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Tibetan Plateau (tibetan + plateau)
Kinds of Tibetan Plateau Selected AbstractsMicrobial response to salinity change in Lake Chaka, a hypersaline lake on Tibetan plateauENVIRONMENTAL MICROBIOLOGY, Issue 10 2007Hongchen Jiang Summary Previous investigations of the salinity effects on the microbial community composition have largely been limited to dynamic estuaries and coastal solar salterns. In this study, the effects of salinity and mineralogy on microbial community composition was studied by using a 900-cm sediment core collected from a stable, inland hypersaline lake, Lake Chaka, on the Tibetan Plateau, north-western China. This core, spanning a time of 17 000 years, was unique in that it possessed an entire range of salinity from freshwater clays and silty sands at the bottom to gypsum and glauberite in the middle, to halite at the top. Bacterial and archaeal communities were studied along the length of this core using an integrated approach combining mineralogy and geochemistry, molecular microbiology (16S rRNA gene analysis and quantitative polymerase chain reaction), cultivation and lipid biomarker analyses. Systematic changes in microbial community composition were correlated with the salinity gradient, but not with mineralogy. Bacterial community was dominated by the Firmicutes -related environmental sequences and known species (including sulfate-reducing bacteria) in the freshwater sediments at the bottom, but by halophilic and halotolerant Betaproteobacteria and Bacteroidetes in the hypersaline sediments at the top. Succession of proteobacterial groups along the salinity gradient, typically observed in free-living bacterial communities, was not observed in the sediment-associated community. Among Archaea, the Crenarchaeota were predominant in the bottom freshwater sediments, but the halophilic Halobacteriales of the Euryarchaeota was the most important group in the hypersaline sediments. Multiple isolates were obtained along the whole length of the core, and their salinity tolerance was consistent with the geochemical conditions. Iron-reducing bacteria were isolated in the freshwater sediments, which were capable of reducing structural Fe(III) in the Fe(III)-rich clay minerals predominant in the source sediment. These data have important implications for understanding how microorganisms respond to increased salinity in stable, inland water bodies. [source] SONG VARIATION IN AN AVIAN RING SPECIESEVOLUTION, Issue 3 2000Darren E. Irwin Abstract., Divergence of mating signals can occur rapidly and be of prime importance in causing reproductive isolation and speciation. A ring species, in which two reproductively isolated taxa are connected by a chain of intergrading populations, provides a rare opportunity to use spatial variation to reconstruct the history of divergence. I use geographic variation in the song of a likely ring species, the greenish warbler (Phylloscopus trochiloides) to reconstruct the microevolutionary steps that occurred during divergence of a trait that is often important in speciation in birds. Populations of a western Siberian (P. t. viridanus) and an eastern Siberian (P. t. plumbeitarsus) form of the greenish warbler meet, but do not interbreed in central Siberia; these forms are connected by a chain of interbreeding populations extending in a ring to the south around the treeless Tibetan Plateau. I show that: (1) song structure differs greatly between the two Siberian forms, which share the same habitat; (2) song structure changes gradually around the ring; (3) singing behavior is relatively simple in the Himalayas, but becomes increasingly complex to the north, both to the west and east of the Tibetan Plateau; and (4) song varies along independent axes of complexity in the western and eastern south-north clines. By comparing geographic variation in singing behavior and ecological variables, I distinguish among possible causes of song divergence, including selection based on the acoustic environment, stochastic effects of sexual selection, and selection for species recognition. I suggest that parallel south-to-north ecological gradients have caused a greater intensity of sexual selection on song in northern populations and that the stochastic effects of sexual selection have led to divergence in song structure. [source] Changes in topsoil carbon stock in the Tibetan grasslands between the 1980s and 2004GLOBAL CHANGE BIOLOGY, Issue 11 2009YUANHE YANG Abstract Climate warming is likely inducing carbon loss from soils of northern ecosystems, but little evidence comes from large-scale observations. Here we used data from a repeated soil survey and remote sensing vegetation index to explore changes in soil organic carbon (SOC) stock on the Tibetan Plateau during the past two decades. Our results showed that SOC stock in the top 30 cm depth in alpine grasslands on the plateau amounted to 4.4 Pg C (1 Pg=1015 g), with an overall average of 3.9 kg C m,2. SOC changes during 1980s,2004 were estimated at ,0.6 g C m,2 yr,1, ranging from ,36.5 to 35.8 g C m,2 yr,1 at 95% confidence, indicating that SOC stock in the Tibetan alpine grasslands remained relatively stable over the sampling periods. Our findings are nonconsistent with previous reports of loss of soil C in grassland ecosystems due to the accelerated decomposition with warming. In the case of the alpine grasslands on the Tibetan Plateau studied here, we speculate that increased rates of decomposition as soils warmed during the last two decades may have been compensated by increased soil C inputs due to increased grass productivity. These results suggest that soil C stock in terrestrial ecosystems may respond differently to climate change depending on ecosystem type, regional climate pattern, and intensity of human disturbance. [source] Large-scale pattern of biomass partitioning across China's grasslandsGLOBAL ECOLOGY, Issue 2 2010Yuanhe Yang ABSTRACT Aim, To investigate large-scale patterns of above-ground and below-ground biomass partitioning in grassland ecosystems and to test the isometric theory at the community level. Location, Northern China, in diverse grassland types spanning temperate grasslands in arid and semi-arid regions to alpine grasslands on the Tibetan Plateau. Methods, We investigated above-ground and below-ground biomass in China's grasslands by conducting five consecutive sampling campaigns across the northern part of the country during 2001,05. We then documented the root : shoot ratio (R/S) and its relationship with climatic factors for China's grasslands. We further explored relationships between above-ground and below-ground biomass across different grassland types. Results, Our results indicated that the overall R/S of China's grasslands was larger than the global average (6.3 vs. 3.7). The R/S for China's grasslands did not