Under conditions of a warmer climate,the advance of the alpine treeline into alpine tundra has implications for carbon dynamics in mountain ecosystems.However,the above- and below-ground live biomass allocations among...Under conditions of a warmer climate,the advance of the alpine treeline into alpine tundra has implications for carbon dynamics in mountain ecosystems.However,the above- and below-ground live biomass allocations among different vegetation types within the treeline ecotones are not well investigated.To determine the altitudinal patterns of above-/below-ground carbon allocation,we measured the root biomass and estimated the above-ground biomass(AGB) in a subalpine forest,treeline forest,alpine shrub,and alpine grassland along two elevational transects towards the alpine tundra in southeast Tibet.The AGB strongly declined with increasing elevation,which was associated with a decrease in the leaf area index and a consequent reduction in carbon gain.The fine root biomass(FRB) increased significantly more in the alpine shrub and grassland than in the treeline forest,whereas the coarse root biomass changed little with increasing altitudes,which led to a stable below-ground biomass(BGB) value across altitudes.Warm and infertile soil conditions might explain the large amount of FRB in alpine shrub and grassland.Consequently,the root toshoot biomass ratio increased sharply with altitude,which suggested a remarkable shift of biomass allocation to root systems near the alpine tundra.Our findings demonstrate contrasting changes in AGB and BGB allocations across treeline ecotones,which should be considered when estimating carbon dynamics with shifting treelines.展开更多
Glaciers with their deposits abound in the alpine areas of Southeast Tibet. Large debris flows occur frequently from these deposits and form dams that block streams. In this paper,3 events of large debris flows report...Glaciers with their deposits abound in the alpine areas of Southeast Tibet. Large debris flows occur frequently from these deposits and form dams that block streams. In this paper,3 events of large debris flows reported in Peilong Valley located in Southeast Tibet,and which resulted 2 blocking dams resulted,are discussed in details,focusing on the major factors controlling dam formation. The results shows that the first surge group caused by snow and ice avalanches,ice-lake breaks,and large-scale landslides,with a high peak discharge and high velocity,and an abundance of boulders,are most likely to form blocking dams.展开更多
Leaf N and P stoichiometry in terrestrial ecosystems has been widely investigated in recent years owing to the importance of these elements in improving the predicted vegetation responses to global changes.The vertica...Leaf N and P stoichiometry in terrestrial ecosystems has been widely investigated in recent years owing to the importance of these elements in improving the predicted vegetation responses to global changes.The vertical distribution of leaf N and P stoichiometry has attracted increasing attention because of the dramatic changes in environmental factors at regional scales.However,the characteristics of leaf N and P stoichiometry in the southeast Qinghai–Tibet plateau(SET)are not clear,although this area is sensitive to global change.Here,we analyzed the leaf N and P concentrations in dominant plant species on natural altitudinal gradients on the Duoxiongla(DXL),Sejila(SJL),Mila(ML),and Gangbala(GBL)mountains across the SET all the way to central Tibet.Our results showed that the leaf N concentrations were comparable among the regions,whereas the leaf P concentrations dramatically decreased from SET to central Tibet(CT).The leaf N concentrations were 23.6,21.3,20.8,and 22.4 g kg^(-1),and the leaf P concentrations were 2.40,2.49,1.94,and 1.59 g kg^(-1) on the SJL,DXL,ML and GBL mountains,respectively.The leaf N/P ratios on the DXL,SJL,ML,and GBL mountains were 8.81,10.3,11.2,and 14.2,respectively.Considering the increasing trend of the leaf N/P ratio from southeast Qinghai–Tibet plateau to central Tibet,N limitation might widely exist in well vegetated ecosystems in the Qinghai–Tibet plateau.展开更多
In June 2013,a field experiment was conducted in Southeast Tibet in which the air temperature,moisture,and wind were measured by using a GPS sounding system.In the present study,based on these observations and ERA-Int...In June 2013,a field experiment was conducted in Southeast Tibet in which the air temperature,moisture,and wind were measured by using a GPS sounding system.In the present study,based on these observations and ERA-Interim reanalysis data,the vertical structures of these atmospheric properties and the possible influence of the South Asian summer monsoon(SASM) were investigated.On average,the temperature had a lapse rate of 6.8℃ km^(-1) below the tropopause of 18.0 km.A strong moisture inversion occurred at the near-surface,with a strength of 1.7 g kg^(-1)(100 m)^(-1) for specific humidity.During the observation period,the SASM experienced a south phase and a north phase in the middle and by the end of June,respectively.The monsoon's evolution led to large changes in convection and circulation over Southeast Tibet,which further affected the local thermal,moisture,and circulation conditions.The strong convection resulted in an elevated tropopause height over Southeast Tibet during the north phase of the SASM,and the large-scale warm and wet air masses delivered by the monsoon caused high local temperature and moisture conditions.展开更多
