[Objective] The causes of drought in summer in Alashan League in 2010 were discussed. [Method] Through the discussion of climate background, circulation characteristics, subtropical high and ocean temperature of the s...[Objective] The causes of drought in summer in Alashan League in 2010 were discussed. [Method] Through the discussion of climate background, circulation characteristics, subtropical high and ocean temperature of the severe drought in Alashan League in Inner Mongolia during the flooding time, the potential causes of drought in Alashan League in summer in 2010 were discussed. [Result] The circulation around Alashan League and surroundings in 850 hPa was weak. Especially the southerly was extremely weak and it restricted the transportation of southerly water vapor towards Inner Mongolia, which was one of the direct reasons of drought; the 500 hPa high pressure ridge controlled Alashan League, and resulted into long-term drought and lasting high temperature. The summer seasonal wind was weak and arrived land in Alashan League. The northwest pacific subtropical high was large and strong. Only when subtropical high was strong and merged as well as strengthened with high pressure ridge around middle and high latitude in the lower reaches 130°-140° E, can rain be generated. However, the latter condition was limited in summer in 2010. When the ocean temperature around 30°-50° N and 140°-150° E was low in the north and high in the south, there would be less rain in Alashan League. [Conclusion] The study provided relevant information and technological support for the drought disaster warning forecast, drought observation system, and disaster prevention and mitigation measures.展开更多
Although neotectonic activity is considered to be the main factor of the terrain evolution of the Qinghai Tibet Plateau and its surrounding high-altitude areas,further geomorphological analysis and literature analysis...Although neotectonic activity is considered to be the main factor of the terrain evolution of the Qinghai Tibet Plateau and its surrounding high-altitude areas,further geomorphological analysis and literature analysis are needed for the understanding of the geomorphic evolution and the Quaternary environment change of the western area of the Alxa Plateau near the northern Tibet Plateau.The purpose of this study is to investigate the distribution of site-specific geomorphic units of the landforms developed in the vast topography of Ejina Basin(Western Alxa),in order to identify the geostructural and climatic causes of the geomorphic landscape and its impact on the change of paleoenvironment.At present,the climate and hydrological conditions in Ejina are relatively monotonous and stable.In addition to tectonic dynamic factors,the most widely distributed landform in the basin is climate landform.There are both geomorphological and sedimentological anomalies of Aeolian landforms occurred in the whole basin,indicating that the underlying surface effect(retention effect)of river(Ejina River)and its related uneven ground and weak wind erosion(deflation)process in the nearby area may be the important factors controlling the formation of Ejina dunes,rather than the arid climate.It is believed that the extensive interaction between the aeolian and fluvial processes is the main mechanism of the regional geomorphic difference in Ejina Basin.According to the comparability of regional geomorphology and sedimentology,the period of the formation of relic geomorphology in the edge of Ejina Basin can be reasonably attributed to the local glacial maximum of the last glacial.The geomorphic transformation from quasi plain and desert valley to desert plain,the appearance of widely moving sand dunes and the presence of large ancient lake geomorphology all indicate that the drought index of Ejina Basin is increasing on the scale of geomorphic formation.Paleogeomorphological and chronological evidences show that the climatic and hydrological conditions of the basin in the last glacial period and the early Holocene are much better than those at present.For example,the average annual precipitation in the area before 39-23ka BP is between 60-350 mm(about 36 mm today),but there are large waves in the Holocene.The coexistence of various climates and landforms in Ejina Basin and the resulting geomorphic diversity should be the composite result of various geomorphic processes and surface processes besides glaciation.The low aridity(relative humidity)in the Ejina Region in the late Pleistocene may be the result of the enhancement of the westerly rain belt and the weakening of the Asian Winter Monsoon in the arid region of Central Asia.展开更多
