Roots exert pullout resistance under pullout force,allowing plants to resist uprooting.However,the pullout resistance characteristics of taproot-type shrub species of different ages remain unclear.In this study,in ord...Roots exert pullout resistance under pullout force,allowing plants to resist uprooting.However,the pullout resistance characteristics of taproot-type shrub species of different ages remain unclear.In this study,in order to improve our knowledge of pullout resistance characteristics of taproot systems of shrub species,we selected the shrub species Caragana korshinskii Kom.in different growth periods as the research plant and conducted in situ root pullout test.The relationships among the maximum pullout resistance,peak root displacement,shrub growth period,and aboveground growth indices(plant height and plant crown breadth)were analyzed,as well as the mechanical process of uprooting.Pullout resistance of 4-15 year-old C.korshinskii ranged from 2.49(±0.25)to 14.71(±4.96)kN,and the peak displacement ranged from 11.77(±8.61)to 26.50(±16.09)cm.The maximum pullout resistance and the peak displacement of roots increased as a power function(R^(2)=0.9038)and a linear function(R^(2)=0.8242)with increasing age,respectively.The maximum pullout resistance and the peak displacement increased with increasing plant height;however,this relationship was not significant.The maximum pullout resistance increased exponentially(R^(2)=0.5522)as the crown breadth increased.There was no significant relationship between the peak displacement and crown breadth.The pullout resistance and displacement curve were divided into three stages:the initial nonlinear growth,linear growth,and nonlinear stages.Two modes of failure of a single root occurred when the roots were subjected to vertical loading forces:the synchronous breakage mode and the periderm preferential breakage mode.These findings provide a foundation for further investigation of the soil reinforcement and slope protection mechanisms of this shrub species in the loess area of northeastern Qinghai-Tibet Plateau,China.展开更多
The Qilian Mountain permafrost area located in the northern of Qinghai-Tibet Plateau is a favorable place for natural gas hydrate formation and enrichment,due to its well-developed fractures and abundant gas sources.U...The Qilian Mountain permafrost area located in the northern of Qinghai-Tibet Plateau is a favorable place for natural gas hydrate formation and enrichment,due to its well-developed fractures and abundant gas sources.Understanding the formation and distribution of multi-component gas hydrates in fractures is crucial in accurately evaluating the hydrate reservoir resources in this area.The hydrate formation experiments were carried out using the core samples drilled from hydrate-bearing sediments in Qilian Mountain permafrost area and the multi-component gas with similar composition to natural gas hydrates in Qilian Mountain permafrost area.The formation and distribution characteristics of multi-component gas hydrates in core samples were observed in situ by X-ray Computed Tomography(X-CT)under high pressure and low temperature conditions.Results show that hydrates are mainly formed and distributed in the fractures with good connectivity.The ratios of volume of hydrates formed in fractures to the volume of fractures are about 96.8%and 60.67%in two different core samples.This indicates that the fracture surface may act as a favorable reaction site for hydrate formation in core samples.Based on the field geological data and the experimental results,it is preliminarily estimated that the inventory of methane stored in the fractured gas hydrate in Qilian Mountain permafrost area is about 8.67×1013 m3,with a resource abundance of 8.67×108 m3/km2.This study demonstrates the great resource potential of fractured gas hydrate and also provides a new way to further understand the prospect of natural gas hydrate and other oil and gas resources in Qilian Mountain permafrost area.展开更多
The Qinghai-Tibet Plateau is now experiencing ecological degradation risks as a result of climate change and human activities.The alpine grassland ecology in permafrost zones is fragile and susceptible to deterioratio...The Qinghai-Tibet Plateau is now experiencing ecological degradation risks as a result of climate change and human activities.The alpine grassland ecology in permafrost zones is fragile and susceptible to deterioration due to its high altitude,low temperature,and limited oxygen,which complicates the repair of damaged land.Biological soil crusts(BSCs)are crucial for land restoration in plateau regions because they can thrive in harsh conditions and have environmentally beneficial traits.Inoculated biological soil crust(IBSC)has shown success in low-altitude desert regions,but may not be easily duplicated to the plateau environment.Therefore,it is essential to do a comprehensive and multifaceted analysis of the basic theoretical comprehension and practical application of BSCs on the Tibetan Plateau.This review article aims to provide a brief summary of the ecological significance and the mechanisms related to the creation,growth,and progression of BSCs.It discusses the techniques used for cultivating BSCs in laboratories and using them in the field,focusing on the Qinghai-Tibet Plateau circumstance.We thoroughly discussed the potential and the required paths for further studies.This study may be used as a basis for selecting suitable microbial strains and accompanying supplemental actions for implementing IBSCs in the Qinghai-Tibet Plateau.展开更多
