[Objective] This paper aims to confirm that Yunnan is one origin center of rice and human in the world.[Method] The complicated and unique ecological environment in Yunnan makes Yunnan Province the largest center of g...[Objective] This paper aims to confirm that Yunnan is one origin center of rice and human in the world.[Method] The complicated and unique ecological environment in Yunnan makes Yunnan Province the largest center of genetic diversity and cultural diversity of rice and human being as well as the cradle of human childhood.[Result] The genetic diversity and cultural diversity of rice and human being is closely related to the ecosystem diversity.Rice civilization in Yunnan can be divided into four types,including the diversity center region of rice civilization in southwestern Yunnan,diffusion region of rice civilization of Hani-Zhuang in southern Yunnan,rice civilization region of water-drought rotation in central Yunnan and poverty region of rice civilization in northern Yunnan.Southwestern Yunnan is not only the center of genetic ecological diversity and rice cultural diversity,but also the center of origin and diversity of crop genetic diversity.It is not only a transitional region among East Asia continent,South Asian sub-continent and Indo-China Peninsula,but also a core integration area of Chinese culture,Indian culture and Mid-south Peninsula culture which all merge with the local culture.[Conclusion] Yunnan is one common sphere where the origin of human evolution is closely related to the origin of rice evolution.展开更多
To create a graceful living environment is the core responsibility of landscape designers in the designing process of residential environment. Residential environment design should pay attention to correctly involving...To create a graceful living environment is the core responsibility of landscape designers in the designing process of residential environment. Residential environment design should pay attention to correctly involving cultural feature and environmental and ecological elements which should be integrated in certain living environment through a good design method, so as to reflect landscape designers’ concern on the urban living space. Taking the buildings of Urban Paradise (Paradise in Chinese literature is also called Taohua Yuan, that is, Land of Peach Blossom, originated from the essay by TAO Yuan-ming in the Eastern Jin Dynasty) in Nanning City for example, the research investigated how to integrate ecology and culture in the environment creation of residential district.展开更多
The scientific research theory of Chinese contemporary art residential environment were carried out from the aspects of the people-centered and ecological environment. This study absorbed the essence of Chinese local ...The scientific research theory of Chinese contemporary art residential environment were carried out from the aspects of the people-centered and ecological environment. This study absorbed the essence of Chinese local ecological of the residential environment, for the use of contemprorary design. Through the practice of residential planning in Subu Town of Anhui Province, based on the protection of rural environment, the research completed according to local conditions and strategies for sustainable development.展开更多
Wetlands in the Jianghan Plain are important components of wetland types in lake area in the middle and lower reaches the Changjiang (Yangtze) River and they fulfill many uses and functions related to hydrology, waste...Wetlands in the Jianghan Plain are important components of wetland types in lake area in the middle and lower reaches the Changjiang (Yangtze) River and they fulfill many uses and functions related to hydrology, waste assimilation, ecosystem productivity and biodiversity. Owing to natural factors and human activities, especially excessive reclamation from lakes, the shrinking process of the lakes has been accelerated. Wetland ecosystem has shown the characteristics of vulnerability. According to the analysis of wetland ecological function in the Jianghan Plain, this paper presented an index system related to productivity, stability and environmental capacity. By using the method of Analytic Hierarchy Process, we computed the values of the relative weights of the indexes, and evaluated the vulnerability level of the wetland ecosystem by the method of multi-indexes. The case study showed that the fragile extent of wetland ecosystem in the Jianghan Plain is 5.6. This means that the wetland ecosystem in the Jianghan Plain is laid to the state of middle vulnerability. Therefore, the wetland conservation and eco-rehabilitation in the Jianghan Plain should be paid attention to.展开更多
