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種類：　原著論文／社会経済－計画－経営
Title： 　Predicting load path and tensile forces during cable yarding operations on steep terrain
巻頁：　J For Res 21 (1): 1-14
題名：　急傾斜地での架線集材作業における荷重経路と張力の予測
著者：　Sylvain Dupire・Franck Bourrier・Frédéric Berger
所属：　Irstea, UR EMGR, France
抄録： Cable yarding systems constitute an adapted solution for steep-slope harvesting in mountain forests. However, it requires many specific skills for both forest managers and operators. The objectives of this research were to: (1) develop a CableHelp model for the set-up of cable yarding systems where inputs are operational field data and outputs are load path and tensile forces, and (2) to validate it with field experiments. The results show a high accuracy between the data predicted by the model and field measurements. Furthermore, this work stresses the importance of taking into account both the mainline effect and the friction between skyline and intermediate supports to properly calculate the skyline tension and load path. The CableHelp model shows great adaptability and ensures highly accurate predictions for any position on the line profile and for different configurations: single-span or multiple-span profiles, uphill or downhill yarding and for different kinds of carriage. A direct application of this research is to optimize the set-up of cable lines in order to reduce equipment wear, as well as operating cost, while respecting operator safety.

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種類：　原著論文／社会経済－計画－経営
Title： 　Spatially constrained harvest scheduling for multiple harvests by exact formulation with common matrix algebra
巻頁：　J For Res 21 (1): 15-22
題名：　空間制約下における複数回伐採を考慮した行列表記定式化に基づく伐採計画
著者：　吉本　敦・木島 真志
所属：　統計数理研究所
抄録：　空間制約下の伐採計画問題を取り扱った研究では、個々の林分に対して計画期間内の伐採は１回のみと仮定することが多い。本研究では、複数回の伐採を考慮した最適伐採計画を行列表記による定式化によりモデル構築を行う新たな手法を提案する。複数回伐採への対応には施業単位に対し定義する決定変数を用いて、空間制約への対応には新たに導入する”隣接行列”による制約式を用いる。”隣接行列”の生成には、従来の空間的な隣接関係を描写する”空間隣接行列”と、施業間の同時期伐採を特定する”施業隣接行列”を新たに導入し、それらのクロネッカー積により、決定変数に対する”隣接行列”を生成し、空間制約を導入する。その結果、すべての林分に対して、隣接林分における同時伐採を避け、複数回伐採を考慮した空間制約式が定式化できる。ここで提案する手法を用いることで、行列表記による定式化に基づきシステマティックに空間制約を満たした伐採計画問題を定式化でき、既存の森林伐採計画モデル（例：FORPLAN）の空間制約を考慮したモデルへの改良・拡張が容易になる。

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種類：　原著論文／社会経済－計画－経営
Title： 　Error in the estimation of emission factors for forest degradation in central Africa
巻頁：　J For Res 21 (1): 23-30
題名：　中央アフリカにおける森林劣化にともなう排出要因推定における誤差
著者：　Nicolas Picard・Matieu Henry・Noël H. Fonton・Josiane Kondaoulé・Adeline Fayolle・Luca Birigazzi・Gaël Sola・Anatoli Poultouchidou・Carlo Trotta・Hervé Maïdou
所属：　COMIFAC, Cameroon
抄録：　The implementation of forest-based projects to mitigate greenhouse gas emissions requires the estimation of emission factors (here the difference in biomass stocks between two forest types). The estimation of these quantities using forest inventory data and allometric models implies different sources of errors that need to be prioritized to improve the precision of estimation. Using data from permanent sample plots in a tropical moist forest in central Africa and considering four allometric models with equal likelihood, the largest source of error in the estimate of the difference of biomass between intact and logged-over forest was that due to the model choice (40 % of the sum of squares). The error due to the model choice did not cancel out in the difference due to an interaction between the model’s prediction and the diameter structure of the forest. The variability in biomass between plots was the second largest source of error, but was underestimated because of post-stratification. The error due to the model choice could be reduced by weighting the models’ predictions.

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種類：　原著論文／生物－生態
Title： 　Diel patterns of fine root respiration in a dryland shrub, measured in situ over different phenological stages
巻頁：　J For Res 21 (1): 31-42
題名：　異なる生物季節における乾燥地灌木の野外測定による細根呼吸の日変化
著者：　Zongrui Lai・Su Lu・Yuqing Zhang・Bin Wu・Shugao Qin・Wei Feng・Jiabin Liu・ Keyu Fa
所属：　Beijing Forestry University, China
抄録：　Fine root (<2 mm) respiration (R fr) may play an important role in carbon cycles in drylands; thus R frin desert ecosystems may have important implications for belowground processes and global carbon cycles. This study aimed to (1) investigate the diel and seasonal changes in R fr of a shrub (Caragana microphylla Lam.) in situ during the growing season and to (2) detect the relationship between both photosynthesis and phenology and R fr. The study was conducted in an even-aged C. microphylla plantation in a semiarid area in the Mu Us Desert of China. Rates of R fr and net photosynthesis were measured using a standard chamber equipped with a portable gas analysis system. The data revealed two diel patterns that varied with different phenological stages. Diurnal Rfr rates were 2.2-fold greater than nocturnal R fr rates. Our results showed that diurnal changes in Rfr strongly correlated with rates of net photosynthesis, suggesting that the diel changes were strongly associated with the current supply of photosynthates. Furthermore, aboveground phenology could partially explain some of the variations in seasonal R fr. Our results provide basic information on the link between R fr and aboveground activities, and enhance our understanding of carbon processes in dryland ecosystems.

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種類：　原著論文／生物－生態
Title： 　Potential of soil seed banks in the ecological restoration of overgrazed floor vegetation in a cool-temperate old-growth damp forest in eastern Japan
巻頁：　J For Res 21 (1): 43-56
題名：　丹沢山地の冷温帯湿性林においてシカにより退行した林床植生の回復の可能性―埋土種子からの検討―
著者：　田村　淳
所属：　神奈川県自然環境保全センター
抄録：　湿性林は脆弱な生態系であり、特有の種組成をもっている。シカは湿性林の種組成と構造に強い影響を及ぼしている。本研究の目的は、20年にわたりシカの強い採食圧を受けてきた丹沢山地の冷温帯湿性林で、埋土種子からの植生回復の可能性を明らかにすることである。そのために、シカの採食圧を除いた植生状態に維持されている植生保護柵内とその柵外で埋土種子と地上部植生の種組成、それぞれの類似度百分率を調べた。林床植生の種組成は、柵内で嗜好性種が71%を占めたのに対し、柵外では嗜好性種は6%のみで不嗜好性種が83%を占めた。埋土種子では、発芽種数は柵内で44種、柵外で39種と同程度であったが、発芽個体数は柵内で642個体/m2、柵外では985個体/m2となり柵外で多かった。埋土種子の種組成は、柵内では嗜好性種が29%、不嗜好性種が43%を占めたのに対し、柵外では嗜好性種は1%のみで不嗜好性種が73%を占めた。柵内外の埋土種子と地上部植生の類似度百分率は、柵外の埋土種子と柵内の地上部植生でもっとも低かった。これらの結果は、シカの影響を強く受けた湿性林では、埋土種子により柵内と同じ種組成の植生に回復する可能性は低いことを示している。植生が衰退してからの対策では遅く、嗜好性種が地上部に残っている段階で柵の設置やシカの捕獲などのシカ対策が必要である。