Faculty Profiles - KOTANI, Ayumi

Presentations -

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Winter Soil Temperature and Growing Season Net COĉ Exchange in Eastern Siberian Larch Forests International coauthorship International conference

A. Kotani, T. Hiyama, T. Nakai, T. C. Maximov

7th International Symposium on Arctic Research 2023.3.8

常緑広葉樹林の葉面積指数測定方法の不安定性とその改善－林床からの光学的な4手法の比較－

給樂巴幹，田中隆文，小谷亜由美，中沖元哉

水文・水資源学会日本水文科学会2022年度研究発表会 2022.9.6

東シベリアの落葉針葉樹林における冬季温度と植物成長期のCO2収支

小谷亜由美，中井太郎，檜山哲哉

水文・水資源学会日本水文科学会2022年度研究発表会 2022.9.7 水文・水資源学会　日本水文科学会

Event date： 2022.9

Language：Japanese Presentation type：Oral presentation (general)

Venue：京都

高緯度陸域生態系とくに永久凍土上の落葉針葉樹林での森林CO2吸収量の変動への温度上昇などの気候変動の影響を明らかにすることを目的として，東シベリアのレナ川中流域のカラマツ林における，森林気象およびCO2フラックスの観測データを用いて，カラマツ展葉などの春季オンセット現象や森林－大気間のCO2フラックスの動態と冬季温度環境との関係を解析した．凍土表層の融解やカラマツの展葉など春のオンセット現象のタイミングには2週間程度の年々変動があり，必ずしも気温だけでなく前年凍結前の土壌水分やサイトごとの植生や活動層の水分状態に依存した．春季（5月）のCO2フラックスは成長期間総量に比べて1桁小さいがこれらの間には相関があり，その年々変動には4月の気温（正相関），前年の夏―秋の気温（負相関）に加えて，冬季の地温との相関がみられた．冬季の積算寒度は5月のCO2吸収の光応答パラメータとの相関を示し，冬季の冷却が翌年春の植物活動の開始および成長期間のCO2フラックスに影響を及ぼすことが示唆された．春季のCO2フラックスの年変動に対して，気温よりも地温が重要とする結果が得られたが，冬季地温には土壌凍結を通して土壌水分の増減が影響を及ぼすことから，前年の暖候期の気候や植物・土壌プロセスの結果としての土壌水分のメモリー効果を考える必要がある．

はげ山履歴がなく長大斜面を有する森林流域の水文過程への着眼と観測の開始

中沖元哉，田中隆文，小谷亜由美，金森直人，津田その子，中瀬孝

水文・水資源学会日本水文科学会2022年度研究発表会 2022.9.6

Forest carbon cycle based on tower flux observation Invited

Ayumi Kotani

National Summer Field School "Greenhouse Gases and Climate: Monitoring, Manipulation, Modeling and Management“ 2022.8.15 Institute of Biological Problems of Cryolithozone SB RAS (IBPC) Yakut Scientific Center SB RAS

Spatio-temporal variability of vegetation response to climate in the forest-tundra ecotone of northeastern Siberia

Yohei Kurosawa, Ayumi Kotani, Takafumi Tanaka

Japan Geoscience Union meeting 2022 2022.5.27

東シベリア森林における陸面乾湿変動と大気境界層の応答

小谷亜由美

水文・水資源学会2021年度研究発表会 2021.9.16

Seasonality of public interest in trees detected by internet search activity International conference

Ayumi Kotani

the All-Russian Conference with International Participation: THE ROLE OF BOTANICAL GARDENS IN THE CONSERVATION AND ENRICHMENT OF NATURAL AND CULTURAL FLORA 2021.7.13 North-Eastern Federal University

Decadal scale variation of permafrost active layer thickness at larch forests in eastern Siberia

A. Kotani, T. Nakai, T. Hiyama,T. Yamazaki, T. Ohta

The 11th Symposium on Polar Science 2020.12

Collaborative study of ecosystem carbon and water cycles in eastern Siberia

A. Kotani

NORTHERN SUSTAINABLE DEVELOPMENT FORUM 2020.9

Effect of precipitation on interannual variability of permafrost active layer thickness at larch forests in eastern Siberia

A. Kotani, T. Hiyama, T. Nakai, T. Yamazaki, T. Maximov

Japan Geoscience Union meeting 2020 2020.7

Altering seasonal transition of surface energy fluxes in larch forest on permafrost: warming spring and wetting autumn International conference

東シベリア森林における陸面乾湿変動下の大気境界層の特徴

小谷亜由美

日本気象学会秋季大会

Variability in seasonal transition indices and surface energy balance in larch forest of eastern Siberia International conference

Factors influencing the variation of CO2 flux and evapotranspiration in larch forest ecosystem affected by the extreme wet-soil condition International conference

Response of larch forest ecosystem to wetting permafrost active layer in eastern Siberia International conference

東シベリアのカラマツ林における永久凍土の季節融解層

小谷亜由美，太田岳史，檜山哲哉，マキシモフ

水文・水資源学会研究発表会

Variation of seasonal thaw depth at permafrost larch forest in eastern Siberia

東シベリアカラマツ林における永久凍土季節融解深

小谷亜由美，中坪稔，中井太郎，太田岳史

第129回日本森林学会大会

Active-layer thickness at permafrost larch forests in eastern Siberia International conference

Kotani, A., Nakatsubo, M., Ohta, T., Hiyama, T., Iijima, Y., Maximov

Fifth International Symposium on Arctic Research (ISAR-5)

Response of larch forest CO2 exchange on wetness variability of permafrost active layer in eastern Siberia International conference

Kotani, A., Ohta, T., Maximov, T.C.