The trans-boundary scope of the Tume n River Basin(TRB)going through China,Russia and DPRK has been defined,and on the basis of this,status of urbanization and its impacts on water environment in recent 20years in TRB...The trans-boundary scope of the Tume n River Basin(TRB)going through China,Russia and DPRK has been defined,and on the basis of this,status of urbanization and its impacts on water environment in recent 20years in TRB have been analyzed.Urbanizatio n in TRB can be characterized as:1)There is medium level of overall urbanization in TRB.Certain distance still exists compared with developed countries.And it is lower than the average urbanization level of Russia and higher than that o f China.2)There is unbalanced distribution of urbanization development in TRB.Urbanization in China part owns the c haracter of low starting point and hi gh-speed development.In Russia part,charac-ter of urbanization can be described as high starting point and stable development.In DPRK part,urbanizatio n level is low,and motive power lacks.3)Due to large population,in China part there is broader region urbanized,larger radius and higher frequency of human activities,which lead to heavier pressure on environment.Meanwhile,the paper has point-ed that impacts of urbanization on wa ter environment are as follows:1)Urban population growth and industr y develop-ment increase the demand for freshwa ter,and also exacerbate the contrad iction between limited water supply and increas-ing freshwater demand.2)Urban infrastructure doesn’t match with urban productive function especially treatment facili-ties,which results in the pollution of the Tumen River.3)The pollution situation in the Tumen River got peak point in1995,and presently,such situation has been improved in great scale,due to effective interventions adopted.However,there still exist 2enterprises that are urgent to be harnessed.Moreover,pollution of municipal sewage will become more and more apparent.4)The influence of urbanization on soil is mainly caused by industrial effl uent and slag,and pollut-ed water irrigation.Soil and water l oss has also been a serious problem caused by urbanization.5)Urbanization results in the decrease of wetlands area.Fur thermore,the paper has given a brief account of the perspective and recom menda-tions on urbanization and environme ntal impacts.展开更多
The imbalance between supply and demand of Artemia cysts in China and around the world is increasing now.Salt lakes in Tibet may contribute to the solution of the problem.In Northern Tibet there are 26 saline lakes wh...The imbalance between supply and demand of Artemia cysts in China and around the world is increasing now.Salt lakes in Tibet may contribute to the solution of the problem.In Northern Tibet there are 26 saline lakes whose salinity and temperature may support Artemia survival at an altitude of 4 000–5 100 m.We found Artemia in 15 of these lakes.The saline lakes with Artemia populations mainly belong to the shallow basin lakes,and the majority of these lakes are small in area.The total area of lakes without Artemia is more than 1 000 km 2.Lake Dangxiong Co(Co means lake in Tibet) was chosen for the intentional introduction of Artemia sinica.In 2004,850 g of A.sinica cysts,originating from Qinghai,were introduced in the lake.Surveys in 2006–2014 showed that the average abundance of Artemia adults in the lake gradually increased from 20 ind./m 3 in 2006 to 1950 ind./m 3 in 2013.We assume that two subpopulations of A.sinica,separated by depth,may exist in the lake.The new Artemia population caused an increase in the number of species of phytoplankton and heterotrophic protozoa with a decrease of their total abundance.Water transparency also increased.Dominance in phytoplankton passed from cyanobacteria to diatoms.Changes occurred not only in the lake ecosystem;the number of water birds using the lakes also dramatically increased.Preliminary calculations showed that is it possible to harvest at least about 150 t cysts per year from the lake as well as 3.2 thousand tons of frozen or 350 t of dried biomass of adult Artemia.展开更多