show any significant trend with either mean annual temperature or mean annual precipitation. Above-ground biomass was nearly proportional to below-ground biomass with a scaling exponent (the slope of log,log linear relationship between above-ground and below-ground biomass) of 1.02 across various grassland types. The slope did not differ significantly between temperate and alpine grasslands or between steppe and meadow. Main conclusions, Our findings support the isometric theory of above-ground and below-ground biomass partitioning, and suggest that above-ground biomass scales isometrically with below-ground biomass at the community level. [source] Effect of seed coating on plant growth and soil conditions: A preliminary study for restoration of degraded rangeland in the Qinghai,Tibetan Plateau, ChinaGRASSLAND SCIENCE, Issue 3 2010Yingchun Liu Abstract Rangeland degradation is a significant problem in the Qinghai,Tibetan Plateau, China. Restoration of the degraded rangelands through reseeding is being undermined by poor seedling growth under adverse soil moisture and nutrition conditions. Accordingly, seeds of Italian ryegrass (Lolium multiflorum) and Chinese milk vetch (Astragalus sinicus) were coated with a mixture of hygroscopic and plant-derived polysaccharide gums and alga powder (Phaeocystis sp. necolon-1), and inoculated with spores of microorganisms (Aspergillus sp. and Streptomyces sp.), serving as coating mixture decomposers, in order to improve rhizosphere moisture and nutrition. In a growth chamber simulating spring climate on the Plateau, seedling emergence of the coated seeds was 60,80 and 48,82%, respectively, for the two plant species in comparison to 38 and 24% for the uncoated seeds, which was due to moisture being supplied by the coat. In the outdoor pots with soil texture and moisture conditions similar to those of the degraded rangelands on the Plateau, dry weight of the plants from the coated seeds was 109,184 and 118,156 mg plant,1 for the respective plant species, while that of the plants from uncoated seeds was 18,20 and 10,11 mg plant,1. The number of Rhizobium sp. nodules on Chinese milk vetch plants from the coated seeds was 21,25 plant,1 while 0,2 in plants from uncoated seeds. Enhancement of plant growth was caused by increased activity of soil microbes. Plant growth on the soil after sampling plants from the coated seeds was also enhanced, indicating sustainability of improvement of soil conditions. Thus seed coating with hygroscopic nutrient-source materials and inoculation with microorganism spores as slow decomposers of the coating materials is a promising method for restoring degraded rangelands. [source] Decadal trend of climate in the Tibetan Plateau,regional temperature and precipitationHYDROLOGICAL PROCESSES, Issue 16 2008Z. X. Xu Abstract The Tibetan Plateau has one of the most complex climates in the world. Analysis of the climate in this region is important for understanding the climate change worldwide. In this study, climate patterns and trends in the Tibetan Plateau were analysed for the period from 1961 to 2001. Air temperature and precipitation were analysed on monthly and annual time scales using data collected from the National Meteorological Centre, China Meteorological Administration. Nonlinear slopes were estimated and analysed to investigate the spatial and temporal trends of air temperature and precipitation in the Tibetan Plateau using a Mann,Kendall method. Spatial analysis of air temperature and precipitation variability across the Tibetan Plateau was undertaken. While most trends are local in nature, there are general basinwide patterns. Temperature during the last several decades showed a long-term warmer trend, especially the areas around Dingri and Zogong stations, which formed two increasing centres. Only one of the stations investigated exhibited decreasing trend, and this was not significant. Precipitation in the Tibetan Plateau has increased in most regions of the study area over the past several decades, especially in the eastern and central part, while the western Tibetan Region exhibited a decreased trend over the same period. Copyright © 2007 John Wiley & Sons, Ltd. [source] Estimating the evolution of vegetation cover and its hydrological impact in the Mekong River basin in the 21st centuryHYDROLOGICAL PROCESSES, Issue 9 2008Hiroshi Ishidaira Abstract The terrestrial biosphere plays a key role in regional energy and water cycles. Thus, for long-term hydrological predictions, possible future changes in vegetation cover must be understood. This study examined the evolution of vegetation cover in the 21st century and its estimated impact on river discharge in the Mekong River basin. Based on climatic predictions (TYN SC 2·03) under the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC SRES) A1FI, A2, B1, and B2, changes in vegetation type and the leaf area index (LAI) were simulated using a Lund-Potsdam-Jena-Dynamic Global Vegetation Model (LPJ-DGVM) and Terrestrial Biogeochemical Cycle Model (BIOME-BGC). The estimated LAI was then used in the rainfall-runoff analysis in the Yamanashi Distributed Hydrological Model (YHyM). The simulation results indicated a significant change in vegetation type mainly on the Tibetan Plateau and in mountainous areas, with the degree of change differing for each SRES scenario; LAI increases around the edge of the Tibetan Plateau and decreases in the lower reaches of the basin; and more conspicuous changes in river discharge in upstream areas than in the middle to lower reaches, mainly due to increases in precipitation in the plateau region. After the 2050s, the results suggested changes in river discharge will be slowed due to changes in evapotranspiration. Copyright © 2008 John Wiley & Sons, Ltd. [source] Determination of regional net radiation and soil heat flux over a heterogeneous landscape of the Tibetan PlateauHYDROLOGICAL PROCESSES, Issue 15 2002Yaoming Ma Abstract This paper explores the potential for documenting regional fields of surface energy fluxes over the Tibetan plateau using published algorithms and previously calibrated empirical formulae with data from NOAA-14 AVHRR and atmospheric data collected during the GAME-Tibet field experiment. Comparison with observations at three field sites suggests errors in the resulting estimates are less than 10% in the clear sky conditions necessary for application of this approach. Because of the need for clear skies, it was only possible to calculate the desired regional fields for one satellite scene during the 5 month study period. Maps of surface energy fluxes, and frequency analyses of these maps, are presented for this scene. The need for an alternative, more consistently applicable, satellite-based method to map surface energy fields is highlighted. Copyright © 2002 John Wiley & Sons, Ltd. [source] Annual temperature