Major progress, problems, and challenges of recent investigation of the Tibetan Plateau uplift processes and resulting environmental changes are reviewed and summarized briefly, which especially covers the National Ti...Major progress, problems, and challenges of recent investigation of the Tibetan Plateau uplift processes and resulting environmental changes are reviewed and summarized briefly, which especially covers the National Tibetan Research Projects of the Chinese Eighth (1992-1996) and Ninth (1997-2001) 'Five-Year Projects'. The Tibetan Plateau uplift is a complicated multiple cyclic process. The Gangdise and Himalayas began to uplift in the展开更多
Waterlogging is one of the major water issues in most cities of China and directly restricts their urbanization processes.The construction of Sponge City is an effective approach to solving the urban water issues,part...Waterlogging is one of the major water issues in most cities of China and directly restricts their urbanization processes.The construction of Sponge City is an effective approach to solving the urban water issues,particularly for the waterlogging.In this study,both the urban issues emerged at the stage of rapid urbanization in China and the demands as well as problems of Sponge City construction related with the water issues were investigated,and the opportunities and challenges for the Sponge City construction in the future were also proposed.It was found that the current stormwater management focused on the construction of gray infrastructures(e.g.,drainage network and water tank) based on the fast discharge idea,which was costly and hard to catch up with the rapid expansion of city and its impervious surface,while green infrastructures(e.g.,river,lake and wetland)were ignored.Moreover,the current construction of Sponge City was still limited to low impacted development(LID) approach which was concentrated on source control measures without consideration of the critical functions of surrounding landscapes(i.e.,mountain,river,wetland,forest,farmland and lake),while application of the integrated urban water system approach and its supported technologies including municipal engineering,urban hydrology,environmental science,social science and ecoscape were relatively weak and needed to be improved.Besides,the lack of special Sponge City plan and demonstration area was also a considerable problem.In this paper,some perspectives on Good Sponge City Construction were proposed such as the point that idea of urban plan and construction should conform to the integral and systematic view of sustainable urban development.Therefore,both the basic theoretical research and the basic infrastructure construction such as monitoring system,drainage facility and demonstration area should be strengthened,meanwhile,the reformation and innovation in the urban water management system and the education system should also be urgently pe展开更多
By combining living trees and archaeological wood, the annual mean temperatures were reconstructed based on ring-width indices of the mid-eastern Tibetan Plateau for the past 2485 years. The climate variations reveale...By combining living trees and archaeological wood, the annual mean temperatures were reconstructed based on ring-width indices of the mid-eastern Tibetan Plateau for the past 2485 years. The climate variations revealed by the reconstruction indicate that there were four periods to have average tem- peratures similar to or even higher than that mean of 1970 to 2000 AD. A particularly notable rapid shift from cold to warm, we call it the "Eastern Jin Event", occurred from 348 AD to 413 AD. Calculation re- sults show that the temperature variations over the mid-eastern Tibetan Plateau are not only repre- sentative for large parts of north-central China, but also closely correspond to those of the entire Northern Hemisphere over long time scales. During the last 2485 years, the downfall of most major dynasties in China coincides with intervals of low temperature. Compared with the temperature records in other regions of China during the last 1000 years, this reconstruction from the Tibetan Plateau shows a significant warming trend after the 1950s.展开更多
Through analyzing the yearly average data obtained from 123 regular meteorological observatories located in the Tibetan Plateau (T-P), this article studies the characteristics of climate change in T-P in the last 40 y...Through analyzing the yearly average data obtained from 123 regular meteorological observatories located in the Tibetan Plateau (T-P), this article studies the characteristics of climate change in T-P in the last 40 years. Prom the distribution of the linear trend, it can be concluded that the southeastern part of T-P becomes warmer and wetter, with an obvious increase of rainfall. The same characteristics are found in the southwestern part of T-P, but the shift is smaller. In the middle of T-P, temperature and humidity obviously increase with the center of the increase in Bangoin-Amdo. The south of the Tarim Basin also exhibits the same tendency. The reason for this area being humid is that it gets less sunshine and milder wind. The northeastern part of T-P turns warmer and drier. Qaidam Basin and its western and southern areas are the center of this shift, in which the living environment is deteriorating. Analyzing the characteristics of the regional average time series, it can be found that in the mid-1970s, a significant sudden change occurred to annual rainfall, yearly average snow-accumulation days and surface pressure in the eastern part of T-P. In the mid-1980s, another evident climatic jump happened to yearly average temperature, total cloud amount, surface pressure, relative humidity, and sunshine duration in the same area. That is, in the mid 1980s, the plateau experienced a climatic jump that is featured by the increase of temperature, snow-accumulation days, relative humidity, surface pressure, and by the decrease of sunshine duration and total cloud amount. The sudden climatic change of temperature in T-P is later than that of the global-mean temperature. Prom this paper it can be seen that in the middle of the 1980s, a climatic jump from warm-dry to warm-wet occurred in T-P.展开更多