The 2nd Asian Conference on Permafrost

Variation of larch tree transpiration and forest evapotranspiration at eastern Siberia - effect of hydro-thermal condition in active layer of permafrost

Effect of variation of environmental factors on forest evapotranspiration : Comparison in eastern Siberian larch forests

The Japanese Forest Society Congress

Turbulence in and above larch forest canopies in eastern Siberia

kamikura yoshito, Kotani Ayumi, Ohta Takeshi

The Japanese Forest Society Congress

Effects of vegetational change on root water uptake of larch forests in Eastern Siberia

Yamada Takuya, Ohta Takeshi, Kotani Ayumi

The Japanese Forest Society Congress

Interannual variability of surface heat balance and atmospheric boundary layer in Siberian and Mongolian boreal forest

Galtbayar Saruul, Kotani Ayumi, Ohta Takeshi

The Japanese Forest Society Congress

Evapotranspiration and carbon dioxide fluxes over larch forests with different soil water condition at eastern Siberia International conference

4th International Symposium on Arctic Research (ISAR-4)

常緑落葉混交林におけるCO2吸収期間の年変動

小谷亜由美

日本農業気象学会研究発表会

Evapotranspiration at Larch forest in Eastern Asia : a wavelet analysis across multiple time scales

nakatsubo Minoru, Kotani Ayumi, Ohta Takeshi

Proceeding of Annual Conference

Event date： 2015

Language：Japanese Presentation type：Oral presentation (general)

We analyzed the relationships between evapotranspiration and environmental factors using dataset of east Eurasian larch forest of eastern Siberia, northern Mongolia and Japan for the purpose of understanding the relationships between the forests and environmental changes.  We used the wavelet analysis across multiple timescales. We selected environmental factors, including soil water content, short-wave radiation, air temperature and water vapor deficit to analyze co-variability with the evapotranspiration. There was difference in the timescale in which co-variability is stronger than the other site. Siberian and Mongolian forest have stronger co-variability in the seasonal variation, while Japanese forest has stronger one in relatively short timescale. And the factors that have a great site-to-site difference in co-variability were soil water content and water vapor deficit. Both of them express the water condition at the forest. Therefore, the main reason of difference in site-to-site is water condition in the forest both of above and belowground.

DOI： 10.11520/jshwr.28.0_100075

Effects of interception loss on changing PAI and rainfall intensity by using artificial rainfall system

Yamada Atsushi, Ohta Takeshi, Kotani Ayumi

The Japanese Forest Society Congress

Evapotranspiration at Larch forests in Eastern Asia: a wavelet analysis across multiple time scales

Nakatsubo Minoru, Ohta Takeshi, Kotani Ayumi

The Japanese Forest Society Congress

Role of soil texture and canopy composition on evapotranspiration and CO2 exchange over larch forest International conference

小谷亜由美・太田岳史・AV Kononov・TC Maximov

8th annual international symposium on "C/H2O/energy balance and climate over boreal and arctic regions with special emphasis on eastern Siberia"

常緑落葉混交林における二酸化炭素交換量と吸収期間の年変動

小谷亜由美・太田岳史

日本気象学会秋季大会

東シベリアのカラマツ林でみられる凍土・森林・大気のかかわり

小谷亜由美

日本雪氷学会雪氷研究大会/気象水文・凍土合同分科会

D351 常緑落葉混交林における二酸化炭素交換量と吸収期間の年変動(大気-陸面間の水・エネルギー・炭素フラックスに関する最新研究2014,スペシャル・セッション)

小谷亜由美, 太田岳史

大会講演予講集

Primary factors in interannual variation of latent heat fluxes from overstory and understory in Siberian larch forest

Saito Atsushi, Kotani Ayumi, Ohta Takeshi, Iijima Yoshihiro

The Japanese Forest Society Congress

Characteristics of long term evapotransration and responses in a evergreenand deciduous forest

innnami kento, Ohta Takeshi, Kotani Ayumi, Nakai Taro

The Japanese Forest Society Congress

Analysis of characteristics of evapotranspiration in northern Namibia for introducing the mixed cropping of rice and pearl millet

Hanamura Miho, Ohta Takeshi, Kotani Ayumi, Hiyama Tetsuya, Jack Kambatuku, Iijima Morio

Proceeding of Annual Conference

Event date： 2014

Language：Japanese Presentation type：Oral presentation (general)

In order to introduce mixed cropping of rice and pearl millet, the effect of mixed cropping on evapotranspiration in a small seasonal wetland (<i>ondombe</i>) of northern Namibia was investigated. An experimental sloped-field was established to irrigate spatially different in water levels. Meteorological observation including Bowen-ratio technique was conducted at two sites of different surface conditions in the field. Net radiation and latent heat flux at the lower site was larger than the upper site without water surface, while sensible heat flux is smaller at the lower site than at the upper site. The responses of the surface conductance to the environmental variables were investigated by means of Jarvis-type conductance model. It has been shown that soil water content was an important factor for evapotranspiration at both of sites. Continuous observation is required to clarify the effect of mixed cropping system on evapotranspiration characteristics in this region.