Karst rocky desertification is one of the major ecological and environmental problems that threaten the sustainable development of southwestern China. It is caused by irrational and intensive land-use patterns in kars...Karst rocky desertification is one of the major ecological and environmental problems that threaten the sustainable development of southwestern China. It is caused by irrational and intensive land-use patterns in karst geo-ecological environment. Therefore, it is vital to identify how human forces work on this degraded environment. Based on the soil erosion information in 2000 and remote sensing images of Guanling County collected in 2000 and 2007, four grades of karst rocky desertification data in 14 villages of Guanling County were extracted. Impacts of population, affluence, and other human forces on karst rocky desertification were analyzed using STIRPAT model. The results show that:1) Factors of population and affluence had strong influence on karst rocky desertification. In the STIRPAT model analysis, the population and affluence coefficients were positive, indicating that the increase in population and affluence would lead to more serious desertification. 2) Factors of farmer correlated with karst rocky desertification negatively, especially the way of viewing the relationship between people and nature, and the level of knowledge about rocky desertification. Government behavior was not a significant factor in this analysis. 3) The findings provide evidence that STIRPAT model can be used to analyze the relationship between human driving forces and rocky desertification.展开更多
Based on the theory of geo-economy,under the new situation of global economy,information network and China’s entry into WTO,also with the holding of APEC (in 2001) and the International Exposition in the near future,...Based on the theory of geo-economy,under the new situation of global economy,information network and China’s entry into WTO,also with the holding of APEC (in 2001) and the International Exposition in the near future,the Changjiang (Yangtze) River Delta is striding toward the spectacular international multi-polar situation and becomes one of core regions with high-speed development. Facing the ocean and world all along,leading the progressive tides of the age and scintillating the splendor of the nation,she does advance with time. Through a long period of irrigation projects construction and intensive operation of lands in previous agricultural society,the artificial wetland ecosystem with a positive cycle had ever been formed in this region. At present,environmental pollution and urban expansion resulted from post-industrialization are being rectified. The delta will be the paradigm of industrial and agricultural modernization along the sustainable development road. With the rapid development of urbanization,she has been one of the regions with the highest density population and high urbanization level. Taking the Changjiang River estuary and the Hangzhou Bay as two parts,she is continuously strengthening and adjusting her interior structure,expanding mothball space and constructing the oriental modern "logistics center" to link the whole world. The butterfly-style urban system of the Changjiang River Delta is flying,probably engendering earthshaking "butterfly effect".展开更多
Over the last 2000 years, approximately 38 ancient cities were abandoned through desertification in Hexi Corridor, Northwest China. Among them, 21.05% were abandoned during the Northern and Southern Dynasties, 21.05% ...Over the last 2000 years, approximately 38 ancient cities were abandoned through desertification in Hexi Corridor, Northwest China. Among them, 21.05% were abandoned during the Northern and Southern Dynasties, 21.05% during the end of the Tang Dynasty and the Five Dynasties, and 57.9% during the Ming and Qing dynasties. At the same time, main lakes were shrinking rapidly from the 5th Century to the 6th Century and the end of the Qing Dynasty. The climate in these periods was relatively arid and cold with frequent dusts. The phase of these changes indicated that there were three periods of desertification enlargement in the northern China. They were Northern and Southern Dynasties, the end of Tang Dynasty and Five Dynasties, the Ming and Qing dynasties. The macro-process of desertification in the study area was controlled mainly by the climatic changes. But from the facts that the population density in the middle of Qing Dynasty had exceeded the critical index of population pressure in arid area and the usage rate of water resources had exceeded 40% in Hexi Corridor, this paper also suggests that human activities have played an important role in desertification processes of the study area mainly during the recent 300 years.展开更多
