Faculty Profiles - NAKATSUKA, Takeshi

Papers - NAKATSUKA, Takeshi

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奄美リュウキュウマツ年輪酸素同位体比データと海洋変動指数との関連性

増岡晃大, 庄建治朗, 中塚武, 李貞

水文・水資源学会研究発表会要旨集 Vol. 35 ( 0 ) page： 115 2022

Language：Japanese Publisher：水文・水資源学会

樹木年輪セルロース酸素同位体比は過去の気候変動をよく反映していることが確かめられている。近年では，年輪に含まれる酸素同位体比の測定手法の発達により，より純粋な気象因子との結びつきを検討できる可能性が期待されている．一方で樹木年輪の既往研究の多くは１年輪の測定により行われており，１年の時間分解能を持つデータが一般的である．そのため気候変動や海洋変動が日本陸域へ及ぼす季節ごとの影響を検討することが困難な場合がある．本研究では１年輪を年層内分割し得られた酸素同位体比データを用いて，気象代替データの時間分解能向上と年輪から考えられる海洋変動による陸域での季節変動について検討する．奄美大島の樹齢２００年のリュウキュウマツ３個体を対象として、年輪を形成するセルロースの抽出を行う。セルロース試料から測定サンプルを切り分ける際に、各年輪を成長方向へ分割する。測定データを用いて海洋変動が南西諸島陸域にもたらす影響を検討するために複数の海洋因子との相関分析を行う．結果としてENSO、PDOとの強い関連は得られなかった。一部年層内の成長期の終わり（11月頃）に相当する部分の酸素同位体比とENSOの間で正相関が得られた。ラニーニャ発生時期に奄美周辺の11月頃の日照時間が低下することが、同位体比変動に現れたと考えられる。一方でNPGOに関しては、1年遅いNPGOと梅雨入りに相当する部分の酸素同位体比、４年先行したNPGOと年層内の成長期の始まり（4月頃）に相当する部分の酸素同位体比との正相関が得られた。先行研究で東北地方を対象とした年輪同位体比と初夏の報告があり、東北地方のみならず南西諸島にも関連した指標であると考えられる。以上のように年輪の年層内分割は季節性の代替データを提供するとともに、大規模な海洋変動が陸域へ及ぼす関係を検討するのに有効な手段になると考えられる。

DOI： 10.11520/jshwr.35.0_115

CiNii Research

樹木年輪古気候学の現状と課題：バレリー・トロエ『年輪で読む世界史』

中塚武

史苑 Vol. 82/2 page： 155 - 161 2022

纒向遺跡の出土材年輪年代決定に向けて―酸素同位体比の年層内変動解析

中塚武

纒向学研究 Vol. 10 page： 309 - 316 2022

温暖化が駆動する大気海洋相互作用－樹木とサンゴの年輪共同研究の重要性

中塚武

月刊海洋 Vol. 622 page： 441 - 451 2022

樹木年輪の水素・酸素同位体比の統合による長期気候変動の復元

中塚武

月刊地球 Vol. 44 page： 255 - 266 2022

シリーズ『気候変動から読みなおす日本史』をめぐって

中塚武, 三木敦朗

日本の科学者 Vol. 57 ( 1 ) page： 46 - 51 2022

[書評] 樹木年輪古気候学の現状と課題－バレリー・トロエ『年輪で読む世界史』

中塚武

史苑 Vol. 82 page： 155 - 161 2022

樹木年輪酸素同位体比の周期性からみた「高地性集落」の背景

中塚武

古代文化 Vol. 74 page： 68 - 75 2022

Spatial synchrony in delta O-18 time-series from a tree-ring network are driven by synchronous hydroclimate variability in the transitional zone of the Asian summer monsoon Reviewed International coauthorship International journal

Fan Haowen, Gou Xiaohua, Nakatsuka Takeshi, Li Zhen, Su Jiajia, Sano Masaki, Liu Wenhuo, Fang Keyan

AGRICULTURAL AND FOREST METEOROLOGY Vol. 311 2021.12

Language：English Publishing type：Research paper (scientific journal)

