scholarly journals A Tree-Ring-Based Precipitation Reconstruction since 1760 CE from Northeastern Tibetan Plateau, China

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 416
Author(s):  
Youping Chen ◽  
Feng Chen ◽  
Heli Zhang

Hydroclimatic conditions and related water resources change in the Tibetan Plateau is one of the main concerns for future sustainable development in China. This study presents a 254-year precipitation reconstruction from August of the previous year to June of the current year for the northeastern Tibetan Plateau based on tree-ring width data of tree-ring cores of Picea crassifolia from three sampling sites. The precipitation reconstruction explained 51.4% of the variance in instrumental precipitation during the calibration period 1958–2013. Dry periods with precipitation below the 254-year average value occurred during 1848–1865, 1873–1887, 1898–1923, and 1989–2003, and wet periods (precipitation above the mean) occurred during 1769–1785, 1798–1833, 1924–1938, 1957–1968, and 2004–2013. Spatial correlation analyses with the precipitation gridded dataset showed that our reconstruction contains some strong regional-scale precipitation signals for the upper Yellow River Basin. Our precipitation reconstruction also agreed in general with other dendroclimatic precipitation reconstructions from surrounding regions. In addition, reconstructed precipitation changes were consistent with the streamflow variation of the Yellow River.

2021 ◽  
Vol 17 (6) ◽  
pp. 2381-2392
Author(s):  
Maierdang Keyimu ◽  
Zongshan Li ◽  
Bojie Fu ◽  
Guohua Liu ◽  
Fanjiang Zeng ◽  
...  

Abstract. Trees record climatic conditions during their growth, and tree rings serve as proxy to reveal the features of the historical climate of a region. In this study, we collected tree-ring cores of hemlock forest (Tsuga forrestii) from the northwestern Yunnan area of the southeastern Tibetan Plateau (SETP) and created a residual tree-ring width (TRW) chronology. An analysis of the relationship between tree growth and climate revealed that precipitation during the non-growing season (NGS) (from November of the previous year to February of the current year) was the most important constraining factor on the radial tree growth of hemlock forests in this region. In addition, the influence of NGS precipitation on radial tree growth was relatively uniform over time (1956–2005). Accordingly, we reconstructed the NGS precipitation over the period spanning from 1600–2005. The reconstruction accounted for 28.5 % of the actual variance during the common period of 1956–2005. Based on the reconstruction, NGS was extremely dry during the years 1656, 1694, 1703, 1736, 1897, 1907, 1943, 1982 and 1999. In contrast, the NGS was extremely wet during the years 1627, 1638, 1654, 1832, 1834–1835 and 1992. Similar variations of the NGS precipitation reconstruction series and Palmer Drought Severity Index (PDSI) reconstructions of early growing season from surrounding regions indicated the reliability of the present reconstruction. A comparison of the reconstruction with Climate Research Unit (CRU) gridded data revealed that our reconstruction was representative of the NGS precipitation variability of a large region in the SETP. Our study provides the first historical NGS precipitation reconstruction in the SETP which enriches the understanding of the long-term climate variability of this region. The NGS precipitation showed slightly increasing trend during the last decade which might accelerate regional hemlock forest growth.


2014 ◽  
Vol 81 (3) ◽  
pp. 400-423 ◽  
Author(s):  
Jijun Li ◽  
Xiaomin Fang ◽  
Chunhui Song ◽  
Baotian Pan ◽  
Yuzhen Ma ◽  
...  

AbstractThe way in which the NE Tibetan Plateau uplifted and its impact on climatic change are crucial to understanding the evolution of the Tibetan Plateau and the development of the present geomorphology and climate of Central and East Asia. This paper is not a comprehensive review of current thinking but instead synthesises our past decades of work together with a number of new findings. The dating of Late Cenozoic basin sediments and the tectonic geomorphology of the NE Tibetan Plateau demonstrates that the rapid persistent rise of this plateau began ~8 ± 1 Ma followed by stepwise accelerated rise at ~3.6 Ma, 2.6 Ma, 1.8–1.7 Ma, 1.2–0.6 Ma and 0.15 Ma. The Yellow River basin developed at ~1.7 Ma and evolved to its present pattern through stepwise backward-expansion toward its source area in response to the stepwise uplift of the plateau. High-resolution multi-climatic proxy records from the basins and terrace sediments indicate a persistent stepwise accelerated enhancement of the East Asian winter monsoon and drying of the Asian interior coupled with the episodic tectonic uplift since ~8 Ma and later also with the global cooling since ~3.2 Ma, suggesting a major role for tectonic forcing of the cooling.