Above-and belowground biomass allocation not only influences growth of individual plants,but also influences vegetation structures and functions,and consequently impacts soil carbon input as well as terrestrial ecosys...Above-and belowground biomass allocation not only influences growth of individual plants,but also influences vegetation structures and functions,and consequently impacts soil carbon input as well as terrestrial ecosystem carbon cycling.However,due to sampling difficulties,a considerable amount of uncertainty remains about the root:shoot ratio(R/S),a key parameter for models of terrestrial ecosystem carbon cycling.We investigated biomass allocation patterns across a broad spatial scale.We collected data on individual plant biomass and systematically sampled along a transect across the temperate grasslands in Inner Mongolia as well as in the alpine grasslands on the Tibetan Plateau.Our results indicated that the median of R/S for herbaceous species was 0.78 in China's grasslands as a whole.R/S was significantly higher in temperate grasslands than in alpine grasslands(0.84 vs.0.65).The slope of the allometric relationship between above-and belowground biomass was steeper for temperate grasslands than for alpine.Our results did not support the hypothesis that aboveground biomass scales isometrically with belowground biomass.The R/S in China's grasslands was not significantly correlated with mean annual temperature(MAT) or mean annual precipitation(MAP).Moreover,comparisons of our results with previous findings indicated a large difference between R/S data from individual plants and communities.This might be mainly caused by the underestimation of R/S at the individual level as a result of an inevitable loss of fine roots and the overestimation of R/S in community-level surveys due to grazing and difficulties in identifying dead roots.Our findings suggest that root biomass in grasslands tended to have been overestimated in previous reports of R/S.展开更多
Four intensive uplift periods, i.e., 60–35, 25–17 and 12–8 Ma (but 18–13 Ma in the Himalayas of the southern Tibet), and since about 5 Ma, can be determined on the Tibetan Plateau by synthetical analysis of low-te...Four intensive uplift periods, i.e., 60–35, 25–17 and 12–8 Ma (but 18–13 Ma in the Himalayas of the southern Tibet), and since about 5 Ma, can be determined on the Tibetan Plateau by synthetical analysis of low-temperature thermo-chronology data, sedimentary deposit records, and structural deformation records of different areas. The strong tectonic uplift periods in different areas on the Tibetan Plateau are penecontemporaneous, except for the Himalayan area of the southern Tibet, where a rapid uplift and exhumation period, controlled by the activity of the South Tibetan Detachment System faults, occurred during 18–13 Ma. These strong uplift and exhumation periods correspond well to intensive deformation activity periods, suggesting tectonically-controlled uplift and exhumation. The deposit records, such as the distribution of coarse clastic sediments, the distribution of tectonically-controlled basins, stratigraphic discontinuousness or unconformity, and fault-controlled geomorphologic evolution, also match well with the strong uplift and exhumation periods. Expanding processes of the plateau are also discussed.展开更多
A large area of high-pressure garnet-kyanite granulite is exhumed in the Namjagbarwa area, which provides a window for observing the deep crust rocks and structures of the Tibetan Plateau. Three mineral assemblages ca...A large area of high-pressure garnet-kyanite granulite is exhumed in the Namjagbarwa area, which provides a window for observing the deep crust rocks and structures of the Tibetan Plateau. Three mineral assemblages can have been distinguished in the garnet-kyanite HP granulites by petrography, i.e. M1. Mus+Bi+P1+Q, M2. Gt+Ky +perphite/antiperphite+Rt+Q, M3. Gt+Sill+Cord+Sp+Ilm ± Opx. Metamorphic conditions of the peak granulite assemblages (M2) formatted by thickening of crusts, with available isotopic ages of 45–69 Ma, are at 1.4—1.8 Gpa and 750—850°. Their retrograde assemblages overprinted by decompressure during the uplift, with available isotopic ages of 18—23 Ma, were formed at 0.60—0.70 Gpa, 621—726°. The thermobarometric evaluation, petrogenetic grid and corresponding isotopic ages indicate a clockwise isothermal decompression metamorphic path. The HP granulite metamorphic history indicates that the collision of the Indian Plate with the Eurasian Plate had begun at 70 Ma, far earlier than the widely accepted 45 Ma.展开更多
