PERMAFROST DEGENERATION IN THE EAST OF QINGHAI-XIZANG PLATEAU

ＰＥＲＭＡＦＲＯＳＴＤＥＧＥＮＥＲＡＴＩＯＮＩＮＴＨＥＥＡＳＴＯＦＱＩＮＧＨＡＩ－ＸＩＺＡＮＧＰＬＡＴＥＡＵ￥ＺｈｕＬｉｎｎａｎ；ＷｕＺｉｗａｎｇ；ＬｉｕＹｏｎｇｚｈｉ；ＬｉＤｏｎｇｑｉｎｇ（ＳｔａｔｅＫｅｙＬａｂｏｒａｔｏｒｙｏｆＦｒｏｚｅｎＳｏｉ...     

青藏高原大气热源气候特征的研究

用NCEP/NCAR再分析资料和小波分析方法分析研究了1950-2005年青藏高原大气热源气候特征和变化特征,主要结论包括:(1)夏季青藏高原东部大气热源的强度明显较西部大.6月份,高原东部热源的强度是高原西部的近两倍,7月份的值也比西部大了40%以上.(2)青藏高原全区、东部和西部逐年平均的大气热源有明显不同的变化特征.高原全区年平均大气热源的变化主要是一个14年的时间尺度;高原东部不仅有14年的主要时间变化尺度,同时还有一个非常显著的2.6年的时间变化尺度;高原西部则不同,是一个不明显的1-2年的时间尺度.     

Variation of d δ18O/dT in precipitation in the Qinghai-Xizang Plateau

The relations between δ¹⁸O and temperature on the different time scales were analysed, according to the data from Tuotuohe (34°13′N, 96°25′E; 4533 m a. s. l.), Delingha (37°22′N, 97°22′E; 2981 m a. s. l.) and Xining (36°37′N, 101°46′E; 2261 m a. s. l.) in the Qinghai-Xizang Plateau. The results show that the significance of d δ¹⁸O/dT on different time scales are different. The d δ¹⁸O/dT on the synoptic scale reflects the interdependent relation between δ¹⁸O and temperature in the short-term synoptic scale process; the d δ¹⁸O/d T on the seasonal scale reflects the relation between them whithin a year; and the d δ¹⁸O/d T on the climatic scale reflects the relation between them in the long-term climatic change. The calculated d δ¹⁸O/dT on climatic scale is very close to the theoretical values on the condition of advection transport for Tuotuohe Station. However, there are great differences between the calculated and the theoretical values for Delingha and Xining stations.     

Paleosols and their reflection of the environmental changes in the northeast region of the Qinghai-Xizang Plateau

Based on field investigations, laboratory analyses and ¹⁴C dating, this paper discusses the laws of the formation and development of the paleosols in the northeast region of the Qinghai-Xizang Plateau since Late Pleistocene. The authors reconstruct basic conditions of climate, vegetation, soil and natural zones during the three periods in which the paleosols were formed, i.e. the last interglacial of the Late Pleistocene, warm stage of Late Glacial and the Optimum of Holocene. Finally, this paper discusses the relationship between the paleosols and the uplift of the Qinghai-Xizang Plateau.     

The anisotropy of loess magnetic susceptibility in the northeastern fringe of Qinghai-Xizang Plateau as an indicator of palaeowind direction

Estimates of the palaeo-subaerial wind direction were studied systematically for the first time by using the anisotropy of loess magnetic susceptibility (AMS) measurements in the northwestern China. One hundred and forty undisturbed oriented aeolian loess samples were collected from Lanzhou, Linxia and Wudu areas for AMS measurements, which indicated the subaerial wind directions were not the same while the loess deposited. From the Early Pleistocene to Middle Pleistocene till Late Pleistocene, the wind direction experienced an anticlockwise rotation in the studied area. We suggested this change was related to the uplift of the Qinghai-Xizang Plateau and the adjustment of current and landform effects.     