DOI： 10.11520/jshwr.27.0_100105

Flux-based water use efficiency over two larch forests with different soil and canopy structure at eastern Siberia International conference

Kotani A, Ohta T, Maximov T

American Geophysical Union fall meeting

Net ecosystem water use efficiency over two larch forests at eastern Siberia International conference

Kotani A, Ohta T, Kononov A, Maximov T

2nd International Conference on "Global Warming and the Human-Nature Dimension in Siberia

東シベリア森林地帯における大気陸面研究－タワーフラックス観測を中心に International conference

小谷亜由美・太田岳史

日本気象学会秋季大会

Hydrological studies of a larch forest at northeastern Siberia International conference

Kotani, A.

Russian-Japanese Symposium on Global Climate Change

Forest Evapotranspiration and CO2 Flux over Larch Forests with Different Canopy Structure at Eastern International conference

Kotani, A., Hayashi, M., Ohta, T.,Maximov, T.

11th Asiaflux international workshop

Palmer Drought Severity Indexを指標とした日本における乾燥/湿潤期間の時空間変動

高橋瑠想・小谷亜由美

地球惑星連合大会

東シベリアカラマツ林における二酸化炭素吸収特性

林美晴・小谷亜由美

地球惑星連合大会

Effects of waterlogging stress on photosynthetic rate and leaf element content in Quercus serrata

Ito Tsubasa, Ohta Takeshi, Kotani Ayumi, Tomioka Rie

The Japanese Forest Society Congress

The interannual variation of evapotranspiration and photosynthesis of the larch forest in Spasskaya Pad, Russia

Ohta Takeshi, Kotani Ayumi, Ito Syougo, Hanamura Miho, Iijima Yoshihiro, Maximov Trofim, Kononov Alexander

The Japanese Forest Society Congress

Analysis of characteristics of evapotranspiration in northern Namibia for introducing the mixed cropping of rice and pearl millet

Hanamura Miho, Ohta Takeshi, Kotani Ayumi, Suzuki Tetsuji, Hiyama Tetsuya, Jack Kambatuku, Iijima Morio

Proceeding of Annual Conference

Event date： 2013

Language：Japanese Presentation type：Oral presentation (general)

The northern Namibia is known as a semi-arid region, which involves both the risks of drought and flood. Under such an environment, there is the attempt to introduce the mixed cropping of rice and pearl millet in the seasonal wetland for stable food supply. We installed the Bowen ratio measurement systems in the two model fields on the gentle slope: the upper site (pearl millet, unirrigated) and lower site (rice, deep-water irrigated). Measurements of the environmental variables and ET started since Sep. 2012. In this study, we analyze the evapotranspiration characteristics in the model field comparing ET difference between irrigated lower site and unirrigated upper site before planting the crops, including dry and rainfall periods.

DOI： 10.11520/jshwr.26.0.270.0

Vegetation change of whole ecosystem and understory vegetation in eastern Siberian boreal forest

Saito Atsushi, Kotani Ayumi, Ohta Takeshi, Iijima Yoshihiro, Maximov Trofim, Kononov Alexander

The Japanese Forest Society Congress

Effects of Forest structure on the Evapotranspiration

Miyagi Yu, Matsumoto Kazuho, Ohta Takeshi, Nakai Taro, Daikoku Ken'ichi, Sumida Akihiro, Iida Shin'ichi, Kotani Ayumi, Takashima Atsushi, Trofim C. Maximov, Hara Toshihiko, Taniguchi Shingo

The Japanese Forest Society Congress

Net ecosystem exchange of CO2 and Evapotransipration over Siberian boreal forests

Kotani Ayumi, Hayashi Miharu, Ohta Takeshi, Maximov Trofim

The Japanese Forest Society Congress

東シベリア森林における陸面乾湿変動と大気境界層の応答

小谷亜由美

水文・水資源学会研究発表会 2021.9

東シベリア南部のカラマツ林における群落蒸発散 International conference

小谷亜由美，太田岳史，Ｔマキシモフ

第123回日本森林学会

P1a6 陸域生物圏モデルBEAMSを用いたシベリア地域の水、エネルギー、炭素収支解析(ポスター・セッション)

相庭一輝, 佐々井崇博, 小谷亜由美, 太田岳史

大会講演予講集

Ecohydrological changes in relation to moistened active layer in eastern Siberia

Iijima Yoshihiro, Kotani Ayumi, Ohta Takeshi, Maximov Trofim

Proceedings of the General Meeting of the Association of Japanese Geographers

Event date： 2012

Language：Japanese Presentation type：Oral presentation (general)

Deepening of the active layer due to moisture saturation within the soil has negatively impacted the growth of larch forests near Yakutsk, eastern Siberia. According to sap flow measurements, transpiration from larch trees was reduced at the concave micro-topography with the deepening and moistening of the active layer. Perennial waterlogged conditions led to mortality of mature trees. Several trees with reduced amounts of foliage showed a remarkable reduction in stomatal conductance during the 2009 growing season. These findings indicate that wetting trends in a permafrost region may lead to unexpected ecohydrological responses with respect to permafrost degradation in eastern Siberia.