The North China and the neighbouring Mongolia in Asian Interior is characterized by extremely dry climate, resulted in one of the world＇s major dust emission centres. Deciphering the source region of Asian dust is cr...The North China and the neighbouring Mongolia in Asian Interior is characterized by extremely dry climate, resulted in one of the world＇s major dust emission centres. Deciphering the source region of Asian dust is critical for revealing the mechanism of the dust production, interpreting the paleo-environrnental records of eolian deposits, predicting the overall environmental effects of dust, and setting the strategies for the control of contemporary dust storms. This paper summarizes the geochemical methods applied to the source tracing of Asian dust. Nd-Sr isotopes were the most extensively studied source tracer of Asian dust and have been successfully applied in many cases. Geochemistry of detrital monomineral shows great theoretical advantages in source tracing and deserves further studies. The short-range transportation of Chinese loess with direction similar to that of the prevailing near surface wind is revealed. Source tracing also shows that the Asian dust has two ultimate material sources from the northern margin of the Tibetan Plateau and the Central Asian Orogen, which confirms the importance of mountain processes in the production of silt eolian particles. Based on the recent progresses on the source tracing of Asian dust, discussions are expanded on the natural background of Asian dust storms and potential anthropogenic influence, the materials evolution of the source regions of Asian dust and its relationships with climate changes and Tibetan uplift, and the role of Tibetan uplift in the Asian dust system.展开更多
Based on the GIMMS AVHRR NDVI data （8 km spatial resolution） for 1982-2000, the SPOT VEGETATION NDVI data （1 km spatial resolution） for 1998-2009, and observa- tional plant biomass data, the CASA model was used to...Based on the GIMMS AVHRR NDVI data （8 km spatial resolution） for 1982-2000, the SPOT VEGETATION NDVI data （1 km spatial resolution） for 1998-2009, and observa- tional plant biomass data, the CASA model was used to model changes in alpine grassland net primary production （NPP） on the Tibetan Plateau （TP）. This study will help to evaluate the health conditions of the alpine grassland ecosystem, and is of great importance to the pro- motion of sustainable development of plateau pasture and to the understanding of the func- tion of the national ecological security shelter on the TP. The spatio-temporal characteristics of NPP change were investigated using spatial statistical analysis, separately on the basis of physico-geographical factors （natural zone, altitude, latitude and longitude）, river basin, and county-level administrative area. Data processing was carried out using an ENVI 4.8 platform, while an ArcGIS 9.3 and ANUSPLIN platform was used to conduct the spatial analysis and mapping. The primary results are as follows： （1） The NPP of alpine grassland on the TP gradually decreases from the southeast to the northwest, which corresponds to gradients in precipitation and temperature. From 1982 to 2009, the average annual total NPP in the TP alpine grassland was 177.2x1012 gC yrl（yr represents year）, while the average annual NPP was 120.8 gC m^-2 yr^-1. （2） The annual NPP in alpine grassland on the TP fluctuates from year to year but shows an overall positive trend ranging from 114.7 gC m^-2 yr^-1 in 1982 to 129.9 gC m^-2 yr^-1 in 2009, with an overall increase of 13.3%; 32.56% of the total alpine grassland on the TP showed a significant increase in NPP, while only 5.55% showed a significant decrease over this 28-year period. （3） Spatio-temporal characteristics are an important control on an- nual NPP in alpine grassland： a） NPP increased in most of the natural zones on the TP, only showing a slight decrease in the Ngari montane desert-steppe and desert zone. The positive 展开更多
The temporal and spatial changes of NDVI on the Tibetan Plateau, as well as the relationship between NDVI and precipitation, were discussed in this paper, by using 8-km resolution multi-temporal NOAA AVHRR-NDVI data f...The temporal and spatial changes of NDVI on the Tibetan Plateau, as well as the relationship between NDVI and precipitation, were discussed in this paper, by using 8-km resolution multi-temporal NOAA AVHRR-NDVI data from 1982 to 1999. Monthly maximum NDVI and monthly rainfall were used to analyze the seasonal changes, and annual maximum NDVI, annual effective precipitation and growing season precipitation （from April to August） were used to discuss the interannual changes. The dynamic change of NDVI and the corre- lation coefficients between NDVI and rainfall were computed for each pixel. The results are as follows： （1） The NDVI reached the peak in growing season （from July to September） on the Tibetan Plateau. In the northern and western parts of the plateau, the growing season was very short （about two or three months）; but in the southern, vegetation grew almost all the year round. The correlation of monthly maximum NDVI and monthly rainfall varied in different areas. It was weak in the western, northern and southern parts, but strong in the central and eastern parts. （2） The spatial distribution of NDVI interannual dynamic change was different too. The increase areas were mainly distributed in southern Tibet montane shrub-steppe zone western part of western Sichuan-eastern Tibet montane coniferous forest zone, western part of northern slopes of Kunlun montane desert zone and southeastern part of southern slopes of Himalaya montane evergreen broad-leaved forest zone; the decrease areas were mainly distributed in the Qaidam montane desert zone, the western and northern parts of eastern Qinghai-Qilian montane steppe zone, southern Qinghai high cold meadow steppe zone and Ngari montane desert-steppe and desert zone. The spatial distribution of correlation coeffi- cient between annual effective rainfall and annual maximum NDVI was similar to the growing season rainfall and annual maximum NDVI, and there was good relationship between NDVI and rainfall in the meadow and grassland with medium ve展开更多