Owing to the increased need to assess global forest behavior under changing climatic conditions within a long-term context, spatial coherence in tree-ring records is of widespread interest. Spatial networks of tree growth have been widely discussed from regional to global scales, but few studies have reported stable oxygen isotopes in networks of tree rings (δ18Otree), thus impeding a comprehensive hydroclimatic interpretation of δ18Otree records over large spatial scales, i.e., isoscapes. In this study, a network of four annually resolved δ18Otree chronologies (1805–2016) was developed for Southwest China, the transitional zone of the Asian summer monsoon, to test spatial coherence in δ18Otree variations and to explore the climatic factors driving synchrony at different spatial scales. The quantitative analyses show that the four chronologies exhibit consistent annual variations, with the first principal component (PC1) accounting for 70% of the total variance, which uniformly respond to local relative humidity (RH) and precipitation δ18O during the monsoon season. This confirms the spatial coherence in δ18Otree records. Furthermore, significant inter-site correlations of local RH and precipitation δ18O are also detected, revealing that it is the regionally homogeneous year-to-year variations in the hydroclimate that should be responsible for spatial coherence. For a larger spatial perspective, spatial correlation analyses reveal that the most prominent correlations between δ18Otree and hydroclimate fields occur in the Indochina Peninsula, in which δ18Otree changes are synchronized with those in Southwest China and the synchrony temporally varies with the Indian summer monsoon (ISM) intensity, indicating that coherent δ18Otree variations are linked to ISM-related moisture transport. In addition, δ18Otree records have shown strong in-phase relationships with the natural variabilities of the ISM and El Niño-Southern Oscillation (ENSO) across interannual and interdecadal timescales over the last 150 years, suggesting that spatial coherence in δ18Otree records can be utilized to reflect the long-term history of large-scale atmospheric circulation.

DOI： 10.1016/j.agrformet.2021.108687

Web of Science

Scopus

A seamless climate reconstruction beyond periodicity - Discovery of multi-decadal variability critical for human and natural sciences Invited

Nakatsuka Takeshi

Abstracts of Annual Meeting of the Geochemical Society of Japan Vol. 68 ( 0 ) page： 53 2021.9

Authorship：Lead author Language：Japanese Publishing type：Research paper (conference, symposium, etc.) Publisher：GEOCHEMICAL SOCIETY OF JAPAN

A seamless reconstruction of summer climate variation for all periodicities has been carried out in central Japan by integrating tree-ring oxygen and hydrogen isotopes. By decomposing the time series, I have found that the amplitude of multi-decadal variations is enhanced at every 400 years, inducing societal regime shifts over East Asia. I will discuss its natural and human scientific meanings referring the results of an inter-disciplinary research project in Research Institute for Humanity and Nature.

DOI： 10.14862/geochemproc.68.0_53

CiNii Research

Onset and maturation of Asian summer monsoon precipitation reconstructed from intra-annual tree-ring oxygen isotopes from the southeastern Tibetan Plateau

Xu Chenxi, Zhu Haifeng, Wang S-Y Simon, Shi Feng, An Wenling, Li Zhen, Sano Masaki, Nakatsuka Takeshi, Guo Zhengtang

QUATERNARY RESEARCH Vol. 103 page： 139 - 147 2021.9

Language：Japanese Publisher：Quaternary Research (United States)

We present a long-term seasonal tree ring cellulose oxygen isotope (δ18Oc) time series created by analyzing four segments (S1, S2, S3, and S4) per year during the period of 1951-2009 from southeastern Tibetan Plateau. This intraseasonal δ18Oc reveals the onset and mature phase of the summer monsoon precipitation in this region. Analysis indicates that the δ18Oc of S1 has the strongest correlation with precipitation during the regional monsoon onset (29-33 pentads, May 21-June 10, r =-0.69), and the δ18Oc values for S2, S3, and S4 correlate strongly with June, July, and August precipitation, respectively. Combined δ18Oc of S2, S3, and S4 shows the most robust correlation (r =-0.82) with the mature-phase monsoon precipitation (June-July-August, JJA), passing rigorous statistical tests for calibration and verification in dendroclimatology. These results demonstrate the feasibility in using long-term intraseasonal δ18Oc to reconstruct the Asian summer monsoon's intraseasonal variations.

