研究者詳細 - 小谷　亜由美

論文 - 小谷　亜由美

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Mining plant phenology records from Kanazawa, Japan in the 1807-1838 Kakuson Diary

Shin, N; Sasai, Y; Kotani, A; Saitoh, TM

INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 68 巻 ( 1 ) 頁： 125 - 131 2024年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：International Journal of Biometeorology

Mining the various records of plant phenology before the era of modern weather observations is an important but challenging task. We mined descriptions of plant phenology in Kanazawa, Japan, during the first half of the nineteenth century in the Kakuson Diary. We retrieved records of full bloom of 28 plant species, appearance of 31 seasonal foods, and peak leaf colouring. In particular, we found more than 10 years of records of plum, peach, cherry blossoms, udo, and bamboo shoots in spring; watermelon in summer; and persimmon, chestnut, and peak leaf colouring in autumn. The records suggest that spring phenology during 1807 to 1838 was later and autumn phenology was earlier than now. Despite spatio-temporal uncertainty in records in old diaries, we need to mine records of plant phenology in more old diaries and publish them in English.

DOI： 10.1007/s00484-023-02576-3

Web of Science

Scopus

PubMed

Comparison of ground temperature and permafrost conditions in the Arctic simulated by land surface process models of different complexity Open Access

Mori, J; Saito, K; Miyazaki, S; Machiya, H; Ise, T; Sueyoshi, T; Yamazaki, T; Iijima, Y; Ikawa, H; O'oishi, R; Ohta, T; Katata, G; Kotani, A; Sato, A; Sato, H; Sugimoto, A; Suzuki, R; Tanaka, K; Nitta, T; Hajima, T; Burke, E; Park, H

BULLETIN OF GLACIOLOGICAL RESEARCH 42 巻頁： 69 - 94 2024年

源頭部湧水湿地における炭素貯蔵量とCO2フラックスの評価 Open Access

青木翔太, 小谷亜由美, 五味高志, 水内佑輔

水文・水資源学会研究発表会要旨集 37 巻 ( 0 ) 頁： 185 2024年

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：水文・水資源学会

この研究は、湧水湿地におけるCO2収支の計測例がないことに着目し、そのCO2フラックスと炭素貯留量を調査しました。湧水湿地は他の湿地と異なる空間的特性を持ち、CO2フラックスや土壌炭素量に影響を与える可能性があります。研究の目的は、湧水湿地におけるCO2フラックスの評価とその季節変動や環境要因の検討です。これにより、地球規模のCO2収支に関する基礎データが提供され、地球温暖化緩和適応策の構築に寄与することが期待されます。本研究は、東京大学生態水文学研究所穴の宮試験流域内の湧水湿地を調査しました。調査地は年平均降雨量1644mm、年平均気温15.2℃で、面積は約40㎡でした。上流部、中流部、下流部でCO2計測チャンバーを使用し、湿地土壌表面のCO２濃度を10分間隔で計測し、濃度変化からフラックスを求めました。また、リターや植生の有無を調査し、土壌サンプルを収集して炭素量を計測しました。気温、地温、土壌水分量、日射、湿度は10分間隔で自動測定し、降水量は研究所のデータを使用しました。フラックスの計測は2023年8月から2024年1月まで合計9回、バイオマスと土壌サンプルの採取は期間内に1回行われました。上流ではコナラやアカマツの枯れ葉が一年中堆積し、その量には地域差がありました。夏と秋のCO2フラックスは似ており、これはリターと気温の関係であると考えられます。冬には枯れ葉の量が少なくなり、フラックスも低下します。下流では植生があり、夏と秋には負の値が見られますが、冬にはそれがなくなります。この研究のCO2フラックスは他の研究と比較して正の値であり、炭素貯留量も干潟に比べて低いことがわかりました。この研究はCO2フラックスの理解と湧水湿地に関する知見を提供しました。

DOI： 10.11520/jshwr.37.0_185

Open Access

CiNii Research

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

日本水文科学会誌 53 巻 ( 0 ) 頁： 20 - 24 2023年3月

テレビ番組映像によりモンゴルの遊牧景観における人々と生態系の関わりの時間変化を紐解く査読有り

小谷亜由美

流域圏学会誌 10 巻頁： 31 - 40 2023年

Carbon Cycles in Forests

Maximov, TC; Maksimov, AP; Kononov, AV; Kotani, A; Dolman, J

WATER-CARBON DYNAMICS IN EASTERN SIBERIA 236 巻頁： 69 - 100 2019年

Can Subdaily LST Be Constructed in High-Latitude Regions Using Polar Orbiting Satellites?