DOI： 10.14866/ajg.2012s.0_100034

Seasonal variability of scalar turbulent transport above forest canopy

Kotani Ayumi, Hamazaki Shunki, Ohta Takeshi

Proceeding of Annual Conference

Event date： 2012

Language：Japanese Presentation type：Oral presentation (general)

This study investigates seasonal variation in applicability of the turbulent similarity theory, and similarity or dissimilarity in the scalar transfer characteristics observed over forest canopy in the tropical monsoon, temperate, and boreal region. Deviation from the similarity theory and the small transfer efficiency was observed for CO2 variation at the boreal and temperature variation at the cool-temperate forest. Forests including deciduous trees showed clear seasonal variation in not only scalar flux itself but also its transfer characteristics especially in the case of CO2 variation, while the evergreen forest did not present such seasonal variation.

DOI： 10.11520/jshwr.25.0.276.0

Interannual and seasonal change of surface energy balance in temperate mixed forest.:Relationship between energy balance closure and energy fluxes.

Tanaka Takayuki, Kotani Ayumi, Ohta Takeshi

The Japanese Forest Society Congress

Variability of evapotranspiration in an eastern Siberian larch forest over a 12 year period from 1998 to 2011:Effects of high soil water conditions on evapotranspiration

HANAMURA Miho, OHTA Takeshi, KOTANI Ayumi, ITO Shogo, MAXIMOV Trofim C., KONONOV Alexander V., MAXIMOV Ayal P.

The Japanese Forest Society Congress

The variable factor of carbon dioxide flux in an eastern Siberian larch forest.

Ito Shogo, Ohta Takeshi, Kotani Ayumi, Maximov Trofirm, Kononov Alexander

The Japanese Forest Society Congress

Response of surface conductance, aerodynamic conductance and evapotranspiration to ambient conditions in boreal to tropical forests in eastern Asia:Sensitivity analysis of evapotranspiration through surface conductance and aerodynamic conductance

Khatun Rehana, Ohta Takeshi, Kotani Ayumi

Comparison of water and carbon flux over different forest in eastern Siberia

Kotani Ayumi, Ohta Takeshi, Maximov Trofim, Kononov Alexsader

The Japanese Forest Society Congress

Comparison of CO2 flux between two eastern Siberian boreal forests.

Hayashi Miharu, Ohta Takeshi, Kotani Ayumi, Maximov Trofim

The Japanese Forest Society Congress

The causes of deviations from turbulent similarity in the atmospheric boundary layer above forests

HAMAZAKI Shunki, KOTANI Ayumi, OHTA Takeshi

The Japanese Forest Society Congress

Interannual variation of the carbon dioxide flux in an eastern Siberian larch forest

ito shogo, Ohta Takeshi, Kotani Ayumi, Trofirm Maximov, Alexander Kononov

The Japanese Forest Society Congress

Comparison of C/H2O/energy fluxes over boreal forest introduction of new measurement site at southern part of Lena basin International conference

5th International Workshop on 'C/H2O/Energy balance and climate over boreal and arctic regions with special emphasis on eastern Eurasia'

Event date： 2010.11

Language：English Presentation type：Poster presentation

To improve our understanding of C/H2O/energy exchange over eastern Siberia boreal forest, new observation was started at a larch dominated forest in the southern part of Lena basin as part of the project “Global Warming and the Human-Nature Dimension in Siberia: Social Adaptation to the Changes of the Terrestrial Ecosystem, with an Emphasis on Water Environments" funded by the Research institute for Humanity and Nature (RIHN, Kyoto).
The new station named Elgeeii (60° 0´N, 133° 49´E) is

東シベリアのカラマツ林における水・熱・炭素交換の比較研究－レナ川南東部の新サイトでの観測開始と初期解析の結果－

太田岳史　トロフィーム・マキシモフ　アレクサンダー・コノノフ

第121回日本森林学会大会

Regional differences on multi-temporal variation of environmental factors controlling forest evapotranspiration

Yoshida Megumi, Ohta Takeshi, Kotani Ayumi

The Japanese Forest Society Congress

Water/Energy/Carbon exchange of two larch forests in eastern Siberia

Kotani Ayumi, Ohta Takeshi, Yoshida Ryuhei, Yoshida Megumi, Inoue Gen, Maximov Trofim

The Japanese Forest Society Congress

Impacts of extreme wet soil water content on surface conductance:Results obtained from the observation in a larch forest, eastern Siberia

OHTA Takeshi, KOTANI Ayumi, IIJIMA Yoshihiro, NAKAI Taro, MAXIMOV Trofim

The Japanese Forest Society Congress

*Detecting a difference in phenological status using scalar dissimilarity observed above the forest canopy International conference

Asiaflux workshop 2009

Dameges in eastern Siberian Taiga due to too long and too heavy wet soil water condition

