scholarly journals Last 1100 yr of precipitation variability in western central Asia as revealed by tree-ring data from the Pamir-Alay

2018 ◽  
Vol 91 (1) ◽  
pp. 81-95 ◽  
Author(s):  
Magdalena Opała-Owczarek ◽  
Tadeusz Niedźwiedź

AbstractWe developed a 1108 yr chronology of tree-ring widths, based on 64 Himalayan pencil juniper (Juniperus semiglobosa Regel) trees, for the Pamir-Alay Mountains, central Asia. Dendroclimatological analysis demonstrates that precipitation has significant effects on tree growth in the semiarid mountainous area of northwestern Tajikistan located on the edge of the great midlatitude Karakum and Kyzylkum deserts. The highest level of linear correlation (r=0.67) is observed between tree growth and seasonalised winter (previous December–February) precipitation. Our studies also show that moisture (precipitation/Palmer Drought Severity Index) from the previous June to the current September was the dominant climatic factor accounting for interannual variations in tree-ring width, suggesting that this should be considered in climate reconstruction. Using the transfer function method, we reconstructed the region’s drought history over the period AD 908–2015. The results of this moisture reconstruction showed that the most recent millennium was characterised by series of dry and wet stages. The driest periods occurred before 1000, 1200–1250, and at the end of the eighteenth century and beginning of the nineteenth century. The wettest conditions existed in 1650–1700 and after 1990.

2020 ◽  
Vol 16 (2) ◽  
pp. 783-798
Author(s):  
Sarir Ahmad ◽  
Liangjun Zhu ◽  
Sumaira Yasmeen ◽  
Yuandong Zhang ◽  
Zongshan Li ◽  
...  

Abstract. The rate of global warming has led to persistent drought. It is considered to be the preliminary factor affecting socioeconomic development under the background of the dynamic forecasting of the water supply and forest ecosystems in West Asia. However, long-term climate records in the semiarid Hindu Kush range are seriously lacking. Therefore, we developed a new tree-ring width chronology of Cedrus deodara spanning the period of 1537–2017. We reconstructed the March–August Palmer Drought Severity Index (PDSI) for the past 424 years, going back to 1593 CE. Our reconstruction featured nine dry periods (1593–1598, 1602–1608, 1631–1645, 1647–1660, 1756–1765, 1785–1800, 1870–1878, 1917–1923, and 1981–1995) and eight wet periods (1663–1675, 1687–1708, 1771–1773, 1806–1814, 1844–1852, 1932–1935, 1965–1969, and 1990–1999). This reconstruction is consistent with other dendroclimatic reconstructions in West Asia, thereby confirming its reliability. The multi-taper method and wavelet analysis revealed drought variability at periodicities of 2.1–2.4, 3.3, 6.0, 16.8, and 34.0–38.0 years. The drought patterns could be linked to the large-scale atmospheric–oceanic variability, such as the El Niño–Southern Oscillation, Atlantic Multidecadal Oscillation, and solar activity. In terms of current climate conditions, our findings have important implications for developing drought-resistant policies in communities on the fringes of the Hindu Kush mountain range in northern Pakistan.


Forests ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 505 ◽  
Author(s):  
Feng Chen ◽  
Tongwen Zhang ◽  
Andrea Seim ◽  
Shulong Yu ◽  
Ruibo Zhang ◽  
...  

Coniferous forests cover the mountains in many parts of Central Asia and provide large potentials for dendroclimatic studies of past climate variability. However, to date, only a few tree-ring based climate reconstructions exist from this region. Here, we present a regional tree-ring chronology from the moisture-sensitive Zeravshan juniper (Juniperus seravschanica Kom.) from the Kuramin Range (Tajikistan) in western Central Asia, which is used to reveal past summer drought variability from 1650 to 2015 Common Era (CE). The chronology accounts for 40.5% of the variance of the June–July self-calibrating Palmer Drought Severity Index (scPDSI) during the instrumental period (1901 to 2012). Seven dry periods, including 1659–1696, 1705–1722, 1731–1741, 1758–1790, 1800–1842, 1860–1875, and 1931–1987, and five wet periods, including 1742–1752, 1843–1859, 1876–1913, 1921–1930, and 1988–2015, were identified. Good agreements between drought records from western and eastern Central Asia suggest that the PDSI records retain common drought signals and capture the regional dry/wet periods of Central Asia. Moreover, the spectral analysis indicates the existence of centennial (128 years), decadal (24.3 and 11.4 years), and interannual (8.0, 3.6, 2.9, and 2.0 years) cycles, which may be linked with climate forces, such as solar activity and El Niño-Southern Oscillation (ENSO). The analysis between the scPDSI reconstruction and large-scale atmospheric circulations during the reconstructed extreme dry and wet years can provide information about the linkages of extremes in our scPDSI record with the large-scale ocean–atmosphere–land circulation systems.