DOI： 10.1017/qua.2020.28

Web of Science

Scopus

Oxygen Isotopes in Tree Rings from Greenland: A New Proxy of NAO Reviewed International coauthorship International journal

Xu Chenxi, Buckley Brendan M., Wang Shih-Yu Simon, An Wenling, Li Zhen, Nakatsuka Takeshi, Guo Zhengtang

ATMOSPHERE Vol. 12 ( 1 ) 2021.1

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Atmosphere

We present the first Greenlandic tree ring oxygen isotope record (δ18OGTR), derived from four birch trees collected from the Qinguadalen Valley in southwestern Greenland in 1999. Our δ18O record spans from 1950–1999 and is significantly and positively correlated with winter ice core δ18O from southern Greenland. δ18OGTR records are positively correlated with southwestern Greenland January–August mean temperatures. North Atlantic Oscillation (NAO) reconstructions have been developed from a variety of proxies, but never with Greenlandic tree rings, and our δ18OGTR record is significantly correlated with NAO (r = −0.64), and spatial correlations with sea-level pressure indicate a classic NAO pressure seesaw pattern. These results may facilitate a longer NAO reconstruction based on long time series of tree ring δ18O records from Greenland, provided that subfossil wood can be found in areas vacated by melting glaciers.

DOI： 10.3390/atmos12010039

Web of Science

Scopus

大規模土砂移動発生履歴の高精度復元に向けた埋没樹木の年代測定－歴史時代に中部山岳地域で発生した事例－ Reviewed

山田隆二・木村　誇・苅谷愛彦・佐野雅規・對馬あかね・李　貞・中塚　武・國分（齋藤）陽子・井上公夫

砂防学会誌 Vol. 73 page： 3 - 14 2021.1

Delayed warming in Northeast China: Insights from an annual temperature reconstruction based on tree-ring delta O-18 Reviewed International coauthorship International journal

Li Qiang, Liu Yu, Nakatsuka Takeshi, Liu Ruoshi, Cai Qiufang, Song Huiming, Wang Shengjie, Sun Changfeng, Fang Congxi

SCIENCE OF THE TOTAL ENVIRONMENT Vol. 749 page： 141432 2020.12

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Science of the Total Environment

Global warming has had an unprecedented impact on environmental changes and thus human life in mid-high latitude regions. As one of the areas most affected by global warming, Northeast China has suffered from a series of ecological crises, including warming-induced water deficits, permafrost thaw, and extended growing seasons. The change in annual average temperature (annual T) variations in Northeast China since the Industrial Revolution are still not fully understood, mainly because of the lack of long-term instrumental data and high-resolution annual T reconstructions. Here, we present the first annual T reconstruction (r = −0.683, p <.001, n = 60) for 1818–2012 in Northeast China, which may also be the first temperature reconstruction based on tree-ring δ18O in China. The reconstruction is significantly related to temperature variations over mid-high latitude Eurasia and agree (p <.01) with several long-term hydroclimatic reconstructions in the surrounding area. When the internal variability in the reconstruction was high, the decadal to multidecadal cycles were significant. Further analysis found that the reconstruction was mainly affected by the East Asian Summer Monsoon (EASM) and North Atlantic Oscillation (NAO). The reconstruction was significantly negatively correlated with several time series of annual T in the Northern Hemisphere, which showed that there is a substantial difference in annual T between Northeast China and other regions of the Northern Hemisphere. The difference mainly existed before the 1950s. From the 1850s to the 1950s, the annual T in Northeast China decreased slightly. However, extreme warming began in the 1950s in Northeast China, and this warming has been unprecedented during the past two centuries. If the warming trend since the 1950s continues, then it will lead to devastating disasters to forest and permafrost ecosystems in Northeast China.