OHTA Takeshi, KOTANI Ayumi, NAKAI Taro, MAXIMOV Trofim

The Japanese Forest Society Congress

Environmental factors affecting fluctuations of forest evapotranspiration on a multi-temporal scale in an eastern Siberian larch forest

Yoshida Megumi, Ohta Takeshi, Kotani Ayumi, Tanaka Takafumi, Maximov Trofim

The Japanese Forest Society Congress

*Characteristics of surface energy balance at boreal forest -comparison of Yakutsk and northern Mongolian larch forest International conference

The 4th annual international workshop on "C/H2O/energy balance and climate over boreal regions with special emphasis on eastern Eurasia"

モンゴル北東部・疎密度草原における熱輸送パラメタリゼーション

小谷亜由美, 杉田倫明

水文・水資源学会2007年大会

粗密度草原における熱輸送パラメータの推定

小谷亜由美, 杉田倫明

日本気象学会2007年春季大会

Parameterization of Heat Transfer between the Land Surface and the Atmosphere in Mongolian Steppe

The 4th International Workshop on Terrestrial Change in Mongolia

航空機観測データを用いた混合層分散法による地表面フラックスの推定

小谷亜由美, 杉田倫明

日本気象学会2006年春季大会，分科会「種々の地表面上に発達する大気境界層の観測とモデリングに関する研究の現状と将来展望」

地表面フラックス推定のための混合層分散法の改良

小谷亜由美, 杉田倫明

水文・水資源学会2005年大会

Estimation of Surface Heat Fluxes around Kherlen River Basin by Airborne Turbulence Data International conference

The 1st International Symposium on Terrestrial and Climate Change in Mongolia

航空機観測データを用いた混合層分散法による地表面フラックスの推定

小谷亜由美, 杉田倫明

日本気象学会2005年春季大会

Aircraft Turbulence Measurements to Estimate Surface Heat Fluxes from the Mixed Layer Variance Methods over Semi-arid Grassland International conference

he 6th International Study Conference on GEWEX in Asia and GAME

Aircraft Measurements to Estimate Surface Heat Fluxes from the Mixed Layer Variance Methods over Semi-arid Grassland

The 3rd International Workshop on Terrestrial Change in Mongolia

航空機データを用いた広域地表面フラックスの推定

小谷亜由美, 杉田倫明

地球惑星関連学会2004年合同大会

半乾燥地域における大気・陸面間の熱・水交換過程の解明―航空機観測による地表面フラックスの推定

小谷亜由美

日本地理学会「水環境の地理学」研究グループ第18回研究集会

地目混在地域における広域熱・水蒸気フラックスと地表面被覆との関係

小谷亜由美，杉田倫明，宮田明，萩野谷成徳，飯田真一

地球惑星関連学会2003年合同大会

地目混在地域における広域熱フラックスと地表面被覆との関係

小谷亜由美，杉田倫明，宮田明，萩野谷成徳，飯田真一

日本気象学会2003年春季大会

Active-layer thickness at permafrost larch forests in eastern Siberia

Kotani, A, Nakatsubo, M, Ohta, T, Hiyama, T, Iijima, Y, Maximov

Fifth International Symposium on Arctic Research (ISAR-5) 2018.1.16

東シベリア森林地帯における大気陸面研究－タワーフラックス観測を中心に

小谷亜由美, 太田岳史

日本気象学会秋季大会 2013.11.19

東シベリア森林における陸面乾湿変動下の大気境界層の特徴 International conference

小谷亜由美

日本気象学会秋季大会 2019.10.30

東シベリア南部のカラマツ林における群落蒸発散

小谷亜由美, 太田岳史, Tマキシモフ

第123回日本森林学会 2012.3.27

Comparison of CO2 flux between two eastern Siberian boreal forests. International conference

Hayashi Miharu, Ohta Takeshi, Kotani Ayumi, Maximov Trofim

The Japanese Forest Society Congress 2011 THE JAPANESE FORESTRY SOCIETY

Net ecosystem exchange of CO2 and Evapotransipration over Siberian boreal forests International conference

Kotani Ayumi, Hayashi Miharu, Ohta Takeshi, Maximov Trofim

The Japanese Forest Society Congress 2013 THE JAPANESE FORESTRY SOCIETY

Vegetation change of whole ecosystem and understory vegetation in eastern Siberian boreal forest International conference

Saito Atsushi, Kotani Ayumi, Ohta Takeshi, Iijima Yoshihiro, Maximov Trofim, Kononov Alexander

The Japanese Forest Society Congress 2013 THE JAPANESE FORESTRY SOCIETY

Variability of evapotranspiration in an eastern Siberian larch forest over a 12 year period from 1998 to 2011:Effects of high soil water conditions on evapotranspiration International conference

HANAMURA Miho, OHTA Takeshi, KOTANI Ayumi, ITO Shogo, MAXIMOV Trofim C, KONONOV Alexander V, MAXIMOV Ayal P

