記述言語：日本語   出版者・発行元：東北森林科学会  

主伐後の民有林の再造林は，東北地方では各県ともほぼ20～30 %の低調な実施面積率となっており，再造林コス トが高いことが大きな原因となっている。そこで，再造林コスト削減の方策として植栽密度を下げるとともに下刈り作 業を省略して，植栽と下刈り作業のコストを低減させる技術開発が行われている。全国各地の再造林コスト削減の取組を見ると，1,000～2,000本/haの低密度植栽の実施と，低密度植栽に全刈りだけでなく坪刈りや高刈り等の下刈りを 組み合わせることで作業の効率化とコスト削減を目指す取組が行われており，従来の方法よりもコストを低減させるこ とに成功している事例も増えている。また，大苗の低密度植栽も下刈りの省力には有効である。今後の課題としては，低密度植栽による除伐費用の増加がないのかを明らかにすること，大苗の生産体制の整備や価格の低下があげられる。

DOI： 10.18982/tjfs.24.1_21

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SISEF-SOC ITALIANA SELVICOLTURA ECOL FORESTALE  

We examined the recovery and dynamics of living tree above-ground biomass (AGB) after selective logging in an Amazonian terra firme forest managed by a private company. The forest consisted of 24 blocks (including one set aside for conservation) selectively logged in different years on a managed schedule. Trees >= 10 cm in diameter at breast height (dbh) were surveyed in 2006 in 192 0.25-ha plots, in 2010 in 119 plots, and in 2012-2013 in 54 plots. A logistic growth model factoring in logging dynamics and mean AGB of a block in these years was established. Referencing the mean AGB of the unlogged forest, the model indicated that the logged forest would take on average 14 years to regain its preharvest AGB after selective logging at 1.9 trees ha(-1) (dbh > 50 cm). In 2010 and 2012-2013, the AGB increased significantly for small and large trees (10-20 cm and > 60 cm dbh, respectively) in the logged forest. In contrast, it decreased significantly for medium-sized trees (30-50 cm dbh) in the unlogged forest. Comparisons with the previous studies mainly conducted in the other regions of Amazon suggested that the estimated AGB recovery period with moderate logging intensity was almost appropriate and likely acceptable to forest managers.

DOI： 10.3832/ifor2534-011

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：OXFORD UNIV PRESS  

Leaf respiration (R) is a major component of carbon balance in forest ecosystems. Clarifying the variability of leaf R within a canopy is essential for predicting the impact of global warming on forest productivity and the potential future function of the forest ecosystem as a carbon sink. We examined vertical and seasonal variations in short-term temperature responses of leaf R as well as environmental factors (light and mean air temperature) and physiological factors [leaf nitrogen (N), leaf mass per area (LMA), and shoot growth] in the canopy of a 10-year-old stand of hinoki cypress [Chamaecyparis obtusa (Sieb. et Zucc.) Endl.] in Kyushu, Japan. Leaf respiration rate adjusted to 20 degrees C (R-20) exhibited evident vertical gradients in each season and was correlated with light, LMA and leaf N. In contrast, the temperature sensitivity of leaf R (Q(10)) did not vary vertically throughout the seasons. Seasonally, Q(10) was higher in winter than in summer and was strongly negatively correlated to mean air temperature. A negative correlation of R-20 with mean air temperature was also observed for each of the three canopy layers. These results clearly indicate that leaf R was able to adjust to seasonal changes in ambient temperature under field conditions and down-regulate during warmer periods. We also found that the degree of thermal acclimation did not vary with canopy position. Overall, our results suggest that vertical and seasonal variations in temperature responses of leaf R within a hinoki cypress canopy could be predicted by relatively simple parameters (light and temperature). There was an exception of extremely high R-20 values in April that may have been due to the onset of shoot growth in spring. Understanding thermal acclimation and variations in leaf R within forest canopies will improve global terrestrial carbon cycle models.

DOI： 10.1093/treephys/tpx012

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATURE PUBLISHING GROUP  

To elucidate the temporal changes in the radiocesium distribution in forests contaminated by the Fukushima Daiichi Nuclear Power Plant accident, we monitored the Cs-137 concentration and inventory within forests from 2011 to 2015 across nine plots containing variable tree species and different contamination levels. The Cs-137 concentrations in needles and branches decreased exponentially at all coniferous plots, with effective ecological half-lives of 0.45-1.55 yr for needles and 0.83-1.69 yr for branches. By contrast, the Cs-137 concentration in deciduous konara oak leaves did not change over the five years. The concentration of Cs-137 in oak wood increased by 37-75%, whereas that in Japanese red pine decreased by 63% over the five years. In Japanese cedar and hinoki cypress, the Cs-137 concentration in wood showed an increasing trend in half of the plots. The changes in Cs-137 in the organic and mineral soil layers were not strongly related to the tree species or contamination level. Our multi-site, multi-species monitoring results revealed that the pattern of temporal changes in radiocesium in the 9 forest plots was similar overall; however, changes in Cs-137 in needles/leaves and wood differed among tree species.

DOI： 10.1038/s41598-017-08261-x

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

福島県田村市に設定した調査地で，東京電力福島第一原発事故後に植栽したコナラとスギ，事故後に天然更新したアカマツの実生，事故後伐採したコナラから発生した萌芽枝について，葉と枝の放射性の137Cs濃度を測定した。調査は，2016年６月と７月に行なった。６月は３樹種とも新葉が展葉中であったが，７月には展葉はほぼ終わっていた。コナラについては７月に二次枝が伸長したためこれも分析した。７月のコナラについては，葉の搾汁液中のカリウムイオン濃度やクロロフィル量の指標となるSPAD値も測定した。樹種間で137Cs濃度に違いが見られ，６月に採取した新葉ではスギの値が最も高く，アカマツ，コナラの順に低くなった。７月には，スギの137Cs濃度が減少したが，コナラとアカマツでは変化は小さかった。コナラの７月の137Cs濃度は，植栽・萌芽個体共に若い二次葉のほうが古い一次葉より高い値を示した。コナラの葉のカリウムイオン濃度は，成熟した一次葉に比べ若い二次葉で高い値を示したが137Csとの相関はなかった。一方，コナラの葉の成熟度を表す葉面積当たりの葉重やクロロフィル量と137Cs濃度には負の相関が見られ，葉の成熟度と137Cs濃度の間に密接な関係があることが分かった。

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記述言語：日本語   出版者・発行元：日本森林学会  

<p>コンテナ苗は植栽後の活着・成長が良いことが期待されている。しかし国内においては, コンテナ苗の成長・活着能力について統一的な見解が未だ得られていない。そこで本研究では, コンテナ苗の成長・活着能力の普遍的な傾向を把握することを目的として, 1道7県・5樹種からなる39カ所の植栽試験の情報に基づき, コンテナ苗と裸苗の植栽後の生存率および樹高・直径成長速度を推定し両者の間で比較した。階層ベイズ法を用いたパラメータ推定の結果, 全種を通してのコンテナ苗の生存率の中央値は0.96であり, 裸苗の生存率 (中央値0.97) とほぼ同じであった。また樹高成長速度および直径成長速度も, 全体推定値・樹種別推定値ともコンテナ苗と裸苗との間で分布範囲に大きな違いはみられなかった。形状比 (樹高/基部直径) は, いずれの種でも植栽直後にはコンテナ苗の方が高いものの, 植栽1年以降には, 全ての種においてコンテナ苗と裸苗との間の差はみられなくなった。以上の結果から, 一般的な傾向としてコンテナ苗の植栽後の活着・成長は裸苗と同程度であり, 育苗の利便性や植栽の効率性がコンテナ苗の優位性を示すのに有効な特徴となることが示唆された。</p>

DOI： 10.4005/jjfs.98.214

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, information about stand-level spatial patterns of radiocesium initially deposited in the surrounding forests was essential for predicting the future dynamics of radiocesium and suggesting a management plan for contaminated forests. In the first summer (approximately 6 months after the accident), we separately estimated the amounts of radio cesium (Cs-134 and Cs-137; Bq m(-2)) in the major components (trees, organic layers, and soils) in forests of three sites with different contamination levels. For a Japanese cedar (Cryptomeria japonica) forest studied at each of the three sites, the radiocesium concentration greatly differed among the components, with the needle and organic layer having the highest concentrations. For these cedar forests, the proportion of the Cs-137 stock in the aboveground tree biomass varied from 22% to 44% of the total Cs-137 stock; it was 44% in highly contaminated sites (7.0 x 10(5) Bq m(-2)) but reduced to 22% in less contaminated sites (1.1 x 104 Bq m(-2)). In the intermediate contaminated site (5.0-5.8 x 10(4) Bq m(-2)), 34% of radiocesium was observed in the aboveground tree biomass of the Japanese cedar stand. However, this proportion was considerably smaller (18-19%) in the nearby mixed forests of the Japanese red pine (Pinus densiflora) and deciduous broad-leaved trees. Non-negligible amounts of Cs-134 and Cs-137 were detected in both the sapwood and heartwood of all the studied tree species. This finding suggested that the uptake or translocation of radiocesium had already started within 6 months after the accident. The belowground compartments were mostly present in the organic layer and the uppermost (0-5 cm deep) mineral soil layer at all the study sites. We discussed the initial transfer process of radiocesium deposited in the forest and inferred that the type of initial deposition (i.e., dry versus wet radiocesium deposition), the amount of rainfall after the accident, and the leaf biomass by the tree species may influence differences in the spatial pattern of radiocesium by study plots. The results of the present study and further studies of the spatial pattern of radiocesium are important for modeling future radiocesium distribution in contaminated forest ecosystems. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jenvrad.2015.09.016

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

As a part of improving forest management practices, we tested the idea that partial defoliation of container-grown and bare-root Hinoki cypress (Chamaecyparis obtusa) seedlings prior to outplanting can reduce transplant shock and enhance seedling survival during their first growing season after transplanting. For container-grown seedlings, the remaining leaves of defoliated seedlings showed photosynthetic capacity (Amax) about 1.5 times higher than the non-defoliated control in the first 3 weeks. For defoliated bare-root seedlings, Amax ranged 3.3-4.8 times higher than non-defoliated control in the first 4 weeks after transplanting. Thereafter, Amax of defoliated seedlings of both types began to decrease slowly. Amax of newly emerged leaves after transplanting was significantly higher than that of existing leaves for container-grown seedlings but not bare-root seedlings. For container-grown seedlings, both defoliated and non-defoliated plants showed high survival rate (&gt;90%) and there were no significant differences among levels of defoliation. For bare-root seedlings, non-defoliated control showed highest mortality (30%) by the end of the growing season but seedlings that were 25%, 50%, 75% defoliated all suffered little mortality. In terms of initial growth, there was no significant difference between defoliated and non-defoliated control in container seedlings suggesting that defoliation treatment had no effect on reducing their growth. In comparison, bare-root seedlings showed marginally but significantly greater height growth in defoliated plants, suggesting that non-defoliated seedlings suffered greater transplant shock and reducing the amount of leaves may contribute to minimize water stress and mortality. Therefore, we found that for bare-root seedlings, partial defoliation can effectively reduce transplant shock resulting in high survivorship and growth performance; the lack of defoliation response in container-grown seedlings would suggest that defoliation is unnecessary for improving their transplant success. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.foreco.2016.03.054

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s00442-015-3509-x

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DOI： 10.6090/jarq.50.379

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記述言語：日本語   出版者・発行元：一般社団法人 日本土壌肥料学会  

DOI： 10.20710/dohikouen.62.0_157_2

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記述言語：日本語   出版者・発行元：日本森林学会  

森林における樹木および土壌の放射性セシウム濃度と蓄積量の経年変化を明らかにするため、福島県および茨城県のスギ林、ヒノキ林、アカマツ林、落葉広葉樹林において、原発事故後から５年間の森林内の葉、枝、樹皮、材、落葉層と鉱質土壌層の放射性セシウム濃度と蓄積量を調査した。葉の濃度は落葉広葉樹以外の林分で低下傾向にあり、枝と樹皮の濃度は全ての林分で低下傾向にあった。また、材の濃度はスギ林では林分により異なる傾向を示したが、落葉広葉樹林では上昇傾向が見られた。多くの林分において、落葉層の濃度は低下し、０ｃｍから５ｃｍの鉱質土壌層の濃度は上昇する傾向が見られた。これら変化に伴い、特にスギ林では、樹木地上部と落葉層の蓄積量は減少し、鉱質土壌層の蓄積量は増加する傾向を示した。ただし、全ての林分において合計蓄積量の有意な変化は見られず、放射性セシウムは森林内に留まっていると考えられた。