2018 ◽  
Vol 45 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Tongwen Zhang ◽  
Shulong Yu ◽  
Yujiang Yuan ◽  
Liping Huang ◽  
Shengxia Jiang

Abstract Forty-one living larch (Larix principis-rupprechtii) trees collected from two sampling sites in 1310–1530 m a.s.l. in the southern Greater Higgnan Mountains in the northeastern China are used to develop a regional tree-ring width chronology. The credible chronology spans 185 years from 1830 to 2014. The results of correlation analyses indicate that moisture is the main climatic factor controlling radial growth of larch trees in this mountainous area. Spatial correlation proves that the regional tree-ring width chronology contains climatic signals representative for a large area including the eastern Mongolian Plateau and Nuluerhu Mountains. A comparison between the newly developed chronology and a May–July Palmer Drought Severity Index (PDSI) reconstruction for the Ortindag Sand Land reveals similar variations, particularly in the low-frequency domain. The tree-ring records also capture a severe and sustained drying trend recorded in the 1920s across a wide area of northern China.


2018 ◽  
Vol 6 (2) ◽  
pp. 359-368 ◽  
Author(s):  
Yu Liu ◽  
Huiming Song ◽  
Changfeng Sun ◽  
Yi Song ◽  
Qiufang Cai ◽  
...  

AbstractThe numerous temperature and precipitation reconstructions in China based on tree-ring-width data have played significant roles in furthering the understanding of past climate changes. However, the geographical variability in the responses of trees to climate variations in China remains largely undetermined. Here, we describe an important spatial boundary in the response of trees to climate variations, namely the 600-mm annual precipitation isoline. We found that, to the north of this line, tree-ring widths are usually positively correlated with precipitation and negatively correlated with growing-season temperature. To the south of this line, the tree-ring widths respond positively to temperature, and winter half-year temperatures are the main reconstructed parameters, especially on the third topographical step of China. We also found that precipitation reconstructions based on tree-ring data and the Palmer Drought Severity Index almost exclusively fall in the region of the 200- to 600-mm annual precipitation isolines, not other regions. Our findings indicate that, when using multiple tree-ring-width chronologies for large-scale past climate reconstructions, the climatic signal of each tree-ring-width series should be carefully considered.


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.


2018 ◽  
Author(s):  
Feng Chen ◽  
Tongwen Zhang ◽  
Andrea Seim ◽  
Shulong Yu ◽  
Ruibo Zhang ◽  
...  

Abstract. Coniferous forests cover the mountains in many parts of central Asia and provide large potentials for dendroclimatic studies of past climate variability. However, to date, only a few tree-ring based climate reconstructions exist from this region. Here we present a regional tree-ring chronology from moisture-sensitive Juniperus seravschanica from the Kuramenian Mountains (Republic of Tajikistan), which is used to reveal past summer drought variability in western Central Asia. The chronology accounts for 40.5 % of the variance of the June–July self-calibrating Palmer Drought Severity Index (scPDSI) during the instrumental period (1901 to 2012). Seven dry periods including 1659–1696, 1705–1722, 1731–1741, 1758–1790, 1800–1842, 1860–1875 and 1931–1987, and five wet periods of 1742–1752, 1843–1859, 1876–1913, 1921–1930 and 1988–2015 were identified. Good agreements between drought records from western and eastern Central Asia suggest that the PDSI records retain common drought signals and captures the regional dry/wet periods of Central Asia. Moreover, the wavelet analysis indicates the existence of centennial (100–150 years), decadal (50–60, 24.4 and 11.4 years) and interannual (8.0 and 2.0-3.5 years) cycles, which may linked with climate forcings, such as solar activity and ENSO. The analysis between the scPDSI reconstruction and large-scale atmospheric circulations during the reconstructed extreme dry and wet years can provide information about the linkages of extremes in our scPDSI record with the Asian summer monsoon activity.