The Japanese Forest Society Congress 2011 THE JAPANESE FORESTRY SOCIETY

Interannual variation of the carbon dioxide flux in an eastern Siberian larch forest International conference

ito shogo, Ohta Takeshi, Kotani Ayumi, Trofirm Maximov, Alexander Kononov

The Japanese Forest Society Congress 2011 THE JAPANESE FORESTRY SOCIETY

Turbulence in and above larch forest canopies in eastern Siberia International conference

kamikura yoshito, Kotani Ayumi, Ohta Takeshi

The Japanese Forest Society Congress 2017 THE JAPANESE FORESTRY SOCIETY

東シベリアカラマツ林における永久凍土季節融解深 International conference

小谷亜由美, 中坪稔, 中井太郎, 太田岳史

第129回日本森林学会大会 2018.3.27

Water/Energy/Carbon exchange of two larch forests in eastern Siberia International conference

Kotani Ayumi, Ohta Takeshi, Yoshida Ryuhei, Yoshida Megumi, Inoue Gen, Maximov Trofim

The Japanese Forest Society Congress 2010 THE JAPANESE FORESTRY SOCIETY

Effects of vegetational change on root water uptake of larch forests in Eastern Siberia International conference

Yamada Takuya, Ohta Takeshi, Kotani Ayumi

The Japanese Forest Society Congress 2017 THE JAPANESE FORESTRY SOCIETY

東シベリアカラマツ林における二酸化炭素吸収特性 International conference

林美晴, 小谷亜由美

地球惑星連合大会 2013.5.21

Primary factors in interannual variation of latent heat fluxes from overstory and understory in Siberian larch forest International conference

Saito Atsushi, Kotani Ayumi, Ohta Takeshi, Iijima Yoshihiro

The Japanese Forest Society Congress 2014 THE JAPANESE FORESTRY SOCIETY

Variation of larch tree transpiration and forest evapotranspiration at eastern Siberia - effect of hydro-thermal condition in active layer of permafrost International conference

2017.5.20

Environmental factors affecting fluctuations of forest evapotranspiration on a multi-temporal scale in an eastern Siberian larch forest International conference

Yoshida Megumi, Ohta Takeshi, Kotani Ayumi, Tanaka Takafumi, Maximov Trofim

The Japanese Forest Society Congress 2009 THE JAPANESE FORESTRY SOCIETY

The variable factor of carbon dioxide flux in an eastern Siberian larch forest. International conference

Ito Shogo, Ohta Takeshi, Kotani Ayumi, Maximov Trofirm, Kononov Alexander

The Japanese Forest Society Congress 2011 THE JAPANESE FORESTRY SOCIETY

東シベリアのカラマツ林における永久凍土の季節融解層 International conference

小谷亜由美, 太田岳史, 檜山哲哉, マキシモフ

水文・水資源学会研究発表会 2018.9.13

東シベリアのカラマツ林でみられる凍土・森林・大気のかかわり International conference

小谷亜由美

日本雪氷学会雪氷研究大会/気象水文・凍土合同分科会 2014.9.20

Ecohydrological changes in relation to moistened active layer in eastern Siberia International conference

Iijima Yoshihiro, Kotani Ayumi, Ohta Takeshi, Maximov Trofim

Proceedings of the General Meeting of the Association of Japanese Geographers 2012 The Association of Japanese Geographers

Language：Japanese Presentation type：Oral presentation (general)

Characteristics of long term evapotransration and responses in a evergreenand deciduous forest International conference

innnami kento, Ohta Takeshi, Kotani Ayumi, Nakai Taro

The Japanese Forest Society Congress 2014 THE JAPANESE FORESTRY SOCIETY

常緑落葉混交林における二酸化炭素交換量と吸収期間の年変動 International conference

小谷亜由美, 太田岳史

日本気象学会秋季大会 2014.10.23

常緑落葉混交林におけるCO2吸収期間の年変動 International conference

小谷亜由美

日本農業気象学会研究発表会 2015.3.17

Effect of variation of environmental factors on forest evapotranspiration : Comparison in eastern Siberian larch forests International conference

The Japanese Forest Society Congress 2017 THE JAPANESE FORESTRY SOCIETY

Effects of interception loss on changing PAI and rainfall intensity by using artificial rainfall system International conference

Yamada Atsushi, Ohta Takeshi, Kotani Ayumi

The Japanese Forest Society Congress 2015 THE JAPANESE FORESTRY SOCIETY

The interannual variation of evapotranspiration and photosynthesis of the larch forest in Spasskaya Pad, Russia International conference

Ohta Takeshi, Kotani Ayumi, Ito Syougo, Hanamura Miho, Iijima Yoshihiro, Maximov Trofim, Kononov Alexander

The Japanese Forest Society Congress 2013 THE JAPANESE FORESTRY SOCIETY

Interannual variability of surface heat balance and atmospheric boundary layer in Siberian and Mongolian boreal forest International conference

Galtbayar Saruul, Kotani Ayumi, Ohta Takeshi

The Japanese Forest Society Congress 2016 THE JAPANESE FORESTRY SOCIETY

Analysis of characteristics of evapotranspiration in northern Namibia for introducing the mixed cropping of rice and pearl millet International conference

Hanamura Miho, Ohta Takeshi, Kotani Ayumi, Suzuki Tetsuji, Hiyama Tetsuya, Jack Kambatuku, Iijima Morio