Liu Z., Ichii K., Yamamoto Y., Ueyama M., Kobayashi H., Hiyama T., Kotani A., Maximov T., Sullivan R.C., Biraud S.

IEEE Geoscience and Remote Sensing Letters 22 巻頁： 1 - 5 2025年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE Geoscience and Remote Sensing Letters

This study introduces a new method for constructing subdaily land surface temperatures (LSTs) in northern high-latitude areas. The method is based on 1) an integration of observations from multiple satellites-sensors, including Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS); and 2) the use of swath data to more comprehensively utilize the information content available from overlapping events from each platform within a day. The initial validation phase demonstrated a comparably high performance for LSTs among different products with a root mean square error (RMSE) at approximately 3~^{\circ } C. Subsequently, the results confirmed that more than 23 observations per day at 70°N could be achieved, almost quadrupling the observation frequency achieved with twice-daily LST products combining MODIS and VIIRS. At one of the sample sites, the subdaily LST was clearly identified as a near-hourly temporal variation, and the gaps in the early morning and late afternoon were effectively filled.

DOI： 10.1109/lgrs.2025.3546797

Scopus

その他リンク： http://xplorestaging.ieee.org/ielx8/8859/10764750/10908397.pdf?arnumber=10908397

A Google Trends analysis of people's sense of seasons in Hokkaido 査読有り Open Access

Nagai Shin, Hiromi Nakagawa, Hiroshi Morimoto, Ayumi Kotani

Frontiers in Sustainable Tourism 3 巻 2024年12月

Decadal increases in carbon uptake offset by respiratory losses across northern permafrost ecosystems Open Access

See, CR; Virkkala, AM; Natali, SM; Rogers, BM; Mauritz, M; Biasi, C; Bokhorst, S; Boike, J; Bret-Harte, MS; Celis, G; Chae, N; Christensen, TR; Murner, SJ; Dengel, S; Dolman, H; Edgar, CW; Elberling, B; Emmerton, CA; Euskirchen, ES; Goeckede, M; Grelle, A; Heffernan, L; Helbig, M; Holl, D; Humphreys, E; Iwata, H; Jaerveoja, J; Kobayashi, H; Kochendorfer, J; Kolari, P; Kotani, A; Kutzbach, L; Kwon, MJ; Lathrop, ER; Lopez-Blanco, E; Mammarella, I; Marushchak, ME; Mastepanov, M; Matsuura, Y; Merbold, L; Meyer, G; Minions, C; Nilsson, MB; Nojeim, J; Oberbauer, SF; Olefeldt, D; Park, SJ; Parmentier, FJW; Peichl, M; Peter, D; Petrov, R; Poyatos, R; Prokushkin, AS; Quinton, W; Rodenhizer, H; Sachs, T; Savage, K; Schulze, C; Sjoegersten, S; Sonnentag, O; Louis, VLS; Torn, MS; Tuittila, ES; Ueyama, M; Varlagin, A; Voigt, C; Watts, JD; Zona, D; Zyryanov, VI; Schuur, EAG

NATURE CLIMATE CHANGE 14 巻 ( 8 ) 頁： 853 - 862 2024年7月

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 Climate Change

Tundra and boreal ecosystems encompass the northern circumpolar permafrost region and are experiencing rapid environmental change with important implications for the global carbon (C) budget. We analysed multi-decadal time series containing 302 annual estimates of carbon dioxide (CO2) flux across 70 permafrost and non-permafrost ecosystems, and 672 estimates of summer CO2 flux across 181 ecosystems. We find an increase in the annual CO2 sink across non-permafrost ecosystems but not permafrost ecosystems, despite similar increases in summer uptake. Thus, recent non-growing-season CO2 losses have substantially impacted the CO2 balance of permafrost ecosystems. Furthermore, analysis of interannual variability reveals warmer summers amplify the C cycle (increase productivity and respiration) at putatively nitrogen-limited sites and at sites less reliant on summer precipitation for water use. Our findings suggest that water and nutrient availability will be important predictors of the C-cycle response of these ecosystems to future warming.