In order to solve the problem of path planning of mobile robots in a dynamic environment,an improved rapidly-exploring random tree^(*)(RRT^(*))algorithm is proposed in this paper.First,the target bias sampling is intr...In order to solve the problem of path planning of mobile robots in a dynamic environment,an improved rapidly-exploring random tree^(*)(RRT^(*))algorithm is proposed in this paper.First,the target bias sampling is introduced to reduce the randomness of the RRT^(*)algorithm,and then the initial path planning is carried out in a static environment.Secondly,apply the path in a dynamic environment,and use the initially planned path as the path cache.When a new obstacle appears in the path,the invalid path is clipped and the path is replanned.At this time,there is a certain probability to select the point in the path cache as the new node,so that the new path maintains the trend of the original path to a greater extent.Finally,MATLAB is used to carry out simulation experiments for the initial planning and replanning algorithms,respectively.More specifically,compared with the original RRT^(*)algorithm,the simulation results show that the number of nodes used by the new improved algorithm is reduced by 43.19%on average.展开更多
Dry valleys are a striking geographic landscape in Hengduan Mountains Region and are characterized by low rainfall, desert type of vegetation and fragile environment. Past efforts and resources have been concentrated ...Dry valleys are a striking geographic landscape in Hengduan Mountains Region and are characterized by low rainfall, desert type of vegetation and fragile environment. Past efforts and resources have been concentrated mainly on rehabilitation of degraded ecosystem and fragile environment, particularly reforestation, while socio-economic development has been largely overlooked. Despite successes in pocket areas, the overall trend of unsustainability and environmental deterioration are continuing. It is important to understand that uplift of the Tibetan Plateau is the root cause of development of dry valleys, and development and formation of dry valleys is a natural process. Human intervention has played a secondary role in development of dry valleys and degradation of dry valleys though human intervention in many cases has speeded up environmental degradation of the dry valleys. It is important to understand that dry valleys are climatic enclaves and an integrated approach that combines rehabilitation of degraded ecosystems and socio-economic development should be adopted if the overall goal of sustainable development of dry valleys is to be achieved. Promotion of niche-based cash crops, rural energy including hydropower, solar energy, biogas and fuelwood plantation is recommended as the priority activities.展开更多
Soil erosion becomes a serious environmental problem in the world, especially in western China. An effective management practice called the Grain for Green Program(GGP), which was launched in 1999, aims to reduce soil...Soil erosion becomes a serious environmental problem in the world, especially in western China. An effective management practice called the Grain for Green Program(GGP), which was launched in 1999, aims to reduce soil and water loss and alleviate the ecological environment problem in western China. Two typical counties in western China, the Zhongxian(in Chongqing Municipality) and Ansai(in Shaanxi Province) were chosen to evaluate the dynamic changes of land use and agricultural production structure before and after the implementation of the Program in this paper. The results showed that the cultivated land area was reduced by 7.08% from 1989 to 2003. The cultivated land per person was decreased by 8.42% during 1999-2003. Moreover, the stability index of the secondary sector of the economy was increased from 0.91 in the period 1990-1999 to 0.94 in the following ten years. In addition, the stability index of tertiary economic sector increased from 0.88 to 0.92 in Zhongxian county. Meanwhile, the cultivated land area was reduced by 15.48% from 1990 to 1999. The soil erosion modulus was decreased by 33.33% from 1999 to 2006. Also, the stability index of secondary and tertiary economic sectors was 0.86 in the period 1998-2002. However, it decreased by 77% during 2002 to 2007 in Ansai County. These results imply that the Grain for Green Program had different impact on the two regions. Several effective strategies of soil and water conservation have been carried out to ameliorate the sustainable development of ecological environment and economy in these two counties of western China.展开更多
The ecotourism is a combination of popularizing ecological, scientific knowledge and increasing the nation's awareness of protection of nature. Therefore, it is a better form for national forest parks and nature r...The ecotourism is a combination of popularizing ecological, scientific knowledge and increasing the nation's awareness of protection of nature. Therefore, it is a better form for national forest parks and nature reserves to fully publicize the necessity of environmental protection. The combination of ecology with tourism is the current world-developing tendency.展开更多