CaN nanorods are successfully fabricated by adjusting the flow rate ratio of hydrogen （H2）/nitrogen （N2） and growth temperature of the selective area growth （SAG） method with metal organic chemical vapor deposit...CaN nanorods are successfully fabricated by adjusting the flow rate ratio of hydrogen （H2）/nitrogen （N2） and growth temperature of the selective area growth （SAG） method with metal organic chemical vapor deposition （MOCVD）. The SAG template is obtained by nanospherical-lens photolithography. It is found that increasing the flow rate of 1-12 will change the CaN crystal shape from pyramid to vertical rod, while increasing the growth temperature will reduce the diameters of GaN rods to nanometer scale. Finally the CaN nanorods with smooth lateral surface and relatively good quality are obtained under the condition that the H2：N2 ratio is 1：1 and the growth temperature is 1030℃. The good crystal quality and orientation of GaN nanorods are confirmed by high resolution transmission electron microscopy. The cathodoluminescence spectrum suggests that the crystal and optical quality is also improved with increasing the temperature.展开更多
The seasonal frozen soil on the Qinghai-Tibet Plateau has strong response to climate change, and its freezing-thawing process also affects East Asia climate. In this paper, the freezing soil maximum depth of 46 statio...The seasonal frozen soil on the Qinghai-Tibet Plateau has strong response to climate change, and its freezing-thawing process also affects East Asia climate. In this paper, the freezing soil maximum depth of 46 stations covering 1961–1999 on the plateau is analyzed by rotated experience orthogonal function (REOF). The results show that there are four main frozen anomaly regions on the plateau, i.e., the northeastern, southeastern and southern parts of the plateau and Qaidam Basin. The freezing soil depths of the annual anomaly regions in the above representative stations show that there are different changing trends. The main trend, except for the Qaidam Basin, has been decreasing since the 1980s, a sign of the climate warming. Compared with the 1980s, on the average, the maximum soil depth decreased by about 0.02 m, 0.05 m and 0.14 m in the northeastern, southeastern and southern parts of the plateau, but increased by about 0.57 m in the Qaidam Basin during the 1990s. It means there are different responses to climate system in the above areas. The spectrum analysis reveals different change cycles: in higher frequency there is an about 2-year long cycle in Qaidam Basin and southern part of the plateau in the four representative areas whereas in lower frequency there is an about 14-year long cycle in all the four representative areas due to the combined influence of different soil textures and solutes in four areas.展开更多
Monitoring rock desert formation caused by two different origins(ice-snow melting and drying)through remote sensing is crucial to our understanding of the interaction between the underlying surface of different rock d...Monitoring rock desert formation caused by two different origins(ice-snow melting and drying)through remote sensing is crucial to our understanding of the interaction between the underlying surface of different rock desert and land-atmosphere types,as well as the relationship between bare land and soil erosion.A number of achievements have been made in remote sensing monitoring of desert areas,but there is a lack of accurate classification and remote sensing identification of rock desert types based on formation mechanism.In this study,the north and south sides of the eastern Kunlun Mountains in the northern part of the Qinghai-Tibet Plateau of China were taken as the study areas.Landsat operational landscape imager,digital elevation model,and precipitation and temperature grid data were used as data sources.By identifying the bare areas based on the normalized difference vegetation index(NDVI),we used the multi-element fusion method of contours,isotherms,and isohyets to identify the rock desert types in the ice-snow melting and dry areas.The results showed that:(1)the rock desert areas identified by remote sensing based on topographic and meteorological elements were highly accurate,with an overall accuracy of 88.45%and kappa coefficient of 0.77.The multi-element fusion method of contours,isotherms,and isohyets could effectively identify the rock desert types in the ice-snow melting and dry areas;(2)the optimal segmentation range of the ice-snow melting and dry areas