Knowledge of seasonal variation of net ecosystem CO2 exchange (NEE) and its biotic and abiotic controllers will further our understanding of carbon cycling process, mechanism and large-scale modelling. Eddy covariance...Knowledge of seasonal variation of net ecosystem CO2 exchange (NEE) and its biotic and abiotic controllers will further our understanding of carbon cycling process, mechanism and large-scale modelling. Eddy covariance technique was used to measure NEE, biotic and abiotic factors for nearly 3 years in the hinterland alpine steppe--Korbresia meadow grassland on the Tibetan Plateau, the present highest fluxnet station in the world. The main objectives are to investigate dynamics of NEE and its components and to determine the major controlling factors. Maximum carbon assimilation took place in August and maximum carbon loss occurred in November. In June, rainfall amount due to monsoon climate played a great role in grass greening and consequently influenced interannual variation of ecosystem carbon gain. From July through September, monthly NEE presented net carbon assimilation. In other months, ecosystem exhibited carbon loss. In growing season, daytime NEE was mainly controlled by photosynthetically active radiation (PAR). In addition, leaf area index (LAI) interacted with PAR and together modulated NEE rates. Ecosystem respiration was controlled mainly by soil temperature and simultaneously by soil moisture. Q10 was negatively correlated with soil temperature but positively correlated with soil moisture. Large daily range of air temperature is not necessary to enhance carbon gain. Standard respiration rate at referenced 10℃(R10) was positively correlated with soil moisture, soil temperature, LAI and aboveground biomass. Rainfall patterns in growing season markedly influenced soil moisture and therefore soil moisture controlled seasonal change of ecosystem respiration. Pulse rainfall in the beginning and at the end of growing season induced great ecosystem respiration and consequently a great amount of carbon was lost. Short growing season and relative low temperature restrained alpine grass vegetation development. The results suggested that LAI be usually in a low level and carbon uptake be relatively low. Rainf展开更多
Lakes on the Tibetan Plateau(TP)are an indicator and sentinel of climatic changes[1].We extended lake area changes on the TP from 2010[2]to 2018,and provided a long and dense lake observations between the 1970s and 20...Lakes on the Tibetan Plateau(TP)are an indicator and sentinel of climatic changes[1].We extended lake area changes on the TP from 2010[2]to 2018,and provided a long and dense lake observations between the 1970s and 2018.We found that the number of lakes,with area larger than 1 km2,has in creased to?1,400 in 2018 from?1,000 in the 1970s.The total area of these lakes decreased between the 1970s and?1995,and then showed a robust increase,with the exception of a slight decrease in 2015.This expansion of the lakes on the highest plateau in rhe world is a response to a hydrological cycle intensified by recent climate changes[3].展开更多
We here report our recent research results on the climatic features of Tibetan thermodynamic functions and their impacts on the regional climates of the Northern Hemisphere. The results show that the thermodynamic pro...We here report our recent research results on the climatic features of Tibetan thermodynamic functions and their impacts on the regional climates of the Northern Hemisphere. The results show that the thermodynamic processes over the Tibetan Plateau not only strongly influence the Asian monsoon and precipitation, but also modulate the atmospheric circulation and climate over North America and Europe through stimulating the large-scale teleconnections such as the Asian-Pacific oscillation and affect the atmospheric circulation over the southern Indian Ocean. The Tibetan climate may be affected by sea surface temperatures over the tropical Pacific. On the other hand, the Tibetan climate also affects the atmosphere-ocean interactions in the tropics and mid-latitudes of the Pacific by the atmospheric circulation over the North Pacific. In spring and summer, the thermodynamic anomalies on the plateau affect the subtropical high pressure, the Hadley circulation, and the intertropical convergence zone over the Pacific, and then modulate the development of the El Ni-o/Southern Oscillation (ENSO). It is necessary to study the forecasting methods for the development of ENSO from the Tibetan climate anomaly. This result also embodies the essence of interactions among land, atmosphere, and ocean over the Northern Hemisphere. Since the previous studies focused on impacts of the plateau on climates in the Asian monsoon regions, it is essential to pay more attention to studying the roles of the plateau in the Northern Hemispheric and even global climates.展开更多
文摘Major progress, problems, and challenges of recent investigation of the Tibetan Plateau uplift processes and resulting environmental changes are reviewed and summarized briefly, which especially covers the National Tibetan Research Projects of the Chinese Eighth (1992-1996) and Ninth (1997-2001) 'Five-Year Projects'. The Tibetan Plateau uplift is a complicated multiple cyclic process. The Gangdise and Himalayas began to uplift in the