DOI： 10.1038/s41558-024-02057-4

Open Access

Web of Science

Scopus

その他リンク： https://www.nature.com/articles/s41558-024-02057-4

Perspective and review: how to develop our understanding of temporal changes in the relationship between people and the landscape under societal and climate change in Northeast Asia? 査読有り Open Access

Shin, N; Saitoh, TM; Kotani, A; Miura, T; Nakagawa, H; Katsumata, C; Morimoto, H; Onishi, H

FRONTIERS IN ENVIRONMENTAL SCIENCE 12 巻頁： 1236664 2024年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Frontiers in Environmental Science

The relationship between people and the landscape consists of multi-layer components such as the atmosphere, water, living things, nutrients, livelihood, society, and information. To clarify temporal changes in this relationship, previous studies have used conventional approaches based on field work and satellite observation. However, interpretations based on these conventional two approaches are subject to temporal, spatial, representative, and interpretability gaps. In this perspective and review paper, we propose three approaches to bridge these gaps: (1) text mining of historical documents and data (mining for handwritten or printed old documents, books, diaries, field notes, and statistics), (2) video mining (mining for descriptions, interviews, narrations, and background of photos/video), and (3) social sensing (observing real-world events by using digital communication tools such as social networking services, YouTube, and Google Trends). We discuss the utility, limitation, and perspective of each of these proposed approaches by presenting case examples of their application from Northeast Asia. We found that (1) the text mining approach can be useful to remove the temporal, representative, and interpretability gaps but requires immense amounts of time and labor; (2) the video mining approach can be useful to remove the temporal, representative, and interpretability gaps, but uncertainties remain and there are usage limitations with video materials; and (3) the social sensing approach can be useful to reduce the spatial, representative, and interpretability gaps, but it requires careful consideration in terms of data quality and ethical issues. To deepen our understanding of the relationship between people and the landscape during periods of social and climate change on a scale of seasons to centuries from the viewpoint of personal attributes and traits, we conclude that an integrated analysis that combines the conventional approaches such as field work and satellite observation and the proposed approaches should be further developed. Through the development of our proposed integrated analytical approaches, we expect to establish a new transdisciplinary study that integrates anthropology, sociology, informatics, history, and natural sciences.

DOI： 10.3389/fenvs.2024.1236664

Open Access

Web of Science

Scopus

Stochastic representation of spatial variability in thaw depth in permafrost boreal forests

Nakai Taro, Hiyama Tetsuya, Kotani Ayumi, Iijima Yoshihiro, Ohta Takeshi, Maximov Trofim C.

PERMAFROST AND PERIGLACIAL PROCESSES 2023年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Permafrost and Periglacial Processes

A simple stochastic representation of the spatial variability in thaw depth is proposed. Thaw depth distribution measured in the two larch-type forests in eastern Siberia, Spasskaya Pad and Elgeeii, showed different spatial, seasonal, and interannual variability, respectively. Year-to-year variation in active-layer thickness was minor in Spasskaya Pad compared to Elgeeii. A gamma distribution adequately represented both sites' thaw depth spatial variability as the cumulative probability. Thus, we developed a simple model using the gamma distribution that illustrates the spatial variability in thaw depth at any thawing stage as a function of a given mean thaw depth. A hierarchy of models was introduced that sequentially considered the constant state, linearity, and nonlinearity in the dependence of the rate parameter of the gamma distribution on the mean thaw depth. Although the requirements of the model levels differed between Spasskaya Pad and Elgeeii, the proposed model successfully represented the spatial variability in thaw depth at both sites during different thaw seasons.

DOI： 10.1002/ppp.2204

Web of Science

Scopus

Perspective: Improving the accuracy of plant phenology observations and land-cover and land-use detection by optical satellite remote-sensing in the Asian tropics

Shin Nagai, Katsumata Chifuyu, Miura Tomoaki, Tsutsumida Narumasa, Ichie Tomoaki, Kotani Ayumi, Nakagawa Michiko, Khoon Kho Lip, Kobayashi Hideki, Kumagai Tomo'omi, Tei Shunsuke, Pungga Runi Anak Sylvester, Yamada Taizo, Kameda Akihiro, Yanagisawa Masayuki, Nasahara Kenlo Nishida, Muraoka Hiroyuki, Ichii Kazuhito, Tokumoto Yuji

FRONTIERS IN FORESTS AND GLOBAL CHANGE 6 巻 2023年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Frontiers in Forests and Global Change