was 3600 m contour,-2°C-2°C isotherms,and 100-130 mm isohyets.The areas with elevation less than 3600 m,annual average temperature higher than 2°C,and average annual precipitation less than 100 mm were rock desert in the dry areas.The range of-2°C-2°C isotherms and 100-130 mm isohyets was the transition area between the ice-snow melting and dry areas.The areas with elevation higher than 3600 m,annual average temperature less than-2°C,and average annual precipitation higher than 130 mm were rock desert in the ice-snow melting areas;and(3)the identification accuracy of the bare areas based on the NDVI method was better,specifically,the identification accuracy of plain bare areas was generally better than that of mountain bare areas.The remote sensing identification method considers not only the topographic factors that have great influence on the spatial distribution of the two types of rock desert areas,but also the meteorological factors,which can provide a scientific reference for the effective identification of the two types of rock desert areas.展开更多
Urbanization,often coupled with industrialization,is generally considered as a boost for improving livelihood as well as alleviating ecological pressures of the rural areas.However,this experience needs to be tested i...Urbanization,often coupled with industrialization,is generally considered as a boost for improving livelihood as well as alleviating ecological pressures of the rural areas.However,this experience needs to be tested in less industrialized areas,particularly where the urbanization is driven by non-economic factors such as urban public services and relevant government policies rather than employment opportunities.Taking two villages on the Qinghai-Tibet Plateau as examples,through the field investigation by using semi-structured questionnaires and in-depth interviews,and statistical data analysis,we explored the impacts of urbanization on migrants’livelihoods and the ecological conditions of their original village rangeland.We found that the disposable income and savings of emigrant households were less than the stay households,which might be correlated to the limited employment due to the lagged industrialization in the local township,and the mismatch between their traditional labor skills and the demands of urban services.Their home-village rangeland overuse was not alleviated since the increasing grazing pressure caused by the stay households,though the emigrant households intended to decrease the number of livestock on their home pasture.We concluded that the urbanization misaligned with local industrialization may fail to improve migrant livelihoods and local ecological conditions in less industrialized areas.Our research supplements the previous urbanization theory by highlighting the non-industrialization driven urbanization,and is particularly pertinent for the transitional countries worldwide.展开更多
基金funded by the National Natural Science Foundation of China (42002283, 42062019)the Science and Technology Plan Project of Qinghai Province,China (2022-ZJ-Y08)the Second Tibetan Plateau Scientific Expedition and Research (STEP) Program (2019QZKK0905, 2019QZKK0805)
文摘Roots exert pullout resistance under pullout force,allowing plants to resist uprooting.However,the pullout resistance characteristics of taproot-type shrub species of different ages remain unclear.In this study,in order to improve our knowledge of pullout resistance characteristics of taproot systems of shrub species,we selected the shrub species Caragana korshinskii Kom.in different growth periods as the research plant and conducted in situ root pullout test.The relationships among the maximum pullout resistance,peak root displacement,shrub growth period,and aboveground growth indices(plant height and plant crown breadth)were analyzed,as well as the mechanical process of uprooting.Pullout resistance of 4-15 year-old C.korshinskii ranged from 2.49(±0.25)to 14.71(±4.96)kN,and the peak displacement ranged from 11.77(±8.61)to 26.50(±16.09)cm.The maximum pullout resistance and the peak displacement of roots increased as a power function(R^(2)=0.9038)and a linear function(R^(2)=0.8242)with increasing age,respectively.The maximum pullout resistance and the peak displacement increased with increasing plant height;however,this relationship was not significant.The maximum pullout resistance increased exponentially(R^(2)=0.5522)as the crown breadth increased.There was no significant relationship between the peak displacement and crown breadth.The pullout resistance and displacement curve were divided into three stages:the initial nonlinear growth,linear growth,and nonlinear stages.Two modes of failure of a single root occurred when the roots were subjected to vertical loading forces:the synchronous breakage mode and the periderm preferential breakage mode.These findings provide a foundation for further investigation of the soil reinforcement and slope protection mechanisms of this shrub species in the loess area of northeastern Qinghai-Tibet Plateau,China.