Results of the field work in recent years reveal that the Taolimiao-Alashan Nur is of specific significance to the survival of the Relict Gull Ordos subpopulation while the wetland birds occurring there represent conc...Results of the field work in recent years reveal that the Taolimiao-Alashan Nur is of specific significance to the survival of the Relict Gull Ordos subpopulation while the wetland birds occurring there represent concentratedly and indicatively the characteristics of the wetland bird community in desert of Ordos;as in July of 1992 China became the contract nation of the Convention on Wetlands of International Importance especially as Waterfowl Habitat (The Ramsar Convention),the study also presents an assessment on the wetland habitat of the T-A Nur following the Criteria recommended by the Convention and suggests that the T-A Nur following the relevant articles/items of the Criteria might be considered as an important wetland locality in China and hence to be listed on List of Wetlands of International Importance.展开更多
Four diverse disturbance types,namely,farmland,rotationally grazed grassland,overgrazed grassland and forbidden grazing grassland,were identified in the Alashan desert region of Inner Mongolia.Rodents were sampled in ...Four diverse disturbance types,namely,farmland,rotationally grazed grassland,overgrazed grassland and forbidden grazing grassland,were identified in the Alashan desert region of Inner Mongolia.Rodents were sampled in April,July and October in 2002 and 2003 using the trap-day method.Their spatial and temporal niches among the four disturbance types were assessed using the Shannon-Wiener niche breadth index and the Pianka niche overlap index.The Shannon-Wiener niche breadth index was the highest for Allactaga sibirica and Meriones meridianus(0.925 and 0.908,respectively),intermediate for Cricetulus eversmanni,Phodopus roborovskii and Citellus dauricus(0.789,0.782 and 0.711,respectively),and lowest for Cardiocranius paradoxus(0.003).The Pianka niche overlap indices of six-paired species were the highest and varied from 0.900 to 1.000,suggesting their spatial niche overlapped almost completely.Conversely,the spatial niche overlap index for Meriones unguiculatus,Cardiocranius paradoxus,and Salpingotus kozlovi was zero,thus indicating a complete absence of competition among them.In addition,the tem-poral niche breadth and overlap indices varied greatly in rela-tion to disturbance types and season.The level of temporal niche overlap in spring and autumn was low while in summer it was high.For all disturbance types and for each season,the temporal niche overlap index of Meriones meridianus and Cricetulus barabansis was always highest but for Meriones unguiculatus and Salpingotus kozlovi always lowest.展开更多
文摘[Objective] The causes of drought in summer in Alashan League in 2010 were discussed. [Method] Through the discussion of climate background, circulation characteristics, subtropical high and ocean temperature of the severe drought in Alashan League in Inner Mongolia during the flooding time, the potential causes of drought in Alashan League in summer in 2010 were discussed. [Result] The circulation around Alashan League and surroundings in 850 hPa was weak. Especially the southerly was extremely weak and it restricted the transportation of southerly water vapor towards Inner Mongolia, which was one of the direct reasons of drought; the 500 hPa high pressure ridge controlled Alashan League, and resulted into long-term drought and lasting high temperature. The summer seasonal wind was weak and arrived land in Alashan League. The northwest pacific subtropical high was large and strong. Only when subtropical high was strong and merged as well as strengthened with high pressure ridge around middle and high latitude in the lower reaches 130°-140° E, can rain be generated. However, the latter condition was limited in summer in 2010. When the ocean temperature around 30°-50° N and 140°-150° E was low in the north and high in the south, there would be less rain in Alashan League. [Conclusion] The study provided relevant information and technological support for the drought disaster warning forecast, drought observation system, and disaster prevention and mitigation measures.
