The Changjiang River Valley is rich in hydraulic energy resources. A rough estimation of the technically developable volume and the economically developable volume for the Changjiang River Valley was drawn out on the ...The Changjiang River Valley is rich in hydraulic energy resources. A rough estimation of the technically developable volume and the economically developable volume for the Changjiang River Valley was drawn out on the basis of new data. According to the estimation, the developable water energy resources of the whole valley is 257 627.60 MW with an annual energy output of 1 195.142 billion kW·h - respectively amounting to 120.6% and 116.3% of the General Investigation result in 1980. The proportion of economically developable volume in the technically developable volume ranges the medium level in the world. According to the 3-step plan for the national economic and social development, the economic situation of our country will come up to the standard of medium-developed countries in the mid of the 21st century. Calculation reports from related departments show that the national electric power requirement in the Year 2050 will be 6 200 billion kW·h (basic scheme) ～11 600 billion kW·h (ideal scheme) while the electric power requirement of the South-west, Central and East areas of the nation within the Changjiang River Valley will amount to 44% ～ 50 %. In order to satisfy the electric power requirement of the national economic and social development, the development and utilization of the hydraulic energy in the Changjiang River Valley should be speeded up by stressing its strategic position and taking effective measures. The structure of the electric energy components of the three areas will be improved with the increasing proportion of the hydroelectricity. The hydroelectricity should be mainly developed in the South-west area; both the hydroelectric and fossil-fired power should be developed in the Central China; the fossil-fired power should be mainly developed in the combination of hydropower while nuclear power will be properly developed in the East China. In the Year 2050, the development of the economically developable hydraulic energy in the whole valley will be basically completed and the proportion of the hydropower in the electric energy components will be 40%.展开更多
Pinus radiata was introduced to the summer rainfall environments of Sichuan Province, China in the 1990s as a part of an afforestation pmgram for soil and water conservation in the arid and semi-arid river valley area...Pinus radiata was introduced to the summer rainfall environments of Sichuan Province, China in the 1990s as a part of an afforestation pmgram for soil and water conservation in the arid and semi-arid river valley area of Aba Prefecture. Within this region a total area of 26 000 ha have been identified through climate matching as suitable and a further 63 000 ha potentially suitable for environmental plantings of P. radiata. The plantations are being established in widely separated small patches on steep and degraded slopes along the dry river valley The newly introduced P. radiata are exposed to two kinds of forest health risks： they may be attacked by （a） indigenous pathogens and pests against which they may not possess any resistance or （b） by inadvertently introduced foreign pests or pathogens. This paper presents a survey of the potential damaging pests and a preliminary assessment of forest health risks facing the P. radiata plantations over a much longer timeframe than the initial phase of introduction and early plantation establishment. An empirical appmach was adopted to evaluate forest health risks by a combination of literature review, examination of historical records of pest and disease outbreaks in the surrounding conifemus forests, field surveys and inspections, specimen collection and identification, and most importantly, expert analysis of the likelihood of attack by specific pests and pathogens and the subsequent impact of such attacks. The assessment identified some specific forest health risks to the long-term success of P. radiata introduction in this area. These risks are closely associated with the indigenous pests and pathogens of the two native pine species, P. tabulaeformis and P. armondii since these pests and pathogens are considered more likely to establish on P. radiata over time. Exotic pests and pathogens are of a quarantine concern at present. Based on the results of assessment, recommendations are pmvided to improve forest vigour and to reduce the forest health risks posed by indigenous as well as exotic pests and pathogens to the introduced P. radiata. Ways to increase the ability to manage the forest health risks once a particular pest infestation and disease eventuates are also recommended. Although detrimental to the survival and growth of the introduced P. radiata, the impact of identified forest health risks are not considered to be fatal to the long term success ofP. radiata in this area.展开更多
Pinus radiata D. Don, native to a Californian coastal environment, has been introduced to many parts of the world as an exotic species for afforestation. It is now a major plantation species in the Southern Hemisphere...Pinus radiata D. Don, native to a Californian coastal environment, has been introduced to many parts of the world as an exotic species for afforestation. It is now a major plantation species in the Southern Hemisphere. In 1990, it was introduced to the heavily degraded, dry Min river valley area in Aba prefecture of Sichuan Province, P. R. China. Survival and growth of young trees planted at several sites appear to be reasonable. This review is to serve as an introduction to the large body of literature on P. radiata for forest scientists in China. It covers the following aspects: P. radiata in its native environment and in ex situ plantations, provenance and genetic variations, environmental limitations and climate niche, diseases and pests, lessons from unsuccessful introductions, and the use of P. radiata for ecological restoration. The early growth of P. radiata planted in the dry river valley area is briefly described. Potential problems associated with the introduction of P. radiata in Aba and future research needs are also identified.展开更多
