Under the background of the uplift of the Qinghai-Tibet Plateau, the settlements in the upper reaches of the Min River are significantly affected by the mountain environment, and their spatial distribution is typical ...Under the background of the uplift of the Qinghai-Tibet Plateau, the settlements in the upper reaches of the Min River are significantly affected by the mountain environment, and their spatial distribution is typical and representative. In this study, the relationship between settlements and topography, rivers and transportation, and the spatial distribution patterns of settlements, such as the aggregation and orientation characteristics of settlements, have been studied. The main conclusions include: 1) The settlement density decreases with the increase of elevation, slope, and distance from rivers and roads;76.25% and 63.17% of the settlements are distributed in the range of elevation 1500 - 3000 m and slope 6° - 25°, the upper reaches of the Min River are mostly alpine valley terrain, the bottom of the river has a low altitude, the landscape is undulating. The warm and humid climate is suitable for farming, conducive to agricultural production, and an ideal living environment for mountain residents. 2) The nuclear density of the settlement is distributed in strips along the axis of the river, and the closer to the river, the greater the nuclear density value. 3) Mathematical statistical methods were applied for the first time to realize the quantitative expression of the coupling of settlement and river direction. The influence of topographic conditions in different watersheds on the coupling degree of settlement extension and river flow direction was revealed. The slope of the fitted straight line between the settlement and river direction was 0.897, and the two directions were consistent. Except for the mainstream of the Min River, the larger values of the standard deviation ellipse flattening of settlements in each basin appeared in the upper reaches of the bay, and the overall trend showed a gradual decrease from the upstream to the downstream, which was consistent with the topographic change characteristics of the basin.展开更多
Based on the field investigation and the analysis of soil moisture curve, it is clearly shown that there is a positive relationship between vegetation coverage rate and soil moisture capacity and soil depth in dry ho...Based on the field investigation and the analysis of soil moisture curve, it is clearly shown that there is a positive relationship between vegetation coverage rate and soil moisture capacity and soil depth in dry hot valley of the Jinsha River, and also there is a desertification process with seasonality. It is suggested that the basic factor of desertification in the area is water deficiency (seasonal drought and low soil water capacity) and the direct dynamic of desertification is soil erosion. Some effective countermeasures are presented, of which water saving planting and irrigation techniques should be firstly applied in the studied area.展开更多
According to the recent practice in Laopingzi Village,Jiaopingdu Town,Luquan Yi and Miao Autonomous County(Luquan County hereinafter)in dry and hot valley of Jinsha River,the development of Zanthoxylum schinifolium Si...According to the recent practice in Laopingzi Village,Jiaopingdu Town,Luquan Yi and Miao Autonomous County(Luquan County hereinafter)in dry and hot valley of Jinsha River,the development of Zanthoxylum schinifolium Sieb.et Zucc planting industry can help farmers gradually get rid of poverty and achieve a virtuous cycle of ecological environment.It is a sustainable poverty alleviation way.Based on the three aspects of soil properties,climatic conditions,and topographical conditions influencing the growth of Z.schinifolium,this paper selected eight evaluation factors to establish a suitability evaluation system for Z.schinifolium,used the analytic hierarchy process to determine the indicator,and determined the weight of the evaluation indicators.Besides,it calculated the comprehensive suitability index of land suitability of Z.schinifolium and evaluated the suitability of Z.schinifolium land in Jiaopingdu Town of Luquan County.The results showed that the suitable area for the cultivation of Z.schinifolium in Jiaopingdu Town reached 7270.78 ha,accounting for 88.69%of the study area;the area of unsuitable land was 922.07 ha,accounting for 11.31%of the study area.Among the suitable land areas,the high suitability area reached562.99 ha,accounting for 7.79%;the moderate suitability area was 2206.76 ha,accounting for 28.61%;the low suitability area was4599.03 ha,accounting for 63.6%.Based on the results of suitability evaluation,it came up with pertinent recommendations for the development of Z.schinifolium industry in Jiaopingdu Town.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
The article considers geological and morphological features of a volcanic relief of a surface of a planet Mars. Effusive magmatism processes at early stages of planet crust forming come out in structure of solidified ...The article considers geological and morphological features of a volcanic relief of a surface of a planet Mars. Effusive magmatism processes at early stages of planet crust forming come out in structure of solidified relief forms of Mars. Volcanic relief of a planet represents relic ancient line oriented forms, areal and central lava flooding. Linear forms generate shield volcanoes, chains of volcanic mountains and radial-concentric faults. This article deals with geological and morphological characteristics of the volcanic terrain of Mars. Hypsometric altitude profiles of volcanoes have been built based on the MOLA （Mars orbiter laser altimeter） of the spacecraft MGS （Mars global surveyor）. The gradient of volcano flanks has been calculated. The relative age of the volcanic terrain was estimated by the classical method of counting of the density of impact craters. Names of the volcanic landforms of Mars are given in the article in accordance with the name nomenclature system approved by the International Astronomical Union. Research results make it possible to compare the scientific and technical information about the planet and analyze the materials of satellite imagery of Mars.展开更多
Designing regional pattern is challenging for ecosystem restoration both in theory and in practice. The present study proposed a new approach to design regional pattern for ecosystem restoration with a case in the ari...Designing regional pattern is challenging for ecosystem restoration both in theory and in practice. The present study proposed a new approach to design regional pattern for ecosystem restoration with a case in the arid valley of Upper Minjiang River, SW China. The procedures are: (1) Determine the regional pattern of main environmental factors based on the relationships between the important environmental factors and the main geographical factors generated from DEM data. (2) Overlay the maps of the main environmental factors. (3) Generate a lookup table according to the species selection rule we proposed to link the candidate restoration species to the main environmental factors.(4) Determine the regional pattern of ecosystem restoration by positioning the restoration species in the map of environmental factors according to the lookup table. The regional restoration pattern designed in this way would be applicable not only to restoring a region, but also to predicting the future landscape change.展开更多