The Panxi Rift Zone is a famous metallogenic province in Southwest China. Continental rifting developed in Hercynian period (P 2, 260～250Ma) accompany with a series of basic\|ultrabasic rocks. Various in lithologies,...The Panxi Rift Zone is a famous metallogenic province in Southwest China. Continental rifting developed in Hercynian period (P 2, 260～250Ma) accompany with a series of basic\|ultrabasic rocks. Various in lithologies, such as layered intrusions (V\|Ti\|Fe formation), small\|sized mafic\|ultramafic bodies (stocks) and large\|scale basalt (Emeishan Basalt) are constituted of a complete melanocratic rock system.Most of Cu\|Ni\|PGE sulfide deposits are related to small\|sized ultramafic rock bodies. It is a perfect possibility for them to be an affinity of basic eruptive lava and for the neck facies. But in ① Panzhihua\|Center Yunnan Province, the Gaojiacun, also Jinbaoshan, as large stratiform basic\|ultrabasic complex used to be thought that is older one intruded to basement rocks in Precambrian. However, new evidences suggest it is similar with the small\|sized ultramafic rock bodies containing Cu\|Ni\|PGE, and also the both are affinity of the Emeishan Basalt; ② Miyi district, Cu\|Pt mineralization was discovered in the Xinjie bedded basic complex, and in where ophitic olivine\|pyroxenite\|peridotite facies are exactly Pt\|bearing layers; ③ Longzhoushan district, we have recently researched basic\|ultrabasic clusters which intruded into fracture zones, and Cu\|Ni\|Pt, Pd mineralization developed at the salbands.Generally, the basalt is poor in PGE and rich in Cu. It is suggested as the result of PGE dispersion\|concentration processing in the melanocratic rock system when rifting happened.展开更多
开发与研究滑坡灾害预警系统,预防监测滑坡灾害的发生,能够在一定程度上降低滑坡灾害对人类生活造成的影响。以藏东南地区为系统研究开发区,系统采用C/S(客户端/服务器)结构,以Visual Studio 2019作为开发平台,采用MySQL数据库存储数据...开发与研究滑坡灾害预警系统,预防监测滑坡灾害的发生,能够在一定程度上降低滑坡灾害对人类生活造成的影响。以藏东南地区为系统研究开发区,系统采用C/S(客户端/服务器)结构,以Visual Studio 2019作为开发平台,采用MySQL数据库存储数据,C#语言开发后台服务器软件。该系统主要实现滑坡监测点的定位、滑坡监测数据的录入及查询、滑坡监测数据的分析以及预警预报等功能。开发滑坡预警系统,为西藏滑坡灾害的管理和预警提供一个较为完善的管理分析平台。展开更多
基金supported by the National Natural Science Foundation of China (41561011)the Natural Science Foundation of Jiangxi Province, China (20151BAB213029)
文摘Under conditions of a warmer climate,the advance of the alpine treeline into alpine tundra has implications for carbon dynamics in mountain ecosystems.However,the above- and below-ground live biomass allocations among different vegetation types within the treeline ecotones are not well investigated.To determine the altitudinal patterns of above-/below-ground carbon allocation,we measured the root biomass and estimated the above-ground biomass(AGB) in a subalpine forest,treeline forest,alpine shrub,and alpine grassland along two elevational transects towards the alpine tundra in southeast Tibet.The AGB strongly declined with increasing elevation,which was associated with a decrease in the leaf area index and a consequent reduction in carbon gain.The fine root biomass(FRB) increased significantly more in the alpine shrub and grassland than in the treeline forest,whereas the coarse root biomass changed little with increasing altitudes,which led to a stable below-ground biomass(BGB) value across altitudes.Warm and infertile soil conditions might explain the large amount of FRB in alpine shrub and grassland.Consequently,the root toshoot biomass ratio increased sharply with altitude,which suggested a remarkable shift of biomass allocation to root systems near the alpine tundra.Our findings demonstrate contrasting changes in AGB and BGB allocations across treeline ecotones,which should be considered when estimating carbon dynamics with shifting treelines.
文摘Glaciers with their deposits abound in the alpine areas of Southeast Tibet. Large debris flows occur frequently from these deposits and form dams that block streams. In this paper,3 events of large debris flows reported in Peilong Valley located in Southeast Tibet,and which resulted 2 blocking dams resulted,are discussed in details,focusing on the major factors controlling dam formation. The results shows that the first surge group caused by snow and ice avalanches,ice-lake breaks,and large-scale landslides,with a high peak discharge and high velocity,and an abundance of boulders,are most likely to form blocking dams.