DOI： 10.1016/j.scitotenv.2020.141432

Web of Science

Scopus

PubMed

Unstable relationship between tree-ring delta O-18 in the transitional zone of the Asian summer monsoon and the Indian summer monsoon Reviewed International coauthorship International journal

Fan Haowen, Gou Xiaohua, Su Jiajia, Liu Wenhuo, Gao Linlin, Nakatsuka Takeshi, Li Zhen, Sano Masaki, Lin Wei

JOURNAL OF HYDROLOGY Vol. 590 2020.11

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of Hydrology

The Asian Summer Monsoon system (ASM) affects a large population in the monsoonal Asia. Previous studies have thoroughly discussed the temporally unstable response of tree-ring oxygen isotope (δ18O) to the regional climate variables and ocean–atmosphere interaction modes, however, the response to the ASM remains ambiguous. In this study, an annually resolved tree-ring δ18O chronology is developed from eastern Yunnan-Guizhou Plateau, in the transitional zone of the ASM. Based on the results from response analyses, the climatic controls of tree-ring δ18O is considered to be the moisture-related variables of the monsoon season. Spatial correlations suggest that in the study area, the water vapor is mainly originated from the Bay of Bengal and transported by the Indian Summer Monsoon (ISM). Furthermore, the temporal stability in relationships between the tree-ring δ18O and the ISM variability are explored. Our findings suggest that on interannual to decadal timescales, the tree-ring δ18O is significantly anti-correlated, but temporally unstable with respect to the ISM. The strength of interannual relationship is affected by the ISM intensity, which is modulated by the El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) variability. Moreover, the strength of decadal relationship is associated with the phase shift of the Pacific Decadal Oscillation (PDO). Additionally, the decreasing trend of tree-ring δ18O after the late 1970 s that diverges from the simultaneous normal level of the ISM is caused by the isotopically-depleted trend in upstream precipitation of the moisture source. The opposite patterns of correlations between the tree-ring δ18O and the ENSO and IOD in recent decades demonstrate that the regional hydroclimate in the study region has been undergoing significant secular variations that are characterised by an increasing effect of the IOD and a decreasing effect of the ENSO. The findings from this study further improve our understanding of the tree-ring δ18O response to the ASM, at multi-time scales, and shed light on the impact of the ASM on regional hydroclimate variability, across the transitional zone of the ASM.

DOI： 10.1016/j.jhydrol.2020.125522

Web of Science

Scopus

Synchronizations of tree-ring delta O-18 time series within and between tree species and provinces in Korea: a case study using dominant tree species in high elevations Reviewed International coauthorship International journal

Choi En-Bi, Sano Masaki, Park Jun-Hui, Kim Yo-Jung, Li Zhen, Nakatsuka Takeshi, Hakozaki Masataka, Kimura Katsuhiko, Jeong Hyun-Min, Seo Jeong-Wook

JOURNAL OF WOOD SCIENCE Vol. 66 ( 1 ) 2020.7

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of Wood Science

The current study was initiated to test the synchronizations of tree-ring δ18O (hereafter δ18OTR) time series within and between tree species and provinces, which are about 144 km apart from each other in Korea. For the test, a 50-year δ18OTR time series (1966–2015) was developed using four trees from each tree species which are Pinus densiflora and Quercus mongolica from Songnisan National Park and Taxus cuspidata, Pinus koraiensis, Abies koreana, and Quercus mongolica from Jirisan National Park. Their synchronizations were evaluated using t-value, Gleichläufigkeit (Glk), and Expressed Population Signal (EPS). The mean t-values and Glk scores within the tree species ranged 5.2–11.2 (p < 0.05) and 69–83%, and between the tree species ranged 6.1–13.2 (p < 0.05) and 73–81%, respectively. The mean t-value and Glk score between the regions were 4.3 (p < 0.05) and 72%, respectively. Furthermore, the EPS showed higher than 0.85, which is the generally accepted threshold value in dendrochronology, except for Q. mongolica at Songnisan National Park for which the value is 0.83 calculated by only two δ18OTR time series. Based on the statistical results, we concluded that a δ18OTR chronology established using more than four trees could serve as a promising reference for dating an undated wood without considering the tree species, as well as for research on climate in the past.

