The aim of this study was to investigate the distribution, density, community structure and biodiversity characteristics of benthic diatoms, and to analyze whether differences in species composition and abundance exis...The aim of this study was to investigate the distribution, density, community structure and biodiversity characteristics of benthic diatoms, and to analyze whether differences in species composition and abundance exist in different regions of the Niyang River, Tibet. Among the 157 taxa observed in 15 sampling sites in the main river and tributary, most were casual species （〉100）, the relative abundance of the genera Achnantkes and Fragilaria was 67% of the total relative abundance. Acknantkes minutissima was the most important species and dominated the whole river reaches （average relative abundance was 30%）; the average diatom densities were 7.4 x 105 cell/cm2 at all sites, and increased slowly from the upper section to downriver. The significant indicator taxa with higher relative abundance were Achnanthes biasolettiana （18.0%） and Fragilaria arcus （18.2%）, Fragilaria capucina var. vaucheriae （31.2%）, Fragilaria construens var. renter （11.3%） and Cymbella affinis （11.0%） in the upper, tributary and mid-river sections, respectively. Achnanthes minutissima was the most abundant species （56%） in the downriver section. Biodiversity indices showed a gradual decrease from the up- to down-river section, and dominant species were more abundant in the upper and mid-river sections than in the downriver section. A two-way indictor species analysis （TWINSPAN） of diatom composition clearly showed four different groups, namely the upper, mid, lower and tributary sections. Detrended correspondence analysis （DCA） supported the results of TW1NSPAN, and the characteristics of site distribution and species composition in the Niyang River supported the spatial structure of diatom assemblages. This study indicates that bio-assessment programs utilizing benthic diatoms could clearly benefit lotic water with regional stratification.展开更多
The purpose of this article is to classify the regional economic types and development dynamics of small towns in suburb Beijing by applying the classification methods developed by Nelson's method and Location Quo...The purpose of this article is to classify the regional economic types and development dynamics of small towns in suburb Beijing by applying the classification methods developed by Nelson's method and Location Quotient method into 183 small towns in Beijing.Four types of small towns are thus identified,including urban agriculture dominated towns,manufacturing dominated towns,service industry dominated towns and comprehensive type towns with balanced economic development.Within the environment of geographical information system,the spatial distribution pattern of four types of small towns with their evolution trend is analyzed.The results indicate that four types of small towns have obvious'core-periphery'spatial structure but with different functional orientations and evolution mechanisms.Based on this,the different development strategies for each type of small towns are summarized,providing a scientific reference for the differentiating planning and development strategies of these small towns.展开更多
The Third Plenary Session of the 18th CPC Central Committee ushered in a new chapter of China＇s comprehensive deepening of reform. The basic objective of comprehensively deepening reform of the state sector of econom...The Third Plenary Session of the 18th CPC Central Committee ushered in a new chapter of China＇s comprehensive deepening of reform. The basic objective of comprehensively deepening reform of the state sector of economy in the new chapter is to fully integrate this sector with a sophisticated market economic system with the market playing the decisive role in resource allocation. In order to achieve this objective, China is confronted with the four major priorities of adjusting the functions and layout of the state sector of economy according to national mandates, expediting the mixed ownership reform, creating a classified and multi- tiered new system for the administration of the sector, and developing a modern corporate system for SOEs to ensure an efficient micro-level governance mechanism for the sector. （1） The functions of the different types of SOEs should be accurately defined and SOEs should be divided into the three types of public policy SOEs, functional SOEs, and commercial SOEs. This classification forms the premises for reforming the state sector of economy. Based on the functions of the three types of SOEs, the directions and emphases for strategic adjustment should differ as well. （2） The mixed ownership reform should adhere to the methodological principles of combining top-down and bottom-up approaches, implementing pilot programs, and promoting coordinated progress. Practical implementation should ensure fair and standard reform procedures, reform programs consistent with laws and regulations, open and fair equity transfers, as well as fair and transparent