Recent advances in satellite-borne optical sensors led to important developments in the monitoring of tropical ecosystems in Asia, which have been strongly affected by recent anthropogenic activities and climate change. Based on our feasibility analyses conducted in Indonesia in Sumatra and Sarawak, Malaysia in Borneo, we discuss the current situation, problems, recent improvements, and future tasks regarding plant phenology observations and land-cover and land-use detection. We found that the Multispectral Instrument (MSI) on board the Sentinel-2A/2B satellites with a 10-m spatial resolution and 5-day observational intervals could be used to monitor phenology among tree species. For the Advanced Himawari Imager (AHI) on board the Himawari-8 geostationary satellite with a 1,000-m spatial resolution and 10-min observational intervals, we found that the time-series in vegetation indices without gaps due to cloud contamination may be used to accurately detect the timing and patterns of phenology among tree species, although the spatial resolution of the sensor requires further improvement. We also found and validated that text and pictures with geolocation information published on the Internet, and historical field notes could be used for ground-truthing land cover and land use in the past and present time. The future development of both high frequency (≤ 10 min) and high spatial resolution (≤ 10 m) optical sensors aboard satellites is expected to dramatically improve our understanding of ecosystems in the tropical Asia.

DOI： 10.3389/ffgc.2023.1106723

Web of Science

Scopus

跡見花蹊日記を用いた明治・大正期における東京のサクラの開花季節記録のマイニング査読有り

永井信, 小谷亜由美, 丸谷靖幸

日本生気象学会雑誌 59 巻 ( 3-4 ) 頁： 89 - 99 2022年11月

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：日本生気象学会

春の気候変動と植物季節の対応関係を長期的に評価するためには，気象庁による生物季節観測が行われていない過去におけるサクラの開花季節の記録の発掘（マイニング）は重要な課題である．本研究は，明治から大正期を対象に，教育者である跡見花蹊（あとみかけい：天保11年 [1840年]〜大正15年・昭和元年 [1926年]）の日記からサクラの開花季節の記録をマイニングし，その品質と系統的な誤差を調査した．明治6年（1873年）から大正13年（1924年）の間に，開花日を22年，満開日を33年，それぞれマイニングできた．この期間における開花日や満開日は，現在と比べて10日程度遅かった．日記の記録は，観察場所や観察者の違い・不連続な観察日・サクラの種や個体差を要因とした系統的な誤差を少なくとも数日程度含むと考えられる一方，植物季節に対する気候変動の影響を明らかにするための有用性が示された．

DOI： 10.11227/seikisho.59.89

CiNii Research

Can Yandex statistics and google trends be used to detect people?s interests in berries in the Russian Far East? 国際共著

Shin Nagai, Kotani Ayumi, Maruya Yasuyuki, Gavrilyeva Tuyara

POLAR SCIENCE 33 巻頁： 100871 - 100871 2022年9月

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

Ripening berries are one of nature's important contributions to people in the Russian Far East. We examined the spatiotemporal variability of people's interests in 12 types of berries and their attributes by accessing Yandex statistics (Yandex) and Google Trends (GT) about these topics in the Russian Far East. On Yandex, time-series data for people's interests in many berries for all target regions showed clear seasonal changes, with an annual peak that occurs at the time of ripening. Interest in berries was observed in many cities and regions in the far east of Russia, where indigenous peoples and Sakha traditionally utilize berries for subsistence. The attributes of accessed terms were closely related to terms about berry varieties and edible berries, berry purchases, photographs, and recipes. These results supported the usability of Yandex and GT data to evaluate the spatiotemporal variability of people's interests in berries. Despite systematic biases, such as in the Internet environment and user characteristics as well as limitations of spatial resolution and access period, the integrated use of Yandex and GT should be developed to evaluate the spatiotemporal variability of people's interests in berries, especially in areas that are difficult to access.

DOI： 10.1016/j.polar.2022.100871

Web of Science

Scopus

Monitoring of cherry flowering phenology with Google Trends 査読有り

Shin Nagai, Kotani Ayumi, Tei Shunsuke, Tsutsumida Narumasa

PLOS ONE 17 巻 ( 7 ) 2022年7月

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

Google Trends (GT) is an online tool designed for searching for changes over time. We assessed its use for evaluating changes in the timing of cherry flowering phenology, which is of intense interest to Japanese people. We examined the relationship between time-series of relative search volume (RSV: relative change in search requests over time obtained from the GT access engine) and cherry flowering information published on websites (as ground truth) in relation to three famous ancient cherry trees. The time-series of RSV showed an annual bell-shaped seasonal variability, and the dates of the maximum RSV tended to correspond to the dates of full bloom. Our results suggest that GT allows monitoring of multiple famous cherry flowering sites where we cannot obtain long-term flowering data to evaluate the spatiotemporal variability of cherry flowering phenology.

