This study aimed to provide theoretical bases for optimized land use in minority settlements at high altitude. On the basis of forest form map and land use type map (1∶250 000) of Ganzi Tibetan Autonomous Prefecture ...This study aimed to provide theoretical bases for optimized land use in minority settlements at high altitude. On the basis of forest form map and land use type map (1∶250 000) of Ganzi Tibetan Autonomous Prefecture in Sichuan Province in 2007, this study carried out further analysis and assessment on the landscape pattern and fragmentation degree of Ganzi from the perspective of overall landscape characteristics, area and perimeter of patches, quantity and fractal dimension of patches and so on with the support of geo-info systematical software ArcCIS and landscape structure analysis software Fragstats. The results showed that among all landscape elements alpine meadow and evergreen broad-leaved shrubs take up a larger part as temperate and cool temperate grassland and marsh are scattered with small areas; deciduous and broad-leaved as well as their mixed forest have higher landscape fragmentation degree, on the whole, the fragmentation degree of forest type is higher than that of meadow and shrub; fractal dimensions of landscape components are all small and tend to 1, which indicates that the folded degree of all landscape boundaries are small.展开更多
A series of numerical experiments are carried out by using the Spectral Atmospheric Model of State Key Laboratory of Numerical Modeling Atmospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Phys...A series of numerical experiments are carried out by using the Spectral Atmospheric Model of State Key Laboratory of Numerical Modeling Atmospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics （SAMIL） to investigate how the Tibetan Plateau （TP） mechanical and thermal forcing affect the circulation and climate patterns over subtropical Asia. It is shown that, compared to mechanical forcing, the thermal forcing of TP plays a dominant role in determining the large-scale circulation in summer. Both the sensible heating and the latent heating over TP tend to generate a surface cyclonic circulation and a gigantic anticyclonic circulation in the mid- and upper layers, whereas the direct effect of the latter is much more significant. Following a requirement of the time-mean quasi-geostrophic vorticity equation for large-scale air motion in the subtropics, convergent flow and vigorous ascending motion must appear to the east of TP. Hence the summer monsoon in East China is reinforced efficiently by TP. In contrast, the atmosphere to the west of TP is characterized by divergent flow and downward motion, which induces the arid climate in Mid-Asia.展开更多
Through investigating Tibetan courtyard landscapes in Linzhi City, Tibet, it was found that Tibetan courtyards attached more importance to flower plants and garden crops, focused on natural style and easy maintenance,...Through investigating Tibetan courtyard landscapes in Linzhi City, Tibet, it was found that Tibetan courtyards attached more importance to flower plants and garden crops, focused on natural style and easy maintenance, but not pruning; Tibetan courtyard landscaping valued shape, color, flower season and visual aesthetics of fl owers, tried to build "gardens" with fl ower confi guration as the major content, similar aesthetic concepts and landscaping style with European gardens; moreover, it paid more attention to plants, but not waterscape design; in Tibetan gardens, lawns occupied a secondary position next to fl owering plants, fruit trees and garden crops.展开更多
Background:Global climate change has had significant effects on animal distribution and population dynamics in mid-latitude alpine areas,but we know little about the basic ecology of high-altitude species due to the d...Background:Global climate change has had significant effects on animal distribution and population dynamics in mid-latitude alpine areas,but we know little about the basic ecology of high-altitude species due to the difficulties of conducting field research in the harsh climate and habitat present at high elevations.The Tibetan Snowcock(Tetraogallus tibetanus) is a little-known phasianid distributing in alpine areas at extremely high elevations in the mountains surrounding the Tibetan Plateau.Estimating the species occupancy rate and discussing the factors affecting its distribution based on infrared-triggered camera techniques would provide both a baseline to measure the influence of global warming and valuable information on its conservation and ecology.Methods:We used infrared-triggered cameras to investigate the Tibetan Snowcock on the western slope of Mt.Gongga from June to November 2016.We used the R package "overlap" to visualize its activity pattern,and used an occupancy model to both examine its habitat use as well as to determine the most influential variables affecting its habitat use.Results:Using 103 camera traps over 9213 camera-days,we recorded 428 instances of Tibetan Snowcock.The diel activity peaks of Tibetan Snowcock occurred during the periods of 8:00-10:00 am and 18:00-20:00 pm.The model estimate of occupancy for Tibetan Snowcock(0.830) was slightly higher than the na?ve site occupancy based on camera detections(0.663),indicating a wider use of habitat than the camera traps recorded.Elevation,slope,settlement density,road density,and EVI(enhanced vegetation index) were the most influential variables for its habitat use.Conclusions:The Tibetan Snowcock is confirmed to be diurnal.This species prefers an environment with a high elevation,gentle slope,and low EVI,apparently facing a trade-off between predator risk,foraging efficiency,and food availability.When human impact was low,there was a positive correlation between the habitat use of the Tibetan Snowcock and both its road and settlement densities.Infrared cameras and proper survey design are valuable for investigating extreme alpine phasianids.展开更多