基金the financial support of the National Natural Science Foundation of China(42176212,41976074 and 41302034)the Marine S&T Fund of Shandong Province for Laoshan Laboratory(2021QNLM020002)the Marine Geological Survey Program(DD20221704)。
文摘The Qilian Mountain permafrost area located in the northern of Qinghai-Tibet Plateau is a favorable place for natural gas hydrate formation and enrichment,due to its well-developed fractures and abundant gas sources.Understanding the formation and distribution of multi-component gas hydrates in fractures is crucial in accurately evaluating the hydrate reservoir resources in this area.The hydrate formation experiments were carried out using the core samples drilled from hydrate-bearing sediments in Qilian Mountain permafrost area and the multi-component gas with similar composition to natural gas hydrates in Qilian Mountain permafrost area.The formation and distribution characteristics of multi-component gas hydrates in core samples were observed in situ by X-ray Computed Tomography(X-CT)under high pressure and low temperature conditions.Results show that hydrates are mainly formed and distributed in the fractures with good connectivity.The ratios of volume of hydrates formed in fractures to the volume of fractures are about 96.8%and 60.67%in two different core samples.This indicates that the fracture surface may act as a favorable reaction site for hydrate formation in core samples.Based on the field geological data and the experimental results,it is preliminarily estimated that the inventory of methane stored in the fractured gas hydrate in Qilian Mountain permafrost area is about 8.67×1013 m3,with a resource abundance of 8.67×108 m3/km2.This study demonstrates the great resource potential of fractured gas hydrate and also provides a new way to further understand the prospect of natural gas hydrate and other oil and gas resources in Qilian Mountain permafrost area.
基金funded by the National Key R&D Program of China (2022YFB4202102)the Key R&D Program of Ningxia Hui Autonomous Region (2022BEG02003)the Excellent Member of Youth Innovation Promotion Association CAS (No.Y202085)。
文摘The Qinghai-Tibet Plateau is now experiencing ecological degradation risks as a result of climate change and human activities.The alpine grassland ecology in permafrost zones is fragile and susceptible to deterioration due to its high altitude,low temperature,and limited oxygen,which complicates the repair of damaged land.Biological soil crusts(BSCs)are crucial for land restoration in plateau regions because they can thrive in harsh conditions and have environmentally beneficial traits.Inoculated biological soil crust(IBSC)has shown success in low-altitude desert regions,but may not be easily duplicated to the plateau environment.Therefore,it is essential to do a comprehensive and multifaceted analysis of the basic theoretical comprehension and practical application of BSCs on the Tibetan Plateau.This review article aims to provide a brief summary of the ecological significance and the mechanisms related to the creation,growth,and progression of BSCs.It discusses the techniques used for cultivating BSCs in laboratories and using them in the field,focusing on the Qinghai-Tibet Plateau circumstance.We thoroughly discussed the potential and the required paths for further studies.This study may be used as a basis for selecting suitable microbial strains and accompanying supplemental actions for implementing IBSCs in the Qinghai-Tibet Plateau.
基金Supported by the Key Program of the National Natural Science Foundation of China under Grant No 61334009the National High Technology Research and Development Program of China under Grant No 2014AA032604
文摘CaN nanorods are successfully fabricated by adjusting the flow rate ratio of hydrogen （H2）/nitrogen （N2） and growth temperature of the selective area growth （SAG） method with metal organic chemical vapor deposition （MOCVD）. The SAG template is obtained by nanospherical-lens photolithography. It is found that increasing the flow rate of 1-12 will change the CaN crystal shape from pyramid to vertical rod, while increasing the growth temperature will reduce the diameters of GaN rods to nanometer scale. Finally the CaN nanorods with smooth lateral surface and relatively good quality are obtained under the condition that the H2：N2 ratio is 1：1 and the growth temperature is 1030℃. The good crystal quality and orientation of GaN nanorods are confirmed by high resolution transmission electron microscopy. The cathodoluminescence spectrum suggests that the crystal and optical quality is also improved with increasing the temperature.
基金Key project of CAS, No.KZCX1-10-07 Key project of Cold and Arid Regions Environmental and Engineering Research Institute, CAS, No.CX210097 NSFC No.49805006.