Proceeding of Annual Conference 2013 THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES

Language：Japanese Presentation type：Oral presentation (general)

Analysis of characteristics of evapotranspiration in northern Namibia for introducing the mixed cropping of rice and pearl millet International conference

Hanamura Miho, Ohta Takeshi, Kotani Ayumi, Hiyama Tetsuya, Jack Kambatuku, Iijima Morio

Proceeding of Annual Conference 2014 THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES

Language：Japanese Presentation type：Oral presentation (general)

Evapotranspiration at Larch forests in Eastern Asia: a wavelet analysis across multiple time scales International conference

Nakatsubo Minoru, Ohta Takeshi, Kotani Ayumi

The Japanese Forest Society Congress 2015 THE JAPANESE FORESTRY SOCIETY

Evapotranspiration at Larch forest in Eastern Asia : a wavelet analysis across multiple time scales International conference

nakatsubo Minoru, Kotani Ayumi, Ohta Takeshi

Proceeding of Annual Conference 2015 THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES

Language：Japanese Presentation type：Oral presentation (general)

Variation of seasonal thaw depth at permafrost larch forest in eastern Siberia International conference

2018.5.24

Variability in seasonal transition indices and surface energy balance in larch forest of eastern Siberia

2019.10.5

Role of soil texture and canopy composition on evapotranspiration and CO2 exchange over larch forest

小谷亜由美, 太田岳史, AV Kononov, TC Maximov

8th annual international symposium on "C/H2O/energy balance and climate over boreal and arctic regions with special emphasis on eastern Siberia" 2014.11.10

Khatun Rehana, Ohta Takeshi, Kotani Ayumi

2011

Response of larch forest ecosystem to wetting permafrost active layer in eastern Siberia

2018.9.18

Response of larch forest CO2 exchange on wetness variability of permafrost active layer in eastern Siberia

Kotani, A, Ohta, T, Maximov, T

The 2nd Asian Conference on Permafrost 2017.7.3

Palmer Drought Severity Indexを指標とした日本における乾燥/湿潤期間の時空間変動 International conference

高橋瑠想, 小谷亜由美

地球惑星連合大会 2013.5.21

P1a6 陸域生物圏モデルBEAMSを用いたシベリア地域の水、エネルギー、炭素収支解析(ポスター・セッション) International conference

相庭一輝, 佐々井崇博, 小谷亜由美, 太田岳史

大会講演予講集 2012 日本気象学会

Net ecosystem water use efficiency over two larch forests at eastern Siberia

Kotani A, Ohta T, Kononov A, Maximov T

2nd International Conference on "Global Warming and the Human-Nature Dimension in Siberia 2013.11.21

Hydrological studies of a larch forest at northeastern Siberia

Kotani, A

Russian-Japanese Symposium on Global Climate Change 2013.9.5

Forest Evapotranspiration and CO2 Flux over Larch Forests with Different Canopy Structure at Eastern

Kotani, A, Hayashi, M, Ohta, T, Maximov, T

11th Asiaflux international workshop 2013.8.21

Flux-based water use efficiency over two larch forests with different soil and canopy structure at eastern Siberia

Kotani A, Ohta T, Maximov T

American Geophysical Union fall meeting 2013.12.9

Factors influencing the variation of CO2 flux and evapotranspiration in larch forest ecosystem affected by the extreme wet-soil condition

2019.10.4

Evapotranspiration and carbon dioxide fluxes over larch forests with different soil water condition at eastern Siberia

4th International Symposium on Arctic Research (ISAR-4) 2015.4.27

D351 常緑落葉混交林における二酸化炭素交換量と吸収期間の年変動(大気-陸面間の水・エネルギー・炭素フラックスに関する最新研究2014,スペシャル・セッション) International conference

小谷亜由美, 太田岳史

大会講演予講集 2014 日本気象学会

Altering seasonal transition of surface energy fluxes in larch forest on permafrost: warming spring and wetting autumn

2019.12.10

Effects of Forest structure on the Evapotranspiration International conference

Miyagi Yu, Matsumoto Kazuho, Ohta Takeshi, Nakai Taro, Daikoku Ken'ichi, Sumida Akihiro, Iida Shin'ichi, Kotani Ayumi, Takashima Atsushi, Trofim C. Maximov, Hara Toshihiko, Taniguchi Shingo

The Japanese Forest Society Congress 2013 THE JAPANESE FORESTRY SOCIETY

Dameges in eastern Siberian Taiga due to too long and too heavy wet soil water condition International conference

OHTA Takeshi, KOTANI Ayumi, NAKAI Taro, MAXIMOV Trofim

The Japanese Forest Society Congress 2009 THE JAPANESE FORESTRY SOCIETY

Impacts of extreme wet soil water content on surface conductance:Results obtained from the observation in a larch forest, eastern Siberia International conference

OHTA Takeshi, KOTANI Ayumi, IIJIMA Yoshihiro, NAKAI Taro, MAXIMOV Trofim

The Japanese Forest Society Congress 2010 THE JAPANESE FORESTRY SOCIETY

Comparison of water and carbon flux over different forest in eastern Siberia International conference