history in Southwest Tibet during the last 400 years recorded by tree ringsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 7 2010Bao Yang Abstract We present a tree ring-width record from the southern Tibetan Plateau (TP) which spans from 1612,1998 AD (387 years). The series was developed from Tibetan juniper (Juniperus tibetica Kom) growing at sites near the western distribution limit of the species. Two versions of the chronology, a traditionally standardized chronology (TSC) and a regional curve standardization (RCS)chronology were developed. Linear regression models between ring width and mean annual temperature account for 41% (TSC) and 43% (RCS) of the annual (July,June) temperature variance for the period 1957,1998. According to the TSC reconstruction, warm periods occurred during the 1620s, 1650,1675, 1720s, 1740,1790, 1810s, 1850s,1890s, 1935,1950, and 1957,1964 and since 1980. Cold conditions prevailed during the 1630s,1640s, 1680s,1710s, 1730s, 1820,1840s, 1900s,1920s and the 1970s. Within the last 400 years, the late-20th century warming is distinctive but still within the range of natural climatic variability of this region. Comparison of our TSC reconstruction with proxy temperature records from other parts of the TP shows that the cold conditions during the 1730s, 1900s,1920s, and 1970s, and the warm periods during the 1770,1800, 1850s,1890s, 1935,1950, and 1957,1964 and since 1980 were synchronously occurring broad-scale climate anomalies on the whole TP. Differences between the reconstructions are found during the 17th century and around 1760, which were probably caused by local differences in temperature change and different sensitivity in seasonality. The RCS series portrays low-frequency variations such as warm periods during 1620,1640, 1650,1690, 1715,1790, and 1845,1875, and cold conditions during 1640,1650, 1690,1715, and 1875,1995. These long-term trends need to be verified by developing other proxy records that target to capture low-frequency signals in the future. Copyright © 2009 Royal Meteorological Society [source] Reconstruction of a 1436-year soil moisture and vegetation water use history based on tree-ring widths from Qilian junipers in northeastern Qaidam Basin, northwestern ChinaINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 1 2008Zhi-Yong Yin Abstract Tree-ring widths have been used widely in studies of environmental changes and reconstructions of past climate. Eleven tree-ring chronologies of approximately 800,1500 years long were developed from Qilian junipers (Sabina przewalskii Kom.) for northeastern Qaidam Basin, along the margin of the Qinghai,Tibetan Plateau. Previous studies have revealed that water usage stress is the most limiting factor for tree growth in the study region. To evaluate the impact of the combined effects of temperature and precipitation changes over time, we performed water balance modelling using 1955,2002 meteorological data. We found that the tree-ring widths were strongly correlated with variables representing soil moisture conditions obtained from the water balance model. Specifically we considered actual evapotranspiration (AE) to represent the combined effect of water use demand and moisture availability, deficit as the difference between potential evapotranspiration (PE) and AE to represent the severity of water use stress, and relative soil moisture as the measure of moisture availability. For certain individual monthly and seasonal combinations, the tree-ring chronologies explained up to 80% of the variation in the soil moisture variables in regression analysis, indicating very good potential for reconstruction of regional soil moisture conditions in the past. These soil moisture variables outperformed precipitation and Palmer's drought severity index in most cases. We reconstructed the soil moisture conditions from 566 AD to 2001, which revealed major dry and wet periods and a general trend toward a wetter condition during the most recent 300 years. By comparing with other proxies in the region, we concluded that the moisture conditions reconstructed from tree-ring widths very well reflected the climate variability at the interannual and interdecadal scales. Copyright © 2007 Royal Meteorological Society [source] Global analyses of satellite-derived vegetation index related to climatological wetness and warmthINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 4 2006Rikie Suzuki Abstract Wetness and warmth are the principal factors that control global vegetation distribution. This paper investigates climate,vegetation relationships at a global scale using the normalized difference vegetation index (NDVI), warmth index (WAI), and wetness index (WEI). The NDVI was derived from a global, 20-year Advanced Very High Resolution Radiometer (AVHRR) dataset with 4-min resolution. The WEI was defined as the ratio of precipitation to potential evaporation. The WAI was defined as the cumulative monthly mean temperature that exceeds 5 °C annually. Meteorological data from the International Satellite Land-Surface Climatology Project Initiative II (ISLSCP II) dataset were used to calculate the WEI and WAI. All analyses used annual values based on averages from 1986 to 1995 at 1 × 1 degree resolution over land. Relationships among NDVI, WEI, and WAI values were examined using a vegetation-climate diagram with the WEI and WAI as orthogonal coordinates. The diagram shows that large NDVI values correspond to areas of tropical and temperate forests and large WEI and WAI values. Small WEI and WAI values are associated with small NDVI values that correspond to desert and tundra, respectively. Two major regimes are revealed by the NDVI vegetation-climate diagram: wetness dominant and warmth dominant. Wetness dominates mid- and low latitudes. Warmth dominates high latitudes north of 60°N or elevated land such as the Tibetan Plateau. The boundary between the two regimes roughly corresponds to the vegetation boundary between taiga forest and southern vegetation. Over northern Eurasia, the boundary occurs in areas where the NDVI is large and the maximum monthly temperature is around 18 °C. Copyright © 2006 Royal Meteorological Society. [source] Features of cross-Pacific climate shown in the variability of China and US precipitationINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 13 2005Q. Li Abstract In this study, we have analyzed the climate features of China and the United States with a focus on the differences, similarities, connectivity, and predictability of precipitation and the relationships between precipitation and large-scale patterns of natural variability. China precipitation is characterized by large seasonality, with a maximum in summer and a minimum in winter. The seasonality of precipitation shows an increasing linear tendency in northwest China, with a change of about 20% from 1901 to 