基金supported by the National Natural Science Foundation of China(Grant No.41571028)Key Programs of the Chinese Academy of Sciences(Grant No.KFZD-SW-301)
文摘Waterlogging is one of the major water issues in most cities of China and directly restricts their urbanization processes.The construction of Sponge City is an effective approach to solving the urban water issues,particularly for the waterlogging.In this study,both the urban issues emerged at the stage of rapid urbanization in China and the demands as well as problems of Sponge City construction related with the water issues were investigated,and the opportunities and challenges for the Sponge City construction in the future were also proposed.It was found that the current stormwater management focused on the construction of gray infrastructures(e.g.,drainage network and water tank) based on the fast discharge idea,which was costly and hard to catch up with the rapid expansion of city and its impervious surface,while green infrastructures(e.g.,river,lake and wetland)were ignored.Moreover,the current construction of Sponge City was still limited to low impacted development(LID) approach which was concentrated on source control measures without consideration of the critical functions of surrounding landscapes(i.e.,mountain,river,wetland,forest,farmland and lake),while application of the integrated urban water system approach and its supported technologies including municipal engineering,urban hydrology,environmental science,social science and ecoscape were relatively weak and needed to be improved.Besides,the lack of special Sponge City plan and demonstration area was also a considerable problem.In this paper,some perspectives on Good Sponge City Construction were proposed such as the point that idea of urban plan and construction should conform to the integral and systematic view of sustainable urban development.Therefore,both the basic theoretical research and the basic infrastructure construction such as monitoring system,drainage facility and demonstration area should be strengthened,meanwhile,the reformation and innovation in the urban water management system and the education system should also be urgently pe
基金Supported by National Natural Science Foundation of China (Grant Nos. 40525004, 40599420, 40890051)National Basic Research Program of China (Grant Nos. 2007BAC30B00, 2004CB720200, 2006CB400503)the Swedish International Development Cooperation Agency (SIDA, Grant to Hans W. Linderholm)
文摘By combining living trees and archaeological wood, the annual mean temperatures were reconstructed based on ring-width indices of the mid-eastern Tibetan Plateau for the past 2485 years. The climate variations revealed by the reconstruction indicate that there were four periods to have average tem- peratures similar to or even higher than that mean of 1970 to 2000 AD. A particularly notable rapid shift from cold to warm, we call it the "Eastern Jin Event", occurred from 348 AD to 413 AD. Calculation re- sults show that the temperature variations over the mid-eastern Tibetan Plateau are not only repre- sentative for large parts of north-central China, but also closely correspond to those of the entire Northern Hemisphere over long time scales. During the last 2485 years, the downfall of most major dynasties in China coincides with intervals of low temperature. Compared with the temperature records in other regions of China during the last 1000 years, this reconstruction from the Tibetan Plateau shows a significant warming trend after the 1950s.
文摘Through analyzing the yearly average data obtained from 123 regular meteorological observatories located in the Tibetan Plateau (T-P), this article studies the characteristics of climate change in T-P in the last 40 years. Prom the distribution of the linear trend, it can be concluded that the southeastern part of T-P becomes warmer and wetter, with an obvious increase of rainfall. The same characteristics are found in the southwestern part of T-P, but the shift is smaller. In the middle of T-P, temperature and humidity obviously increase with the center of the increase in Bangoin-Amdo. The south of the Tarim Basin also exhibits the same tendency. The reason for this area being humid is that it gets less sunshine and milder wind. The northeastern part of T-P turns warmer and drier. Qaidam Basin and its western and southern areas are the center of this shift, in which the living environment is deteriorating. Analyzing the characteristics of the regional average time series, it can be found that in the mid-1970s, a significant sudden change occurred to annual rainfall, yearly average snow-accumulation days and surface pressure in the eastern part of T-P. In the mid-1980s, another evident climatic jump happened to yearly average temperature, total cloud amount, surface pressure, relative humidity, and sunshine duration in the same area. That is, in the mid 1980s, the plateau experienced a climatic jump that is featured by the increase of temperature, snow-accumulation days, relative humidity, surface pressure, and by the decrease of sunshine duration and total cloud amount. The sudden climatic change of temperature in T-P is later than that of the global-mean temperature. Prom this paper it can be seen that in the middle of the 1980s, a climatic jump from warm-dry to warm-wet occurred in T-P.