DOI： 10.11519/jfsc.127.0_801

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記述言語：日本語   出版者・発行元：日本森林学会  

台風攪乱後の縞枯れ林の回復過程を明らかにするため、1959年の台風で攪乱を受けた北八ヶ岳縞枯山の発達段階の異なる3地点（M:成熟林、I:中間林、Y:若木林）において、伐倒調査と樹幹解析、2001年から2008年にかけての毎木調査により、攪乱後約40年間における現存量の変化を推定した。各地点には本数密度の異なる2調査区（高密度区、低密度区）を設置し、台風攪乱時の林齢と更新木の成立密度の違いに対する現存量変化の違いについて検討した。結果、3地点には発達段階に対応した林齢の違いがあったが、MとIにおいては風倒後の成長経過は同様のパターンを示し、林分現存量もほぼ等しかった。すなわち、Mにおいては台風攪乱時に林床にあった前生稚樹が主に現在の林冠を形成しているのに対し、Iの林冠木は攪乱後に侵入した後生稚樹が成長したものと考えられた。稚樹の不均質な定着によって生じたと考えられる低密度区の成立本数は、M、Iともに高密度区の5割程度であるが、2002年時点においても林分当たりの現存量には明かな差がみられた。縞枯れ林における台風攪乱後の現存量の回復過程は、林分の発達段階、前生稚樹の有無、更新木の成立密度などによって異なると考えられた。

DOI： 10.11519/jfsc.127.0_543

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記述言語：日本語   出版者・発行元：日本森林学会  

土壌から樹木への放射性セシウム（¹³⁷Cs）の移行と、カリウム（K）施肥による移行抑制効果を検討するため、福島県川内村の新規植栽地において、長期モニタリング試験を開始した。2014年5月に50 x 50mプロットを8つ設定し、ヒノキ苗木を植栽した（約3000本 ha^-1）。植栽後の同年8月に各プロット5地点で土壌を採取した後、4プロットにKとして100kg ha^-1のKClを施肥した。堆積有機物層から深さ20cmまでの土壌の¹³⁷Cs蓄積量は平均で261kBq m^-2で、55%が堆積有機物層に、31%が土壌表層（0-5cm深）に存在していた。その後、2014年11月と2015年4月に、それぞれ各プロット1本および4本ずつヒノキ苗木を採取するとともに、近傍（約50cm横）の土壌を採取した。これらを合わせて解析した結果、ヒノキの葉の¹³⁷Cs濃度は近傍の土壌（0-5cm深）の¹³⁷Cs蓄積量と有意な相関が認められたが、K施肥区における葉の¹³⁷Cs濃度の有意な低下は認められなかった。一方で、根の¹³⁷Cs濃度はK施肥区において有意に低下していた。2015年4月には苗木と土壌の採取後に追加のK施肥を実施した。また、同年11月にも苗木と土壌の採取を行っており、新たに得られた結果についても報告する予定である。

DOI： 10.11519/jfsc.127.0_813

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記述言語：日本語   出版者・発行元：日本森林学会  

ヒノキ若齢林を対象に，葉の呼吸特性すなわちR20（温度が20度の時の呼吸速度）とQ10（温度が10度増加した時の呼吸速度の増加率）について調べ，R20はいずれの季節においても下層よりも上層の葉で高いこと，Q10は冬に高くて夏に低いものの層間差がないことを明らかにした（125回森林学会）。これら葉レベルの呼吸特性から，葉面積の垂直分布あるいは気温の季節変化を組み込むことで，林冠呼吸量あるいは年間呼吸量が推定される。本発表では，R20の垂直変化とQ10の季節変化がこれらの推定値にどの程度影響を与えるのか検討した。例えば7月の林冠呼吸量は，R20の垂直変化を考慮に入れた場合に対して，R20が一律として上層の葉のR20の値を用いた場合は2.2倍，中層の値だと0.9倍，下層の値だと0.5倍となった。一方，Q10の季節変化を考慮に入れた年間呼吸量に対して，Q10が一律としてQ10の年平均値（2.09）を用いた場合は1.13倍，冬の値（2.35）だと1.43倍，夏の値（1.93）だと0.96倍となった。したがって，年間の林冠呼吸量を推定する際，呼吸特性の時空間変動を考慮に入れることは非常に重要である。

DOI： 10.11519/jfsc.127.0_308

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER  

In the present study, we aimed to map canopy heights in the Brazilian Amazon mainly on the basis of spacebome LiDAR and cloud-free MODIS imagery with a new method (the Self-Organizing Relationships method) for spatial modeling of the LiDAR footprint. To evaluate the general versatility, we compared the created canopy height map with two different canopy height estimates on the basis of our original field study plots (799 plots located in eight study sites) and a previously developed canopy height map. The compared canopy height estimates were obtained by: (1) a stem diameter at breast height (D)- tree height (H) relationship specific to each site on the basis of our original field study, (2) a previously developed D-H model involving environmental and structural factors as explanatory variables (Feldpausch et al., 2011), and (3) a previously developed canopy height map derived from the spacebome LiDAR data with different spatial modeling method and explanatory variables (Simard et al., 2011). As a result, our canopy height map successfully detected a spatial distribution pattern in canopy height estimates based on our original field study data (r=0.845, p = 8.31 x 10(-3)) though our canopy height map showed a poor correlation (r= 0.563, p =0.146) with the canopy height estimate based on a previously developed model by Feldpausch et al. (2011). We also confirmed that the created canopy height map showed a similar pattern with the previously developed canopy height map by Simard et al. (2011). It was concluded that the use of the spaceborne LiDAR data provides a sufficient accuracy in estimating the canopy height at regional scale. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jag.2015.04.003

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記述言語：日本語  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

Key message Besides stem temperature, seasonality and vertical gradient in stem diameter growth strongly affect both seasonal and vertical variations in stem CO2 efflux.
Abstract Stem CO2 efflux (E-s) is known to vary seasonally and vertically along tree stems. We measured E-s at various heights in a 50-year-old hinoki cypress [Chamaecyparis obtusa (Sieb. et Zucc) Endl.] stand over 2 consecutive years in Central Japan. Effects of stem temperature (T-s), daily stem diameter increment (D-i), and difference in vapor pressure deficit between nighttime and daytime (VPDdiff) on seasonal variation in daily E-s were examined by a generalized linear model (GLM). Daily E-s exhibited a substantial seasonal variation, which was mostly affected by T-s and D-i. Any effect of VPDdiff, which was assumed to be an index of daily sap flow rate, was not detected. The GLM prediction of daily E-s from the combination of T-s and D-i showed good agreement with the observed seasonal trend in daily E-s. These results suggest that, in addition to stem temperature as the important environmental factor, stem radial growth is a significant phenological factor influencing seasonal variation in E-s. Additionally, the intercept of GLM, which indicates the basal daily efflux that is independent of T-s and D-i, was closely related to the annual diameter increment. Furthermore, a strong relationship was found between annual E-s and annual diameter increment. These findings suggest that variation in stem diameter growth along stems is considerably responsible for the observed vertical variation in E-s. Therefore, stem radial growth can affect both seasonal and spatial variations in stem CO2 efflux.

DOI： 10.1007/s00468-014-1127-6

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER JAPAN KK  

Bischofia javanica is a non-native tree species in Japan's Ogasawara Islands, where it threatens native tree species due to its rapid propagation and growth. An effective method is needed to limit the expansion of B. javanica populations and to conserve the natural forest ecosystem of the islands. For this purpose, we examined the effectiveness of a new application technique for the herbicide glyphosate on B. javanica. In this method, glyphosate solution is directly injected into holes drilled in the stem, and each hole is then plugged with a cork stopper to prevent loss of the solution, namely the drill-and-plug method. We also developed an allometric regression model linking stem diameter with total aboveground biomass (AGB) to estimate the necessary herbicide dosage. Our results suggest that between 0.1 and 0.5 g kg(-1) (active ingredient per unit AGB) is required to control most B. javanica trees. Verification of the drill-and-plug method using the minimum dosage (0.1 g kg(-1)) showed that most of the herbicide-treated trees were killed. These results suggest that the drill-and-plug method can help control the B. javanica invasion of the Ogasawara Islands.

DOI： 10.1007/s10310-014-0457-y

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本森林学会  

We examined the dynamics of radiocesium in the forest ecosystems which were contaminated by the Fukushima Daiichi Nuclear Power Plant Accident. Field measurement and sampling were conducted in eight stands; plantations of Japanese cedar (Cryptomeria japonica, n=4), Hinoki cypress (Chamaecyparis obtusa, n=2), Japanese red pine (Pinus densiflora, n=1), and deciduous broad-leaved forest dominated by oak (Quercus serrata, n=1). In each stand, &lt;sup&gt;137&lt;/sup&gt;Cs deposition in trees was estimated separately for each aboveground component (leaves, branches, and stem) using the data of specific &lt;sup&gt;137&lt;/sup&gt;Cs activities and biomass of these components obtained during 2011-2013. We found that tree- &lt;sup&gt;137&lt;/sup&gt;Cs decreased substantially during the period for all forest types. In 2013 however, the &lt;sup&gt;137&lt;/sup&gt;Cs ratio of trees to stand total (i.e., trees plus litter and soil) differed by forest type: Japanese cedar (6-24%) and Hinoki cypress (10-12%) were higher than pine (2%) and deciduous broad-leaved (3%) forests. The results suggested that the early 2-year transfer process of radiocesium from the tree crown to the ground differed depending on the amount of initial &lt;sup&gt;137&lt;/sup&gt;Cs deposition and differences in leaf longevity and biomass of dominant species.

DOI： 10.4005/jjfs.97.33

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier B.V.  

In the present study, we aimed to map canopy heights in the Brazilian Amazon mainly on the basis of spaceborne LiDAR and cloud-free MODIS imagery with a new method (the Self-Organizing Relationships method) for spatial modeling of the LiDAR footprint. To evaluate the general versatility, we compared the created canopy height map with two different canopy height estimates on the basis of our original field study plots (799 plots located in eight study sites) and a previously developed canopy height map. The compared canopy height estimates were obtained by: (1) a stem diameter at breast height (D) - tree height (H) relationship specific to each site on the basis of our original field study, (2) a previously developed D-H model involving environmental and structural factors as explanatory variables (Feldpausch et al., 2011 ), and (3) a previously developed canopy height map derived from the spaceborne LiDAR data with different spatial modeling method and explanatory variables (Simard et al., 2011 ). As a result, our canopy height map successfully detected a spatial distribution pattern in canopy height estimates based on our original field study data (r = 0.845, p = 8.31 × 10 ) though our canopy height map showed a poor correlation (r= 0.563, p = 0.146) with the canopy height estimate based on a previously developed model by Feldpausch et al. (2011). We also confirmed that the created canopy height map showed a similar pattern with the previously developed canopy height map by Simard et al. (2011). It was concluded that the use of the spaceborne LiDAR data provides a sufficient accuracy in estimating the canopy height at regional scale. -3

DOI： 10.1016/j.jag.2015.04.003

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MDPI AG  

Allometric models to estimate biomass components such as stem mass M , foliage mass Ml, root mass M and aboveground mass M , were developed for the palm species Euterpe precatoria Mart., which is the most abundant tree species in the Amazon. We harvested twenty palms including above- and below-ground parts in an old growth Amazonian forest in Brazil. The diameter at breast height D ranged from 3.9-12.7 cm, and the stem height H ranged from 2.3-16.4 m. The D, diameter at ground basis D , crown diameter CD, H, stem specific gravity ρ, and number of fronds Nf were considered as independent variables and incorporated into a power function model. The best predictors were D Hρ for M and M , D HN for Ml, and D for M . Slender index (H/D) ranged from 0.56-1.46 m cm , and the D-H relationship suggested that the stem shape becomes more slender with increasing D. On the other hand, ρ increased with D implying a stiffening of stem tissue. The average root/shoot ratio was estimated as 0.29 which was higher than that reported for the non-palm tree species in the Amazon. Comparisons of several models to estimate M of different palm species, suggested that the variations of the D-H relationship and ρ should be considered to develop allometric models for estimating biomass in palm species. In particular the ρ largely varied depending on individual size, which should be important to consider, when developing the allometric models for palms. s r a 0 s a f r a 2 2 . -1