2017 ◽  
Vol 41 (4) ◽  
pp. 478-495 ◽  
Author(s):  
UK Thapa ◽  
S St. George ◽  
DK Kharal ◽  
NP Gaire

The climate of Nepal has changed rapidly over the recent decades, but most instrumental records of weather and hydrology only extend back to the 1980s. Tree rings can provide a longer perspective on recent environmental changes, and since the early 2000s, a new round of field initiatives by international researchers and Nepali scientists have more than doubled the size of the country’s tree-ring network. In this paper, we present a comprehensive analysis of the current tree-ring width network for Nepal, and use this network to estimate changes in forest growth nation-wide during the last four centuries. Ring-width chronologies in Nepal have been developed from 11 tree species, and half of the records span at least 290 years. The Nepal tree-ring width network provides a robust estimate of annual forest growth over roughly the last four centuries, but prior to this point, our mean ring-width composite fluctuates wildly due to low sample replication. Over the last four centuries, two major events are prominent in the all-Nepal composite: (i) a prolonged and widespread growth suppression during the early 1800s; and (ii) heightened growth during the most recent decade. The early 19th century decline in tree growth coincides with two major Indonesian eruptions, and suggests that short-term disturbances related to climate extremes can exert a lasting influence on the vigor of Nepal’s forests. Growth increases since AD 2000 are mainly apparent in high-elevation fir, which may be a consequence of the observed trend towards warmer temperatures, particularly during winter. This synthesis effort should be useful to establish baselines for tree-ring data in Nepal and provide a broader context to evaluate the sensitivity or behavior of this proxy in the central Himalayas.


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.


2000 ◽  
Vol 78 (7) ◽  
pp. 851-861 ◽  
Author(s):  
Marc D Abrams ◽  
Saskia van de Gevel ◽  
Ryan C Dodson ◽  
Carolyn A Copenheaver

Dendrochronological techniques were used to investigate the dynamics of an old-growth forest on the extreme slope (65%) at Ice Glen Natural Area in southwestern Massachusetts. The site represented a rare opportunity to study the disturbance history, successional development, and responses to climatic variation of an old-growth hemlock (Tsuga canadensis (L.) Carr) - white pine (Pinus strobus L.) - northern hardwood forest in the northeastern United States. Hemlock is the oldest species in the forest, with maximum tree ages of 305-321 years. The maximum ages for white pine and several hardwood species are 170-200 years. There was continuous recruitment of hemlock trees from 1677 to 1948. All of the existing white pine was recruited in the period between 1800 and 1880, forming an unevenly aged population within an unevenly aged, old-growth hemlock canopy. This was associated with large increases in the Master tree-ring chronologies, indicative of major stand-wide disturbances, for both hemlock and white pine. Nearly all of the hardwood species were also recruited between 1800 and 1880. After 1900, there was a dramatic decline in recruitment for all species, including hemlock, probably as a result of intensive deer browsing. White pine and hemlock tree-ring growth during the 20th century was positively correlated with the annual Palmer drought severity index (r = 0.61 and 0.39, respectively). This included reduced growth during periods of low Palmer drought severity index values, the drought years of 1895-1922, and dramatic increases during periods of high Palmer drought severity index values in the 1970s and 1990s. Significant positive and negative correlations of certain monthly Palmer drought severity index values with 20th century tree-ring chronologies also exist for white pine and hemlock using response function analysis. The results of this study suggest that old-growth forests on extreme sites in the eastern United States may be particularly sensitive to direct and indirect allogenic factors and climatic variations and represent an important resource for studying long-term ecological and climatic history.Key words: age structure, radial growth analysis, disturbance, climate, fire, tree rings.


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