Kotani Ayumi, Ohta Takeshi, Maximov Trofim, Kononov Alexsader

The Japanese Forest Society Congress 2011 THE JAPANESE FORESTRY SOCIETY

Regional differences on multi-temporal variation of environmental factors controlling forest evapotranspiration International conference

Yoshida Megumi, Ohta Takeshi, Kotani Ayumi

The Japanese Forest Society Congress 2010 THE JAPANESE FORESTRY SOCIETY

Effects of waterlogging stress on photosynthetic rate and leaf element content in Quercus serrata International conference

Ito Tsubasa, Ohta Takeshi, Kotani Ayumi, Tomioka Rie

The Japanese Forest Society Congress 2013 THE JAPANESE FORESTRY SOCIETY

Interannual and seasonal change of surface energy balance in temperate mixed forest.:Relationship between energy balance closure and energy fluxes. International conference

Tanaka Takayuki, Kotani Ayumi, Ohta Takeshi

The Japanese Forest Society Congress 2011 THE JAPANESE FORESTRY SOCIETY

Seasonal variability of scalar turbulent transport above forest canopy International conference

Kotani Ayumi, Hamazaki Shunki, Ohta Takeshi

Proceeding of Annual Conference 2012 THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES

Language：Japanese Presentation type：Oral presentation (general)

The causes of deviations from turbulent similarity in the atmospheric boundary layer above forests International conference

HAMAZAKI Shunki, KOTANI Ayumi, OHTA Takeshi

The Japanese Forest Society Congress 2011 THE JAPANESE FORESTRY SOCIETY

Winter Soil Temperature and Growing Season Net COĉ Exchange in Eastern Siberian Larch Forests International coauthorship International conference

A. Kotani, T. Hiyama, T. Nakai, T. C. Maximov

Seventh International Symposium on Arctic Research 2023.3.8

Spatio-temporal variability of vegetation response to climate in the forest-tundra ecotone of northeastern Siberia International conference

Japan Geoscience Union meeting 2022 2022.5.27

Language：Japanese Presentation type：Oral presentation (general)

Northern hemisphere terrestrial greening (positive trends in vegetation productivity) along with amplifying warming has been detected via field measurements and satellite observation over the past 40 years. Meanwhile, in some regions, a slowing or reversing response to warming trends has been reported in the recent decade. Understanding spatial and temporal heterogeneity in vegetation response on climate variability, which depends on differences in plant functional type or regional environment, is critical to studying vegetation dynamics over the northern high latitude under climate change.
This study investigated spatio-temporal variability of vegetation response in the forest-tundra ecotone region of northeastern Siberia to reveal 1) spatial variability in greening/browning trends, 2) regulation factors shift from temperature to water, and 3) perennial accumulated effect of land wetness condition on vegetation activity. We analyzed spatial variation of satellite-derived vegetation index and its correlation to climate variables in the last two decades from 2001 to 2020. Our study area covers the arctic coastal lowland to the mountainous region (over 2000 m) underlying continuous permafrost in northeast Siberia (60–75° N and 110–170° E). Vegetation also shifts from tundra to shrub and taiga along latitude and altitude. The annual maximum of the normalized difference vegetation index (hereafter, NDVImax) was derived from Moderate Resolution Imaging Spectrometer (MOD13A2) data. Climate variables such as thawing index (TI, annual sum of daily air temperature above 0°C), freezing index (FI, similar to TI but below 0°C in a year starting from previous September) and Climate Moisture Index (CMI, difference between annual precipitation and potential evapotranspiration) calculated from climate reanalysis data of ERA5-Land are prepared.
We examined 20-year time series of NDVImax, which were aggregated to 1° grid, by K-means cluster analysis, and divided them into four representative clusters; no clear trend region along the arctic sea, increase trend region east to south part, and the rest two intermediate clusters were scattered over the study area. The correlation of NDVImax and climate variables calculated for each pixel (0.1° resolution) showed heterogeneous spatial distribution. Positive correlation with the TI concentrated in the higher latitude area, while the positive correlation with FI expanded over the entire study area. The area with the significant correlation with FI shifted to the southeast from the first decade (2000-2010) to the latter (2011-2020). Vegetation response to climate is heterogeneous temporally and spatially, but we indicate climate parameters for seasons when vegetation doesn't grow may be important for vegetation. We calculated CMI for a year (from the previous September to the current year August) and two and three years (from two and three autumns ago). A positive correlation of NDVImax and 1-year CMI was mainly found around the northeast part, and its distribution area reduced in the recent decade. Toward the southeast, a positive correlation with perennial CMIs was pronounced rather than with 1-year CMI. This result indicates the possibility that precipitation allowed vegetation to grow after two years via water storage in the upper permafrost.

Forest carbon cycle based on tower flux observation Invited

A Kotani

National Summer Field School "Greenhouse Gases and Climate: Monitoring, Manipulation, Modeling and Management“ 2022.8.15 Institute of Biological Problems of Cryolithozone SB RAS

東シベリアの落葉針葉樹林における冬季温度と植物成長期のCO2収支

小谷亜由美，中井太郎，檜山哲哉

水文・水資源学会研究発表会 2022.9.7

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