DOI： 10.3390/f6020450

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記述言語：日本語   出版者・発行元：日本森林学会  

森林内部における放射性セシウムの分布状況の変化を明らかにするため，原発事故後の2011年から毎年夏季に，森林内の樹木の葉や幹，落葉層や鉱質土壌などの部位別の放射性セシウム濃度と蓄積量を調査した。調査林分は，福島県川内村，大玉村，只見町の41年生から58年生のスギ林と大玉村の45年生アカマツ林と落葉広葉樹林である。これまでの調査から，上川内のスギ林を除き，放射性セシウムの多くは，2012年までに樹体および落葉層から鉱質土壌へ移動していた。これら調査林分では，2014年の樹体および落葉層の放射性セシウムの濃度と蓄積量は2013年より減少したが，2013年同様，その減少量は少なかった。その結果，2013年に引き続き，樹体と落葉層に蓄積した放射性セシウムの分布割合は減少し，鉱質土壌に蓄積した放射性セシウムの分布割合は増加した。また，これら林分の放射性セシウムの蓄積量の分布は，どの林分も似た割合を示すようになった。一方，これまでの調査で，放射性セシウムの分布割合が他の林分と異なっていた上川内のスギ林では，2014年に樹体の割合が減少し，鉱質土壌の割合が大幅に増加した。今後，他の林分と同じような分布になると推測された。

DOI： 10.11519/jfsc.126.0_845

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記述言語：日本語   出版者・発行元：森林総合研究所  

森林総合研究所では、福島第一原発事故により汚染された森林における放射性セシウムの分布や長期的な動態を把握するために、事故直後から福島県内の複数地点のスギ林や広葉樹林など異なる森林に試験地を設けて研究を行ってきた。ここでは、調査林分の概況と、研究手法のうち、樹木地上部、小径木及び下層植生を対象にした放射性セシウム濃度と林分全体の蓄積量の測定及び推定法を紹介する。とくに、幹の各部位（樹皮、辺材、心材）に区別した試料の採取や調整の仕方と、これら幹各部位と枝葉の現存量推定法については、調査林分での推定結果の一部を踏まえながら、方法上の問題点や今後の課題などを検討する。

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY  

The winter climate is changing in many parts of the world, and it is predicted that winter climate change will modify the structure and function of plant-soil systems. An understanding of these changes and their consequences in terrestrial ecosystems requires knowledge of the linkage between above- and below-ground components as well as the species interactions found in plant-soil systems, which have important implications for biogeochemical cycles. However, winter climate-change studies have focused on only a part of the ecosystem or ecological process. We summarize here recent findings related to the effects of winter climate and its changes on soil nitrogen (N) dynamics, greenhouse gas (N2O) emissions from the soil, N use by individual plants, vegetation development, and interactions between vegetation and pollinators to generate an integrative understanding of the response of the plant-soil system to winter climate change. This review indicates that the net effects on plants, soil microbes, pollinators, and the associated biogeochemical cycles are balanced among several processes and are highly variable depending on the context, such as the target species/functional group, original winter condition of the habitat, and type of climate change. The consequences of winter climate change for species interactions among plants, associated animals, and biogeochemical cycles are largely unknown. For further research, a large-scale comparative study to measure ecosystem-level functions is important, especially in less-cold ecosystems.

DOI： 10.1007/s11284-013-1115-0

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Forest soils are generally sinks of CH4 and sources of N2O. To characterize the dynamics of these major greenhouse gases in central Siberia during the growing season, we measured fluxes from forest soil and assessed the relationships between CH4 and N2O fluxes and forest floor vegetation types, soil temperature, and moisture conditions. At the soil surface, both CH4 uptake and emission (-6.6 to 3.1 mu g CH4-C m(-2) h(-1)) were observed, and CH4 fluxes did not differ among vegetation types. CH4 flux was positively correlated with soil moisture, but not with soil temperature. The small CH4 uptake compared with previous reports was due to CH4 production in response to high precipitation. N2O was also emitted and taken up by soil (-0.2 to 0.4 mu g N2O-N m(-2) h(-1)), and N2O fluxes did not differ among vegetation types. N2O flux was negatively correlated with soil moisture and not correlated with soil temperature. Our findings suggest that high soil moisture and low availability of mineral nitrogen resulted in N2O uptake due to denitrification. Furthermore, both CH4 and N2O were emitted from a river at the site; these were produced in the basin of the riverbank rather than deep in the soil. (C) 2014 Elsevier B.V. and NIPR. All rights reserved.

DOI： 10.1016/j.polar.2014.01.004

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan International Research Center for Agricultural Sciences  

Fine roots are an important component of the carbon flow of forests. Soil properties in tropical forest (terra firme forest) of the Central Amazon differ substantially along topography, and the biomass and vertical distribution of fine roots may also differ accordingly. Information on the vertical distribution of fine roots is essential to obtain unbiased estimates of fine root biomass. Accordingly, we examined fine root biomass and its vertical pattern along the gradient of topography in a typical terra firme forest in this region. The regressions on the cumulative fine root biomass along soil depth (at 5 cm intervals from 0-40 cm in depth) revealed significantly different vertical distribution of fine root biomass among three topographic habitats (lower-slope valley called baixio, mid-slope, and upper-slope plateau). A shallower rooting pattern was observed in the plateau than the other habitats, while fine root biomass was larger in the baixio than the plateau-a difference likely attributable to the soil physical properties than the aboveground stand structures among the sites. More than 74 and 93% of the fine root biomass was estimated to be distributed within the upper 20-and 40-cm soil layers, respectively. Our results suggested that a shallow sampling depth, which is common in fine root research in the Amazon, would be reasonable, though we should examine the consistency of our results in different regions.

DOI： 10.6090/jarq.48.231

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan International Research Center for Agricultural Sciences  

Allometric models to estimate the aboveground mass AGM, belowground mass BGM and total mass TM of juvenile trees (stem diameter at breast height DBH ≤ 5 cm, tree height H ≥ 30 cm) in open-canopy terra-firme forests after wind disturbance were developed in the Amazon. For comparison, the allometric models were also developed for a closed-canopy terra-firme forest. After six models had been compared in each forest type, the model with diameter at ground basis DGB and H was selected as the best for estimating AGM and TM, and the model with diameter at ground basis DGB as a single variable was selected as the best for estimating BGM considering the adjusted coefficient of determination and standard deviation of the mean. Models based on the diameter at breast height DBH showed poor correlation with each biomass component compared with those based on DGB for the open-canopy forest. The juvenile trees in the open-canopy forest showed higher AGM and H at a given DGB than in the closed-canopy forest, while the DGB-BGM relationships did not differ significantly between the open-and closed-canopy forests. It was concluded that the allometric models used to estimate AGM and TM were unique to each forest type. This would be because light-demanding species show higher allocation to AGM than BGM to be advantageous for competition for light by achieving rapid growth in height.

DOI： 10.6090/jarq.48.213

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記述言語：日本語   出版者・発行元：日本森林学会  

福島第一原発の事故があった2011年より，福島県川内村・大玉村・只見町の3町村の森林に調査地を設定し，毎年8-9月に森林に降下した放射性セシウムの単位地表面積あたり蓄積量について調査を行ってきた。これまで，2011年と2012年の部位別放射性セシウム蓄積量の変動より，樹木地上部や落葉層から表層土壌(0-5cm層)への放射性セシウムの移行が示されている。2013年に行った調査では，樹木地上部の放射性セシウム蓄積量は2012年より減少したものの，2011年から2012年の減少量より少なかった。また，落葉層や土壌の放射性セシウム蓄積量は2012年から2013年にかけて微増したサイトが多く，2011年から2012年にかけて認められた蓄積量の大きな変化とは異なるパターンを示した。これらの結果から，森林空間の上層から下層への放射性セシウムの移行は引き続き起きているが，その速度は事故当初よりも低下していることが示された。森林内に降下したセシウムが各部位に固定化され，溶脱されにくくなったことが，放射性セシウムの移行が低減した理由として考えられた。

DOI： 10.11519/jfsc.125.0_766

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC TROPICAL ECOLOGY  

Limited information on fine roots is hindering understanding of the geographical-scale variations in belowground carbon stock across the Amazon Basin. Fine root biomass (< 2 mm in diameter) was studied in the upper Negro River basin of Brazil, where no previous study on fine roots had been reported. Two plots (20x125 m), each of which included 3 subplots (20x20 m), were set in a tropical moist forest at Sao Gabriel da Cachoeira, north-western Brazil. The diameter of the trees (dbh > 10 cm) within each subplot was measured, and fine roots were sampled by coring soils from depths of 0-5, 5-10 and 10-20 cm at 12 points in each subplot. The fine root, coarse root, and aboveground biomass in the study forest were estimated as 7.03 +/- 0.65 (95 % CI), 32.6 +/- 15.0 and 253.6 +/- 152.7 Mg ha-1, respectively. Most of the spatial variance in fine root biomass was accounted among and within the subplot spatial scale of less than 20x20 m. The fine root biomass of the study site exceeded the values reported for some tropical forests in the central and eastern Amazon, which suggested regional differences in the fine root biomass in Amazonian forests.

DOI： 10.3759/tropics.22.179

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

We developed a stem diameter D-height H allometric model that included variability in the D-H relationship along a topographic gradient. The study site was located along a belt transect (2500 × 20 m) established in a primary tropical forest near Manaus, Brazil. The transect included typical topography of the region, characterized by plateaus and valleys called "baixios". The D-H allometric model (n = 1307) indicated that potential tree height increased significantly, from 28 m at the lowest baixio plot to 35 m at the highest plateau plot. Consequently, by combining the D-H allometric model and an allometric equation with the variable D2H, biomass was estimated for trees (D &gt
10 cm) in each sub-plot (20 × 20 m). Ignoring variability in the D-H relationship introduced wide-ranging error to biomass estimation
error values ranged from -5% at a baixio plot to +6% at a plateau plot. Average biomass was 317 ± 28 (SE) Mg ha-1, and tree density and biomass fell significantly with decreasing relative elevation.

DOI： 10.6090/jarq.47.109

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記述言語：日本語   出版者・発行元：日本森林学会  

細根は森林の炭素循環の重要な構成要素であるが、その動態を測定する各種の手法には、微環境の改変や測定値の信頼性、機材の価格等、それぞれに問題点がある。とくにアマゾン等の熱帯地域では細根の成長・枯死・分解のサイクルも早いと考えられるため、環境条件に応じた適切な測定方法の検討が不可欠である。本研究では、ブラジル・マナウス近郊の熱帯林において、砂質土壌が分布する斜面下部と、粘土質の土壌が分布する斜面上部で、フラットベッド・スキャナを用いて直径2 mm未満の細根の成長と枯死の動態を測定した。イングロースコアを用いた細根成長量の測定も併せて実施し、結果を比較した。また地形単位ごとに土壌含水率の変動も測定し、細根の動態との関係を検討した。スキャナによる測定では、とくに多雨期に斜面下部で活発な成長と枯死が観察されていたが、斜面上部では成長・枯死のサイクルは非常に緩慢であった。一方、イングロースコアによる測定では、斜面下部と上部で1年間の細根生長量にほとんど差がなかった。後者では埋設期間中の枯死分を測定できず、とくに斜面下部ではかなりの過小評価になっていた可能性が高い。

DOI： 10.11519/jfsc.124.0.208.0

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記述言語：日本語   出版者・発行元：日本森林学会  

東電福島第一原発事故で放出された放射性セシウム(Cs)の森林における汚染状況の変化を明らかにするために、2011年8-9月に調査をした福島県の3試験地（5林分）で2012年8～9月に再調査を行った。森林内の地上1mの空間線量率は昨年に比べて低下傾向にあったものの、Csの物理学的壊変から予想される放射能の減衰（前年比86%）に比べて低減率（前年比91-104%）は小さかった。また樹木の葉や枝のCs濃度は前年に比べて大幅に減少し、堆積有機物中のCsも全般に低下したのに対し、表層土壌(0-30cm)のCs濃度は増加した。その結果、森林内のCs分布は、樹木と堆積有機物のCs割合が低下し、表層土壌のCs割合がいずれの林分でも約70％と高まった。森林のCs蓄積量は、川内試験地および大玉試験地のスギ林では前年比87％と低下したが、それ以外の林分ではCs蓄積量は昨年とほとんど変わらなかった。以上、この1年間に森林内のCsは樹木や堆積有機物から表層土壌へ移動し森林内のCs分布は変化したが、Cs蓄積量に大きな変化がないことから森林に沈着したCsのほとんどは森林に留まっていることが明らかになった。