基金supported by the National Natural Science Foundation of China (Grant No. 30870381)the Key Project of Scientific and Technical Supporting Programs Funded by the Ministry of Science & Technology of China (Grant No. 2007BAC06B01)
文摘Above-and belowground biomass allocation not only influences growth of individual plants,but also influences vegetation structures and functions,and consequently impacts soil carbon input as well as terrestrial ecosystem carbon cycling.However,due to sampling difficulties,a considerable amount of uncertainty remains about the root:shoot ratio(R/S),a key parameter for models of terrestrial ecosystem carbon cycling.We investigated biomass allocation patterns across a broad spatial scale.We collected data on individual plant biomass and systematically sampled along a transect across the temperate grasslands in Inner Mongolia as well as in the alpine grasslands on the Tibetan Plateau.Our results indicated that the median of R/S for herbaceous species was 0.78 in China's grasslands as a whole.R/S was significantly higher in temperate grasslands than in alpine grasslands(0.84 vs.0.65).The slope of the allometric relationship between above-and belowground biomass was steeper for temperate grasslands than for alpine.Our results did not support the hypothesis that aboveground biomass scales isometrically with belowground biomass.The R/S in China's grasslands was not significantly correlated with mean annual temperature(MAT) or mean annual precipitation(MAP).Moreover,comparisons of our results with previous findings indicated a large difference between R/S data from individual plants and communities.This might be mainly caused by the underestimation of R/S at the individual level as a result of an inevitable loss of fine roots and the overestimation of R/S in community-level surveys due to grazing and difficulties in identifying dead roots.Our findings suggest that root biomass in grasslands tended to have been overestimated in previous reports of R/S.
基金supported by China Geological Survey (Grant No. 1212010610103)National Natural Science Foundation of China (Grant Nos. 40902060, 40672137)
文摘Four intensive uplift periods, i.e., 60–35, 25–17 and 12–8 Ma (but 18–13 Ma in the Himalayas of the southern Tibet), and since about 5 Ma, can be determined on the Tibetan Plateau by synthetical analysis of low-temperature thermo-chronology data, sedimentary deposit records, and structural deformation records of different areas. The strong tectonic uplift periods in different areas on the Tibetan Plateau are penecontemporaneous, except for the Himalayan area of the southern Tibet, where a rapid uplift and exhumation period, controlled by the activity of the South Tibetan Detachment System faults, occurred during 18–13 Ma. These strong uplift and exhumation periods correspond well to intensive deformation activity periods, suggesting tectonically-controlled uplift and exhumation. The deposit records, such as the distribution of coarse clastic sediments, the distribution of tectonically-controlled basins, stratigraphic discontinuousness or unconformity, and fault-controlled geomorphologic evolution, also match well with the strong uplift and exhumation periods. Expanding processes of the plateau are also discussed.
基金Project supported by the National Natural Science Foundation of China (Grant No. 49732100)the National Key Project for Basic Research, Chinese Academy of Sciences Project for Tibetan Research Project (Grant Nos. KZ951-A1-204, KZ95T-06).
文摘A large area of high-pressure garnet-kyanite granulite is exhumed in the Namjagbarwa area, which provides a window for observing the deep crust rocks and structures of the Tibetan Plateau. Three mineral assemblages can have been distinguished in the garnet-kyanite HP granulites by petrography, i.e. M1. Mus+Bi+P1+Q, M2. Gt+Ky +perphite/antiperphite+Rt+Q, M3. Gt+Sill+Cord+Sp+Ilm ± Opx. Metamorphic conditions of the peak granulite assemblages (M2) formatted by thickening of crusts, with available isotopic ages of 45–69 Ma, are at 1.4—1.8 Gpa and 750—850°. Their retrograde assemblages overprinted by decompressure during the uplift, with available isotopic ages of 18—23 Ma, were formed at 0.60—0.70 Gpa, 621—726°. The thermobarometric evaluation, petrogenetic grid and corresponding isotopic ages indicate a clockwise isothermal decompression metamorphic path. The HP granulite metamorphic history indicates that the collision of the Indian Plate with the Eurasian Plate had begun at 70 Ma, far earlier than the widely accepted 45 Ma.