This study takes Gannan Tibetan Autonomous Prefecture as the place of case study and tourists as research objects. From the perspectives of geographical distribution of source tourist markets, Tourist activity behavio...This study takes Gannan Tibetan Autonomous Prefecture as the place of case study and tourists as research objects. From the perspectives of geographical distribution of source tourist markets, Tourist activity behavioral and spatial patterns of Tourists, this study looks into the geographical structure of the source tourists and spatial patterns by geography. The analysis of 341 questionnaires on tourists shows that:(1) The tourism cycle of Gannan is in the development phase, competing with adjacent Aba, and greatly impacted by the substitution effect and shadow effect of Aba.(2) The spatial distribution of tourist sources is concentrated, indicating that Gannan is a regional tourism destination. The temporal distance of tourists is mainly concentrated within the 6-hour traffi c circle.(3) Gannan Tibetan Autonomous Prefecture has already become the composite tourist destination dominated by leisure vacation. The minority folkcustom and special landscape are the most attractive tourism resources. Due to the impact of man-land harmonious lifestyle in the tourist areas, the environmental attitude of tourists is improved, and the transportation and shopping are the most vulnerable links in tourism service in Gannan Tibetan Autonomous Prefecture.(4) The spatial behavior of tourists in Gannan is mainly of single-destination style(52%), Transit leg and circle tour style(7%) as well as circle tour style(41%). The spatial distribution of tourist fl ow in Gannan shows a signifi cant feature "more in the north, less in the south and dependent on National Road". Tourism resources, transport facilities, regional competition and lack of route connecting different ecological units are important causes of the spatial distribution of self-help tourists.展开更多
By using a surface air temperature index （SATI） averaged over the eastern Tibetan Plateau （TP）, investigation is conducted on the short-term climate variation associated with the interannual air warming （or cool...By using a surface air temperature index （SATI） averaged over the eastern Tibetan Plateau （TP）, investigation is conducted on the short-term climate variation associated with the interannual air warming （or cooling） over the TP in each summer month. Evidence suggests that the SATI is associated with a consistent teleconnection pattern extending from the TP to central-western Asia and southeastern Europe. Associated rainfall changes include, for a warming case, a drought in northern India in May and June, and a stronger mei-yu front in June. The latter is due to an intensified upper-level northeasterly in eastern China and a wetter and warmer condition over the eastern TP. In the East Asian regions, the time-space distributions of the correlation patterns between SATI and rainfall are more complex and exhibit large differences from month to month. Some studies have revealed a close relationship between the anomalous heating over the TP and the rainfall anomaly along the Yangtze River valley appearing in the summer on a seasonal mean time-scale, whereas in the present study, this relationship only appears in June and the signal＇s significance becomes weaker after the long-term trend in the data was excluded. Close correlations between SATI and the convection activity and SST also occur in the western Pacific in July and August： A zonally-elongated warm tone in the SST in the northwestern Pacific seems to be a passive response of the associated circulation related to a warm SATI. The SATI-associated teleconnection pattern provides a scenario consistently linking the broad summer rainfall anomalies in Europe, central-western Asia, India, and East Asia.展开更多
Paleocurrent indicator data collected in field work were used to study the early Cenozoic regional paleodrainage patterns in the Hob Xil basin in northern Tibetan plateau. The paleocurrent directions of the Eocene Fen...Paleocurrent indicator data collected in field work were used to study the early Cenozoic regional paleodrainage patterns in the Hob Xil basin in northern Tibetan plateau. The paleocurrent directions of the Eocene Fenghuoshan Group obviously show that the flows were northward with a unidirectional dispersal pattern. This probably reflects the uplift of the Qiangtang terrain during the initial basin deposition period and indicates that the Tanggula Moutains occurred as topographic highlands at least in the Eocene. Paleoflows of the Oligocene Yaxicuo Group were dominantly oriented to the north and then flowed eastwards during its late deposition. This regional variability of paleodrainage patterns of the Yaxicuo Group is interpreted to record the dispersal style of sediments from transverse rivers to longitudinal river systems. It is inferred that the Oligocene uplift of the Kunlun Mountains obstructed by northward paleoflows and created longitudinal river systems parallel to the orogenic belts. The temporal and spatial changes of the paleodrainage patterns suggest that the northern boundary of the Tibetan plateau during the early Cenozoic was situated in the Hoh Xil area and its uplift has progressed northwards through time.展开更多