DOI： 10.11519/jfsc.124.0.383.0

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記述言語：日本語   出版者・発行元：日本森林学会  

植物群落の光環境を推定するモデルは、門司・佐伯モデルをはじめとして数多く開発・改良がなされてきている。これらのモデルの多くは、均一な構造の植物群落を想定している。しかしながら実際の植物群落、とりわけ森林の樹冠構造は不均一であることが多い。さらに近年では、列状間伐などにより不均一性の増した林冠構造をもつ林分が数多く存在する。 そこで本研究では、不均一な樹冠構造を表現し、さらに樹冠内の異なる位置における光環境を推定するための簡便なコンピュータ・モデルを構築することを目的とした。そのために、まず樹冠を適当なサイズの葉群球（葉群クラスタ）の集合体とみなし、葉群クラスタを基本単位とした樹冠構造をもつ個体を仮想的に構築することを試みた。そのうえで、複数の仮想個体からなる林分において、任意の葉群クラスタにおける光環境を推定するモデルをR言語を用いて構築した。 その結果、構築したモデルにより、1. 均一な樹冠環境における光条件の垂直分布、2. 不均一な樹冠環境における光条件の垂直分布のバリエーションを表現できることが判った。

DOI： 10.11519/jfsc.124.0.707.0

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記述言語：日本語   出版者・発行元：日本森林学会  

施業に伴う森林の葉群分布と光環境の変化が推定できれば、陽樹冠の量的変化から着花量予想につなげられる可能性がある。花粉症対策のスギ雄花着花量のモニタリング試験地において、個体別に樹冠の光条件の分布を推定し、雄花着花傾度との適合を検証した。 千葉県富津市桜井総稱鬼泪山の北面谷筋のスギ人工林に40m ×40m の試験区を3個設置し、毎木調査と林木位置から、試験林分全個体分の円錐形の樹冠モデルを生成し、個体ごとの開空度の頻度を求めた。間伐方法が着花量に与える影響を検証するため、2009年に3試験区にはそれぞれ多雄花個体優先間伐、通常間伐、無間伐の3種の間伐を行った。2008年から4年間、開花直前の冬季に双眼鏡観察し、「着花なし」から「樹冠全体に高密度に着花」までの5段階の傾度を記録した。 間伐直後の2009年の3試験区の平均樹高は約17mで、林分密度は多雄花木優先間伐区418本/ha 、通常間伐区393本/ha、無間伐区668本/haである。モデル樹冠で判断して明るい樹冠は通常間伐区に多かった。樹勢の優れた多雄花が多く残されためと考えられる。

DOI： 10.11519/jfsc.124.0.530.0

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Precise estimation of biomass at a regional scale is required for evaluating forest carbon stocks throughout the Amazon. We examined six types of allometric models to identify the best estimator of biomass in primary forests (terra firme) in the northwestern sector of the Brazilian Amazon. We also tested six regression models for estimating tree height. We developed each allometric model using measurements of 101 trees excavated in a primary forest distributed along the upper Rio Negro. A simple power function with stem diameter at breast height D as a single variable was selected as the best model for estimating each biomass component, i.e. above-ground total mass AGW, below-ground total mass BGW, and whole individual mass. Among models developed to estimate tree height H from D, we selected a regression model with a coefficient corresponding to an asymptotic height as the best fit. The D-AGW relationship at our study site differed significantly from models developed previously for other regions of the Amazon. We explain this regional variation in part by regional differences in D-H relationships of sample trees. The D-BGW relationship at our site also differed significantly from that in the central Amazon. However, AGW-BGW relationships were consistent between the upper Rio Negro forest and other forests in the central Amazon, in that the BGW-AGW ratio was constant as 0.136 regardless of tree size. On the basis of D-based allometry and census data from 23 plots established in the upper Rio Negro region, we estimated a stand-level total biomass (dry mass) of 252.6Mgha -1. This estimate is at least 73% lower than the potential stand biomass for the region previously suggested by several meta-analyses. © 2012 Elsevier B.V.

DOI： 10.1016/j.foreco.2012.04.028

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記述言語：日本語  

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記述言語：日本語   出版者・発行元：日本森林学会  

Individual growth change of Pinus densiflora during 8 years after thinning prescription in a 94-year-old plantation was investigated comparing it with an unthinned plantation of the same age and a 140-year-old natural stand, to test whether growth of trees could be improved by thinning, what individual traits would affect growth improvement, and whether it would be possible or not to produce large sized timber in the plantations as found in the natural stand at 140 years. Trees in the plantations were characterized by smaller size (DBH=41 cm, H=25-30 m) than old-growth natural stand (DBH=68 cm, H=30-35 m). H/DBH ratio and proportion of crown length suggested that trees in the plantations were more vulnerable to external disturbance such as heavy snow and had less leaf mass than those in the natural stand. After thinning, about 40% of the trees showed an improved annual DBH increment (by ca. 0.1 cm yr -1), whereas 80% of the trees in the unthinned plantation showed deceleration of DBH growth. Change in degree of competition with neighbors or individual variation in leaf mass did not explain inter-individual variation in growth improvement. Improved growth did not appear to be enough to reach equivalent size to trees in the natural stand at the age of 140 years.

DOI： 10.4005/jjfs.93.48

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記述言語：日本語   出版者・発行元：日本森林学会  

DOI： 10.11519/jfsc.123.0.Pa154.0

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記述言語：日本語   出版者・発行元：日本森林学会  

DOI： 10.11519/jfsc.123.0.Pa064.0

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記述言語：日本語   出版者・発行元：日本森林学会  

DOI： 10.11519/jfsc.123.0.J06.0

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記述言語：日本語   出版者・発行元：日本森林学会  

DOI： 10.11519/jfsc.123.0.I17.0

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CAMBRIDGE UNIV PRESS  

Precise estimation of root biomass is important for understanding carbon stocks and dynamics in tropical rain forests. However, limited information is available on individual root masses, especially large trees. We excavated 121 root systems of various species (78) and sizes (up to 116 cm in dbh). and estimated both above- and below-ground biomass in a lowland primary dipterocarp forest in the Pasoh Forest Reserve, Peninsular Malaysia. A tree census was conducted in four research plots (each 0.2 ha) and stand-level biomass was estimated. We examined relationships between tree size parameters and masses of coarse roots (roots &gt;= 5 mm in diameter) and derived a dbh-based allometric equation. The amounts of coarse roots that were lost during excavation were corrected. Coarse-root biomass before and after correction for lost roots was estimated to be 63.8 and 82.7 Mg ha(-1), indicating that significant amounts of roots (23%) were lost during the sampling. We also estimated the biomass of small root (&lt;5 mm) by applying pipe-model theory. The estimate, 13.3 Mg ha(-1), was similar to another estimate of small roots, 16.4 Mg ha(-1), which was obtained directly by the soil-pit sampling method. Total below-ground (BGB) and above-ground biomass (AGB) was estimated to be 95.9 and 536 Mg ha(-1), respectively. The biomass-partitioning ratio (BGB/AGB) was about 0.18. In conclusion, the dbh-based allometric equation for coarse roots developed in this study, which kept good linearity even including the data of larger trees, might be useful for evaluating below-ground carbon stocks in other stands of similar forest (old-growth dipterocarp) in South-East Asia.

DOI： 10.1017/S0266467410000040

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER TOKYO  

We examined vertical and seasonal variations in stem respiration rates in a 50-year-old plantation of Japanese cypress, Chamaecyparis obtusa (Sieb. et Zucc.) Endl., in central Japan, and discuss a practical and precise method to scale a point-measured stem CO2 efflux rate up to whole-stem respiration. For five selected trees, stem CO2 efflux rates were measured at breast height (1.3 m) and at five or six points above breast height (at approximately 2 m intervals) every 1 or 2 months over two consecutive years. Daily total stem respiration rate (surface area basis) was greater inside the crown than below the crown, especially during the growing season. By incorporating the vertical profile of the respiration rate, annual whole-stem respiration was estimated for each sample tree (R (y)). We then compared this estimate (R (y)) with another estimate of annual whole-stem respiration (R&apos;(y)) obtained using a conventional method; it is assumed that the area-based respiration rate at breast height is constant throughout the stem. The ratio of these two estimates (R&apos;(y)/R (y)) was usually less than 1, indicating that the assumptions used to calculate R&apos;(y) underestimate annual whole-stem respiration. We found that R&apos;(y)/R (y) was negatively correlated with the ratio of crown length to tree height (crown ratio). These results suggest that annual whole-stem respiration in this C. obtusa plantation is substantially affected by the relative proportion of within-crown stem with higher respiratory activity. Methodologically, our results imply that incorporating the crown ratio into the conventional method would improve the accuracy of annual whole-stem respiration estimates.

DOI： 10.1007/s10310-009-0163-3

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATL ACAD SCIENCES  

The scaling of respiratory metabolism with body mass is one of the most pervasive phenomena in biology. Using a single allometric equation to characterize empirical scaling relationships and to evaluate alternative hypotheses about mechanisms has been controversial. We developed a method to directly measure respiration of 271 whole plants, spanning nine orders of magnitude in body mass, from small seedlings to large trees, and from tropical to boreal ecosystems. Our measurements include the roots, which have often been ignored. Rather than a single power-law relationship, our data are fit by a biphasic, mixed-power function. The allometric exponent varies continuously from 1 in the smallest plants to 3/4 in larger saplings and trees. Therefore, our findings support the recent findings of Reich et al. [Reich PB, Tjoelker MG, Machado JL, Oleksyn J (2006) Universal scaling of respiratory metabolism, size, and nitrogen in plants. Nature 439: 457-461] and West, Brown, and Enquist [West GB, Brown JH, Enquist BJ (1997) A general model for the origin of allometric scaling laws in biology. Science 276: 122 - 126.]. The transition from linear to 3/4-power scaling may indicate fundamental physical and physiological constraints on the allocation of plant biomass between photosynthetic and nonphotosynthetic organs over the course of ontogenetic plant growth.

DOI： 10.1073/pnas.0902554107

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記述言語：英語  

DOI： 10.1007/978-1-4020-9693-8_16

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DOI： 10.1007/978-1-4020-9693-8_6

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER WIEN  

Gmelin larch ( Larix gmelinii) forests are representative vegetation in the continuous permafrost region of Central Siberia. Information on the carbon budget is still limited for this Siberian larch taiga in comparison to boreal forests in other regions, while the larch forests are expected to play a key role in the global carbon balance due to their wide distribution over North-East Eurasia. The authors reported results of eddy covariance CO2 flux measurements at a mature Gmelin larch stand in Central Siberia, Russia (64 degrees 16'N, 100 degrees 12'E, 250m a.s.l.). The measurements were conducted during one growing season (June-early September in 2004). CO2 uptake was initiated in early June and increased sharply until late June, which was closely related to the phenology of the larch trees (i.e., bud-break and needle flush). Maximum half-hourly net CO2 uptake was similar to 6 mu mol m(-2) s(-1). Maximum daily net uptake of similar to 2 g C m(-2) day(-1) occurred at the end of June and in mid-July. Cumulative net uptake was 76-78 g C m(-2), indicating that the mature larch forest acted as a net sink for CO2 during the growing season (91 days). In comparison with other boreal forests, however, the magnitude of net CO2 uptake and night-time release of the forest, and cumulative net CO2 uptake were lower. We suggest that lower net ecosystem CO2 uptake of the study stand was primarily associated with low leaf area index.

DOI： 10.1007/s00704-007-0337-x

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記述言語：日本語   出版者・発行元：日本森林学会  

DOI： 10.11519/jjsk.53.0_68

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER TOKYO  

An analysis was performed of the climatic responses of the radial growth of Larix gmelinii (Rupr.) Rupr. at two sites-both of which included contrasting north- and south-facing slopes-in Tura, central Siberia, with the development of ring width and maximum-density chronologies for each slope. Both residual and standard chronologies of ring widths were positively correlated with temperature from late May until mid June on all four slopes. By contrast, standard chronologies of ring widths were negatively correlated with precipitation during the winter (from October to April) and in May on the north-facing slope at site 1 and on the south-facing slope at site 2 respectively. The negative correlations with precipitation during the winter and in May on some of the slopes suggested that delayed snowmelt in early spring might inhibit the radial growth of L. gmelinii, and the effects of snow are likely to vary with topography. Both residual and standard chronologies of maximum densities were positively correlated with temperature in early July on all four slopes. Maximum densities were also positively correlated with precipitation during summer of the previous year on all the slopes. These suggest that no major differences exist in terms of responses of maximum density to climatic factors between the north- and south-facing slopes.