基金supported by National Natural Science Foundation of China (Grant No. 41021002)
文摘The North China and the neighbouring Mongolia in Asian Interior is characterized by extremely dry climate, resulted in one of the world＇s major dust emission centres. Deciphering the source region of Asian dust is critical for revealing the mechanism of the dust production, interpreting the paleo-environrnental records of eolian deposits, predicting the overall environmental effects of dust, and setting the strategies for the control of contemporary dust storms. This paper summarizes the geochemical methods applied to the source tracing of Asian dust. Nd-Sr isotopes were the most extensively studied source tracer of Asian dust and have been successfully applied in many cases. Geochemistry of detrital monomineral shows great theoretical advantages in source tracing and deserves further studies. The short-range transportation of Chinese loess with direction similar to that of the prevailing near surface wind is revealed. Source tracing also shows that the Asian dust has two ultimate material sources from the northern margin of the Tibetan Plateau and the Central Asian Orogen, which confirms the importance of mountain processes in the production of silt eolian particles. Based on the recent progresses on the source tracing of Asian dust, discussions are expanded on the natural background of Asian dust storms and potential anthropogenic influence, the materials evolution of the source regions of Asian dust and its relationships with climate changes and Tibetan uplift, and the role of Tibetan uplift in the Asian dust system.
基金National Basic Research Program of China,No.2010CB951704Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDB03030501No.XDA05060704
文摘Based on the GIMMS AVHRR NDVI data （8 km spatial resolution） for 1982-2000, the SPOT VEGETATION NDVI data （1 km spatial resolution） for 1998-2009, and observa- tional plant biomass data, the CASA model was used to model changes in alpine grassland net primary production （NPP） on the Tibetan Plateau （TP）. This study will help to evaluate the health conditions of the alpine grassland ecosystem, and is of great importance to the pro- motion of sustainable development of plateau pasture and to the understanding of the func- tion of the national ecological security shelter on the TP. The spatio-temporal characteristics of NPP change were investigated using spatial statistical analysis, separately on the basis of physico-geographical factors （natural zone, altitude, latitude and longitude）, river basin, and county-level administrative area. Data processing was carried out using an ENVI 4.8 platform, while an ArcGIS 9.3 and ANUSPLIN platform was used to conduct the spatial analysis and mapping. The primary results are as follows： （1） The NPP of alpine grassland on the TP gradually decreases from the southeast to the northwest, which corresponds to gradients in precipitation and temperature. From 1982 to 2009, the average annual total NPP in the TP alpine grassland was 177.2x1012 gC yrl（yr represents year）, while the average annual NPP was 120.8 gC m^-2 yr^-1. （2） The annual NPP in alpine grassland on the TP fluctuates from year to year but shows an overall positive trend ranging from 114.7 gC m^-2 yr^-1 in 1982 to 129.9 gC m^-2 yr^-1 in 2009, with an overall increase of 13.3%; 32.56% of the total alpine grassland on the TP showed a significant increase in NPP, while only 5.55% showed a significant decrease over this 28-year period. （3） Spatio-temporal characteristics are an important control on an- nual NPP in alpine grassland： a） NPP increased in most of the natural zones on the TP, only showing a slight decrease in the Ngari montane desert-steppe and desert zone. The positive
基金National Basic Research Program of China, No.2005CB422006 National Natural Science Foundation o China, No.40331006 No.90202012
文摘The temporal and spatial changes of NDVI on the Tibetan Plateau, as well as the relationship between NDVI and precipitation, were discussed in this paper, by using 8-km resolution multi-temporal NOAA AVHRR-NDVI data from 1982 to 1999. Monthly maximum NDVI and monthly rainfall were used to analyze the seasonal changes, and annual maximum NDVI, annual effective precipitation and growing season precipitation （from April to August） were used to discuss the interannual changes. The dynamic change of NDVI and the corre- lation coefficients between NDVI and rainfall were computed for each pixel. The results are as follows： （1） The NDVI reached the peak in growing season （from July to September） on the Tibetan Plateau. In the northern and western parts of the plateau, the growing season was very short （about two or three months）; but in the southern, vegetation grew almost all the year round. The correlation of monthly maximum NDVI and monthly rainfall varied in different areas. It was weak in the western, northern and southern parts, but strong in the central and eastern parts. （2） The spatial distribution of NDVI interannual dynamic change was different too. The increase areas were mainly distributed in southern Tibet montane shrub-steppe zone western part of western Sichuan-eastern Tibet montane coniferous forest zone, western part of northern slopes of Kunlun montane desert zone and southeastern part of southern slopes of Himalaya montane evergreen broad-leaved forest zone; the decrease areas were mainly distributed in the Qaidam montane desert zone, the western and northern parts of eastern Qinghai-Qilian montane steppe zone, southern Qinghai high cold meadow steppe zone and Ngari montane desert-steppe and desert zone. The spatial distribution of correlation coeffi- cient between annual effective rainfall and annual maximum NDVI was similar to the growing season rainfall and annual maximum NDVI, and there was good relationship between NDVI and rainfall in the meadow and grassland with medium ve
基金This study was performed under the auspice of the National Key Project for Basic Research (Grant No. 2002CB412501) the National Natural Science Foundation of China (Grant no. 30470280)+1 种基金 Knowledge Innovation Program of Chinese Academy of Sciences (KZCX3-SW-339)Damxung Grassland Station of Tibetan Autonomous Region provided observation site and person-nel. Special thanks are extended to Mr Guo Wanjun, Suo- lang Ciren, Huang Qingyi and Yang Junping for their help in data collecting.
