A Late Quaternary lake record from the Qilian Mountains (NW China): lake level and salinity changes inferred from sediment properties and ostracod assemblages

2005 ◽  
Vol 46 (1-4) ◽  
pp. 337-359 ◽  
Author(s):  
S. Mischke ◽  
U. Herzschuh ◽  
C. Zhang ◽  
J. Bloemendal ◽  
F. Riedel
2011 ◽  
Vol 76 (3) ◽  
pp. 430-440 ◽  
Author(s):  
Alyson Cartwright ◽  
Jay Quade ◽  
Scott Stine ◽  
Kenneth D. Adams ◽  
Wallace Broecker ◽  
...  

AbstractEvidence from shoreline and deep-lake sediments show Laguna Cari-Laufquén, located at 41°S in central Argentina, rose and fell repeatedly during the late Quaternary. Our results show that a deep (> 38 m above modern lake level) lake persisted from no later than 28 ka to 19 ka, with the deepest lake phase from 27 to 22 ka. No evidence of highstands is found after 19 ka until the lake rose briefly in the last millennia to 12 m above the modern lake, before regressing to present levels. Laguna Cari-Laufquén broadly matches other regional records in showing last glacial maximum (LGM) highstands, but contrasts with sub-tropical lake records in South America where the hydrologic maximum occurred during deglaciation (17–10 ka). Our lake record from Cari-Laufquén mimics that of high-latitude records from the Northern Hemisphere. This points to a common cause for lake expansions, likely involving some combination of temperature depression and intensification of storminess in the westerlies belt of both hemispheres during the LGM.


2003 ◽  
Vol 22 (2) ◽  
pp. 137-138 ◽  
Author(s):  
Steffen Mischke ◽  
Ulrike Herzschuh ◽  
Harald Kürschner ◽  
Fahu Chen ◽  
Fei Meng ◽  
...  

Abstract. To our knowledge, the Qilian Mountains in NW China have been investigated with respect to Recent or sub-Recent ostracods for the first time. The Qilian Mountains (95–103°E/37–40°N) extend along the northeastern margin of the Tibetan Plateau reaching a maximum altitude of 5826 m above sea-level (m asl).In September 2001, surface mud from the bottom of various water bodies including brooks, rivers and small shallow meadow and oxbow pools were sampled at an altitude ranging from 2900 m to 3570 m asl. In addition, surface mud samples and short cores were obtained from the small (c. 1 km2) and shallow (<0.4 m) freshwater Lake Luanhaizi situated at about 3200 m asl.Ostracod valves were usually abundant in all of the 32 samples and comprised the taxa listed in Table 1, some of which are illustrated in Plate 1.The recorded taxa are mainly distributed in the holarctic realm but Fabaeformiscandona danielopoli and Ilyocypris echinata appear to be restricted to the cold mountainous regions in China (Huang, 1985; Wang &amp; Zhu, 1991; Sun et al., 1995; Yin &amp; Martens, 1997).Following the first survey, a 14 m long core was drilled in Lake Luanhaizi in January 2002 which is currently under multidisciplinary investigation to reconstruct the Holocene vegetation and climatic history of the Qilian Mountains.


2013 ◽  
Vol 80 (3) ◽  
pp. 534-544 ◽  
Author(s):  
Xianyan Wang ◽  
Dimitri Vandenberghe ◽  
Shuangwen Yi ◽  
Jef Vandenberghe ◽  
Huayu Lu ◽  
...  

The Tibetan Plateau is regarded as an amplifier and driver of environmental change in adjacent regions because of its extent and high altitude. However, reliable age control for paleoenvironmental information on the plateau is limited. OSL appears to be a valid method to constrain the age of deposits of glacial and fluvial origin, soils and periglacial structures in the Menyuan basin on the northeastern Tibetan Plateau. Dating results show glaciers advanced extensively to the foot of the Qilian mountains at ~ 21 ka, in agreement with the timing of the global Last Glacial Maximum (LGM) recorded in Northern Hemisphere ice cores. Comparison with results from the eastern Tibetan Plateau suggests that the factor controlling glacial advance in both regions was decreased temperature, not monsoon-related precipitation increase. The areas of the Menyuan basin occupied by glacio-fluvial deposits experienced continuous permafrost during the LGM, indicated by large cryoturbation features, interpreted to indicate that the mean annual temperature was ≥ 7 °C lower than at present. Glacio-fluvial systems in the Menyuan basin aggraded and terraces formed during cold periods (penultimate glaciation, LGM, and possibly the Younger Dryas) as a response to increased glacial sediment production and meltwater runoff then.


Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1015
Author(s):  
Xuan Wu ◽  
Liang Jiao ◽  
Dashi Du ◽  
Changliang Qi ◽  
Ruhong Xue

It is important to explore the responses of radial tree growth in different regions to understand growth patterns and to enhance forest management and protection with climate change. We constructed tree ring width chronologies of Picea crassifolia from different regions of the Qilian Mountains of northwest China. We used Pearson correlation and moving correlation to analyze the main climate factors limiting radial growth of trees and the temporal stability of the growth–climate relationship, while spatial correlation is the result of further testing the first two terms in space. The conclusions were as follows: (1) Radial growth had different trends, showing an increasing followed by a decreasing trend in the central region, a continuously increasing trend in the eastern region, and a gradually decreasing trend in the isolated mountain. (2) Radial tree growth in the central region and isolated mountains was constrained by drought stress, and tree growth in the central region was significantly negatively correlated with growing season temperature. Isolated mountains showed a significant negative correlation with mean minimum of growing season and a significant positive correlation with total precipitation. (3) Temporal dynamic responses of radial growth in the central region to the temperatures and SPEI (the standardized precipitation evapotranspiration index) in the growing season were unstable, the isolated mountains to total precipitation was unstable, and that to SPEI was stable. The results of this study suggest that scientific management and maintenance plans of the forest ecosystem should be developed according to the response and growth patterns of the Qinghai spruce to climate change in different regions of the Qilian Mountains.


2021 ◽  
Vol 13 (12) ◽  
pp. 2400
Author(s):  
Quntao Duan ◽  
Lihui Luo ◽  
Wenzhi Zhao ◽  
Yanli Zhuang ◽  
Fang Liu

Human activities have dramatically changed ecosystems. As an irreplaceable ecological barrier in western China, the Qilian Mountains (QLM) provide various ecosystem services for humans. To evaluate the changes in the intensity of human activities in the QLM and their impact on the ecosystem, the human footprint (HF) method was used to conduct a spatial dataset of human activity intensity. In our study, the NDVI was used to characterize the growth of vegetation, and six categories of human pressures were employed to create the HF map in the QLM for 2000–2015 at a 1-km scale. The results showed that the mean NDVI during the growing season showed a significant increasing trend over the entire QLM in the period 2000–2015, while the NDVI showed a significant declining trend of more than 70% concentrated in Qinghai. Human pressure throughout the QLM occurred at a low level during 2000–2015, being greater in the eastern region than the western region, while the Qinghai area had greater human pressure than the Gansu area. Due to the improvement in traffic facilities, tourism, overgrazing, and other illegal activities, grasslands, shrublands, forests, wetlands, and bare land were the vegetation types most affected by human activities (in decreasing order). As the core area of the QLM, the Qilian Mountains National Nature Reserve (NR) has effectively reduced the impact of human activities. However, due to the existence of many ecological historical debts caused by unreasonable management in the past, the national park established in 2017 is facing great challenges to achieve its goals. These data and results will provide reference and guidance for future protection and restoration of the QLM ecosystem.


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