1998. A relatively weaker increasing tendency also appears in the Big Bend of Yellow River (BBYR) and the Tibetan Plateau, while southwest China experiences a decreasing tendency. Furthermore, the seasonality in the BBYR shows particularly significant interdecadal variability, while that of southern and eastern China has decreased slightly in the recent decades. Compared to China, the United States as a whole has less precipitation in summer but more precipitation in other seasons. Here, the seasonality of precipitation is only about 24% of that in China. The annual mean precipitation is 64.1 mm per month in the United States, compared to 54.6 mm per month in China. The seasonality of precipitation exhibits a decreasing tendency in the southeast, Pacific Northwest, and Gulf Coast and an increasing tendency in the Great Lakes. The seasonality in the Great Plains exhibits large interdecadal variability. The long-term variations of precipitation are highly seasonally dependent. In summer, a decreasing trend is observed in north China and an increasing trend is found in eastern-central China. However, these trends are almost opposite in spring. In addition, the fall precipitation decreases with time nearly everywhere in China except for the middle and lower reaches of the Yangtze River Valley. Results also indicate that the El Niño/Southern Oscillation (ENSO), the Arctic Oscillation (AO), the North Atlantic Oscillation (NAO), the Pacific Decadal Oscillation (PDO), and the North Pacific (NP) fluctuation affect strongly the variations of China and US precipitation. Although these influences vary with regions and seasons, we in particular emphasize the importance of AO and NAO for China precipitation and NP and PDO for US precipitation. In fall, ENSO and PDO are the two phenomena that influence predominantly precipitation variability in both China and the United States We also identify the common phenomena that influence China and US regional precipitation and provide a better understanding of the physical mechanism for precipitation variability through the associated changes in atmospheric and oceanic conditions. Furthermore, we develop a linear regression model, based on multiple regression method by combining the regionally and seasonally varying impacts, to increase the skill of precipitation prediction. Copyright © 2005 Royal Meteorological Society [source] Responses of China's summer monsoon climate to snow anomaly over the Tibetan PlateauINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2003Prof. Y. F. Qian Abstract The climatological features of the winter snow depth over the Tibetan Plateau and the summer precipitation in China are diagnosed using datasets obtained from 78 snow observation stations and 160 rainfall stations during 1957 to 1998. The climatic effects of the snow anomaly over the Tibetan Plateau on the regional summer monsoon climate in China are diagnosed and numerically simulated by use of a regional climate model (RegCM2). The singular value decomposition technique is adopted to diagnose the relationships between the previous winter and spring plateau snow depth anomalies and the spring and summer regional precipitation in China. It is found that the snow depth anomaly, especially in winter, is one of the factors influencing precipitation in China; however, it is perhaps not the only one, and even not the most important one. Nevertheless, it is proved that the winter snow anomaly over the Tibetan Plateau is relatively more important than that in spring for the regional precipitation in China. Results of numerical simulations show that the snow anomaly over the plateau has effects that are evident on China's summer monsoon climate. The increase of both snow cover and snow depth can delay the onset and weaken the intensity of the summer monsoon obviously, resulting in a decrease in precipitation in southern China and an increase in the Yangtze and Huaihe River basins. The influence of the winter snow depth is more substantial than that of both the winter snow cover and the spring snow depth. The mechanism of how the plateau snow anomaly influences the regional monsoon climate is briefly analysed. It is found that snow anomalies over the Tibetan Plateau change the soil moisture and the surface temperature through the snowmelt process at first, and subsequently alter heat, moisture and radiation fluxes from the surface to the atmosphere. Abnormal circulation conditions induced by changes of surface fluxes may affect the underlying surface properties in turn. Such a long-term interaction between the wetland and the atmosphere is the key process resulting in later climatic changes. Copyright © 2003 Royal Meteorological Society [source] Evaluation of broad scale vertical circulation and thermal indices in relation to the onset of Indian summer monsoonINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2002S. K. Roy Bhowmik Abstract The onset of the Indian summer monsoon over Kerala for an individual year of delayed (1997), early (1999) and normal onset (2000) was examined in relation to the intensity of vertical circulation and thermal indices during the pre-monsoon months (April and May). The study showed that in the delayed monsoon onset year (1997) negative anomalies of vertical zonal index dominated over the north Indian Ocean during pre-monsoon months, particularly in April. In contrast, in the early onset year (1999) the positive anomalies of this index over the north Indian Ocean during the pre-monsoon months were considerably stronger (April and May). However, the meridional vertical index did not show any appreciable difference. The gradient of the vertical thermal index anomalies over the Tibetan Plateau in the month of April was prominently stronger during the years of early and normal onset (1999 and 2000). The anomalies of geopotential height at 200 hPa over the Tibetan Plateau in the pre-monsoon months were significantly lower in the year of delayed onset (1997). The precipitable water content was found to be another major feature, which grew rapidly over the equatorial belt of the Indian Ocean extending up to the Arabian Sea and Bay of Bengal during the two weeks prior to onset. Most of these features were observed very distinctly in the month of April, well before the monsoon onset, and promise to provide important predictive signals for the onset over Kerala. Copyright © 2002 Royal Meteorological Society. [source] Geomorphic characteristics of the Minjiang drainage basin (eastern Tibetan Plateau) and its tectonic implications: New insights from a digital elevation model studyISLAND ARC, Issue 2 2006Hui-Ping Zhang Abstract The Minshan Mountain and adjacent region are the major continental escarpments along the eastern Tibetan Plateau. The Minjiang drainage basin is located within the plateau margin adjacent to the Sichuan Basin. Based on the