DOI： 10.1007/s11284-006-0062-4

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER TOKYO  

We present results of individual-based root system measurement and analysis applied for Larix gmelinii trees growing on the continuous permafrost region of central Siberia. The data of root excavation taken from the three stands were used for the analyses; young (26 years old), mature (105 years old), and uneven-aged over-mature stand (220 years old). In this article, we highlight two topics: (1) factors affecting spatio-temporal pattern of root system development, and (2) interactions between aboveground (i.e., crown) and belowground (i.e., root) competition. For the first topic, the detailed observation of lateral roots was applied to one sample tree of the overmature stand. The tree constructed a superficial (&lt; 30 cm in depth) and rather asymmetric root system, and each lateral root expanded mainly into elevated mounds rather than depressed troughs. This indicated that spatial development of an individual root system was largely affected by microtopography (i.e., earth hummocks). For these lateral roots, elongation growth curves were reconstructed using annual-ring data, and annual growth rates and patterns were compared among them. The comparison suggested that temporal root system development is associated with differences in carbon allocation among the lateral roots. For the second topic, we examined relationships between individual crown projection area (CA) and horizontal rooting area (RA) for the sample trees of each stand. RA was almost equal to CA in the young stand, while RA was much larger (three or four times) than CA in the mature and overmature stands. Two measures of stand-level space occupation, crown area index (aboveground: CAI; sum of CAs per unit land area) and rooting area index (belowground: RAI; sum of RAs), were estimated in each stand. The estimates of RA1 (1.3-1.8 m(2) m(-2)) exceeded unity in all stands. In contrast, CAI exceeded unity (1.3 m(2) m(-2)) only in the young stand, and was much smaller (&lt; 0.3 m(2) m(-2)) in the two older stands. These between-stand differences in RAI-CAI relationships suggest that intertree competition for both aboveground and belowground spaces occurred in the young stand, but only belowground competition still occurred in the two older stands. Based on this finding, we hypothesized that competition below the ground may become predominant as a stand ages in L. gmelinii forests. Methodological limitations of our analysis are also discussed, especially for the analysis using the two indices of space occupation (CAI, RAI).

DOI： 10.1007/s10310-006-0259-y

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER TOKYO  

An analysis was performed on the climatic responses of the radial growth of Larix gmelinii (Rupr.) Rupr. on contrasting north-facing and south-facing slopes in Tura, central Siberia. We developed chronologies of tree-ring width for four plots, designated as north-upper, northlower, south-upper, and south-lower. Both residual and standard chronologies of tree-ring widths exhibited a significant positive correlation with temperature from the end of May until early June in all four plots. The chronologies of ring width did not reveal any major difference in the response to temperature among the four plots. The standard chronologies of ring widths on the north-facing slope were negatively correlated with precipitation during the winter (October-April) and in early and mid-May, whereas the residual chronologies did not reveal clear relationships with precipitation during the winter and May. The significant correlation between ring width and temperature from the end of May until early June indicates that temperatures in springtime play a significant role in the radial growth of L. gmelinii. The negative correlations between standard chronologies of tree-ring width and precipitation in the winter and in May on the north-facing slope indicate that lowfrequency fluctuations in snowfall have negative effects on the radial growth. However, these effects vary and depend on the microscale topography.

DOI： 10.1007/s10086-006-0837-9

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記述言語：日本語   出版者・発行元：一般社団法人日本森林学会  

九州の針葉樹人工林(n=59),皆伐地(n=41)を対象に,定着した樹木の本数を調査し,定着本数密度の簡易な予測モデルを提示した。人工林,皆伐地の全種の定着密度は,対照として調査した広葉樹天然林と比べ低かった。とくにブナ科高木種などの林冠優占種の定着は困難であることがわかった。数量化I類による定着密度予測モデルの決定係数は,人工林,皆伐地とも,全種の場合に比べ,明るいところを成育適地とする陽性高木種に区分した方が高かった。定着密度に大きく影響した要因は,人工林では傾斜角,皆伐地では標高と,両者で異なる点もみられたが,成立後の年数(林齢,皆伐後経過年数)が最も大きい点は共通していた。本研究では,光環境に対する樹種特性を反映させた種群でまとめることにより,標高や林齢など地理情報や森林簿から容易に得られる情報から定着密度を比較的高い精度で予測することができた。

DOI： 10.4005/jjfs.88.482

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER TOKYO  

The individual growth of tree diameter at breast height (dbh) is analyzed in an even-aged plantation of Cryptomeria japonica from stand age of 45 to 94 years, to examine how the growth of individual trees has been affected by the changes in spacing resulting from thinning operations. At any age, a significant proportion (0.37-0.46) of the variation in dbh growth during a 5-11-year period was explained by dbh at the beginning of the period, probably due to greater leaf mass of larger trees. Next, either one-sided or two-sided competition was added to the model, by calculating the basal area (BA) of neighboring trees around each tree within a given radius or BA for trees having larger dbh than the focal tree within the radius. After preliminary analyses, a radius of 8 m was selected as the critical range for tree competition. Although both types of competition explained a significant proportion (0.09-0.43) of growth variation, one-sided competition was not significant at ages greater than 54 years. Based on the model at 45 years of age, the initial deviation of growth rate for each tree from the predicted rate was calculated and added to the models as a third variable. This raised the coefficient of determination up to 0.50-0.74. These findings have practical significance for forest plantation management, particularly for controlling the growth of standing trees via thinning, to produce high-quality timber in the future.

DOI： 10.1007/s10310-005-0175-6

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER TOKYO  

We analyzed the growth patterns of Thujopsis dolabrata var. hondai trees in an old plantation (161 years old), where no silvicultural treatments (e.g., thinning) have been conducted since the initial planting. The analysis focused on understanding individual growth under a long-term self-thinning process, and the stand-level stemwood production at the mature stage was evaluated. Nine canopy-layer trees and one suppressed tree were used for the analysis of annual increments in stem diameters, heights, and stemwood volumes for a given past year using the ring-width data. Both the diameter (at basal portion) and height of all the canopy-layer trees increased at similar rates during the early stage (i.e., 60-70 years after planting); however, after this period, only the height growth rates declined sharply. The annual growth rates of stemwood volume also simultaneously leveled off at the stand age of 40-60 years. Subsequently, the patterns diverged conspicuously, e.g., the growth rates were maintained or increased in some individuals, while it gradually decreased in the case of others until the present year. The divergence of growth pattern was likely to be triggered by intertree competition at several decades after the onset of canopy closure. The current stemwood production of the sample trees, including the suppressed one, was positively correlated with certain size parameters such as stem diameter at breast height and sap-wood area at a height of 4m. Based on the diameter-base allometry, the total stand stemwood production was estimated to be about 12.8 m(3) ha(-1) year(-1). This estimate was higher than those of some old natural T. dolabrata forests (2.0-8.6 m(3) ha(-1) year(-1)) that have been well managed by repetitive selection thinning. Furthermore, individual mean stemwood production of the study plantation (0.03 m(3) tree(-1) year(-1)) was within the range of these natural stands (0.01-0.05 m(3) tree(-1) year(-1)). These comparisons suggested that the old T dolabrata plantation still maintained a relatively high stemwood production potential despite the absence of artificial controls of tree density in the past. In terms of timber production, this fact implied that a rather long rotation (&gt; 100 years) can be applicable in the management of T. dolabrata plantations.

DOI： 10.1007/s10310-005-0193-4

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We examined size-mass allometry and biomass allocation of two larch species (Larix gmelinii (Rupr.) Rupr. and Larix cajanderi Mayer) that grow on the continuous permafrost regions in Siberia. Sample tree data (total n = 27) gathered from four mature stands (&gt; 100 years old) were employed for analysis. First, to determine good size predictor of biomass, site-specific allometric relationships (log-linear equation form) were derived between dry mass of four components (stem, branch, needle and coarse root; &gt;= 5 mm in diameter) and seven size variables; stem diameters (breast height, 30 cm height and crown base), sapwood areas (breast height and 30 cm height), and two combined-variables (tree height x dia-diameter). For all components, site-specific allometric equations based on breast-height diameter (D) always gave high correlations as those using other size variables. However, between-stand comparisons of the D-base site-specific allometry indicated that size dependency (i.e., regression slope) differed for stem mass. Besides, needle and coarse root mass for a given size (i.e., regression intercept) differed significantly among the four stands. These facts implied that D-base regression model was reliable for biomass estimation by site-specific allometry, but was not suitable for developing general (i.e., site-common) allometry. Second, to examine carbon allocation pattern, we estimated each stand biomass by applying corresponding site-specific D-base allometry. Stand total biomass ranged from 8.6 to 33.1 Mg ha(-1), and aboveground-total/coarse root biomass ratio (i.e., T/R) ranged from 1.5 to 2.6. The variation was mainly due to trade-offs between stem and root biomass. Average T/R was about 2.3 that was calculated for some reported L. gmelinii and L. cajanderi stands (n = 16), including our four stands. This average T/R was extremely small in comparison to that (5.1) of Scots pine (Pinus sylvestris L.) stands on the non- or discontinuous permafrost regions in Siberia. This finding strongly suggested that the two Larix species invested annual carbon gains largely into root growth. We discussed its ecological implications in relation to stand structure and permafrost soil-N conditions in the larch taiga ecosystem. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.foreco.2005.10.031

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS  

Fluxes of dissolved organic carbon (DOC) in forested watersheds underlain by permafrost are likely to vary with changes in climatic regime that increase soil moisture and temperature. We examined the effects of temporal and spatial variations in soil temperature and moisture on DOC fluxes from the forest floor of contrasting north- and south-facing slopes in central Siberia. DOC fluxes increased throughout the growing season (June-September) on both slopes in 2002 and 2003. The most favorable combination of moisture content and temperature (deepest active soil layer) occurred in September, and we believe this was the primary driver of increased DOC concentrations and flux in autumn. Total DOC flux for June-September was 12.6-17.6 g C(.)m(-2) on the south-facing slope and 4.6-8.9 g C(.)m(-2) on the north-facing slope. DOC concentrations in forest floor leachates increased with increasing temperature on the north-facing slope, but were almost unaffected by temperature on the south-facing slope. Our results suggest that water input in midseason from melting of ice or precipitation events is the primary factor limiting DOC production. Significant positive correlations between amounts of precipitation and DOC flux were found on both slopes. Dilution of DOC concentrations by high precipitation volumes was observed only for the forest floor leachates collected from the north-facing slope. Our results suggest that global warming will result in increased DOC production in forest floors of permafrost regions, and that precipitation patterns will play an important role in determining the magnitude of these changes in DOC flux as well as its interannual variability. However, the longer-term response of soils and DOC flux to a warming climate will be driven by changes in vegetation and microbial communities as well as by the direct results of temperature and moisture conditions.