Last glaciation and maximum glaciation in the Qinghai-Xizang (Tibet) Plateau: A controversy to M. Kuhle’s ice sheet hypothesis

Since the late 1950’s, many Chinese scientists have explored the remains of the Quaternary glaciation in the Qinghai-Xizang (Tibet) Plateau and its surrounding mountains. In the main, 3–4 glaciations have been recognized. The largest one occurred in the Late Middle Pleistocene with piedmont glaciers, ice caps and trellis valley glaciers in many high peak regions. But here is no evidence of a unified ice sheet covering the whole plateau as described by M. Kuhle. Due to the further uplifting of the Himalayas and Qinghai-Xizang Plateau the climate became progressively driver, diminishing the extension of glaciers during the Late Pleistocene. The elevation of the snow line during the Last Glaciation was about 4,000 m on the south, east and northeast edges of the plateau and ascended to 5500 m on the hinder northwest of the plateau. The thermal effect of the big plateau massif, the sharp increase of aridity from the southeast rim to the northwest inland area and the abrupt decrease of precipitation during the Ice Age largely account for the distribution of the Quaternary glaciers in the Qinghai-Xizang Plateau. The neglect of Chinese literature may be one of the causes accounting for M. Kuhle’s misinterpretation on the environment of the Quaternary glaciations in the Qinghai-Xizang Plateau.     

THE FLORISTIC STRUCTURE OF THE XIZANG PART OF THE QINGHAI-XIZANG PLATEAU PLANT SUBKINGDOM

The flora of the Qinghai-Xizang Plateau belongs to the floristic subkingdom of the Holarctic plant kingdom. The Xizang part of this subkingdom can be divided into 4 plant regions. 1) the Yarlung Zangbo River valley region. There are 1,003 species of seed plants, making up 19.38% of the total species in Xizang, and 159 endemic species, 15.89% of the total seed plants. The flora originates mainly from the East Himalayas and the Hengduan Mountains. 2) The Tanggute region. There are 349 species of seed plants and 10 endemic species. The flora represents an intermediate one between the Qinghai-Xizang Plateau and the Hengduan Mountains.3) The Qiangtang region. There are 255 species of seed plants and 18 endemic species. The flora derived from the Himalayan flora and mixed with a great number of Tethysian elements. 4) the Ali region. There are 547 species of seed plants and 41 endemic species. The flora seems to be closely related to Tethysian one.     

GLACIER MELTWATER RUNOFF IN CHINA AND ITS NOURISHMENT TO RIVER

ＧＬＡＣＩＥＲＭＥＬＴＷＡＴＥＲＲＵＮＯＦＦＩＮＣＨＩＮＡＡＮＤＩＴＳＮＯＵＲＩＳＨＭＥＮＴＴＯＲＩＶＥＲ￥ＹａｎｇＺｈｅｎｎｉａｎｇ（杨针娘）（ＬａｎｚｈｏｕＩｎｓｔｉｔｕｔｅｏｆＧｌａｃｉｏｌｏｇｙａｎｄＧｅｏｃｒｙｏｌｏｇｙ，ｔｈｅＣｈｉｎｅｓ...     

PERMAFROST CHANGES AND ENVIRONMENTAL PROBLEMS ALONG THE QINGHAI－XIZANG HIGHWAY

ＰＥＲＭＡＦＲＯＳＴＣＨＡＮＧＥＳＡＮＤＥＮＶＩＲＯＮＭＥＮＴＡＬＰＲＯＢＬＥＭＳＡＬＯＮＧＴＨＥＱＩＮＧＨＡＩ－ＸＩＺＡＮＧＨＩＧＨＷＡＹ￥ＷａｎｇＳｈａｏｌｉｎｇ（王绍令）（ＬａｎｚｈｏｕＩｎｓｔｉｔｕｔｅｏｆＧｌａｃｉｏｌｏｇｙａｎｄＧｅｏｃｒ...     

夏季青藏高原“湿池”变化特征的小波分析

采用1948-2007年共60年的NCEP/NCAR资料,计算了夏季青藏高原地区的可降水量,并采用小波分析方法对可降水量的变化特征进行分析.结果表明:夏季青藏高原上有一个明显的"湿池",湿池有3个可降水量中心,分别位于高原西南部、高原南侧和高原东南部.湿池3个中心的可降水量变化有着明显的年代际特征,高原西南部以13.9a的周期变化最为明显,高原南侧9.2a的周期变化最为明显,高原东南部时间尺度2.6a的周期变化最为明显.趋势分析表明,高原西南部的可降水量可能开始增加,而高原南侧和高原东南部的可降水量应该依然处于偏少的阶段.     