A synthesis of Holocene pollen records from the Tibetan Plateau shows the history of vegetation and climatic changes during the Holocene. Palynological evidences from 24 cores/sections have been compiled and show that...A synthesis of Holocene pollen records from the Tibetan Plateau shows the history of vegetation and climatic changes during the Holocene. Palynological evidences from 24 cores/sections have been compiled and show that the vegetation shifted from subalpine/alpine conifer forest to subalpine/alpine evergreen sclerophyllous forest in the southeastern part of the plateau; from alpine steppe to alpine desert in the central, western and northern part; and from alpine meadow to alpine steppe in the eastern and southern plateau regions during the Holocene. These records show that increases in precipitation began about 9 ka from the southeast, and a wide ranging level of increased humidity developed over the entire of the plateau around 8-7 ka, followed by aridity from 6 ka and a continuous drying over the plateau after 4-3 ka. The changes in Holocene climates of the plateau can be interpreted qualitatively as a response to orbital forcing and its secondary effects on the Indian Monsoon which expanded northwards during the early Holocene and retreated from the plateau since the mid-Holocene. Also, there is teleconnection between the Tibetan Plateau and North Atlantic.展开更多
Much geological research has illustrated the transition of paleoenvironmental patterns during the Cenozoic from a planetary-wind-dominant type to a monsoon-dominant type, indicating the initiation of the East Asian mo...Much geological research has illustrated the transition of paleoenvironmental patterns during the Cenozoic from a planetary-wind-dominant type to a monsoon-dominant type, indicating the initiation of the East Asian monsoon and inland-type aridity. However, there is a dispute about the causes and mechanisms of the transition, especially about the impact of the Himalayan/Tibetan Plateau uplift and the Paratethys Sea retreat, Thirty numerical sensitivity experiments under different land-sea distributions and Himalayan/Tibetan Plateau topography conditions are performed here to simulate the evolution of climate belts with emphasis on changes in the rain band, and these are compared with the changes in the paleoenvironmental patterns during the Cenozoic recovered by geological records. The consistency between simulations and the geological evidence indicates that both the Tibetan Plateau uplift and the Paratethys Sea retreat play important roles in the formation of the monsoon-dominant environmental pattern. Furthermore, the simulations show the monsoon-dominant environmental pattern comes into being when the Himalayan/Tibetan Plateau reaches 1000-2000 m high and the Paratethys Sea retreats to the Turan Plate.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 trend in NPP in the high-cold shrub-meadow zone, high-cold meadow steppe zone and high-cold steppe zone is more significant than that of the high-cold desert zone; b） with in- creasing altitude, the percentage area with a positive trend in annual NPP follows a trend of ＂increasing-stable-decreasing＂, while the percentage area with a negative trend in annual NPP follows a trend of ＂decreasing-stable-increasing＂, with increasing altitude; c） the varia- tion in annual NPP with latitude and longitude co-varies with the vegetation distribution; d） the variation in annual NPP within the major river basins has a generally positive trend, of which the growth in NPP in the Yellow River Basin is most significant. Results show that, based on changes in NPP trends, vegetation coverage and phonological phenomenon with time, NPP has been declining in certain places successively, while the overall health of the alpine grassland on the TP is improving.展开更多
文摘This study aimed to provide theoretical bases for optimized land use in minority settlements at high altitude. On the basis of forest form map and land use type map (1∶250 000) of Ganzi Tibetan Autonomous Prefecture in Sichuan Province in 2007, this study carried out further analysis and assessment on the landscape pattern and fragmentation degree of Ganzi from the perspective of overall landscape characteristics, area and perimeter of patches, quantity and fractal dimension of patches and so on with the support of geo-info systematical software ArcCIS and landscape structure analysis software Fragstats. The results showed that among all landscape elements alpine meadow and evergreen broad-leaved shrubs take up a larger part as temperate and cool temperate grassland and marsh are scattered with small areas; deciduous and broad-leaved as well as their mixed forest have higher landscape fragmentation degree, on the whole, the fragmentation degree of forest type is higher than that of meadow and shrub; fractal dimensions of landscape components are all small and tend to 1, which indicates that the folded degree of all landscape boundaries are small.