一、wide,broad wide和broad都是“广阔”的意思。但说wide时,着重于距离,而说broad时着重于面积。例如: The cloth is 4 feet long by 2 feet wide. 布长四尺,宽二尺。 The door is wide open.门大开。 The track is 9 feet wide.轨道...一、wide,broad wide和broad都是“广阔”的意思。但说wide时,着重于距离,而说broad时着重于面积。例如: The cloth is 4 feet long by 2 feet wide. 布长四尺,宽二尺。 The door is wide open.门大开。 The track is 9 feet wide.轨道九尺宽。 The river is one mile broad here.这条河流此处宽一英里。展开更多
文摘The Changjiang River Valley is rich in hydraulic energy resources. A rough estimation of the technically developable volume and the economically developable volume for the Changjiang River Valley was drawn out on the basis of new data. According to the estimation, the developable water energy resources of the whole valley is 257 627.60 MW with an annual energy output of 1 195.142 billion kW·h - respectively amounting to 120.6% and 116.3% of the General Investigation result in 1980. The proportion of economically developable volume in the technically developable volume ranges the medium level in the world. According to the 3-step plan for the national economic and social development, the economic situation of our country will come up to the standard of medium-developed countries in the mid of the 21st century. Calculation reports from related departments show that the national electric power requirement in the Year 2050 will be 6 200 billion kW·h (basic scheme) ～11 600 billion kW·h (ideal scheme) while the electric power requirement of the South-west, Central and East areas of the nation within the Changjiang River Valley will amount to 44% ～ 50 %. In order to satisfy the electric power requirement of the national economic and social development, the development and utilization of the hydraulic energy in the Changjiang River Valley should be speeded up by stressing its strategic position and taking effective measures. The structure of the electric energy components of the three areas will be improved with the increasing proportion of the hydroelectricity. The hydroelectricity should be mainly developed in the South-west area; both the hydroelectric and fossil-fired power should be developed in the Central China; the fossil-fired power should be mainly developed in the combination of hydropower while nuclear power will be properly developed in the East China. In the Year 2050, the development of the economically developable hydraulic energy in the whole valley will be basically completed and the proportion of the hydropower in the electric energy components will be 40%.
文摘Pinus radiata was introduced to the summer rainfall environments of Sichuan Province, China in the 1990s as a part of an afforestation pmgram for soil and water conservation in the arid and semi-arid river valley area of Aba Prefecture. Within this region a total area of 26 000 ha have been identified through climate matching as suitable and a further 63 000 ha potentially suitable for environmental plantings of P. radiata. The plantations are being established in widely separated small patches on steep and degraded slopes along the dry river valley The newly introduced P. radiata are exposed to two kinds of forest health risks： they may be attacked by （a） indigenous pathogens and pests against which they may not possess any resistance or （b） by inadvertently introduced foreign pests or pathogens. This paper presents a survey of the potential damaging pests and a preliminary assessment of forest health risks facing the P. radiata plantations over a much longer timeframe than the initial phase of introduction and early plantation establishment. An empirical appmach was adopted to evaluate forest health risks by a combination of literature review, examination of historical records of pest and disease outbreaks in the surrounding conifemus forests, field surveys and inspections, specimen collection and identification, and most importantly, expert analysis of the likelihood of attack by specific pests and pathogens and the subsequent impact of such attacks. The assessment identified some specific forest health risks to the long-term success of P. radiata introduction in this area. These risks are closely associated with the indigenous pests and pathogens of the two native pine species, P. tabulaeformis and P. armondii since these pests and pathogens are considered more likely to establish on P. radiata over time. Exotic pests and pathogens are of a quarantine concern at present. Based on the results of assessment, recommendations are pmvided to improve forest vigour and to reduce the forest health risks posed by indigenous as well as exotic pests and pathogens to the introduced P. radiata. Ways to increase the ability to manage the forest health risks once a particular pest infestation and disease eventuates are also recommended. Although detrimental to the survival and growth of the introduced P. radiata, the impact of identified forest health risks are not considered to be fatal to the long term success ofP. radiata in this area.
基金This paper is part of a project funded by Australian Centre for International Agricultural Research (ACIAR), State Forests of New South Wales, Australia and Department of Forestry, Sichuan Province China.
文摘Pinus radiata D. Don, native to a Californian coastal environment, has been introduced to many parts of the world as an exotic species for afforestation. It is now a major plantation species in the Southern Hemisphere. In 1990, it was introduced to the heavily degraded, dry Min river valley area in Aba prefecture of Sichuan Province, P. R. China. Survival and growth of young trees planted at several sites appear to be reasonable. This review is to serve as an introduction to the large body of literature on P. radiata for forest scientists in China. It covers the following aspects: P. radiata in its native environment and in ex situ plantations, provenance and genetic variations, environmental limitations and climate niche, diseases and pests, lessons from unsuccessful introductions, and the use of P. radiata for ecological restoration. The early growth of P. radiata planted in the dry river valley area is briefly described. Potential problems associated with the introduction of P. radiata in Aba and future research needs are also identified.
文摘一、wide,broad wide和broad都是“广阔”的意思。但说wide时,着重于距离,而说broad时着重于面积。例如: The cloth is 4 feet long by 2 feet wide. 布长四尺,宽二尺。 The door is wide open.门大开。 The track is 9 feet wide.轨道九尺宽。 The river is one mile broad here.这条河流此处宽一英里。