analysis of the digital elevation model (DEM) acquired by the Shuttle Radar Topography Mission (SRTM), we know that the Minjiang drainage basin has distinct geomorphic characteristics. The regular increasing of local topographic relief from north to south is a result of the Quaternary sediment deposition within the plateau and the holistic uplift of the eastern margin of the Tibetan Plateau versus the Sichuan Basin. Results from DEM-determined Minjiang drainage sub-basins and channel profiles show that the tributaries on the opposite sides are asymmetric. Lower perimeter and area of drainage sub-basins, total channel length and bifurcation ratio within eastern flank along the Minjiang mainstream are the result of the Quaternary differential uplift of the Minshan Mountain region. Shorter stream lengths and lower bifurcation ratio might be the indications of the undergrowth and newborn features of these eastern streams, which are also representative for the eastern uplift of the Minshan Mountain. [source] Absence of Archean basement in the South Kunlun Block: Nd-Sr-O isotopic evidence from granitoidsISLAND ARC, Issue 1 2003Chao Yuan Abstract The West Kunlun mountain range along the northwestern margin of the Tibetan Plateau is crucial in understanding the early tectonic history of the region. It can be divided into the North and South Kunlun Blocks, of which the former is considered to be part of the Tarim Craton, whereas consensus was not reached on the nature and origin of the South Kunlun Block. Samples were collected from the 471 Ma Yirba Pluton, the 405 Ma North Kudi Pluton and the 214 Ma Arkarz Shan Intrusive Complex. These granitoids cover approximately 60% of the Kudi area in the South Kunlun Block. Sr, Nd, and O isotope compositions preclude significant involvement of mantle-derived magma in the genesis of these granitoids; therefore, they can be used to decipher the nature of lower,mid crust in the area. All samples give Mesoproterozoic Nd model ages (1.1,1.5 Ga) similar to those of the exposed metamorphic complex of this block but significantly different from those of the basement of the North Kunlun Block (2.8 Ga). This indicates that the South Kunlun Block does not have an Archean basement, and, thus, does not support the microcontinent model that suggests the South Kunlun Block was a microcontinent once separated from and later collided back with the North Kunlun Block. [source] Biogeographical patterns of Chinese spiders (Arachnida: Araneae) based on a parsimony analysis of endemicityJOURNAL OF BIOGEOGRAPHY, Issue 7 2008Kaibaryer Meng Abstract Aim, The distributions of Chinese spiders are used to form biotic regions and to infer biogeographical patterns. Location, China. Methods, China was initially divided into 294 quadrats of 2° latitude by 2° longitude. The distributions of 958 species of spiders were summarized for each quadrat. Subsequently, these quadrats were pooled into 28 areas based on topographical characteristics and to a lesser extent on the distributions of spiders. Parsimony analysis of endemicity (PAE) was used to classify the 28 areas based on the shared distributional patterns of spiders. Results, China was found to have seven major biogeographical regions based on the distributional patterns of spiders: Western Northern region (clade B2: Tibetan Plateau and Inner Mongolia-Xinjiang subregions), Central Northern region (clade B3), Eastern Northern region (clade B4), Central region (clade C2), Eastern Southern region (clade C3), Western Southern region (clade C4), and Central Southern region (clade C5). Main conclusions, The distributional patterns of Chinese spiders correspond broadly to geological provinces. A comparison of the geological provinces and the distributional patterns of spiders reveals that the spiders occur south of the geological provinces. Furthermore, a general biogeographical classification with five natural areas is suggested as follows: Tibetan Plateau, Central Northern, Eastern Northern, Western Northern (excluding Tibetan Plateau), and Southern regions. [source] Biogeography and molecular phylogeny of the genus Schizothorax (Teleostei: Cyprinidae) in China inferred from cytochrome b sequencesJOURNAL OF BIOGEOGRAPHY, Issue 8 2006Dekui He Abstract Aim, To test a vicariant speciation hypothesis derived from geological evidence of large-scale changes in drainage patterns in the late Miocene that affected the drainages in the south-eastern Tibetan Plateau. Location, The Tibetan Plateau and adjacent areas. Methods, The cytochrome b DNA sequences of 30 species of the genus Schizothorax from nine different river systems were analysed. These DNA sequences were analysed using parsimony, maximum likelihood and Bayesian methods. The approximately unbiased and Shimodaira,Hasegawa tests were applied to evaluate the statistical significance of the shortest trees relative to alternative hypotheses. Dates of divergences between lineages were estimated using the nonparametric rate smoothing method, and confidence intervals of dates were obtained by parametric bootstrapping. Results, The phylogenetic relationships recovered from molecular data were inconsistent with traditional taxonomy, but apparently reflected geographical associations with rivers. Within the genus Schizothorax, we observed a divergence between the lineages from the Irrawaddy,Lhuit and Tsangpo,Parlung rivers, and tentatively dated this vicariant event back to the late Miocene (7.3,6.8 Ma). We also observed approximately simultaneous geographical splits within drainages of the south-eastern Tibetan Plateau, the Irrawaddy, the Yangtze and the Mekong,Salween rivers in the late Miocene (7.1,6.2 Ma). Main conclusions, Our molecular evidence tentatively highlights the importance of palaeoriver connections and the uplift of the Tibetan Plateau in understanding the evolution of the genus Schizothorax. Molecular estimates of divergence times allowed us to date these vicariant scenarios back to the late Miocene, which agrees with geological suggestions for the separation of these drainages caused by tectonic uplift in south-eastern Tibet. Our results indicated the substantial role of vicariant-based speciation in shaping the current distribution pattern of the genus Schizothorax. [source] Carbon Sequestration in Two Alpine Soils on the Tibetan PlateauJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 9 2009Yu-Qiang Tian Abstract Soil carbon sequestration was estimated in a conifer forest and an alpine meadow on the Tibetan Plateau using a carbon-14 radioactive label provided by thermonuclear weapon tests (known as bomb- 14C). Soil organic matter was physically separated into light and heavy fractions. The concentration spike of bomb- 14C occurred at a soil depth of 4 cm in both the forest soil and the alpine meadow soil. Based on the depth of the bomb- 14C spike, the carbon sequestration