基金This work was supported jointly by the Chinese Ministry of Science and Technology under Grant No.2006CB403607the National Natural Science Foundation of China under Grant No.40523001.
文摘A series of numerical experiments are carried out by using the Spectral Atmospheric Model of State Key Laboratory of Numerical Modeling Atmospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics （SAMIL） to investigate how the Tibetan Plateau （TP） mechanical and thermal forcing affect the circulation and climate patterns over subtropical Asia. It is shown that, compared to mechanical forcing, the thermal forcing of TP plays a dominant role in determining the large-scale circulation in summer. Both the sensible heating and the latent heating over TP tend to generate a surface cyclonic circulation and a gigantic anticyclonic circulation in the mid- and upper layers, whereas the direct effect of the latter is much more significant. Following a requirement of the time-mean quasi-geostrophic vorticity equation for large-scale air motion in the subtropics, convergent flow and vigorous ascending motion must appear to the east of TP. Hence the summer monsoon in East China is reinforced efficiently by TP. In contrast, the atmosphere to the west of TP is characterized by divergent flow and downward motion, which induces the arid climate in Mid-Asia.
基金Sponsored by Key Project of National Sci-Tech Support Plan(2013BAJ03B00)
文摘Through investigating Tibetan courtyard landscapes in Linzhi City, Tibet, it was found that Tibetan courtyards attached more importance to flower plants and garden crops, focused on natural style and easy maintenance, but not pruning; Tibetan courtyard landscaping valued shape, color, flower season and visual aesthetics of fl owers, tried to build "gardens" with fl ower confi guration as the major content, similar aesthetic concepts and landscaping style with European gardens; moreover, it paid more attention to plants, but not waterscape design; in Tibetan gardens, lawns occupied a secondary position next to fl owering plants, fruit trees and garden crops.
基金supported by the National Natural Science Foundation of China(No.31772478,31501851)the Administration of the Gongga Mountain National Nature Reserve
文摘Background:Global climate change has had significant effects on animal distribution and population dynamics in mid-latitude alpine areas,but we know little about the basic ecology of high-altitude species due to the difficulties of conducting field research in the harsh climate and habitat present at high elevations.The Tibetan Snowcock(Tetraogallus tibetanus) is a little-known phasianid distributing in alpine areas at extremely high elevations in the mountains surrounding the Tibetan Plateau.Estimating the species occupancy rate and discussing the factors affecting its distribution based on infrared-triggered camera techniques would provide both a baseline to measure the influence of global warming and valuable information on its conservation and ecology.Methods:We used infrared-triggered cameras to investigate the Tibetan Snowcock on the western slope of Mt.Gongga from June to November 2016.We used the R package "overlap" to visualize its activity pattern,and used an occupancy model to both examine its habitat use as well as to determine the most influential variables affecting its habitat use.Results:Using 103 camera traps over 9213 camera-days,we recorded 428 instances of Tibetan Snowcock.The diel activity peaks of Tibetan Snowcock occurred during the periods of 8:00-10:00 am and 18:00-20:00 pm.The model estimate of occupancy for Tibetan Snowcock(0.830) was slightly higher than the na?ve site occupancy based on camera detections(0.663),indicating a wider use of habitat than the camera traps recorded.Elevation,slope,settlement density,road density,and EVI(enhanced vegetation index) were the most influential variables for its habitat use.Conclusions:The Tibetan Snowcock is confirmed to be diurnal.This species prefers an environment with a high elevation,gentle slope,and low EVI,apparently facing a trade-off between predator risk,foraging efficiency,and food availability.When human impact was low,there was a positive correlation between the habitat use of the Tibetan Snowcock and both its road and settlement densities.Infrared cameras and proper survey design are valuable for investigating extreme alpine phasianids.