internal distributions. The mixed ownership reform of SOEs should introduce the employee stock ownership system and adhere to the principles of compatible incentives, shared growth, and long-term development. Monopolistic sectors should be transformed into competitive market structures to create conditions for the implementation of mixed ownership for SOEs. （3） The new system for the administration of the state sector of economy should comprise three hierarchies： the Commission for the Administration of State Economy at the top level, state capital operation companies or state capital investment companies at the intermediate level and general for-profit enterprises at the bottom level, which administer public policy, functional SOEs, and commercial SOEs respectively. （4） Under the new system for the administration of the state sector of economy characterized by the three hierarchies and categories, the key for perfecting the modern corporate system of SOEs is to establish a differentiated, classified governance mechanism, i.e., different corporate governance mechanisms should be created for SOEs of different functions and roles.展开更多
The Koshi River Basin is in the middle of the Himalayas,a tributary of the Ganges River and a very important cross-border watershed.Across the basin there are large changes in altitude,habitat complexity,ecosystem int...The Koshi River Basin is in the middle of the Himalayas,a tributary of the Ganges River and a very important cross-border watershed.Across the basin there are large changes in altitude,habitat complexity,ecosystem integrity,land cover diversity and regional difference and this area is sensitive to global climate change.Based on Landsat TM images,vegetation mapping,field investigations and 3S technology,we compiled high-precision land cover data for the Koshi River Basin and analyzed current land cover characteristics.We found that from source to downstream,land cover in the Koshi River Basin in 2010 was composed of water body（glacier）,bare land,sparse vegetation,grassland,wetland,shrubland,forest,cropland,water body（river or lake） and built-up areas.Among them,grassland,forest,bare land and cropland are the main types,accounting for 25.83%,21.19%,19.31% and 15.09% of the basin＇s area respectively.The composition and structure of the Koshi River Basin land cover types are different between southern and northern slopes.The north slope is dominated by grassland,bare land and glacier;forest,bare land and glacier are mainly found on northern slopes.Northern slopes contain nearly seven times more grassland than southern slopes;while 97.13% of forest is located on southern slopes.Grassland area on northern slope is 6.67 times than on southern slope.The vertical distribution of major land cover types has obvious zonal characteristics.Land cover types from low to high altitudes are cropland,forest,Shrubland and mixed cropland,grassland,sparse vegetation,bare land and water bodies.These results provide a scientific basis for the study of land use and cover change in a critical region and will inform ecosystem protection,sustainability and management in this and other alpine transboundary basins.展开更多
基金Supported by the National Natural Science Foundation of China(No.30970550)
文摘The aim of this study was to investigate the distribution, density, community structure and biodiversity characteristics of benthic diatoms, and to analyze whether differences in species composition and abundance exist in different regions of the Niyang River, Tibet. Among the 157 taxa observed in 15 sampling sites in the main river and tributary, most were casual species （〉100）, the relative abundance of the genera Achnantkes and Fragilaria was 67% of the total relative abundance. Acknantkes minutissima was the most important species and dominated the whole river reaches （average relative abundance was 30%）; the average diatom densities were 7.4 x 105 cell/cm2 at all sites, and increased slowly from the upper section to downriver. The significant indicator taxa with higher relative abundance were Achnanthes biasolettiana （18.0%） and Fragilaria arcus （18.2%）, Fragilaria capucina var. vaucheriae （31.2%）, Fragilaria construens var. renter （11.3%） and Cymbella affinis （11.0%） in the upper, tributary and mid-river sections, respectively. Achnanthes minutissima was the most abundant species （56%） in the downriver section. Biodiversity indices showed a gradual decrease from the up- to down-river section, and dominant species were more abundant in the upper and mid-river sections than in the downriver section. A two-way indictor species analysis （TWINSPAN） of diatom composition clearly showed four different groups, namely the upper, mid, lower and tributary sections. Detrended correspondence analysis （DCA） supported the results of TW1NSPAN, and the characteristics of site distribution and species composition in the Niyang River supported the spatial structure of diatom assemblages. This study indicates that bio-assessment programs utilizing benthic diatoms could clearly benefit lotic water with regional stratification.