Modeling regional and local-scale permafrost distribution in Qinghai-Tibet Plateau using equivalent-elevation method

This study proposes an equivalent-elevation method to evaluate the integrated effects of latitude and elevation on regional and local-scale permafrost distribution in the Qinghai-Tibet Plateau,and to model the general permafrost-distribution patterns in regional and local-scale area.It is found that the Gaussian curve―an empirical model describing the relation between variations of altitudinal permafrost lower limit (PLL) and latitude in the Northern Hemisphere―could be applied in regional-and local-scale areas in the Qinghai-Tibet Plateau in a latitude-sensitive interval of 30°-50°N.The curve was then used to evaluate the latitudinal effect on permafrost distribution through transforming the latitudinal effect into a kind of altitudinal difference of PLL.This study then calculated the local equivalent-elevation value by overlaying the altitudinal difference of PLL onto real elevation at a certain location.The equivalent-elevation method was verified in an experimental subwatershed of the Qinghai-Tibet Plateau.However,feasibility of the method should be further tested in order to extend for future studies.The use of equivalent-elevation values can build a platform for comparing the regional general permafrost distribution in the plateau,and for basing further evaluations of local factors’ effects on regional permafrost distribution.     

The anisotropy of loess magnetic susceptibility in the northeastern fringe of Qinghai-Xizang Plateau as an indicator of palaeowind direction

ＴＨＥＡＮＩＳＯＴＲＯＰＹＯＦＬＯＥＳＳＭＡＧＮＥＴＩＣＳＵＳＣＥＰＴＩＢＩＬＩＴＹＩＮＴＨＥＮＯＲＴＨＥＡＳＴＥＲＮＦＲＩＮＧＥＯＦＱＩＮＧＨＡＩＸＩＺＡＮＧＰＬＡＴＥＡＵＡＳＡＮＩＮＤＩＣＡＴＯＲＯＦＰＡＬＡＥＯＷＩＮＤＤＩＲＥＣＴＩＯＮＷａｎ...     

Rangeland privatization and its impacts on the Zoige wetlands on the Eastern Tibetan Plateau

The high Zoige Basin （Ruoergai Plateau） on the eastern Tibetan Plateau is a fault depression formed during intensive uplifting of the Tibetan Plateau. The wetland is globally important in biodiversity and is composed of marshes, bogs, fens, wet meadows and shallow water interspersed with low hills and sub-alpine meadows. Most of the Zoige wetlands have long been one of the most important grazing lands in China. Recent rangeland policy has allowed grazing, and usable wetland areas have been being legally allocated to individuals or groups of households on a long-term lease basis. Privatizafion of the wetland has impacted the Zoige wetlands in aspects of hydrologic condition, landscape and biodiversity. The uneven spatial distribution of water resources onprivatelands has led to the practice of extracting ground water, which has decreased the perched water table in Zoige. Fencing off the rangelands and grazing on expanding sand dunes have affected landscapes. Variation in the water table has led to the changes in vegetation diversity, resulting in the changes in wildlife and aquatic diversities and ecosystem processes. Making use all year round of the pasture that was previously grazed only in summer has shrunk the daily activity space of wildlife, and the newly erected fences blocked the movement of wild animals looking for food in the snow to lower and open areas. To maintain the favorable conditions of the Zoige wetland ecosystem, the author suggests that, in addition to biophysical research and implementation of conservation practices, there is an immediate need to initiate an integrated management program, increase public awareness of wetland functions and provide better training for the local conservation staff.     