文摘This study takes Gannan Tibetan Autonomous Prefecture as the place of case study and tourists as research objects. From the perspectives of geographical distribution of source tourist markets, Tourist activity behavioral and spatial patterns of Tourists, this study looks into the geographical structure of the source tourists and spatial patterns by geography. The analysis of 341 questionnaires on tourists shows that:(1) The tourism cycle of Gannan is in the development phase, competing with adjacent Aba, and greatly impacted by the substitution effect and shadow effect of Aba.(2) The spatial distribution of tourist sources is concentrated, indicating that Gannan is a regional tourism destination. The temporal distance of tourists is mainly concentrated within the 6-hour traffi c circle.(3) Gannan Tibetan Autonomous Prefecture has already become the composite tourist destination dominated by leisure vacation. The minority folkcustom and special landscape are the most attractive tourism resources. Due to the impact of man-land harmonious lifestyle in the tourist areas, the environmental attitude of tourists is improved, and the transportation and shopping are the most vulnerable links in tourism service in Gannan Tibetan Autonomous Prefecture.(4) The spatial behavior of tourists in Gannan is mainly of single-destination style(52%), Transit leg and circle tour style(7%) as well as circle tour style(41%). The spatial distribution of tourist fl ow in Gannan shows a signifi cant feature "more in the north, less in the south and dependent on National Road". Tourism resources, transport facilities, regional competition and lack of route connecting different ecological units are important causes of the spatial distribution of self-help tourists.
基金supported by the Key Laboratory of Meteorological Disaster of Ministry of Education (KLME050202 and 050205)the Jiangsu provincial 333 Talent Cultivation Projectthe Jiangsu provincial Qing-Lan Project and the Special Funds for Public Welfare of China [Grant No. GYHY(QX) 2007-6-26]Education Foundation, Hong Kong
文摘By using a surface air temperature index （SATI） averaged over the eastern Tibetan Plateau （TP）, investigation is conducted on the short-term climate variation associated with the interannual air warming （or cooling） over the TP in each summer month. Evidence suggests that the SATI is associated with a consistent teleconnection pattern extending from the TP to central-western Asia and southeastern Europe. Associated rainfall changes include, for a warming case, a drought in northern India in May and June, and a stronger mei-yu front in June. The latter is due to an intensified upper-level northeasterly in eastern China and a wetter and warmer condition over the eastern TP. In the East Asian regions, the time-space distributions of the correlation patterns between SATI and rainfall are more complex and exhibit large differences from month to month. Some studies have revealed a close relationship between the anomalous heating over the TP and the rainfall anomaly along the Yangtze River valley appearing in the summer on a seasonal mean time-scale, whereas in the present study, this relationship only appears in June and the signal＇s significance becomes weaker after the long-term trend in the data was excluded. Close correlations between SATI and the convection activity and SST also occur in the western Pacific in July and August： A zonally-elongated warm tone in the SST in the northwestern Pacific seems to be a passive response of the associated circulation related to a warm SATI. The SATI-associated teleconnection pattern provides a scenario consistently linking the broad summer rainfall anomalies in Europe, central-western Asia, India, and East Asia.
基金supported by the National Natural Science Foundation of China(No.40572077)Specialized Research Fund for the Doctoral Program of Higher Education(No.20060616005).