To build the artificial forest ecosystem is the major eco-economic development model in the watershed of Miyun Reservoir. It is very important to evaluate the benefits of those ecosystems. Emergy theories are very hel...To build the artificial forest ecosystem is the major eco-economic development model in the watershed of Miyun Reservoir. It is very important to evaluate the benefits of those ecosystems. Emergy theories are very helpful for us to establish a science-based assessment framework. Emergy evaluation of the artificial forest ecosystems in the watershed of Miyun Reservoir is used to asses the relative values of several ecological functions (sometimes called ecosystem services) and main ecosystem storages (sometimes called natural capital). The main driving energies, internal processes and storages are evaluated. The main functions, including transpiration, GPP and infiltration, are evaluated, which are 609em$/ha/yr, 6,245em$/ha/yr and 340em$/ha/yr respectively. The total values of major environmental services are 4,683em$/ha/yr in the artificial forest ecosystem. The main storages of natural capital including live biomass, soil moisture, organic matter, underground water and landform are estimated, which are 112,028em$/ha, 9em$/ha, 40,718em$/ha, 34em$/ha and 6,400,514em$/ha respectively. The largest value is landform, which accounts for 97.7% of these calculated total emdollar values. The concept of replacement value is explored using the emergy values of both ecosystem services and natural capital. The total calculated replacement values are 302,160em$/ha.展开更多
Zoonotic transmissions of emerging pathogens from wildlife to human have shaped the history of mankind. These events have also highlighted our poor understanding of microorganisms circulated in wild animals. Coronavir...Zoonotic transmissions of emerging pathogens from wildlife to human have shaped the history of mankind. These events have also highlighted our poor understanding of microorganisms circulated in wild animals. Coronaviruses and astroviruses,which can be found from a wide range of mammals,were recently detected in bats. Strikingly,these bat viruses are genetically highly diverse and these interesting findings might help to better understand the evolution and ecology of these viruses. The discoveries of these novel bats viruses not only suggested that bats are important hosts for these virus families,but also reiterated the role of bats as a reservoir of viruses that might pose a zoonotic threat to human health.展开更多
Seeking water and earning their livelihoods is the natural selection of human beings.Like other rivers on the earth,the Yangtze River is the birthplace of human civilization and survival.As an ecosystem,the Yangtze Ri...Seeking water and earning their livelihoods is the natural selection of human beings.Like other rivers on the earth,the Yangtze River is the birthplace of human civilization and survival.As an ecosystem,the Yangtze River Basin is evolving under the influences of natural factors and human activities.Because of soil erosion,pollution and human activities,the imbalance of secondary environment is exacerbated and the ecological environment has become more vulnerable,so it is urgent to mitigate and prevent the ecological crisis.The practice has proved that implementation of engineering measures is an effective way to improve the ecological environment.The Three Gorges Project (TGP) has a flood control storage capacity of 22.15 billion m 3,effectively storing the flood water upstream of Yichang,and protects 15 million people and 1.5 million hm 2 farmland.Furthermore,the project can prevent or slow down the sedimentation and shrinkage of the lakes in the middle Yangtze River such as Dongting Lake;with an average annual power generation of about 90 billion kW· h,it can significantly reduce the emissions of harmful gas like CO 2.In general,the construction of TGP is conducive to the ecological and environmental protection in the Yangtze River Basin and China,even the world.展开更多
Path planning and formation structure forming are two of the most important problems for autonomous underwater vehicles(AUVs) to collaborate with each other.In this work,a dynamic formation model was proposed,in which...Path planning and formation structure forming are two of the most important problems for autonomous underwater vehicles(AUVs) to collaborate with each other.In this work,a dynamic formation model was proposed,in which several algorithms were developed for the complex underwater environment.Dimension changeable particle swarm algorithm was used to find an optimized path by dynamically adjusting the number and the distribution of the path nodes.Position relationship based obstacle avoidance algorithm was designed to detour along the edges of obstacles.Virtual potential point based formation-keeping algorithm was employed by incorporating dynamic strategies which were decided by the current states of the formation.The virtual potential point was used to keep the formation structure when the AUV or the formation was deviated.Simulation results show that an optimal path can be dynamically planned with fewer path nodes and smaller fitness,even with a concave obstacle.It has been also proven that different formation-keeping strategies can be adaptively selected and the formation can change its structure in a narrow area and restore back after passing the obstacle.展开更多