Topographic characteristics for the geomorphologic zones in the northwestern edge of the Qinghai-Tibet Plateau

Based on geomorphologic and digital elevation model （DEM） data, the topographic characteristics of the northwestern edge of the Qinghai-Tibet Plateau are analyzed. Five representative peaks are first determined according to the topographic profile maps for the ridge and piedmont lines, and then the topographic gradient characteristics are analyzed according to the representative topographic profile acquisition method. Based on the geomorphologic database data, the regions between the ridge and the piedmont lines are divided into four geomorphologic zones; and the topographic characteristics are finally analyzed for the different geomorphologic zones regions using the DEM data. The research results show that from the piedmont to the ridge, there exist four geomorphologic zones： arid, fluvial, periglacial and glacial. The arid has the lowest elevation, topographic gradient, relief and slope characteristics. The fluvial has lower elevation and the highest topographic gradient, but with lower relief and slope characteristics. With higher elevation, the periglcial has lower topographic gradient, but the highest relief and slope characteristics. The glacial has the highest elevation with higher topographic gradient, relief and slope characteristics.     

Florogeography of mire plants in southern part of qinghai-xizang plateau and its adjacent areas

The southern part of the Qinghai-Xizang (Tibet) Plateau and its adjacent area are rich in mire flora. There are 51 families, 101 genera and 220 species. The geographical compositions of this region are very complex, consisting of the following-geographical elements: tropic-subtropic elements approximating to 8.33% of the entire flora in the region, tropic-temperate elements 22.71%, temperate elements 43.18%, cosmopolitan elements 9.85%, the Qinghai-Xizang endemic elements 14.39%, north polemountain elements 1.51%. Temperate elements in this region are dominant. The dominant species of mires, Carex lasiocarpa, in this region is also found in northeast China, Finland and North America. The origin of mires of this region is earlier than northeast China and Finland. This shows that the southern part of the Qinghai-Xizang Plateau and its adjacent areas may be the centre of the origin and distribution of temperate elements.     

IMPACT OF ROAD CONSTRUCTION ON VEGETATION ALONGSIDE QINGHAI-XIZANG HIGHWAY AND RAILWAY

Based on the field investigation in August 2001 and August 2002, digital China Vegetation Map in 2001 and Qinghai-Xizang(Tibet) Plateau Vegetation Regionalization Map in 1996, vegetation characteristics along two sides of Qinghai-Xizang highway and railway are studied in this paper. Meanwhile, the impact of Qinghai-Xizang highway and railway constructions on the vegetation types are analyzed using ARCVIEW. ARC/1NFO and PATCH ANALYSIS. It was found that: 1) Qinghai-Xizang highway and railway span 9 latitudes, 12 longitudes and 6 physical geographic regions (East Qinghai and Qilian mountain steppe region, Qaidam mountain desert region,South Qinghai-Xizang alpine meadow steppe region. Qiangtang alpine steppe region, Golog-Nagqu alpine shrubmeadow region and South Xizang mountain shrub steppe region); 2) the construction of Qinghai-Xizang highway and railway destroyed natural vegetation and landscape, especially in 50m-wide buffer regions along both sides of the roads, it was estimated that the net primary productivity deceased by about 30 504.62t/a and the gross biomass deceased by 432 919.25-1 436 104.3t. The losing primary productivity accounted for 5.70% of the annual primary productivity within lkm-wide buffer regions (535 005.07-535 740.11t/a), and only 0.80%-0.89% of that within 10km-wide buffer regions (3 408 950.45-3 810 480.92t/a). The losing gross biomass was about 9.47%-17.06% of the gross biomass within lkm-wide buffer regions (7 502 971.85-25 488 342.71t), and only 1.47%-2.94% of that within 10km-wide buffer regions (43 615 065.35-164 150 665.37t).     

Analysis of dynamics and driving factors of wetland landscape in Zoige, Eastern Qinghai-Tibetan Plateau