DOI： 10.1139/X05-150

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INST ARCTIC ALPINE RES  

On a gentle leeward slope in a snowy forest limit in northern Honshu Island, Japan, mechanical damage by snow settlement and creep on Abies mariesii trees buried below the snowpack was examined to detect signs of the snow-damage effect on future survival and crown development. Damage types were recorded based on direct observation of crowns in 1996, a year of high snow accumulation exceeding 4.5 m, and 1997, a year of moderate snow accumulation. Of 153 trees examined, 63% were damaged in 1996 and 15% were damaged in 1997. The most destructive damage type was breakage of stems &GE; 5 cm in diameter, which occurred on eight trees in 1996 and three in 1997, resulting in foliage loss and death of some trees. The prevalent damage type was branch tearing, at branch-stem junctions primarily within a height range of 4-6 In, which occurred on 171 branches in 1996 and 5 in 1997. Under snowy and windy conditions, stem breakage and branch tearing, caused by forces active within restricted layers of the snowpack, may reduce the future survival and crown development of A. mariesii buried below the snowpack in years of heavy snowfall.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：FERDINAND BERGER SOEHNE  

Deciduous coniferous taiga, larch (genus Larix) ecosystem is one of unique biomes in northeastern Eurasian Continent, where vast area of forest exists on continuous permafrost. We selected three representative sites for ecosystem research: 1) a forest near Yakutsk in Yakutian Basin, eastern Siberia (62N-129E), 2) a forest near Tura in central Siberian Plataeu (64N-100E), and 3) a forest tundra transition near Chersky in Kolyma lowland (69N-160E). We estimated C storage in both aboveground and belowground biomass, in forest floor, and in active layer as soil organic C and as carbonate-carbon. Soil organic C in active layer was the largest component in each site. Soils in Yakutsk and Tura showed carbonate-C accumulation in active layer, which might result from extreme continental climate with low annual precipitation. C storage in aboveground and belowground biomass varied among sites, however, ratios of above/belowground biomass C had a relatively narrow range from 1.1 to 1.5. High allocation rate of C to belowground part resulted from a kind of adaptation to effective nutrient acquisition under nutrient limited environment due to low soil temperature.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INST ARCTIC ALPINE RES  

We examined the effects of snow avalanche on stand structure and the subsequent regeneration of subalpine Abies mariesii Mast forest in northern Japan, and discussed whether gap formation after avalanche disturbance leads to immediate seedling establishment or not. Tree size and age, tree-ring chronology, and seedling density were compared between, on, and around a relatively large avalanche path, which was created in the mid-1980s within Hachimantai National Park. On the avalanche path, only smaller and younger trees (height &lt;5 m, 50-100 yr old) escaped the mechanical damage of avalanche by leaning into the remaining snowpack, and old canopy trees were mostly killed by stem breakage. Tree size structure of the avalanche path, including both living and dead individuals, was relatively similar to that of nearby undisturbed forest, indicating that a mature stand (&gt;ca. 200 yr old) had been previously developed on the avalanche slope without large-scale disturbances in the past. Most of the surviving, younger trees showed abrupt growth release during the few years (1987-1989) after the avalanche event. However, densities of both post-avalanche (&lt; 15 yr old) and pre-avalanche (&gt; 15 yr old) seedlings were much lower on the avalanche path than in the nearby forest, especially at microsites covered with dense dwarf bamboo (Sasa kurilensis) shrub. The pre-avalanche seedlings on the avalanche path sharply increased annual height growth rates after the mid-1980s avalanche, but such positive growth response did not continue longer than 6 to 7 yr. These findings suggested that gap formation following the infrequent, large-scale avalanche disturbance did not necessarily lead to immediate seedling recruitment and/or further growth release of pre-avalanche seedlings. The constraint of seedling establishment was primarily explained by the lack of potential seed supply, and shading effect of the dwarf bamboo bush. Consequently, post-avalanche regeneration of the subalpine fir forest was likely to depend on the smaller individuals (2-5 m in height) that were able to avoid both the mechanical damage of avalanche and mortality from shading by the dwarf bamboo.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

Spatial distributions of root systems of Larix gmelinii (Rupr.) Rupr. trees were examined in two stands in central Siberia: an even-aged stand (ca. 100 yrs-old) and a mature, uneven-aged (240-280 yrs-old) stand. Five larch trees of different sizes were sampled by excavating coarse roots (diameter &gt; 5 mm) in each stand. Dimensions and ages of all first-order lateral roots were measured. Micro-scale conditions of soil temperature and soil water suction ( each 10 cm deep) were also examined in relation to earth hummock topography (mound vs. trough) and/or ground floor vegetation types (moss vs. lichens). All larch trees developed superficial root systems, consisting of the aborted short tap root (10-40 cm in soil depth) and some well-spread lateral roots (n = 4-13). The root network of each tree was asymmetric, and its rooting area reached about four times the crown projection area. Lateral roots generally expanded into the upper soil layers of the mounds where summer soil temperature was 1-6degreesC higher than inside nearby troughs. Chronological analysis indicated that lateral root expansion started successively from lower to upper parts of each aborted tap root, and some lateral roots occurred simultaneously at several decades after tree establishment. The process of root system development was likely to be primarily linked with post-fire dynamics of rhizosphere environment of the permafrost soils.

DOI： 10.1023/A:1026175718177

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER TOKYO  

To clarify the factors affecting the seedling establishment of the subalpine stone pine (Pinus pumila Regl.) from nutcracker-cached seeds, subsequently emerged seedlings were examined in two plots on Mt Akitakomagadake, northern Japan. The survivorship of older seedlings (2-20 years old) was also monitored during six seasons at nine different sites. In one plot with 18 caches, seed germination occurred between June and mid-July. During this period, nutcracker&apos;s retrieved the stored pine seeds from 16 caches and ate some seeds immediately. Simultaneously, this nutcracker behavior caused mechanical damage to newly emerging seedlings (e.g. uprooting and tearing off cotyledons). Such initial loss to in situ harvesting and mechanical damage accounted for 75% of the total seeds remaining in the caches. The number of established current seedlings sharply declined during the first 2 years, and the survival rate was 4.4% over four winters. Two major mortality factors were identified: uprooting by frost-heave soil disturbance in the spring of the second year and standing death by drought or other physiological stresses in early summer. In another plot with 13 caches, survivorship of newly emerged seedlings was also low (4.2%), but mortality was mostly due to summer drought, indicating that the frost-heave event was a site-specific disturbance factor. For older seedlings, survival rates reached approximately 90% even after six seasons and summer drought stress was a major mortality factor. My findings suggest that seedling recruitment of P. pumila was largely limited by both nutcracker disturbance and external disturbance (and/or stresses) at an early stage. However, after the critical first few years, pine seedlings were highly likely to survive and grow to the sapling stage despite the harsh environment of the high mountains.

DOI： 10.1046/j.1440-1703.2002.00505.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We reconstruct the paleoclimatic background of buried peat layers formed around the 10th century, which occur in a snowpatch grassland in a snowy mountain in northern Japan. In the snowpatch grassland, peat accumulation is presently restricted by the presence of a summer snowpatch. Thus, the buried peat layers imply that the summer snowpatch around the 10th century was smaller than it has been in recent times. Climatic control of the year-to-year variation of the present snowpatch was examined based on a snowpatch survey and analysis of meteorological data. The observed snowpatch profiles suggested that winter wind speed played an important role in controlling summer snowpatch size. The buried peat layers indicate not only warming in the melt season, but also a possible weakened winter monsoon in the Medieval Warm Period. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0341-8162(02)00009-7

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Institute of Arctic and Alpine Research  

We examined effects of annual snowfall fluctuation on tree growth and establishment in a mature stand (ca. 200 yr old) of Japanese subalpine Abies mariesii Mast. near upper forest-limits at leeward site. Relatively tall and aged fir trees (&gt
5 m, &gt
100 yr old) retained various scars of past mechanical damage due to snow pressures, e.g., multiple-, tip dieback- and broken-stems, and canopy anomaly. Ring-width pattern analysis showed that these deformed trees mostly experienced abrupt growth reduction. Some events of such abrupt growth reduction occurred simultaneously just after winters with heavy snowfall (e.g., mid-1960s), indicating that the A. mariesii trees often suffered from snow damage due to settlement force of excess snowpack. Particularly, in snowy winters, mechanical breakage of branches was likely to occur intensively at the height of 1 to 3 m above the maximum snowpack level of normal snowfall winters (ca. 3 m). On the other hand, some aged, but suppressed, trees sharply enhanced their growth rates simultaneously after such period of the intensive snow damage. This indicated that the snow damage upon the relatively tall trees sometimes facilitated regeneration of nearby shaded-trees by creating small-scale gaps. The snow-induced disturbance events may have occurred at about 10-yr intervals during the last half of 20th century. Our findings suggested that population dynamics of A. mariesii near its upper forest-limit, especially located at leeward and snowy site, was closely affected by the repetitive events of snow damage following snowy winters: the event primarily acted as a major limiting factor for canopy development of individuals, and sometimes triggered growth of suppressed-trees.

DOI： 10.2307/1552471

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：National Research Council of Canada  

Feasibility was tested of estimating the total stem volume and aboveground biomass from data of only the largest trees in even-aged pure stands. We applied a method of fitting a size-distribution function to data that exclude information of smaller individuals in a stand and compared the predicted stem volume and aboveground biomass with those calculated with data of all living trees in the stand. The paired t test showed that the predicted values of the total stem volume and aboveground biomass were not different (p = 0.05) from those observed even if only the largest 10% of the trees were used for estimation with the -3/2 power distribution. Results were similar with the beta-type distribution
however, data from at least the largest 30% of the trees in the stand must be included. Absolute values of the relative error of the predicted total stem volume or aboveground biomass were generally in the range 10-20%, indicating that the present method is accurate enough to be used for calculation of these variables. However, there is systematic bias in the predictions of the total stem volume and aboveground biomass of a stand. Possible causes of the indicated biases and potential ways for improvement of the predictions were discussed.

DOI： 10.1139/x01-137

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記述言語：日本語   出版者・発行元：The Japanese Society of Snow and Ice  

1999年4月21日, 岩手県岩手郡松尾村籐七温泉付近の斜面で幅約100m長さ約300mの全層雪崩が発生した.雪崩が発生した斜面は谷地形の発達が悪い地すべり滑落崖で, アバランチシュートなどの常習的な雪崩の発生を示唆する地形は見られなかった.この雪崩は発生斜面における雪食地の拡大と堆積地における亜高山帯林の破壊という景観変化を伴っていた.空中写真判読と現地調査の結果, 同様の景観変化は八幡平の稜線部の鏡沼付近においても, 1986年頃に起きたことが明らかになった.これまで雪崩災害の報告が少かった八幡平地域においても, 頻度は低いものの比較的大規模な全層雪崩が発生していると考えられる.

DOI： 10.5331/seppyo.62.463

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：OXFORD UNIV PRESS  

We assessed above- and belowground biomass and net primary production (NPP) of a mature Larix gmelinii (Rupr.) Rupr. forest (240-280 years old) established on permafrost soils in central Siberia. Specifically, we investigated annual carbon budgets in roots in relation to root system development and availability of soil resources. Total stand biomass estimated by allometry was about 39 Mg ha(-1). Root biomass (17 Mg ha(-1)) comprised about 43% of total biomass. Coarse root (greater than or equal to 5 mm in diameter) biomass was about twice that of fine roots (&lt; 5 mm). The aboveground biomass/root biomass ratio (T/R) of the larch stand was about unity, which is much less than that of other boreal and subalpine conifer forests. The proportion of fine roots in total root biomass (35%) was relatively high compared with other cold-climate evergreen conifer forests. Total NPP, defined as the sum of annual biomass increment of woody parts and needle biomass, was estimated to be 1.8 Mg ha(-1) year(-1). Allocation of total NPP to needle production was 56%. The proportion of total NPP in belowground production (27%) was less than for evergreen taiga forests. However, belowground NPP was probablyunderestimatedbecauserootmortalitywasexcluded.We conclude that L. gmelinii trees invested annual carbon gains largely into needle production or roots, or both, at the expense of growth of aboveground woody parts. This carbon allocation pattern, which resulted in the construction of exploitative root networks, appeared to be a positive growth response to the nutrient-poor permafrost soil of central Siberia.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INST ARCTIC ALPINE RES  

Seedling establishment of Japanese stone pine, Pinus pumila, primarily depends on seed dispersal by Japanese nutcrackers (Nucifraga caryocatactes var, japonica). To assess how this mode of seed dispersal affects regeneration and habitat expansion of P. pumila, we mode held observations concerning foraging behavior of nutcrackers, past annual production of pine cones, and age structure of established pine seedlings. Nutcrackers used various microsites for feeding and removing the pine seeds, especially on bare ground or around rocks. The pine seedlings occurred mainly in open patches sparsely covered with dwarf woody shrubs in wind-exposed sites, suggested that the nutcrackers preferred such open patches for caching. Age structure of the seedlings (&lt;20 yr old) showed a clumped age distribution. Most of the younger pine seedlings (&lt;10 yr old) grew as clusters, averaging four to five in number per cluster. Past cone production, estimated using a cone scar technique, varied annually, with some remarkable poor-crop years during the recent 12 yr. However, extensive recruitment of the pine seedlings did not necessarily follow a mast year. Fluctuation of the seedling recruitment was closely related to annual changes in early summer precipitation rather than air-temperature, indicating positive effect of water supply on seed germination. Our findings suggested that regeneration success of P. pumila was limited for two reasons: (1) spatially due to site preference of nutcrackers for seed caching, i.e., open patches at windy sites near the seed source of mature pine scrubs; and (2) temporally by annual fluctuation in climatic factors, especially soil moisture availability. Consequently, nutcrackers do not seem to help the pines expand more widely in the Japanese subalpine region.