文摘Paleocurrent indicator data collected in field work were used to study the early Cenozoic regional paleodrainage patterns in the Hob Xil basin in northern Tibetan plateau. The paleocurrent directions of the Eocene Fenghuoshan Group obviously show that the flows were northward with a unidirectional dispersal pattern. This probably reflects the uplift of the Qiangtang terrain during the initial basin deposition period and indicates that the Tanggula Moutains occurred as topographic highlands at least in the Eocene. Paleoflows of the Oligocene Yaxicuo Group were dominantly oriented to the north and then flowed eastwards during its late deposition. This regional variability of paleodrainage patterns of the Yaxicuo Group is interpreted to record the dispersal style of sediments from transverse rivers to longitudinal river systems. It is inferred that the Oligocene uplift of the Kunlun Mountains obstructed by northward paleoflows and created longitudinal river systems parallel to the orogenic belts. The temporal and spatial changes of the paleodrainage patterns suggest that the northern boundary of the Tibetan plateau during the early Cenozoic was situated in the Hoh Xil area and its uplift has progressed northwards through time.
基金the National Fundamental Key Project(KZ951-A1-202)from the Chinese Academythe National Science Committee of ChinaMajor Projects of Knowledge Innovation Program,CAS(KZCX1-10-01-05).
文摘A synthesis of Holocene pollen records from the Tibetan Plateau shows the history of vegetation and climatic changes during the Holocene. Palynological evidences from 24 cores/sections have been compiled and show that the vegetation shifted from subalpine/alpine conifer forest to subalpine/alpine evergreen sclerophyllous forest in the southeastern part of the plateau; from alpine steppe to alpine desert in the central, western and northern part; and from alpine meadow to alpine steppe in the eastern and southern plateau regions during the Holocene. These records show that increases in precipitation began about 9 ka from the southeast, and a wide ranging level of increased humidity developed over the entire of the plateau around 8-7 ka, followed by aridity from 6 ka and a continuous drying over the plateau after 4-3 ka. The changes in Holocene climates of the plateau can be interpreted qualitatively as a response to orbital forcing and its secondary effects on the Indian Monsoon which expanded northwards during the early Holocene and retreated from the plateau since the mid-Holocene. Also, there is teleconnection between the Tibetan Plateau and North Atlantic.
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.40125014 and 40231001)the Key Program of the Chinese Academy of Sciences KZCX3-SW-139.
文摘Much geological research has illustrated the transition of paleoenvironmental patterns during the Cenozoic from a planetary-wind-dominant type to a monsoon-dominant type, indicating the initiation of the East Asian monsoon and inland-type aridity. However, there is a dispute about the causes and mechanisms of the transition, especially about the impact of the Himalayan/Tibetan Plateau uplift and the Paratethys Sea retreat, Thirty numerical sensitivity experiments under different land-sea distributions and Himalayan/Tibetan Plateau topography conditions are performed here to simulate the evolution of climate belts with emphasis on changes in the rain band, and these are compared with the changes in the paleoenvironmental patterns during the Cenozoic recovered by geological records. The consistency between simulations and the geological evidence indicates that both the Tibetan Plateau uplift and the Paratethys Sea retreat play important roles in the formation of the monsoon-dominant environmental pattern. Furthermore, the simulations show the monsoon-dominant environmental pattern comes into being when the Himalayan/Tibetan Plateau reaches 1000-2000 m high and the Paratethys Sea retreats to the Turan Plate.
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 trend in NPP in the high-cold shrub-meadow zone, high-cold meadow steppe zone and high-cold steppe zone is more significant than that of the high-cold desert zone; b） with in- creasing altitude, the percentage area with a positive trend in annual NPP follows a trend of ＂increasing-stable-decreasing＂, while the percentage area with a negative trend in annual NPP follows a trend of ＂decreasing-stable-increasing＂, with increasing altitude; c） the varia- tion in annual NPP with latitude and longitude co-varies with the vegetation distribution; d） the variation in annual NPP within the major river basins has a generally positive trend, of which the growth in NPP in the Yellow River Basin is most significant. Results show that, based on changes in NPP trends, vegetation coverage and phonological phenomenon with time, NPP has been declining in certain places successively, while the overall health of the alpine grassland on the TP is improving.