Zoige Wetland is one of the largest plateau wetlands in the world. This paper provides a dynamic analysis of spatial and temporal patterns of the wetland in Zoige, Eastern Qinghai-Tibetan Plateau, supported by ERDAS8.7 and ArcGIS9.0. It is the first comparative analysis of a system of rapidly changing wetland with landscape patterns in Zoige, using 3 classified landsat Thematic Mapper images of 1977, 1994 and 2001. The classified images were used to generate wetland distributing maps, and shape index （S）, diversity index （H）, dominance index （D）, evenness index （E）, fragmentation index （F） and fractal dimension （Fd） were calculated and analyzed spatiotemporally across pure grazing area in Zoige for each landscape type and in different periods （before 1977, during 1977-1994 and 1994-2001）, as well as the driving forces of natural and anthropogenic. The study shows that for a comprehensive understanding of the shapes and trajectories of the shrinking and desertificated land expansion of the wetland, a spatiotemporal landscape metrics analysis in different periods is an improvement than only with landscape changing rates. This type of analysis can also be used to infer underlying social, economic, and political processes that drive the observed wetland forms. The results indicate that wetland patterns can be changed over relatively short periods of time. The total area of lake reduced by 164.86 km^2, grassland extended by 141.74 km^2, semi-marsh extended by 105.94 km^2, marsh reduced by 86.00 km^2 the number of landscape patches reduced by 56, and their average area decreased by 2.68 km^2, the successions within lake, marsh, semi-marsh and grassland were found obviously. S decreased stepwise： D and F increased but H decreased： The changing rate after 1994 was 2.3 to 2.9 times greater than that before. The change of the wetland landscape patterns resulted in the interaction between socio-ceenomic and natural forces of positive and negative aspects; and natural factors affected as assistant aspect. Some important human activities in this period led to the change of the landscape patterns in this region directly. Some measurements made by government and NGO delayed the converting process partly.     

Progress in studies on geographical environments of the Qinghai-Xiang plateau

The Qinghai-Xizang (Tibet) Plateau area was subjected to twice uplift and planation in the Tertiary. Intense uplifting of the plateau area has given rise to drastic changes and differentiation of physical environment on the plateau and the surrounding area since 3.4 Ma B.P. Significant environmental changes with dry tendency in interior of the plateau had occurred during the last 150 ka B.P. By comparative study on several mountains of the plateau, two systems of the structure-type of the altitudinal belt are identified and nine groups are subdivided. A distribution model with close relevance to highland uplift effect has been generalized. A number of striking geo-ecological phenomen and their spatial pattern such as moisture corridor, dry valleys, high-cold meadow zone, and high-cold arid core area are investigated and discussed. Based on the thermal conditions, moisture regimes and variation in landforms of the plateau is sequentially demarcated. A tentative scheme of 2 temperature belts, 10 natural zones and 28 physical districts has been proposed not including southern slopes of the East Himalayas. The Qinghai-Xizang Plateau is sensitive to “green house effect”, showing close relation with global change. Characteristics of temperature and precipitation on the plateau during the last 2000 years, and response of glaciers, snow deposit and permafrost on the plateau to global change are dealt with in the present paper. Under the auspices of Chinese National Key Project for Basic Research (G1998040800) and CAS project on the Qinghai-Xizang Plateau (KZ951 - A1 - 204, KZ95T - 06)     

喜马拉雅山脉与我国东部中低山区冰蚀地貌对比研究

我国东部中低山区第四纪冰川的存在与否一直存在争议,但冰川必然对山体进行冰蚀作用形成冰蚀地貌。为了分析我国东部中低山区的山体地貌是否具有冰蚀特征,该文选取了现代冰川集中发育区-喜马拉雅山脉作为冰蚀地貌的研究对象,通过宏观分析,除了由缩口、三角脊、残弧组成的冰斗系统外,还发现冰蚀作用过程存在避谷、吞脊、切壁、穿梁等特殊习性。分析认为冰蚀过程主要受制于雪线高程、积雪高程与坡向坡角三方面因素的控制。以此为基础,对我国东部的江西庐山、山东蒙山、大兴安岭主峰黄岗梁三个地区的山体地貌进行对比分析,发现这些山区的山体地貌与喜马拉雅山脉的冰蚀地貌具有一致性。文章从冰蚀过程的角度确认了我国东部中低山区存在第四纪冰川的事实。     

SALT LAKES ON THE INNER MONGOLIAN PLATEAU OF CHINA

Salt lakes,the main source of trona resources in China, are widely distributed on the Inner Mongolian Plateau. Their characteristics are large in number, various in type, and short in salt-forming stage, especially their considerable number is well-known at home and abroad. The paper discusses the physical constituents, hydrochemical features, classification, formation, evolution, and salt-forming regularities of salt lakes through analyzing their distribution, lacustrine deposits and salt-forming conditions.