基金The study was financially supported by the National Natural Science Foundation of China(grant nos.41930640,41771014)the Project of the Second Comprehensive Scientific Investigation on the Qinghai Tibet Plateau(2019QZKK1003)。
文摘Although neotectonic activity is considered to be the main factor of the terrain evolution of the Qinghai Tibet Plateau and its surrounding high-altitude areas,further geomorphological analysis and literature analysis are needed for the understanding of the geomorphic evolution and the Quaternary environment change of the western area of the Alxa Plateau near the northern Tibet Plateau.The purpose of this study is to investigate the distribution of site-specific geomorphic units of the landforms developed in the vast topography of Ejina Basin(Western Alxa),in order to identify the geostructural and climatic causes of the geomorphic landscape and its impact on the change of paleoenvironment.At present,the climate and hydrological conditions in Ejina are relatively monotonous and stable.In addition to tectonic dynamic factors,the most widely distributed landform in the basin is climate landform.There are both geomorphological and sedimentological anomalies of Aeolian landforms occurred in the whole basin,indicating that the underlying surface effect(retention effect)of river(Ejina River)and its related uneven ground and weak wind erosion(deflation)process in the nearby area may be the important factors controlling the formation of Ejina dunes,rather than the arid climate.It is believed that the extensive interaction between the aeolian and fluvial processes is the main mechanism of the regional geomorphic difference in Ejina Basin.According to the comparability of regional geomorphology and sedimentology,the period of the formation of relic geomorphology in the edge of Ejina Basin can be reasonably attributed to the local glacial maximum of the last glacial.The geomorphic transformation from quasi plain and desert valley to desert plain,the appearance of widely moving sand dunes and the presence of large ancient lake geomorphology all indicate that the drought index of Ejina Basin is increasing on the scale of geomorphic formation.Paleogeomorphological and chronological evidences show that the climatic and hydrological conditions of the basin in the last glacial period and the early Holocene are much better than those at present.For example,the average annual precipitation in the area before 39-23ka BP is between 60-350 mm(about 36 mm today),but there are large waves in the Holocene.The coexistence of various climates and landforms in Ejina Basin and the resulting geomorphic diversity should be the composite result of various geomorphic processes and surface processes besides glaciation.The low aridity(relative humidity)in the Ejina Region in the late Pleistocene may be the result of the enhancement of the westerly rain belt and the weakening of the Asian Winter Monsoon in the arid region of Central Asia.
文摘Results of the field work in recent years reveal that the Taolimiao-Alashan Nur is of specific significance to the survival of the Relict Gull Ordos subpopulation while the wetland birds occurring there represent concentratedly and indicatively the characteristics of the wetland bird community in desert of Ordos;as in July of 1992 China became the contract nation of the Convention on Wetlands of International Importance especially as Waterfowl Habitat (The Ramsar Convention),the study also presents an assessment on the wetland habitat of the T-A Nur following the Criteria recommended by the Convention and suggests that the T-A Nur following the relevant articles/items of the Criteria might be considered as an important wetland locality in China and hence to be listed on List of Wetlands of International Importance.
基金This paper was supported by the National Natural Science Foundation of China(Grant No.30160019)the Plan of Chun Hui from the Ministry of Education of China.
文摘Four diverse disturbance types,namely,farmland,rotationally grazed grassland,overgrazed grassland and forbidden grazing grassland,were identified in the Alashan desert region of Inner Mongolia.Rodents were sampled in April,July and October in 2002 and 2003 using the trap-day method.Their spatial and temporal niches among the four disturbance types were assessed using the Shannon-Wiener niche breadth index and the Pianka niche overlap index.The Shannon-Wiener niche breadth index was the highest for Allactaga sibirica and Meriones meridianus(0.925 and 0.908,respectively),intermediate for Cricetulus eversmanni,Phodopus roborovskii and Citellus dauricus(0.789,0.782 and 0.711,respectively),and lowest for Cardiocranius paradoxus(0.003).The Pianka niche overlap indices of six-paired species were the highest and varied from 0.900 to 1.000,suggesting their spatial niche overlapped almost completely.Conversely,the spatial niche overlap index for Meriones unguiculatus,Cardiocranius paradoxus,and Salpingotus kozlovi was zero,thus indicating a complete absence of competition among them.In addition,the tem-poral niche breadth and overlap indices varied greatly in rela-tion to disturbance types and season.The level of temporal niche overlap in spring and autumn was low while in summer it was high.For all disturbance types and for each season,the temporal niche overlap index of Meriones meridianus and Cricetulus barabansis was always highest but for Meriones unguiculatus and Salpingotus kozlovi always lowest.