基金funded by the Natural Science Foundation of Tibet Autonomous Region Department and Agriculture and Animal Husbandry University(XZ202101ZR0023G)the National Natural Science Foundation of China(42067036)the Forestry Innovation Team Construction project of Xizang Agriculture and Animal Husbandry University(2020-001)。
文摘Leaf N and P stoichiometry in terrestrial ecosystems has been widely investigated in recent years owing to the importance of these elements in improving the predicted vegetation responses to global changes.The vertical distribution of leaf N and P stoichiometry has attracted increasing attention because of the dramatic changes in environmental factors at regional scales.However,the characteristics of leaf N and P stoichiometry in the southeast Qinghai–Tibet plateau(SET)are not clear,although this area is sensitive to global change.Here,we analyzed the leaf N and P concentrations in dominant plant species on natural altitudinal gradients on the Duoxiongla(DXL),Sejila(SJL),Mila(ML),and Gangbala(GBL)mountains across the SET all the way to central Tibet.Our results showed that the leaf N concentrations were comparable among the regions,whereas the leaf P concentrations dramatically decreased from SET to central Tibet(CT).The leaf N concentrations were 23.6,21.3,20.8,and 22.4 g kg^(-1),and the leaf P concentrations were 2.40,2.49,1.94,and 1.59 g kg^(-1) on the SJL,DXL,ML and GBL mountains,respectively.The leaf N/P ratios on the DXL,SJL,ML,and GBL mountains were 8.81,10.3,11.2,and 14.2,respectively.Considering the increasing trend of the leaf N/P ratio from southeast Qinghai–Tibet plateau to central Tibet,N limitation might widely exist in well vegetated ecosystems in the Qinghai–Tibet plateau.
基金Supported by the China Meteorological Administration Special Public Welfare Research Fund(GYHY201206041)Project of Comprehensive Evaluation of Polar Areas on Global and Regional Climate Changes(CHINARE2016-04-04)Polar Environment Comprehensive Investigation and Assessment(CHINARE2016-02-03)
文摘In June 2013,a field experiment was conducted in Southeast Tibet in which the air temperature,moisture,and wind were measured by using a GPS sounding system.In the present study,based on these observations and ERA-Interim reanalysis data,the vertical structures of these atmospheric properties and the possible influence of the South Asian summer monsoon(SASM) were investigated.On average,the temperature had a lapse rate of 6.8℃ km^(-1) below the tropopause of 18.0 km.A strong moisture inversion occurred at the near-surface,with a strength of 1.7 g kg^(-1)(100 m)^(-1) for specific humidity.During the observation period,the SASM experienced a south phase and a north phase in the middle and by the end of June,respectively.The monsoon's evolution led to large changes in convection and circulation over Southeast Tibet,which further affected the local thermal,moisture,and circulation conditions.The strong convection resulted in an elevated tropopause height over Southeast Tibet during the north phase of the SASM,and the large-scale warm and wet air masses delivered by the monsoon caused high local temperature and moisture conditions.
文摘The Panxi Rift Zone is a famous metallogenic province in Southwest China. Continental rifting developed in Hercynian period (P 2, 260～250Ma) accompany with a series of basic\|ultrabasic rocks. Various in lithologies, such as layered intrusions (V\|Ti\|Fe formation), small\|sized mafic\|ultramafic bodies (stocks) and large\|scale basalt (Emeishan Basalt) are constituted of a complete melanocratic rock system.Most of Cu\|Ni\|PGE sulfide deposits are related to small\|sized ultramafic rock bodies. It is a perfect possibility for them to be an affinity of basic eruptive lava and for the neck facies. But in ① Panzhihua\|Center Yunnan Province, the Gaojiacun, also Jinbaoshan, as large stratiform basic\|ultrabasic complex used to be thought that is older one intruded to basement rocks in Precambrian. However, new evidences suggest it is similar with the small\|sized ultramafic rock bodies containing Cu\|Ni\|PGE, and also the both are affinity of the Emeishan Basalt; ② Miyi district, Cu\|Pt mineralization was discovered in the Xinjie bedded basic complex, and in where ophitic olivine\|pyroxenite\|peridotite facies are exactly Pt\|bearing layers; ③ Longzhoushan district, we have recently researched basic\|ultrabasic clusters which intruded into fracture zones, and Cu\|Ni\|Pt, Pd mineralization developed at the salbands.Generally, the basalt is poor in PGE and rich in Cu. It is suggested as the result of PGE dispersion\|concentration processing in the melanocratic rock system when rifting happened.
文摘开发与研究滑坡灾害预警系统,预防监测滑坡灾害的发生,能够在一定程度上降低滑坡灾害对人类生活造成的影响。以藏东南地区为系统研究开发区,系统采用C/S(客户端/服务器)结构,以Visual Studio 2019作为开发平台,采用MySQL数据库存储数据,C#语言开发后台服务器软件。该系统主要实现滑坡监测点的定位、滑坡监测数据的录入及查询、滑坡监测数据的分析以及预警预报等功能。开发滑坡预警系统,为西藏滑坡灾害的管理和预警提供一个较为完善的管理分析平台。