rate was determined to be 38.5 g C/m2 per year for the forest soil and 27.1 g C/m2 per year for the alpine meadow soil. Considering that more than 60% of soil organic carbon (SOC) is stored in the heavy fraction and the large area of alpine forests and meadows on the Tibetan Plateau, these alpine ecosystems might partially contribute to "the missing carbon sink". [source] Water Sources of Dominant Species in Three Alpine Ecosystems on the Tibetan Plateau, ChinaJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 3 2008De-Yu Duan Abstract Plant water sources were estimated by two or three compartment linear mixing models using hydrogen and oxygen isotope (,D and ,18O) values of different components such as plant xylem water, precipitation and river water as well as soil water on the Tibetan Plateau in the summer of 2005. Four dominant species (Quercus aquifolioides, Pinus tabulaeformis, Salix rehderiana and Nitraria tangutorum) in three typical ecosystems (forest, shrub and desert) were investigated in this study. Stable isotope ratios of the summer precipitations and the soil water presented variations in spatial and temporal scales. ,18O values of N. tangutorum xylem water were constant in the whole growth season and very similar to those of deep soil water. Water sources for all of the plants came from both precipitations and soil water. Plants switched rapidly among different water sources when environmental water conditions changed. Rainwater had different contributions to the plants, which was influenced by amounts of precipitation. The percentage of plant xylem water derived from rainwater rose with an increase in precipitation. Water sources for broad-leaved and coniferous species were different although they grew in the same environmental conditions. For example, the broad-leaved species Q. aquifolioides used mainly the water from deep soil, while 92.5% of xylem water of the coniferous species P. tabulaeformis was derived from rainwater during the growth season. The study will be helpful for us to fully understand responses of species on the Tibetan Plateau to changes in precipitation patterns, and to assess accurately changes of vegetation distribution in the future. [source] Timing and style of Late Pleistocene glaciation in the Queer Shan, northern Hengduan Mountains in the eastern Tibetan Plateau,JOURNAL OF QUATERNARY SCIENCE, Issue 6 2010Liubing Xu Abstract Glacial landforms and sediments provide evidence for the existence of two Late Pleistocene major glacial advances in the Queer Shan, northern Hengduan Mountains in the eastern Tibetan Plateau. In the current study, optically stimulated luminescence and electron spin resonance dating results reveal that the two glacial advances occurred during Marine Isotope Stage (MIS) 3 and the Last Glacial Maximum (LGM) in MIS 2, respectively. Geomorphic evidence shows that the glacial advance during MIS 3 was more extensive than that in MIS 2. This glacial advance is synchronous with other glaciated areas in the Himalaya and Tibet, but contrasts with global ice volumes that reached their maximum extent during the LGM. Glaciers in the Queer Shan are of the summer accumulation type and are mainly fed by precipitation from the south Asian monsoon. Palaeoclimate proxies show that during MIS 3 the south Asian monsoon strengthened and extended further north into the Tibetan Plateau to supply more precipitation as snow at high altitudes. This in turn led to positive glacier mass balances and caused glaciers to advance. However, during the LGM, despite cooler temperature than in MIS 3, the weakened south Asian monsoon and the associated reduced precipitation were not as favourable for glacier expansion as in MIS 3. Copyright © 2010 John Wiley & Sons, Ltd. [source] A test of the generality of leaf trait relationships on the Tibetan PlateauNEW PHYTOLOGIST, Issue 4 2006Jin-Sheng He Summary ,,Leaf mass per area (LMA), nitrogen concentration (on mass and area bases, Nmass and Narea, respectively), photosynthetic capacity (Amass and Aarea) and photosynthetic nitrogen use efficiency (PNUE) are key foliar traits, but few data are available from cold, high-altitude environments. ,,Here, we systematically measured these leaf traits in 74 species at 49 research sites on the Tibetan Plateau to examine how these traits, measured near the extremes of plant tolerance, compare with global patterns. ,,Overall, Tibetan species had higher leaf nitrogen concentrations and photosynthetic capacities compared with a global dataset, but they had a slightly lower Amass at a given Nmass. These leaf trait relationships were consistent with those reported from the global dataset, with slopes of the standardized major axes Amass,LMA, Nmass,LMA and Amass,Nmass identical to those from the global dataset. Climate only weakly modulated leaf traits. ,,Our data indicate that covarying sets of leaf traits are consistent across environments and biogeographic regions. Our results demonstrate functional convergence of leaf trait relationships in an extreme environment. [source] Comparative phylogeography of four Apodemus species (Mammalia: Rodentia) in the Asian Far East: evidence of Quaternary climatic changes in their genetic structureBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2010HÉLA SAKKA The phylogeography of four Apodemus species (Apodemus agrarius, Apodemus peninsulae, Apodemus latronum, and Apodemus draco) was studied in the Far East of Asia, based on sequences of the mitochondrial DNA cytochrome b gene. The results obtained show the existence of many different genetic lineages within the studied Apodemus species, suggesting the isolation and differentiation of populations in multiple refuge areas. Higher genetic diversities in some regions such as Yunnan, Sichuan (China), and eastern Russia suggest these areas are potential refuges for these species. The existence of such complex genetic structures could be linked to the presence of many biogeographic barriers (Himalaya Mountains, Tien-shan Mountains, Altai Mountains, Tibetan Plateau, Gobi desert, Yunnan Guizhou Plateau, Dzungaria basin, and others) in these regions, which were probably reinforced during the Quaternary climate changes. These barriers also played an important role concerning the low dispersal abilities of the two studied Apodemus species adapted to forest habitats (A. latronum and A. draco) with respect to colonizing regions other than China. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 797,821. [source] Island-like radiation of Saussurea (Asteraceae: Cardueae) triggered by uplifts of the Qinghai,Tibetan PlateauBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009YU-JIN WANG Increasing evidence suggests that geological or climatic events in the past triggered the radiative diversification of both animals and plants on islands as well as continents. The Qinghai,Tibetan Plateau (QTP) has been extensively uplifted since the Miocene, but there is little information on possible links between these events and biological diversification in this and adjacent regions. Partly to explore such links, we have examined the diversification of Saussurea (Asteraceae: Cardueae), a species-rich genus that is mostly endemic to QTP, but also occurs in arid highlands elsewhere in the Northern Hemisphere. The phylogenetic analyses were conducted on the basis of the nuclear (internal transcribed spacer, ITS) and plastid (trnL-F and psbA-trnH) sequences from 55 species, representing 19 sections from all six subgenera of Saussurea, and species from 15 genera of the Cardueae. The results suggest that the currently circumscribed genus Saussurea (s.l.) is a polyphyletic group and that five sections should be excluded from the genus. Samples from the other 14 sections (representing five subgenera) clustered as a monophyletic group (here designated the Saussurea s.s. lineage, SSSL) with high statistical support. However, none of the analyses (nuclear, plastid or combined) resolved SSSL's infrageneric phylogeny, and the parallel clades of the lineage indicate that island-like adaptive radiation occurred. Furthermore, this radiation appears to have occurred 14,7 Mya, during the period of the major uplift events of QTP. Thus, our results support the hypothesis that geological events may play important roles in driving biological diversification through continental radiation. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 893,903. [source] Distribution and Forming Model of Fluvial Terrace in the Huangshui Catchment and its Tectonic IndicationACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 2 2010Xianyan WANG Abstract: The Huang Shui River, a main tributary of the Yellow River, crosses a series of tectonically subsided and uplifted areas that show different patterns of terrace formation. The distribution of fluvial terrace of the Huang Shui River is studied through topographic and sedimentologic terrace mapping. Three terraces in the Haiyan Basin, four terraces in the Huangyuan Basin, 19 terraces in the Xi'ning Basin (the four high terraces may belong to another river), nine terraces in the Ping'an Basin, five terraces in the Ledu Basin and 12 terraces in the Minhe Basin are recognized. Sedimentology research shows that the geomorphologic and sedimentological pattern of the Huang Shui River, which is located at the margin of Tibet, are different from that of the rivers at other regions. The formation process of the terrace is more complicated at the Huang Shui catchment: both accumulation terrace and erosion terrace were formed in each basin and accumulation terraces were developed in some basins when erosion terraces were formed in other basins, indicating fluvial aggradation may occur in some basins simultaneously with river incision in other basins. A conceptual model of the formation process of these two kinds of fluvial terraces at Huang Shui catchment is brought forward in this paper. First, the equilibrium state of the river is broken because of climatic change and/or tectonic movement, and the river incises in all basins in the whole catchment until reaching a new equilibrium state. Then, the downstream basin subsides quickly and the equilibrium state is broken again, and the river incises at upstream basins while the river accumulates at the subsidence basin quickly until approaching a new equilibrium state again. Finally, the river incises in the whole catchment because of climatic change and/or tectonic movement and the accumulation terrace is formed at the subsidence basin while the erosion terrace is formed at other basins. The existence of the accumulation terrace implied the tectonic subsidence in the sub-basins in Huang Shui catchment. These tectonic subsidence movements gradually developed from the downstream Minhe Basin to the upstream Huangyuan Basin. Dating the terrace sequence has potential to uncover the relationship between the subsidence in the catchment and the regional tectonic at the northeastern Tibetan Plateau. [source] Normal Faulting Type Earthquake Activities in the Tibetan Plateau and Its Tectonic ImplicationACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2010Jiren XU Abstract: This paper analyzes various earthquake fault types, mechanism solutions, stress field as well as other geophysical data to study the crust movement in the Tibetan plateau and its tectonic implications. The results show that a lot of normal faulting type earthquakes concentrate in the central Tibetan plateau. Many of them are nearly perfect normal fault events. The strikes of the fault planes of the normal faulting earthquakes are almost in the N-S direction based on the analyses of the equal area projection diagrams of fault plane solutions. It implies that the dislocation slip vectors of the normal faulting type events have quite great components in the E-W direction. The extension is probably an eastward extensional motion, mainly a tectonic active regime in the altitudes of the plateau. The tensional stress in the E-W or WNW-ESE direction predominates the earthquake occurrence in the normal event region of the central plateau. A number of thrust fault and strike-slip fault type earthquakes with strong compressive stress nearly in the NNE-SSW direction occurred on the edges of the plateau. The eastward extensional motion in the Tibetan plateau is attributable to the eastward movement of materials in the upper mantle based onseismo-tomographic results. The eastward extensional motion in the Tibetan plateau may be related to the eastward extrusion of hotter mantle materials beneath the east boundary of the plateau. The northward motion of the Tibetan plateau shortened in the N-S direction probably encounters strong obstructions at the western and northern margins. Extensional motions from the relaxation of the topography and/or gravitational collapse in the altitudes of the plateau occur hardly in the N-S direction. The obstruction for the plateau to move eastward is rather weak [source] A stable isotope record from freshwater lake shells of the eastern Tibetan Plateau, China, during the past two centuriesBOREAS, Issue 1 2007JINGLU WU Wu, J. L., Schleser, G. H., Lücke, A. & Li, S. 2007 (January): A stable isotope record from freshwater lake shells of the eastern Tibetan Plateau, China, during the past two centuries. Boreas, Vol. 36, pp. 38,46. Oslo. ISSN 0300,9483. Lake Xingcuo is a small, closed, hardwater lake situated in the eastern Tibetan Plateau. Stable isotope data (,18O and ,13C) from the freshwater snail Gyraulus sibirica (Dunker) in a 34-cm-long, radioactive isotope-dated sediment core represent the past 200 years of Lake Xingcuo environmental history. Carbon and oxygen isotope ratios in the shells of the snail yield information on the