基金Supported by National Natural Science Foundation of China(31060186)Exploitue of Emphases New Production from Yunnan Provincial Scientific and Technology Department(2010BB001)Project for Innovative Pilot Enterprises from Science and Technology Bureau of Kunming City(Kunkejizi10N060204)~~
文摘[Objective] This paper aims to confirm that Yunnan is one origin center of rice and human in the world.[Method] The complicated and unique ecological environment in Yunnan makes Yunnan Province the largest center of genetic diversity and cultural diversity of rice and human being as well as the cradle of human childhood.[Result] The genetic diversity and cultural diversity of rice and human being is closely related to the ecosystem diversity.Rice civilization in Yunnan can be divided into four types,including the diversity center region of rice civilization in southwestern Yunnan,diffusion region of rice civilization of Hani-Zhuang in southern Yunnan,rice civilization region of water-drought rotation in central Yunnan and poverty region of rice civilization in northern Yunnan.Southwestern Yunnan is not only the center of genetic ecological diversity and rice cultural diversity,but also the center of origin and diversity of crop genetic diversity.It is not only a transitional region among East Asia continent,South Asian sub-continent and Indo-China Peninsula,but also a core integration area of Chinese culture,Indian culture and Mid-south Peninsula culture which all merge with the local culture.[Conclusion] Yunnan is one common sphere where the origin of human evolution is closely related to the origin of rice evolution.
文摘To create a graceful living environment is the core responsibility of landscape designers in the designing process of residential environment. Residential environment design should pay attention to correctly involving cultural feature and environmental and ecological elements which should be integrated in certain living environment through a good design method, so as to reflect landscape designers’ concern on the urban living space. Taking the buildings of Urban Paradise (Paradise in Chinese literature is also called Taohua Yuan, that is, Land of Peach Blossom, originated from the essay by TAO Yuan-ming in the Eastern Jin Dynasty) in Nanning City for example, the research investigated how to integrate ecology and culture in the environment creation of residential district.
文摘The scientific research theory of Chinese contemporary art residential environment were carried out from the aspects of the people-centered and ecological environment. This study absorbed the essence of Chinese local ecological of the residential environment, for the use of contemprorary design. Through the practice of residential planning in Subu Town of Anhui Province, based on the protection of rural environment, the research completed according to local conditions and strategies for sustainable development.
文摘Wetlands in the Jianghan Plain are important components of wetland types in lake area in the middle and lower reaches the Changjiang (Yangtze) River and they fulfill many uses and functions related to hydrology, waste assimilation, ecosystem productivity and biodiversity. Owing to natural factors and human activities, especially excessive reclamation from lakes, the shrinking process of the lakes has been accelerated. Wetland ecosystem has shown the characteristics of vulnerability. According to the analysis of wetland ecological function in the Jianghan Plain, this paper presented an index system related to productivity, stability and environmental capacity. By using the method of Analytic Hierarchy Process, we computed the values of the relative weights of the indexes, and evaluated the vulnerability level of the wetland ecosystem by the method of multi-indexes. The case study showed that the fragile extent of wetland ecosystem in the Jianghan Plain is 5.6. This means that the wetland ecosystem in the Jianghan Plain is laid to the state of middle vulnerability. Therefore, the wetland conservation and eco-rehabilitation in the Jianghan Plain should be paid attention to.