文摘Under the background of the uplift of the Qinghai-Tibet Plateau, the settlements in the upper reaches of the Min River are significantly affected by the mountain environment, and their spatial distribution is typical and representative. In this study, the relationship between settlements and topography, rivers and transportation, and the spatial distribution patterns of settlements, such as the aggregation and orientation characteristics of settlements, have been studied. The main conclusions include: 1) The settlement density decreases with the increase of elevation, slope, and distance from rivers and roads;76.25% and 63.17% of the settlements are distributed in the range of elevation 1500 - 3000 m and slope 6° - 25°, the upper reaches of the Min River are mostly alpine valley terrain, the bottom of the river has a low altitude, the landscape is undulating. The warm and humid climate is suitable for farming, conducive to agricultural production, and an ideal living environment for mountain residents. 2) The nuclear density of the settlement is distributed in strips along the axis of the river, and the closer to the river, the greater the nuclear density value. 3) Mathematical statistical methods were applied for the first time to realize the quantitative expression of the coupling of settlement and river direction. The influence of topographic conditions in different watersheds on the coupling degree of settlement extension and river flow direction was revealed. The slope of the fitted straight line between the settlement and river direction was 0.897, and the two directions were consistent. Except for the mainstream of the Min River, the larger values of the standard deviation ellipse flattening of settlements in each basin appeared in the upper reaches of the bay, and the overall trend showed a gradual decrease from the upstream to the downstream, which was consistent with the topographic change characteristics of the basin.
文摘Based on the field investigation and the analysis of soil moisture curve, it is clearly shown that there is a positive relationship between vegetation coverage rate and soil moisture capacity and soil depth in dry hot valley of the Jinsha River, and also there is a desertification process with seasonality. It is suggested that the basic factor of desertification in the area is water deficiency (seasonal drought and low soil water capacity) and the direct dynamic of desertification is soil erosion. Some effective countermeasures are presented, of which water saving planting and irrigation techniques should be firstly applied in the studied area.
文摘According to the recent practice in Laopingzi Village,Jiaopingdu Town,Luquan Yi and Miao Autonomous County(Luquan County hereinafter)in dry and hot valley of Jinsha River,the development of Zanthoxylum schinifolium Sieb.et Zucc planting industry can help farmers gradually get rid of poverty and achieve a virtuous cycle of ecological environment.It is a sustainable poverty alleviation way.Based on the three aspects of soil properties,climatic conditions,and topographical conditions influencing the growth of Z.schinifolium,this paper selected eight evaluation factors to establish a suitability evaluation system for Z.schinifolium,used the analytic hierarchy process to determine the indicator,and determined the weight of the evaluation indicators.Besides,it calculated the comprehensive suitability index of land suitability of Z.schinifolium and evaluated the suitability of Z.schinifolium land in Jiaopingdu Town of Luquan County.The results showed that the suitable area for the cultivation of Z.schinifolium in Jiaopingdu Town reached 7270.78 ha,accounting for 88.69%of the study area;the area of unsuitable land was 922.07 ha,accounting for 11.31%of the study area.Among the suitable land areas,the high suitability area reached562.99 ha,accounting for 7.79%;the moderate suitability area was 2206.76 ha,accounting for 28.61%;the low suitability area was4599.03 ha,accounting for 63.6%.Based on the results of suitability evaluation,it came up with pertinent recommendations for the development of Z.schinifolium industry in Jiaopingdu Town.
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The article considers geological and morphological features of a volcanic relief of a surface of a planet Mars. Effusive magmatism processes at early stages of planet crust forming come out in structure of solidified relief forms of Mars. Volcanic relief of a planet represents relic ancient line oriented forms, areal and central lava flooding. Linear forms generate shield volcanoes, chains of volcanic mountains and radial-concentric faults. This article deals with geological and morphological characteristics of the volcanic terrain of Mars. Hypsometric altitude profiles of volcanoes have been built based on the MOLA （Mars orbiter laser altimeter） of the spacecraft MGS （Mars global surveyor）. The gradient of volcano flanks has been calculated. The relative age of the volcanic terrain was estimated by the classical method of counting of the density of impact craters. Names of the volcanic landforms of Mars are given in the article in accordance with the name nomenclature system approved by the International Astronomical Union. Research results make it possible to compare the scientific and technical information about the planet and analyze the materials of satellite imagery of Mars.
基金supported by the National Natural Science Foundation of China(Grant No.40504067)the State Key Fundamental Research Development Plan of China(973)(Grant Nos.2000046807 and 2003CCB00400).
文摘Designing regional pattern is challenging for ecosystem restoration both in theory and in practice. The present study proposed a new approach to design regional pattern for ecosystem restoration with a case in the arid valley of Upper Minjiang River, SW China. The procedures are: (1) Determine the regional pattern of main environmental factors based on the relationships between the important environmental factors and the main geographical factors generated from DEM data. (2) Overlay the maps of the main environmental factors. (3) Generate a lookup table according to the species selection rule we proposed to link the candidate restoration species to the main environmental factors.(4) Determine the regional pattern of ecosystem restoration by positioning the restoration species in the map of environmental factors according to the lookup table. The regional restoration pattern designed in this way would be applicable not only to restoring a region, but also to predicting the future landscape change.