文摘Knowledge of seasonal variation of net ecosystem CO2 exchange (NEE) and its biotic and abiotic controllers will further our understanding of carbon cycling process, mechanism and large-scale modelling. Eddy covariance technique was used to measure NEE, biotic and abiotic factors for nearly 3 years in the hinterland alpine steppe--Korbresia meadow grassland on the Tibetan Plateau, the present highest fluxnet station in the world. The main objectives are to investigate dynamics of NEE and its components and to determine the major controlling factors. Maximum carbon assimilation took place in August and maximum carbon loss occurred in November. In June, rainfall amount due to monsoon climate played a great role in grass greening and consequently influenced interannual variation of ecosystem carbon gain. From July through September, monthly NEE presented net carbon assimilation. In other months, ecosystem exhibited carbon loss. In growing season, daytime NEE was mainly controlled by photosynthetically active radiation (PAR). In addition, leaf area index (LAI) interacted with PAR and together modulated NEE rates. Ecosystem respiration was controlled mainly by soil temperature and simultaneously by soil moisture. Q10 was negatively correlated with soil temperature but positively correlated with soil moisture. Large daily range of air temperature is not necessary to enhance carbon gain. Standard respiration rate at referenced 10℃(R10) was positively correlated with soil moisture, soil temperature, LAI and aboveground biomass. Rainfall patterns in growing season markedly influenced soil moisture and therefore soil moisture controlled seasonal change of ecosystem respiration. Pulse rainfall in the beginning and at the end of growing season induced great ecosystem respiration and consequently a great amount of carbon was lost. Short growing season and relative low temperature restrained alpine grass vegetation development. The results suggested that LAI be usually in a low level and carbon uptake be relatively low. Rainf
基金supported by the National Key R&D Program of China (2018YFB0505005)the National Natural Science Foundation of China (41871056, 21661132003, and 41571068)the Strategic Priority Research Program (A) of the Chinese Academy of Sciences (XDA20060201)
文摘Lakes on the Tibetan Plateau(TP)are an indicator and sentinel of climatic changes[1].We extended lake area changes on the TP from 2010[2]to 2018,and provided a long and dense lake observations between the 1970s and 2018.We found that the number of lakes,with area larger than 1 km2,has in creased to?1,400 in 2018 from?1,000 in the 1970s.The total area of these lakes decreased between the 1970s and?1995,and then showed a robust increase,with the exception of a slight decrease in 2015.This expansion of the lakes on the highest plateau in rhe world is a response to a hydrological cycle intensified by recent climate changes[3].
基金Supported by National Natural Science Foundation of China (Grant Nos. 40890052, 40921003)the Chinese COPES Project (Grant No. GYHY200706005)
文摘We here report our recent research results on the climatic features of Tibetan thermodynamic functions and their impacts on the regional climates of the Northern Hemisphere. The results show that the thermodynamic processes over the Tibetan Plateau not only strongly influence the Asian monsoon and precipitation, but also modulate the atmospheric circulation and climate over North America and Europe through stimulating the large-scale teleconnections such as the Asian-Pacific oscillation and affect the atmospheric circulation over the southern Indian Ocean. The Tibetan climate may be affected by sea surface temperatures over the tropical Pacific. On the other hand, the Tibetan climate also affects the atmosphere-ocean interactions in the tropics and mid-latitudes of the Pacific by the atmospheric circulation over the North Pacific. In spring and summer, the thermodynamic anomalies on the plateau affect the subtropical high pressure, the Hadley circulation, and the intertropical convergence zone over the Pacific, and then modulate the development of the El Ni-o/Southern Oscillation (ENSO). It is necessary to study the forecasting methods for the development of ENSO from the Tibetan climate anomaly. This result also embodies the essence of interactions among land, atmosphere, and ocean over the Northern Hemisphere. Since the previous studies focused on impacts of the plateau on climates in the Asian monsoon regions, it is essential to pay more attention to studying the roles of the plateau in the Northern Hemispheric and even global climates.