文摘The trans-boundary scope of the Tume n River Basin(TRB)going through China,Russia and DPRK has been defined,and on the basis of this,status of urbanization and its impacts on water environment in recent 20years in TRB have been analyzed.Urbanizatio n in TRB can be characterized as:1)There is medium level of overall urbanization in TRB.Certain distance still exists compared with developed countries.And it is lower than the average urbanization level of Russia and higher than that o f China.2)There is unbalanced distribution of urbanization development in TRB.Urbanization in China part owns the c haracter of low starting point and hi gh-speed development.In Russia part,charac-ter of urbanization can be described as high starting point and stable development.In DPRK part,urbanizatio n level is low,and motive power lacks.3)Due to large population,in China part there is broader region urbanized,larger radius and higher frequency of human activities,which lead to heavier pressure on environment.Meanwhile,the paper has point-ed that impacts of urbanization on wa ter environment are as follows:1)Urban population growth and industr y develop-ment increase the demand for freshwa ter,and also exacerbate the contrad iction between limited water supply and increas-ing freshwater demand.2)Urban infrastructure doesn’t match with urban productive function especially treatment facili-ties,which results in the pollution of the Tumen River.3)The pollution situation in the Tumen River got peak point in1995,and presently,such situation has been improved in great scale,due to effective interventions adopted.However,there still exist 2enterprises that are urgent to be harnessed.Moreover,pollution of municipal sewage will become more and more apparent.4)The influence of urbanization on soil is mainly caused by industrial effl uent and slag,and pollut-ed water irrigation.Soil and water l oss has also been a serious problem caused by urbanization.5)Urbanization results in the decrease of wetlands area.Fur thermore,the paper has given a brief account of the perspective and recom menda-tions on urbanization and environme ntal impacts.
基金Supported by the Special Fund for Public Welfare Land and Resources(No.201011001-4)the Project of China Geological Survey(No.1212011120982)
文摘The imbalance between supply and demand of Artemia cysts in China and around the world is increasing now.Salt lakes in Tibet may contribute to the solution of the problem.In Northern Tibet there are 26 saline lakes whose salinity and temperature may support Artemia survival at an altitude of 4 000–5 100 m.We found Artemia in 15 of these lakes.The saline lakes with Artemia populations mainly belong to the shallow basin lakes,and the majority of these lakes are small in area.The total area of lakes without Artemia is more than 1 000 km 2.Lake Dangxiong Co(Co means lake in Tibet) was chosen for the intentional introduction of Artemia sinica.In 2004,850 g of A.sinica cysts,originating from Qinghai,were introduced in the lake.Surveys in 2006–2014 showed that the average abundance of Artemia adults in the lake gradually increased from 20 ind./m 3 in 2006 to 1950 ind./m 3 in 2013.We assume that two subpopulations of A.sinica,separated by depth,may exist in the lake.The new Artemia population caused an increase in the number of species of phytoplankton and heterotrophic protozoa with a decrease of their total abundance.Water transparency also increased.Dominance in phytoplankton passed from cyanobacteria to diatoms.Changes occurred not only in the lake ecosystem;the number of water birds using the lakes also dramatically increased.Preliminary calculations showed that is it possible to harvest at least about 150 t cysts per year from the lake as well as 3.2 thousand tons of frozen or 350 t of dried biomass of adult Artemia.
基金Under the auspices of National Natural Science Foundation of China(No.40801039,40801066,41001183)
文摘Karst rocky desertification is one of the major ecological and environmental problems that threaten the sustainable development of southwestern China. It is caused by irrational and intensive land-use patterns in karst geo-ecological environment. Therefore, it is vital to identify how human forces work on this degraded environment. Based on the soil erosion information in 2000 and remote sensing images of Guanling County collected in 2000 and 2007, four grades of karst rocky desertification data in 14 villages of Guanling County were extracted. Impacts of population, affluence, and other human forces on karst rocky desertification were analyzed using STIRPAT model. The results show that:1) Factors of population and affluence had strong influence on karst rocky desertification. In the STIRPAT model analysis, the population and affluence coefficients were positive, indicating that the increase in population and affluence would lead to more serious desertification. 2) Factors of farmer correlated with karst rocky desertification negatively, especially the way of viewing the relationship between people and nature, and the level of knowledge about rocky desertification. Government behavior was not a significant factor in this analysis. 3) The findings provide evidence that STIRPAT model can be used to analyze the relationship between human driving forces and rocky desertification.