2006 ◽  
Vol 43 ◽  
pp. 86-90 ◽  
Author(s):  
Xiaohua Gou ◽  
Fahu Chen ◽  
Meixue Yang ◽  
Gordon Jacoby ◽  
Jianfeng Peng ◽  
...  

AbstractThe ecological environment of the headwater area of the Yellow River, west China, is seriously deteriorating because of the harsh natural environment, weakened ecological systems and intensified human activities as well as regional climate changes. Forests and glaciers coexist in this area. Glaciers in the area have retreated over the last decade because of climate change. Most glaciers on the Tibetan Plateau (TP) tend to retreat during warm intervals and advance during cold intervals. Tree-ring records provide an important index for examining past climate changes. A total of 139 core samples from 97 living cypresses (Juniperus przewalskii) in the central region of the Yellow River headwater area, the Animaqin mountains, northeastern TP, were sampled from three sites that are close to each other. The chronologies were developed using the ARSTAN program. Analyses indicate that these tree-ring width records reflect the summer maximum temperature of the study area over the past 700 years. The tree-ring records and the glacier advances recorded by terminal moraines are compared. Inferred summer maximum temperatures suggest three cold periods during the Little Ice Age, around AD1500, 1700 and 1850. These cold intervals are consistent with the glacier moraine record from the region.


2017 ◽  
Vol 14 (12) ◽  
pp. 3083-3095 ◽  
Author(s):  
Lixin Lyu ◽  
Susanne Suvanto ◽  
Pekka Nöjd ◽  
Helena M. Henttonen ◽  
Harri Mäkinen ◽  
...  

Abstract. Latitudinal and altitudinal gradients can be utilized to forecast the impact of climate change on forests. To improve the understanding of how these gradients impact forest dynamics, we tested two hypotheses: (1) the change of the tree growth–climate relationship is similar along both latitudinal and altitudinal gradients, and (2) the time periods during which climate affects growth the most occur later towards higher latitudes and altitudes. To address this, we utilized tree-ring data from a latitudinal gradient in Finland and from two altitudinal gradients on the Tibetan Plateau. We analysed the latitudinal and altitudinal growth patterns in tree rings and investigated the growth–climate relationship of trees by correlating ring-width index chronologies with climate variables, calculating with flexible time windows, and using daily-resolution climate data. High latitude and altitude plots showed higher correlations between tree-ring chronologies and growing season temperature. However, the effects of winter temperature showed contrasting patterns for the gradients. The timing of the highest correlation with temperatures during the growing season at southern sites was approximately 1 month ahead of that at northern sites in the latitudinal gradient. In one out of two altitudinal gradients, the timing for the strongest negative correlation with temperature at low-altitude sites was ahead of treeline sites during the growing season, possibly due to differences in moisture limitation. Mean values and the standard deviation of tree-ring width increased with increasing mean July temperatures on both types of gradients. Our results showed similarities of tree growth responses to increasing seasonal temperature between latitudinal and altitudinal gradients. However, differences in climate–growth relationships were also found between gradients due to differences in other factors such as moisture conditions. Changes in the timing of the most critical climate variables demonstrated the necessity for the use of daily-resolution climate data in environmental gradient studies.


2021 ◽  
Author(s):  
Maierdang Keyimu ◽  
Zongshan Li ◽  
Bojie Fu ◽  
Guohua Liu ◽  
Weiliang Chen ◽  
...  

Abstract. Trees record climatic conditions during their growth, and tree-rings serve as a proxy to reveal the features of the historical climate of a region. In this study, we collected tree-ring cores of forest hemlock (Tsuga forrestii) from the northwestern Yunnan area of the southeastern Tibetan Plateau (SETP), and created a residual tree-ring width (TRW) chronology. An analysis of the relationship between tree growth and climate revealed that precipitation during the non-growth season (NGS) (from November of the previous year to February of the current year) was the most important constraining factor on the radial tree growth of forest hemlock in this region. In addition, the influence of NGS precipitation on radial tree growth was relatively uniform over time (1956–2005). Accordingly, we reconstructed the NGS precipitation over the period spanning from A.D. 1475–2005. The reconstruction accounted for 28.5 % of the actual variance during the common period 1956–2005, and the leave-one-out verification parameters indicated the reliability of the reconstruction. Based on the reconstruction, NGS was extremely dry during the years A.D. 1475, 1656, 1670, 1694, 1703, 1736, 1897, 1907, 1943, 1969, 1982, and 1999. In contrast, the NGS was extremely wet during the years A.D. 1491, 1536, 1558, 1627, 1638, 1654, 1832, 1834–1835, and 1992. Similar variations of the NGS precipitation reconstruction series and Palmer Drought Severity Index (PDSI) reconstructions from surrounding regions indicated the reliability of the reconstruction. A comparison of the reconstruction with Climate Research Unit (CRU) gridded data revealed that our reconstruction was representative of the NGS precipitation variability of a large region in the SETP.