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記述言語：日本語   出版者・発行元：The Japanese Society of Snow and Ice  

本研究では, 雪田土壌を用いて過去の残雪規模の変動を推定する方法について検討した.奥羽山地北部の笊森山の雪田には, 埋没泥炭層が認められる.埋没泥炭層は, 火山灰との層位関係から約1000年前に形成されたものと考えられる.現在の雪田の表層では, 雪田の中心部ほど消雪時期が遅く, 植物の生育期間も短くなるため, 植物遺体の堆積量が減少するとともに土壌有機物の量も減少する.埋没泥炭層は10世紀頃に夏季の残雪規模が縮小して, 現在よりも植物遺体の堆積量が増大したために形成されたものと考えられる.

DOI： 10.5331/seppyo.59.101

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記述言語：日本語   出版者・発行元：一般社団法人日本森林学会  

To clarify the influences of snow depth on the development of basal bending, the growth of tree heights and the breaking process of snow damage to understory trees in a two-storied type and three strip-cut types (strip widths of 10, 15, and 20 m) sugi (Cryptomeria japonica D. DON) stands cut in 1974 in a heavy snow-fall area, a monitoring investigation was made. The mean value of snow depth in a 20 m wide stand was the largest, followed by the two-stried stand, the 15 m wide stand, and the 10 m wide stand. It was confirmed that the stage of development of basal bending kept up with the growth of tree heights. It also was confirmed that basal bending and the growth of tree heights were much influenced by the annual changes of snow depth. The mean values of tree heights and basal bendings were large in the order of the 20 m wide stand, the 15 m wide stand, the 10 m wide stand, and the two-storied stand. The snow damage by the basal splitting of tree trunks occurred to several individuals in the 20 m wide stand, and it became clear that the annual rate of increase for basal bending of such individuals was well above the average rate of the stand. It became clear that partially heavy snow covered areas were formed by extreme snow drifting in the strip cut stand, and that this was the cause of the outbreak of snow damage.

DOI： 10.11519/jjfs1953.78.1_61

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記述言語：日本語   出版者・発行元：一般社団法人日本森林学会  

積雪深の年変動が林型の異なる複層林の下木の根元曲がりの量や樹高成長に与える影響, および, 雪害の発生過程を明らかにするため, 多雪地に造成されて11年が経過したスギ複層林(二段林と10m幅, 15m幅, 20m幅の帯状林)について, モニタリング調査を9年間にわたって実施した。各林分の積雪環境はそれぞれ異なっており, 林内の積雪深の平均値は, 20m幅林, 二段林, 15m幅林, 10m幅林の順に大きかった。根元曲がりの量は樹高成長に伴って増加し, 根元曲がりの量と樹高成長量は連年の積雪深の変動の影響を大きく受けることがわかった。各林分の樹高および根元曲がりの量の平均値は, 20m幅林, 15m幅林, 10m幅林, 二段林の順に大きかった。20m幅林の数個体に根元割れによる雪害の発生がみられ, それらの個体は根元曲がりの量の年間増加率が林分平均値を大きく上回る埋雪木であることがわかった。帯状林内には積雪の極端な吹き溜まりが生じて局所的な豪雪箇所が形成され, そのことが雪害発生の原因となっていることも判明した。

DOI： 10.11519/jjfs1953.78.1_61

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記述言語：日本語   出版者・発行元：森林立地学会  

奥羽山脈中央部に位置する焼石岳南麓の多雪斜面における積雪動態と樹木の生態的特性との関係について調べた。低木形態をとる落葉広葉樹林の大半は厳冬期季節風に対する風背斜面に分布していた。風背斜面には積雪グライドに起因する雪ジワと雪割れ目が広範囲にわたって分布し,しばしば全層雪崩の痕跡も観察された。林地には積雪挙動による浸食地形がみられた。他方,風衝斜面には中・大径木の根返りに伴って形成されたピットとマウンドが数多く観察され,斜面形は凹凸が連続する階段状であった。風背斜面に優先する樹種は,ヒメヤシャブシ,タニウツギ,ブナなどであり,風衝斜面に優占する樹種は,ブナ,マルバマンサク,ハウチワカエデなどであった。風背斜面の森林は風衝斜面の森林と比較してサイズがきわめて小さく,傾幹幅が異常に大きい葡匐形態をとっていた。傾幹幅には樹種による違いが認められるとともに,優占順位の高い樹種の傾幹幅は風背斜面では大きく,風衝斜面では小さかった。風背斜面においては積雪移動圧に対し,風衝斜面においては積雪沈降圧に対して適応した樹種が個体維持に有利であると考えられた。いずれの斜面にも出現するブナは,積雪移動圧よりもむしろ積雪沈降圧が卓越する積雪環境に適応した,耐雪性の高い樹種であると考えられた。多雪斜面に生育する樹木の個体維持は,風背斜面においては主に萌芽・伏条による更新に,風衝斜面においては主に実生による更新に依存していると考えられた。そのような樹木の生態的な特性は積雪環境の違いを反映し,群落分布に係わる積雪環境要因としては,単に積雪の量だけではなく,積雪の変態過程の違いというような質的要素や,積雪グライド・雪崩などの積雪挙動が重要な役割を果たしていると考えられた。

DOI： 10.18922/jjfe.37.2_59

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記述言語：日本語   出版者・発行元：日本生態学会  

P. pumila grows in alpine regions from central Japan to E Siberia and generally forms dwarf scrub. The ecological features of P. pumila were reviewed, focusing especially on its dry matter production and process of regeneration. Based on the annual above-ground net production and gross production of the pine forest, the carbon allocation pattern and efficiency of energy fixation were discussed. The reproduction style of P. pumila is characterized by two different phases: seedling establishment as a result of seed dispersal by nutcrackers, and regeneration by layering in the mature trees. -from English summary

DOI： 10.18960/seitai.45.1_57

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BLACKWELL SCIENCE  

Aboveground net production rates of the subalpine stone pine (Pinus pumila) forests in central Japan were estimated by the summation method; net production was defined as the sum of annual biomass increment and annual loss due to death. In the two pine stands of different scrub heights, P1 (200 cm) and P2 (140 cm), aboveground biomass reached 177 and 126 ton ha-1, respectively. Leaf biomass was about 14 ton ha-1 in each stand. The estimates of aboveground net production during the 2 year period (1987-1989) averaged 4.1 and 3.7 ton ha-1 y-1 in P1 and P2, respectively, which were at the lowest among the pine forests in the world. Two indices of efficiency of energy fixation, that is, the ratio of net production to the total radiation during a growing season and the ratio of net production to total radiation per unit of leaf weight, were evaluated. Both efficiency indices for the two P. pumila stands fell in the range obtained for other Japanese evergreen conifer forests. This suggested that the low annual net production of the stone pine stands were mainly due to a limitation in the length of the growing season. The pine forests were also characterized by a small allocation (about 17%) of aboveground net production into biomass increment, in comparison with other evergreen conifer forest types. Annual net carbon gain in the P. pumila forests was suggested to be largely invested in leaf production at the expense of the growth of woody parts.

DOI： 10.1007/BF02347495

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：HERON PUBLISHING  

Seasonal shoot dynamics of Japanese mountain stone pine (Pinus pumila Regel.) growing at six sites with different altitudes and slope aspects on the Kiso mountain range in central Japan were investigated. The shoots followed a similar growth pattern at all sites; current shoots elongated rapidly during June and July, and the current needles grew during July and August. Final lengths of the current shoots and needles decreased with increasing altitude. Current-shoot lengths were also shorter at the windward sites than at the leeward sites. At all sites, leaf senescence occurred intensively between mid-August and mid-September. Needle longevity, i.e., the age of the oldest living needle attached to a shoot, increased with increasing altitude. Fascicle density, i.e., the number of current needle fascicles on a unit shoot length, was greater at higher altitudes and windward sites than at lower altitudes and leeward sites.
Seasonal dynamics of the P. pumila shoots were characterized by simultaneous replacement of old needles with new needles in the early autumn, thus avoiding any loss of canopy photosynthetic production during the growing season. Increases in needle longevity and fascicle density were associated with declining air temperature and increasing wind exposure. Needle longevity and fascicle density were characteristics of adaptive plasticity in P. pumila that prevent a reduction in growth potential in the stressful conditions of alpine regions.

DOI： 10.1093/treephys/13.1.41

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BLACKWELL SCIENCE  

Size, biomass and spatial distribution patterns of belowground woody organs of Pinus pumila trees were investigated. Dry weight estimates of five sample trees were between 14 and 36 kg tree-1. Belowground stems accounted for about 3 2 % of the total tree weight. However, the belowground stems had extensive barkless portions, indicating that the decomposition of dead belowground stems was an important source of organic matter in the soil. The basal diameters of adventitious roots tended to become smaller as their orginating positions neared the ground surface. It was suggested that P. pumila trees regenerate by successively producing adventitious roots from their buried stems and moving down the slope.

DOI： 10.1007/BF02347100

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer-Verlag  

Rates of net photosynthesis and dark respiration were measured for detached needles of Pinus pumila trees growing on the Kiso mountain range in central Japan in 1987. Dependency of photosynthesis on light and temperature was examined in relation to needle age and season. The light saturation point of net photosynthesis was lower in 3- and 4-yr-old needles than that in current (flushed in 1987), 1- and 2-yr-old needles. Pnmax, net photosynthetic rates at 1000 μmol m-2 s-1 and 15°C, of needles from 1- to 4-yr-old generally decreased with needle age. Pnmax of 1- to 4-yr-old needles became higher in August than in other months, and Pnmax of current needles did so in September. Current needles showed high respiration rates (at 15°C) only in August. Optimum air temperatures for net photosynthesis at 1000 μmol m-2 s-1 were between 10 and 15°C for current and 1-yr-old needles. The temperature coefficient of dark respiration rates was 2.3-3.3 for current needles from August to October, and 2.2 for 1-yr-old needles in mid-July. © 1990 the Ecological Society of Japan.

DOI： 10.1007/BF02347008

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer-Verlag  

Aboveground biomass and litterfall of Pinus pumila scrubs, growing on the Kiso mountain range in central Japan, were investigated from 1984 to 1985. The biomass of two research plots (P1 and P2) with different scrub heights was estimated by two methods, the stratified clip technique and the allometric method. Aboveground total biomass estimated by the latter method reached 181 ton d.w. ha-1 in P1 and 132 ton d.w. ha-1 in P2. Creeping stems contributed to about half of the total biomass. Although estimates of woody organs differed between the two plots, leaf biomass estimates were almost the same at 15.5 ton d.w. ha-1. The canopies of the two P. pumila scrubs were characterized by a large mean leaf area density of 5.0 m2 m-3. Despite this large area density, relatively moderate attenuation of light intensity was observed. Specific leaf area generally increased with reduced leaf height. Annual total litterfall was estimated to be 3.60 ton d.w. ha-1 yr-1 in P1 and 2.39 ton d.w. ha-1 yr-1 in P2. Annual leaf fall in both plots was approximately 2.0 ton d.w. ha-1 yr-1. Leaves fell mainly in early autumn. Annual loss rates of branches, estimated as the sum of annual branch litterfall and the amount of newly formed attached dead branches, were 0.29 ton d.w. ha-1 yr-1 in P1 and 0.37 ton d.w. ha-1 yr-1 in P2. © 1989 Ecological Society of Japan.