isotopic composition of the water in which the shell was formed, which in turn relates to climatic conditions prevailing during the snail's life-span. Living and fossil shells from Lake Xingcuo were collected. ,18O values in the living shells from Lake Xingcuo are in equilibrium with ambient waters, while ,13C values may trace snail dietary carbon. On comparing ,18O and ,13C in the shell of Gyraulus sibirica with monitored data for the period 1954,1995, we found that the ,18O composition in the shell is an efficient proxy revealing air temperature during the warmer months from April to September. There is a positive correlation between the ,18O in the shells of Gyraulus sibirica and the running average temperature of the warmer months. Climatic variability in the eastern Tibetan Plateau for the past two centuries has been inferred from the ,18O record from the freshwater snails in the sediments of Lake Xingcuo. As such, the last 200 years' palaeoclimatic record for this region can be separated into three periods representing oscillations between warm and cool conditions consistent with the Guliya ice record in the Tibetan Plateau. [source] Parameters of Coseismic Reverse- and Oblique-Slip Surface Ruptures of the 2008 Wenchuan Earthquake, Eastern Tibetan PlateauACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 4 2009Xiwei XU Abstract: On May 12th, 2008, the Mw7.9 Wenchuan earthquake ruptured the Beichuan, Pengguan and Xiaoyudong faults simultaneously along the middle segment of the Longmenshan thrust belt at the eastern margin of the Tibetan plateau. Field investigations constrain the surface rupture pattern, length and offsets related to the Wenchuan earthquake. The Beichuan fault has a NE-trending right-lateral reverse rupture with a total length of 240 km. Reassessment yields a maximum vertical offset of 6.5 ± 0.5 m and a maximum right-lateral offset of 4.9 ± 0.5 m for its northern segment, which are the largest offsets found; the maximum vertical offset is 6.2 ± 0.5 m for its southern segment. The Pengguan fault has a NE-trending pure reverse rupture about 72 km long with a maximum vertical offset of about 3.5 m. The Xiaoyudong fault has a NW-striking left-lateral reverse rupture about 7 km long between the Beichuan and Pengguan faults, with a maximum vertical offset of 3.4 m and left-lateral offset of 3.5 m. This pattern of multiple co-seismic surface ruptures is among the most complicated of recent great earthquakes and presents a much larger danger than if they ruptured individually. The rupture length is the longest for reverse faulting events ever reported. [source] Dextral-Slip Thrust Faulting and Seismic Events of the Ms 8.0 Wenchuan Earthquake, Longmenshan Mountains, Eastern Margin of the Tibetan PlateauACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 4 2009Zhenhan WU Abstract: Dextral-slip thrust movement of the Songpan-Garzê terrain over the Sichuan block caused the Ms 8.0 Wenchuan earthquake of May 12, 2008 and offset the Central Longmenshan Fault (CLF) along a distance of ,250 km. Displacement along the CLF changes from Yingxiu to Qingchuan. The total oblique slip of up to 7.6 m in Yingxiu near the epicenter of the earthquake, decreases northeastward to 5.3 m, 6.6 m, 4.4 m, 2.5 m and 1.1 m in Hongkou, Beichuan, Pingtong, Nanba and Qingchuan, respectively. This offset apparently occurred during a sequence of four reported seismic events, EQ1,EQ4, which were identified by seismic inversion of the source mechanism. These events occurred in rapid succession as the fault break propagated northeastward during the earthquake. Variations in the plunge of slickensides along the CLF appear to match these events. The Mw 7.5 EQ1 event occurred during the first 0,10 s along the Yingxiu-Hongkou section of the CLF and is characterized by 1.7 m vertical slip and vertical slickensides. The Mw 8.0 EQ2 event, which occurred during the next 10,42 s along the Yingxiu-Yanziyan section of the CLF, is marked by major dextral-slip with minor thrust and slickensides plunging 25°,35° southwestward. The Mw 7.5 EQ3 event occurred during the following 42,60 s and resulted in dextral-slip and slickensides plunging 10° southwestward in Beichuan and plunging 73° southwestward in Hongkou. The Mw 7.7 EQ4 event, which occurred during the final 60,95 s along the Beichuan-Qingchuan section of the CLF, is characterized by nearly equal values of dextral and vertical slips with slickensides plunging 45°,50° southwestward. These seismic events match and evidently controlled the concentrations of landslide dams caused by the Wenchuan earthquake in Longmenshan Mountains. [source] Active Faulting Pattern, Present-day Tectonic Stress Field and Block Kinematics in the East Tibetan PlateauACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 4 2009Yueqiao ZHANG Abstract: This paper examines major active faults and the present-day tectonic stress field in the East Tibetan Plateau by integrating available data from published literature and proposes a block kinematics model of the region. It shows that the East Tibetan Plateau is dominated by strike-slip and reverse faulting stress regimes and that the maximum horizontal stress is roughly consistent with the contemporary velocity field, except for the west Qinling range where it parallels the striking of the major strike-slip faults. Active tectonics in the East Tibetan Plateau is characterized by three faulting systems. The left-slip Kunlun-Qinling faulting system combines the east Kunlun fault zone, sinistral oblique reverse faults along the Minshan range and two major NEE-striking faults cutting the west Qinling range, which accommodates eastward motion, at 10,14 mm/a, of the Chuan-Qing block. The left-slip Xianshuihe faulting system accommodated clockwise rotation of the Chuan-Dian block. The Longmenshan thrust faulting system forms the eastern margin of the East Tibetan Plateau and has been propagated to the SW of the Sichuan basin. Crustal shortening across the Longmenshan range seems low (2,4 mm/a) and absorbed only a small part of the eastward motion of the Chuan-Qing block. Most of this eastward motion has been transmitted to South China, which is moving SEE-ward at 7,9 mm/a. It is suggested from geophysical data interpretation that the crust and lithosphere of the East Tibetan Plateau is considerably thickened and rheologically layered. The upper crust seems to be decoupled from the lower crust through a décollement zone at a depth of 15,20 km, which involved the Longmenshan fault belt and propagated eastward to the SW of the Sichuan basin. The Wenchuan earthquake was just formed at the bifurcated point of this décollement system. A rheological boundary should exist beneath the Longmenshan fault belt where the lower crust of the East Tibetan Plateau and the lithospheric mantle of the Yangze block are juxtaposed. [source] | ||||||||||||||||