基金supported by the National Natural Science Foundation' Urban Agriculture-based Development Pattern and Spatial Reconstruction of Towns/Townships in Periurban Beijing'(Grant no.40971100)the knowledge innovation project of Chinese Academy of Science' Study on spatial structural reorganization and its effect on eco-environment'(Grant no.KZCX2- YW-321-01)
文摘The purpose of this article is to classify the regional economic types and development dynamics of small towns in suburb Beijing by applying the classification methods developed by Nelson's method and Location Quotient method into 183 small towns in Beijing.Four types of small towns are thus identified,including urban agriculture dominated towns,manufacturing dominated towns,service industry dominated towns and comprehensive type towns with balanced economic development.Within the environment of geographical information system,the spatial distribution pattern of four types of small towns with their evolution trend is analyzed.The results indicate that four types of small towns have obvious'core-periphery'spatial structure but with different functional orientations and evolution mechanisms.Based on this,the different development strategies for each type of small towns are summarized,providing a scientific reference for the differentiating planning and development strategies of these small towns.
文摘The Third Plenary Session of the 18th CPC Central Committee ushered in a new chapter of China＇s comprehensive deepening of reform. The basic objective of comprehensively deepening reform of the state sector of economy in the new chapter is to fully integrate this sector with a sophisticated market economic system with the market playing the decisive role in resource allocation. In order to achieve this objective, China is confronted with the four major priorities of adjusting the functions and layout of the state sector of economy according to national mandates, expediting the mixed ownership reform, creating a classified and multi- tiered new system for the administration of the sector, and developing a modern corporate system for SOEs to ensure an efficient micro-level governance mechanism for the sector. （1） The functions of the different types of SOEs should be accurately defined and SOEs should be divided into the three types of public policy SOEs, functional SOEs, and commercial SOEs. This classification forms the premises for reforming the state sector of economy. Based on the functions of the three types of SOEs, the directions and emphases for strategic adjustment should differ as well. （2） The mixed ownership reform should adhere to the methodological principles of combining top-down and bottom-up approaches, implementing pilot programs, and promoting coordinated progress. Practical implementation should ensure fair and standard reform procedures, reform programs consistent with laws and regulations, open and fair equity transfers, as well as fair and transparent internal distributions. The mixed ownership reform of SOEs should introduce the employee stock ownership system and adhere to the principles of compatible incentives, shared growth, and long-term development. Monopolistic sectors should be transformed into competitive market structures to create conditions for the implementation of mixed ownership for SOEs. （3） The new system for the administration of the state sector of economy should comprise three hierarchies： the Commission for the Administration of State Economy at the top level, state capital operation companies or state capital investment companies at the intermediate level and general for-profit enterprises at the bottom level, which administer public policy, functional SOEs, and commercial SOEs respectively. （4） Under the new system for the administration of the state sector of economy characterized by the three hierarchies and categories, the key for perfecting the modern corporate system of SOEs is to establish a differentiated, classified governance mechanism, i.e., different corporate governance mechanisms should be created for SOEs of different functions and roles.
基金National Natural Science Foundation of China(41371120)Australian Government-funded Koshi Basin Programme at the International Centre for Integrated Mountain Development(ICIMOD)Key Research Program of the Chinese Academy of Sciences(ZDRW-ZS-2016-6)
文摘The Koshi River Basin is in the middle of the Himalayas,a tributary of the Ganges River and a very important cross-border watershed.Across the basin there are large changes in altitude,habitat complexity,ecosystem integrity,land cover diversity and regional difference and this area is sensitive to global climate change.Based on Landsat TM images,vegetation mapping,field investigations and 3S technology,we compiled high-precision land cover data for the Koshi River Basin and analyzed current land cover characteristics.We found that from source to downstream,land cover in the Koshi River Basin in 2010 was composed of water body（glacier）,bare land,sparse vegetation,grassland,wetland,shrubland,forest,cropland,water body（river or lake） and built-up areas.Among them,grassland,forest,bare land and cropland are the main types,accounting for 25.83%,21.19%,19.31% and 15.09% of the basin＇s area respectively.The composition and structure of the Koshi River Basin land cover types are different between southern and northern slopes.The north slope is dominated by grassland,bare land and glacier;forest,bare land and glacier are mainly found on northern slopes.Northern slopes contain nearly seven times more grassland than southern slopes;while 97.13% of forest is located on southern slopes.Grassland area on northern slope is 6.67 times than on southern slope.The vertical distribution of major land cover types has obvious zonal characteristics.Land cover types from low to high altitudes are cropland,forest,Shrubland and mixed cropland,grassland,sparse vegetation,bare land and water bodies.These results provide a scientific basis for the study of land use and cover change in a critical region and will inform ecosystem protection,sustainability and management in this and other alpine transboundary basins.
