2018 Fiscal Year Final Research Report

Certain natural regeneration by control of Sasa and preregenerated Hinoki seedlings before logging

Research Project

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Project/Area Number	15K07498
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Forest science
Research Institution	Forest Research and Management Organization
Principal Investigator	Saitoh Tomoyuki 国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員等 (00414483)
Co-Investigator(Kenkyū-buntansha)	酒井武国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員等 (80353697) 壁谷大介国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員等 (30353650)
Research Collaborator	SUGITA hisashi KUSHIMA hiromichi HOSHINO daisuke
Project Period (FY)	2015-04-01 – 2019-03-31
Keywords	天然更新 / 伐前地拵え / ササの抑制 / ヒノキ林 / 前更更新 / 前生稚樹 / 刈り払い / 薬剤散布
Outline of Final Research Achievements	In a temperate forest with undergrowth of Sasa, regeneration of trees often fails because Sasa grows heavily after logging. In this study, we conducted manipulative experiments to know how to reduce the biomass of Sasa quickly and surely with several methods of Sasa-control before logging. Since the biomass of Sasa under the canopy is relatively small, it has been expected that uproot of Sasa by every year mowing method was effective. After suppression of Sasa, we also consider the regeneration of the natural seedling of Chamaecyparis obtusa. It was found that better condition for the germination of C. obtusa seedlings required the litter removal. It has been demonstrated that suppression of Sasa before logging increases possibility of natural regeneration of C. obtusa. Our results lead to technical improvements of the methods for establishing advanced seedling of highly shade tolerant tree species such as C. obtusa.
Free Research Field	森林生態学
Academic Significance and Societal Importance of the Research Achievements	伐採前に更新のための林床処理を行って、前生稚樹を育成し、これを更新稚樹とする天然更新法は可能性があることが指摘されているにも関わらず、特に針葉樹においては実証事例が殆どなかった。ササ型林床の場合、伐採の前後に関わらずササの抑制が必要となり、特に伐採前のササ抑制に着目すると大きな効果が期待されていたが、検証例は少なかった。これまで伐採後の更新においてササが繁茂してしまい、樹木の更新が失敗してきた。この反省から伐採前のササ抑制を目指した本実験から林冠下のササ抑制が成功し、ヒノキ稚樹の発生数や生残率が高まった。この更新法により社会的ニーズにも答えられる成果が得られた。