DOI： 10.1007/BF02346943

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記述言語：日本語

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記述言語：日本語   出版者・発行元：森林総合研究所  

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記述言語：日本語   出版者・発行元：大日本山林会  

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DOI： 10.4005/jjfs.98.135

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記述言語：日本語  

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記述言語：日本語   出版者・発行元：日本森林学会  

近年，再造林の低コスト化の一環でコンテナ苗の利用・導入が検討されている．しかし，コンテナのキャビティ容量の制限により根系成長が抑制されたり，伐採時期により植栽時期が左右されたりするため，コンテナ苗は特に夏の植栽後に乾燥条件にさらされやすい．そこで本研究は2年生ヒノキコンテナ苗を対象に，摘葉による乾燥ストレスの回避効果を検討した．2015年7月に，苗長の75%から分枝する側枝を切除した摘葉区と対照区を設定し，両区で潅水を停止し水分特性を調べた．その結果，摘葉区では対照区よりも木部通水阻害率がやや高い傾向があったものの，葉の水ポテンシャル（Ψ）は高かった．一方，対照区では全ての個体でΨが著しく低下し葉が乾燥した．7月に各区の一部の個体を森林総研関西の苗畑に植栽したところ，降雨等の影響で2ヶ月後も両区で乾燥により枯死した個体はなかった．対照区では細根量が増加し，Ψおよび木部通水阻害率は摘葉区と同程度であった．以上より，摘葉処理は短期的に葉の乾燥回避の効果がある一方で，夏期でも植栽後の土壌水分条件が良好な場合は，無摘葉個体でも根系が増加し乾燥ストレスを受けにくくなることが示唆された．

DOI： 10.11519/jfsc.127.0_497

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記述言語：日本語   出版者・発行元：日本森林学会  

再造林の低コスト化を図る上で、コンテナ苗の利用が期待されている。苗木の品質は、移植後の活着や成長に大きな影響を及ぼすため、品質向上のための育苗技術の高度化が不可欠である。山出し苗は、出荷の際に根系が損傷し水分吸収機能が低下しており、植栽後枝葉からの蒸散が活発な状態であれば水分不足に陥りやすい。そこで、人為的な葉量の調整が、苗木の水分ストレス緩和に与える効果を検証した。２年生のヒノキコンテナ苗について、地面からの高さ75％、50％、25％までの主軸以外の枝葉を切除したものと、無摘葉の個体について、残った葉の最大光合成速度(Amax)、量子収率(Fv/Fm)、水欠差（WSD）を、灌水停止から６日目まで測定した。６日目でのAmaxは、75％区で最も高く、無摘葉区で最も低かった。一晩暗馴化した葉のFv/Fmは、３日目まではどの処理区も高い値で推移したが、日中に暗馴化させた後のFV/Fmは灌水停止翌日から低下し、６日目では摘葉率が高い個体ほどFv/Fmが高かった。葉のWSDは、無摘葉区で最も高く水分ロスが著しかった。以上から、摘葉することによって個体あたりの蒸散や光阻害が抑えられ、苗木の水分ストレスが緩和されることが示唆された。

DOI： 10.11519/jfsc.127.0_498

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Containerized tree seedlings are expected to exhibit high survivorship and good growth after outplanting; however, a unified consensus on the performance of containerized seedlings in Japan remains undetermined. To understand the universal properties of the performances of containerized seedlings after outplanting, the survival ratio and height and diameter growth rate of two stock types (containerized seedlings and bare-root seedlings) were estimated from 39 experiment sites covering five prefectures and five species and compared between stock types. The result of parameter estimation using hierarchal Bayesian models revealed that the median survival ratio of containerized seedlings across all species was 0. 96, which was not different from that of bare-root seedlings (0. 97). The estimated height and diameter growth rates were also similar between stock types. The sturdiness quotient (SQ, the ratio of height and diameter) was higher in containerized seedlings than in bare-root seedlings of all species immediately after outplanting. However, the difference in SQ between stock types diminished 1 year after outplanting. These results suggest that containerized tree seedlings generally show performances equivalent to those of bare-root seedlings after outplanting. Therefore, other properties of containerized seedlings, such as ease of cultivation and low-labor planting present more attractive advantages than those of good performance after outplanting.

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記述言語：日本語  

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記述言語：日本語   出版者・発行元：日本森林学会  

森林に降下した放射性セシウムは樹冠にトラップされたのち、林内雨や葉枝の脱落によって林床に移行していくと考えられる。そこで、森林内の放射性セシウムの動態を明らかにするため、リターフォールによる放射性セシウムの移行について調査を行った。茨城県石岡市のスギ林およびヒノキ林、茨城県城里町のスギ林および広葉樹林において、リタートラップを用いて樹冠より降下するリターフォールを採取した。サンプルは葉や枝などに分別・計重し、放射性セシウム濃度を測定した。そして重量と濃度から、単位面積あたりのセシウム濃度を求めた。スギ林からのリターフォールによる移行は、主に褐色葉によるものであったが、事故から2か月間、雄花による移行が多いことが明らかになった。城里町のスギ林では、褐色葉のセシウム濃度は指数的に減少しているものの、事故から2年経過後もリターフォールによる移行は継続していた。石岡市の調査地では森林内のセシウム蓄積量分布調査を、また城里町の調査地では林内雨のCs濃度の計測を行っている。リターフォールによる放射性セシウムの移行について、樹種やサイトの比較とともに、これらの結果との関係について考察を行う予定である。

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記述言語：日本語   出版者・発行元：森林総合研究所  

福島の原子力発電所事故に伴う森林の放射能汚染状況を調査するため、チェルノブイリ原子力発電所の事故後の汚染影響に関する研究経過や調査手法をレビューした。チェルノブイリの放射能汚染の影響は現在まで長期化しており、毎年多くの有用な報告が出ているが、欧州と日本とは気象条件、動植物相や土壌の状況が異なるので、福島の実際の現場における調査が重要であること、また、森林や木材中の放射性セシウム動態の長期モニタリングでは、調査対象や目的にあった適切な方法の選択や既存情報との連携が広域評価や将来予測に重要であることを議論した。

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記述言語：日本語  

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記述言語：日本語   出版者・発行元：日本治山治水協会  

東南アジアの熱帯雨林は，アフリカや南米の熱帯雨林に比べ樹高も高く，巨大なバイオマス(現存量)を誇っている(山田，1992)。この巨大なバイオマスは 約半分が炭素と考えられており，地球全体の中で貴重な炭素プールとなっている(吉良，1976,1983)。熱帯雨林の炭素蓄積量を推定するにはまず個々 の樹木のバイオマス推定が必要である。これまで地上部のバイオマス推定は，実際に樹木を伐倒し，各器官の重量を現場で実測して行われてきた。やっかいなの は地下部のバイオマス推定である。地上部を伐倒した上に，さらに根系を丸ごと掘り取る作業は大変な仕事である。しかし，温帯の樹木については先人の努力に よって，多くの樹種で根系の形態とバイオマスの概要が明らかになってきている(苅住，2010a,b)。では熱帯雨林の根系はどのくらい深く，どのような 形態で成長し，どれだけのバイオマスがあるだろうか？われわれはマレーシア半島のパソー森林保護区でこの課題に挑戦した。このパソー森林保護区は日本人研 究者とのつながりが深い。1970年代のIBP(International Biological Program，国際生物学計画)の中で，多くの日本人研究者がパソーの熱帯雨林の生産力測定や関連研究に関わり，大きな成果をあげた(Kato ら，1978; Kira, 1969, 1978b, a; Ogawa, 1978; Yoda, 1978; Yonedaら，1978)。このときに地上部の伐倒調査が行われ，精密な地上部バイオマスを推定するアロメトリー式が完成された(Kato ら，1978)。しかし，地下部については仮定を置いて一定割合を地下部バイオマスとして割り当てるに留まった(Kira，1978b)。この時代は世界 的に森林生態系の一次生産力を求めることに精力が注がれ，多くの森林で，平均のバイオマスと平均の一次生産力が網羅的に明らかになった(Cannell, 1982)。その後，エルニーニョや温暖化といった気候変動が話題になり，熱帯雨林が世界的な炭素収支にどのような役割を果たしているのかが問われるよう になってきた。このような背景の中，改めて土壌とともに地下部のバイオマスと炭素蓄積が重要との認識が高まった。しかし，マレーシアの熱帯雨林の木を伐倒 し，なおかつ地下部を掘り取って測定することは誰の目にも大変な作業と思われた。熱帯雨林の地下部調査を担当できる研究者を探したがなかなか見つからず， 結局，自分達でやることを決断した。樹木の根系は単にバイオマスとして炭素をため込んでいるだけではなく，地上部を支持する役割を持っている。また地表付 近の細根で栄養塩を吸収したり，垂直根で地下深くから水を吸い上げて葉に供給するなど，重要な生理，生態機能を担っている。しかしながら，巨大な熱帯雨林 の樹木では，掘り取ることの困難さから，その形態も機能もバイオマスもほとんどわかっていない状態であった。この報文ではNiiyamaら(2010)の 論文を中心に，現場の調査写真なども加えて，専門外の方々にも熱帯雨林の地下部の特性を理解してもらうことを目指した。目的は，根系の形態を簡単に記述 し，地下部バイオマスの測定方法について検討を行うこと，そして掘り取りデータから得られた熱帯雨林の地下部バイオマスの推定式を解説し，得られた地下部 バイオマスの推定値を議論することである。

DOI： 10.20820/suirikagaku.58.5_104

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記述言語：日本語   出版者・発行元：日本森林学会  

福島県内の川内村、大玉村、只見町の森林8プロットにおける3年間の調査に基づき、、セシウム137(&lt;sup&gt;137Cs&lt;/sup&gt;) 蓄積量(Bq/m&lt;sup&gt;2&lt;/sup&gt;)の土壌中での垂直分布状況の経年変化を検討した。堆積有機物(O)層と土壌(0-5, 5-10, 10-15, 15-20cm)4層位を解析対象とした。いずれの試験地でも&lt;sup&gt;137&lt;/sup&gt;Cs蓄積量はO層＞土壌(0-5cm深)＞土壌(5-20cm深)の順であり、土壌深度が増すにつれて&lt;sup&gt;137&lt;/sup&gt;Cs蓄積量は指数関数的に低下していた。多くの試験地では、2011から2012年にかけてO層中の&lt;sup&gt;137&lt;/sup&gt;Cs蓄積量が減少し、土壌(0-5cm深)の&lt;sup&gt;137&lt;/sup&gt;Cs蓄積量が増加し、2012から2013年にかけてはO層と土壌(0-5cm深)の&lt;sup&gt;137&lt;/sup&gt;Cs蓄積量はほとんど変化しなかった。ただし、一部のプロットでは2012から2013年にかけて土壌(0-5cm深)の137Cs蓄積量が減少していた。土壌(5-20cm深) の&lt;sup&gt;137&lt;/sup&gt;Cs蓄積量は、O層と土壌(0-20cm深)の3.9～15.0%（2011年）、2.8～13.3%(2012年)、5.8～22.1%（2013年）であり、調査期間を通して多くの137CsがO層と土壌最表層に留まっていることが明らかになった。

DOI： 10.11519/jfsc.125.0_396

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記述言語：日本語   出版者・発行元：日本森林学会  

スギ花粉症対策の一つには、発生源のスギ林を間伐等で適切に管理して花粉生産自体を抑制しようとする方向がある。なかでも、雄花を多くつける個体を優先的に間伐する手法（多雄花木間伐）は、立地や間伐率など条件しだいで有効になる場合が示唆されていた。本研究では、こうしたアプローチの可能性を検討するために、千葉県と京都府の2ヶ所のスギ林（約30年生）において、間伐率を揃えて通常の定性間伐（いわゆる下層間伐）と雄花生産量を比較する試験を行った。雄花の生産量の指標には、個体（目視による５段階の着花程度の評価）と林分（トラップ法による脱落量測定）の両レベルでのデータを収集した。今回は、試験開始から4年分の経過データの解析結果について、おもに千葉県の試験地での結果を中心に報告する。スギの雄花（花粉）生産は、およそ5年に1回程度で大豊作になることがわかっているが、これまでの試験結果から、こうした豊作年では多雄花木間伐区では通常間伐区に比べて花粉（雄花）生産量が少なくなる傾向が認められた。報告では、こうした結果を生じたメカニズムを考察するとともに、この間伐法を現場に適用する際の問題点なども検討する。

DOI： 10.11519/jfsc.125.0_87

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記述言語：日本語   出版者・発行元：一般社団法人日本土壌肥料学会  

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記述言語：日本語   出版者・発行元：国際緑化推進センター  

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記述言語：日本語   出版者・発行元：国際緑化推進センター  

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記述言語：日本語   出版者・発行元：国際緑化推進センター  

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記述言語：日本語   出版者・発行元：日本森林学会  

DOI： 10.11519/jfsc.123.0.Pa111.0

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記述言語：日本語   出版者・発行元：日本生態学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本土壌肥料学会  

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記述言語：日本語   出版者・発行元：日本地形学連合  

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その他リンク： http://id.nii.ac.jp/1141/00110477/

記述言語：日本語   出版者・発行元：Faculty of Science, Tohoku University  

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記述言語：日本語  

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記述言語：日本語  

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