Faculty Profiles - KOTANI, Ayumi

Presentations -

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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)

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.

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)

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.

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)

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.

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)

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.

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

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