2013 ◽  
Vol 10 (6) ◽  
pp. 9969-9988 ◽  
Author(s):  
X. Gou ◽  
F. Zhou ◽  
Y. Zhang ◽  
Q. Chen ◽  
J. Zhang

Abstract. The process-based Vaganov–Shashkin (VS) model was used to simulate regional patterns of climate-tree growth relationships linking daily length, temperature and precipitation from meteorological data (AD 1957–2000) over the northeastern Tibetan Plateau (TP). The results exhibit that the leading principle component of the hypothetical growth curves is broadly consistent with that of the actual tree-ring chronologies, demonstrating the interpretability of the simulations as an accurate representation of the climatic controls on tree growth of Qilian Juniper. Output from this model both agrees well with the statistical relationships between tree-ring growth and climate factors as well as observational physiological behavior, i.e. precipitation in June acts as the most contributing role in annual ring formation of Qilian Juniper over the northeastern TP. The non-stationary and nonlinear response of tree growth to climate variability has important implications for calibration of tree-ring records for paleoclimate reconstructions and prediction for forest carbon sequestration.


Atmosphere ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1251
Author(s):  
Yu Zhang ◽  
Jinjian Li ◽  
Zeyu Zheng ◽  
Shenglan Zeng

Due to the lack of long-term climate records, our understanding of paleoclimatic variability in the Tibetan Plateau (TP) is still limited. In this study, we developed a tree-ring width (TRW) chronology based on tree-ring cores collected from our study site, southeastern TP. This chronology responded well to the mean maximum temperatures of May–June and was thus used to reconstruct early summer (May–June) maximum temperature during the period 1541–2019. The reconstruction explained 33.6% of the climatic variance during the calibration period 1962–2019. There were 34 extremely warm years (7.2% of total years) and 36 extremely cold years (7.5% of total years) during the reconstruction period. The spatial correlation analysis and the comparison with other local temperature reconstructions confirmed the reliability and representativeness of our reconstruction. The results of the ensemble empirical mode decomposition (EEMD) analysis indicated quasi-oscillations of 2.9–4.2 years, 4.5–8.3 years, 11.1–15.4 years, 20–33.3 years, 50.4 years, 159.7 years, and 250 years in this temperature reconstruction which may be associated with ENSO cycles, solar activity, and PDO.


2021 ◽  
Vol 12 ◽  
Author(s):  
Guanglin He ◽  
Mengge Wang ◽  
Xing Zou ◽  
Pengyu Chen ◽  
Zheng Wang ◽  
...  

Archeologically attested human occupation on the Tibetan Plateau (TP) can be traced back to 160 thousand years ago (kya) via the archaic Xiahe people and 30∼40 kya via the Nwya Devu anatomically modern human. However, the history of the Tibetan populations and their migration inferred from the ancient and modern DNA remains unclear. Here, we performed the first ancient and modern genomic meta-analysis among 3,017 Paleolithic to present-day Eastern Eurasian genomes (2,444 modern individuals from 183 populations and 573 ancient individuals). We identified a close genetic connection between the ancient-modern highland Tibetans and lowland island/coastal Neolithic Northern East Asians (NEA). This observed genetic affinity reflected the primary ancestry of high-altitude Tibeto-Burman speakers originated from the Neolithic farming populations in the Yellow River Basin. The identified pattern was consistent with the proposed common north-China origin hypothesis of the Sino-Tibetan languages and dispersal patterns of the northern millet farmers. We also observed the genetic differentiation between the highlanders and lowland NEAs. The former harbored more deeply diverged Hoabinhian/Onge-related ancestry and the latter possessed more Neolithic southern East Asian (SEA) or Siberian-related ancestry. Our reconstructed qpAdm and qpGraph models suggested the co-existence of Paleolithic and Neolithic ancestries in the Neolithic to modern East Asian highlanders. Additionally, we found that Tibetans from Ü-Tsang/Ando/Kham regions showed a strong population stratification consistent with their cultural background and geographic terrain. Ü-Tsang Tibetans possessed a stronger Chokhopani-affinity, Ando Tibetans had more Western Eurasian related ancestry and Kham Tibetans harbored greater Neolithic southern EA ancestry. Generally, ancient and modern genomes documented multiple waves of human migrations in the TP’s past. The first layer of local hunter-gatherers mixed with incoming millet farmers and arose the Chokhopani-associated Proto-Tibetan-Burman highlanders, which further respectively mixed with additional genetic contributors from the western Eurasian Steppe, Yellow River and Yangtze River and finally gave rise to the modern Ando, Ü-Tsang and Kham Tibetans.


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