DOI： 10.1186/s10086-020-01901-3

Web of Science

Scopus

An assessment of diatom assemblages in the Sea of Okhotsk as a proxy for sea-ice cover Reviewed International coauthorship International journal

Nakamura H

Journal of Micropalaeontology Vol. 39 ( 1 ) page： 77 - 92 2020.6

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：COPERNICUS GESELLSCHAFT MBH

Knowledge of past variations in sea-ice extent is crucial for understanding the relationship between climate change and changes in sea ice. Diatom assemblages could be applied as a proxy for paleo-sea-ice extent; this requires accurate information on the modern species that are indicative of sea ice. Scanning electron microscope observations were performed on modern diatom assemblages in sea ice, sinking particles, and surface sediments in the Sea of Okhotsk. A sea-ice sample was collected in the southwestern Sea of Okhotsk near Hokkaido island in February 2013. Fragilariopsis cylindrus was the dominant diatom species in the sea-ice sample, accounting for 87% of the total diatom assemblage. Time-series sediment traps were deployed during 1998-2000 at two stations, M4 and M6, off Sakhalin island. Total diatom fluxes ranged from 10(5) to 10(8) valves m(-2) d(-1) with noticeable seasonality. During the sea-ice covering period, the total diatom flux decreased by 1 or 2 orders of magnitude. The highest diatom fluxes were observed in spring and summer. The diatom species composition in sinking particles also showed pronounced seasonal changes. During summer and fall, the Shionodiscus trifultus group and Neodenticula seminae were the major diatom taxa. During the sea-ice covering period, Fragilariopsis cylindrus and Bacterosira bathyomphala resting spores were abundant. Both the sea-ice-related species showed similar flux patterns except for the spring bloom after sea-ice retreat: F. cylindrus fluxes exhibited pronounced spring bloom peaks of 10(8) valves m(-2) d(-1); in contrast, the fluxes of Bacterosira bathyomphala resting spores during the spring bloom were 1 order of magnitude lower than those of F. cylindrus. Surface-sediment core XP98-MC4 was obtained near station M6 sediment-trap site off Sakhalin island. The relative abundance of Fragilariopsis cylindrus in the surface-sediment diatom assemblage was only 6.4 %, markedly lower than that in the sediment-trap samples (43.4 %). In the surface sediment, the relative abundances of diatom taxa with heavily silicified valves such as B. bathyomphala resting spores, Shionodiscus variantius, and Thalassionema nitzschioides were greater than their relative abundances in sinking particles.

DOI： 10.5194/jm-39-77-2020

Web of Science

Scopus

A 338-year tree-ring oxygen isotope record from Thai teak captures the variations in the Asian summer monsoon system. Reviewed International coauthorship International journal

Pumijumnong N, Bräuning A, Sano M, Nakatsuka T, Muangsong C, Buajan S

Scientific reports Vol. 10 ( 1 ) page： 8966 2020.6

Oxygen stable isotopes of a network of shrubs and trees as high-resolution plaeoclimatic proxies in Northwestern China. Reviewed International coauthorship International journal

Qiang Li, Yu Liu, Takeshi Nakatsuka, Qi-Bin Zhang, Keiko Ohnishi, Akiko Sakai, Osamu Kobayashi, Yingnan Pan, Huiming Song, Ruoshi Liu, Changfeng Sun, Congxi Fang

Agricultural and Forest Meteorology Vol. 285 2020.5

Climate variability over the past 100 years in Myanmar derived from tree-ring stable oxygen isotope variations in Teak Reviewed International coauthorship International journal

Pumijumnong, N, Muangsong, C, Buajan, S, Sano, M, Nakatsuka, T

Theoretical and Applied Climatology Vol. 139 ( 3-4 ) page： 1401 - 1414 2020.2

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Papers - NAKATSUKA, Takeshi