文摘The seasonal frozen soil on the Qinghai-Tibet Plateau has strong response to climate change, and its freezing-thawing process also affects East Asia climate. In this paper, the freezing soil maximum depth of 46 stations covering 1961–1999 on the plateau is analyzed by rotated experience orthogonal function (REOF). The results show that there are four main frozen anomaly regions on the plateau, i.e., the northeastern, southeastern and southern parts of the plateau and Qaidam Basin. The freezing soil depths of the annual anomaly regions in the above representative stations show that there are different changing trends. The main trend, except for the Qaidam Basin, has been decreasing since the 1980s, a sign of the climate warming. Compared with the 1980s, on the average, the maximum soil depth decreased by about 0.02 m, 0.05 m and 0.14 m in the northeastern, southeastern and southern parts of the plateau, but increased by about 0.57 m in the Qaidam Basin during the 1990s. It means there are different responses to climate system in the above areas. The spectrum analysis reveals different change cycles: in higher frequency there is an about 2-year long cycle in Qaidam Basin and southern part of the plateau in the four representative areas whereas in lower frequency there is an about 14-year long cycle in all the four representative areas due to the combined influence of different soil textures and solutes in four areas.
基金the Natural Science Foundation of Qinghai Province of China(2021-ZJ-905)the Second Qinghai-Tibet Plateau Scientific Expedition and Research Program of China(2019QZKK0606).
文摘Monitoring rock desert formation caused by two different origins(ice-snow melting and drying)through remote sensing is crucial to our understanding of the interaction between the underlying surface of different rock desert and land-atmosphere types,as well as the relationship between bare land and soil erosion.A number of achievements have been made in remote sensing monitoring of desert areas,but there is a lack of accurate classification and remote sensing identification of rock desert types based on formation mechanism.In this study,the north and south sides of the eastern Kunlun Mountains in the northern part of the Qinghai-Tibet Plateau of China were taken as the study areas.Landsat operational landscape imager,digital elevation model,and precipitation and temperature grid data were used as data sources.By identifying the bare areas based on the normalized difference vegetation index(NDVI),we used the multi-element fusion method of contours,isotherms,and isohyets to identify the rock desert types in the ice-snow melting and dry areas.The results showed that:(1)the rock desert areas identified by remote sensing based on topographic and meteorological elements were highly accurate,with an overall accuracy of 88.45%and kappa coefficient of 0.77.The multi-element fusion method of contours,isotherms,and isohyets could effectively identify the rock desert types in the ice-snow melting and dry areas;(2)the optimal segmentation range of the ice-snow melting and dry areas was 3600 m contour,-2°C-2°C isotherms,and 100-130 mm isohyets.The areas with elevation less than 3600 m,annual average temperature higher than 2°C,and average annual precipitation less than 100 mm were rock desert in the dry areas.The range of-2°C-2°C isotherms and 100-130 mm isohyets was the transition area between the ice-snow melting and dry areas.The areas with elevation higher than 3600 m,annual average temperature less than-2°C,and average annual precipitation higher than 130 mm were rock desert in the ice-snow melting areas;and(3)the identification accuracy of the bare areas based on the NDVI method was better,specifically,the identification accuracy of plain bare areas was generally better than that of mountain bare areas.The remote sensing identification method considers not only the topographic factors that have great influence on the spatial distribution of the two types of rock desert areas,but also the meteorological factors,which can provide a scientific reference for the effective identification of the two types of rock desert areas.
基金supported by National Natural Science Foundation of China(Grant number 41971256 and 42271290)。
文摘Urbanization,often coupled with industrialization,is generally considered as a boost for improving livelihood as well as alleviating ecological pressures of the rural areas.However,this experience needs to be tested in less industrialized areas,particularly where the urbanization is driven by non-economic factors such as urban public services and relevant government policies rather than employment opportunities.Taking two villages on the Qinghai-Tibet Plateau as examples,through the field investigation by using semi-structured questionnaires and in-depth interviews,and statistical data analysis,we explored the impacts of urbanization on migrants’livelihoods and the ecological conditions of their original village rangeland.We found that the disposable income and savings of emigrant households were less than the stay households,which might be correlated to the limited employment due to the lagged industrialization in the local township,and the mismatch between their traditional labor skills and the demands of urban services.Their home-village rangeland overuse was not alleviated since the increasing grazing pressure caused by the stay households,though the emigrant households intended to decrease the number of livestock on their home pasture.We concluded that the urbanization misaligned with local industrialization may fail to improve migrant livelihoods and local ecological conditions in less industrialized areas.Our research supplements the previous urbanization theory by highlighting the non-industrialization driven urbanization,and is particularly pertinent for the transitional countries worldwide.
