increaese the volume growth of Ryukyumatsu by conducting the management as mentioned above.
Type Local :紀要論文
ISSN :0370-4246
Publisher :琉球大学農学部
URI :http://hdl.handle.net/20.500.12000/4505
Citation :琉球大学農学部学術報告 = The Science Bulletin of the Faculty of Agriculture. University of the Ryukyus no.18 p.267 -286
Appears in Collections:No.18 (1971/12)

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