DOI： 10.1371/journal.pone.0271648

Web of Science

Scopus

タンクモデルパラメータ値によるわが国寡雪地域の流域条件と長期流出特性の関係

堀田裕貴, 田中隆文, 小谷亜由美

日本水文科学会誌 52 巻 ( 1 ) 頁： 1 - 22 2022年4月

Contrasting 20-year trends in NDVI at two Siberian larch forests with and without multiyear waterlogging-induced disturbances 査読有り

Nagano Hirohiko, Kotani Ayumi, Mizuochi Hiroki, Ichii Kazuhito, Kanamori Hironari, Hiyama Tetsuya

ENVIRONMENTAL RESEARCH LETTERS 17 巻 ( 2 ) 2022年2月

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

The fate of a boreal forest may depend on the trend in its normalized difference vegetation index (NDVI), such as whether the NDVI has been increasing significantly over the past few decades. In this study, we analyzed the responses of two Siberian larch forests at Spasskaya Pad and Elgeeii in eastern Siberia to various waterlogging-induced disturbances, using satellite-based NDVI and meteorological data for the 2000-2019 period. The forest at Spasskaya Pad experienced waterlogging (i.e. flooding events caused by abnormal precipitation) during 2005-2008 that damaged canopy-forming larch trees and increased the abundance of water-resistant understory vegetation. By contrast, the forest at Elgeeii did not experience any remarkable disturbance, such as tree dieback or changes in the vegetation community. Significant increasing NDVI trends were found in May and June-August at Elgeeii (p < 0.05), whereas no significant trends were found at Spasskaya Pad (p > 0.05). NDVI anomalies in May and June-August at Elgeeii were significantly associated with precipitation or temperature depending on the season (p < 0.05), whereas no significant relationships were found at Spasskaya Pad (p > 0.05). Thus, the 20 year NDVI trend and NDVIerature-precipitation relationship differed between the two larch forests, although no significant trends in temperature or precipitation were observed. These findings indicate that nonsignificant NDVI trends for Siberian larch forests may reflect waterlogging-induced dieback of larch trees, with a concomitant increase in water-resistant understory vegetation.

DOI： 10.1088/1748-9326/ac4884

Web of Science

Scopus

The ABCflux database: Arctic-boreal CO2 flux observations and ancillary information aggregated to monthly time steps across terrestrial ecosystems

Virkkala Anna-Maria, Natali Susan M., Rogers Brendan M., Watts Jennifer D., Savage Kathleen, Connon Sara June, Mauritz Marguerite, Schuur Edward A. G., Peter Darcy, Minions Christina, Nojeim Julia, Commane Roisin, Emmerton Craig A., Goeckede Mathias, Helbig Manuel, Holl David, Iwata Hiroki, Kobayashi Hideki, Kolari Pasi, Lopez-Blanco Efren, Marushchak Maija E., Mastepanov Mikhail, Merbold Lutz, Parmentier Frans-Jan W., Peichl Matthias, Sachs Torsten, Sonnentag Oliver, Ueyama Masahito, Voigt Carolina, Aurela Mika, Boike Julia, Celis Gerardo, Chae Namyi, Christensen Torben R., Bret-Harte M. Syndonia, Dengel Sigrid, Dolman Han, Edgar Colin W., Elberling Bo, Euskirchen Eugenie, Grelle Achim, Hatakka Juha, Humphreys Elyn, Jarveoja Jarvi, Kotani Ayumi, Kutzbach Lars, Laurila Tuomas, Lohila Annalea, Mammarella Ivan, Matsuura Yojiro, Meyer Gesa, Nilsson Mats B., Oberbauer Steven F., Park Sang-Jong, Petrov Roman, Prokushkin Anatoly S., Schulze Christopher, St Louis Vincent L., Tuittila Eeva-Stiina, Tuovinen Juha-Pekka, Quinton William, Varlagin Andrej, Zona Donatella, Zyryanov Viacheslav I.

EARTH SYSTEM SCIENCE DATA 14 巻 ( 1 ) 頁： 179 - 208 2022年1月

Seasonality in Human Interest in Berry Plants Detection by Google Trends 査読有り

Ayumi Kotani, Nagai Shin, Shunsuke Tei, Andrey Makarov, Tuyara Gavrilyeva

Frontiers in Forest Global Change 4 巻頁： 688835 2021年9月

Geographical, Climatological, and Biological Characteristics of Tree Radial Growth Response to Autumn Climate Change 査読有り

Shunsuke Tei, Ayumi Kotani, Atsuko Sugimoto, Nagai Shin

Frontiers in Forest Global Change 4 巻頁： 687749 2021年8月

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