文摘Based on the theory of geo-economy,under the new situation of global economy,information network and China’s entry into WTO,also with the holding of APEC (in 2001) and the International Exposition in the near future,the Changjiang (Yangtze) River Delta is striding toward the spectacular international multi-polar situation and becomes one of core regions with high-speed development. Facing the ocean and world all along,leading the progressive tides of the age and scintillating the splendor of the nation,she does advance with time. Through a long period of irrigation projects construction and intensive operation of lands in previous agricultural society,the artificial wetland ecosystem with a positive cycle had ever been formed in this region. At present,environmental pollution and urban expansion resulted from post-industrialization are being rectified. The delta will be the paradigm of industrial and agricultural modernization along the sustainable development road. With the rapid development of urbanization,she has been one of the regions with the highest density population and high urbanization level. Taking the Changjiang River estuary and the Hangzhou Bay as two parts,she is continuously strengthening and adjusting her interior structure,expanding mothball space and constructing the oriental modern "logistics center" to link the whole world. The butterfly-style urban system of the Changjiang River Delta is flying,probably engendering earthshaking "butterfly effect".
文摘Over the last 2000 years, approximately 38 ancient cities were abandoned through desertification in Hexi Corridor, Northwest China. Among them, 21.05% were abandoned during the Northern and Southern Dynasties, 21.05% during the end of the Tang Dynasty and the Five Dynasties, and 57.9% during the Ming and Qing dynasties. At the same time, main lakes were shrinking rapidly from the 5th Century to the 6th Century and the end of the Qing Dynasty. The climate in these periods was relatively arid and cold with frequent dusts. The phase of these changes indicated that there were three periods of desertification enlargement in the northern China. They were Northern and Southern Dynasties, the end of Tang Dynasty and Five Dynasties, the Ming and Qing dynasties. The macro-process of desertification in the study area was controlled mainly by the climatic changes. But from the facts that the population density in the middle of Qing Dynasty had exceeded the critical index of population pressure in arid area and the usage rate of water resources had exceeded 40% in Hexi Corridor, this paper also suggests that human activities have played an important role in desertification processes of the study area mainly during the recent 300 years.
基金National Natural Science Foundation of China(No.61903291)。
文摘In order to solve the problem of path planning of mobile robots in a dynamic environment,an improved rapidly-exploring random tree^(*)(RRT^(*))algorithm is proposed in this paper.First,the target bias sampling is introduced to reduce the randomness of the RRT^(*)algorithm,and then the initial path planning is carried out in a static environment.Secondly,apply the path in a dynamic environment,and use the initially planned path as the path cache.When a new obstacle appears in the path,the invalid path is clipped and the path is replanned.At this time,there is a certain probability to select the point in the path cache as the new node,so that the new path maintains the trend of the original path to a greater extent.Finally,MATLAB is used to carry out simulation experiments for the initial planning and replanning algorithms,respectively.More specifically,compared with the original RRT^(*)algorithm,the simulation results show that the number of nodes used by the new improved algorithm is reduced by 43.19%on average.
基金supported jointly by the National Key Project for Basic Research on Tibetan Plateau(G1998040800)Promotion Plan of the Ministry of Education and President Foundation of the Chinese Academy of Sciences.
文摘Dry valleys are a striking geographic landscape in Hengduan Mountains Region and are characterized by low rainfall, desert type of vegetation and fragile environment. Past efforts and resources have been concentrated mainly on rehabilitation of degraded ecosystem and fragile environment, particularly reforestation, while socio-economic development has been largely overlooked. Despite successes in pocket areas, the overall trend of unsustainability and environmental deterioration are continuing. It is important to understand that uplift of the Tibetan Plateau is the root cause of development of dry valleys, and development and formation of dry valleys is a natural process. Human intervention has played a secondary role in development of dry valleys and degradation of dry valleys though human intervention in many cases has speeded up environmental degradation of the dry valleys. It is important to understand that dry valleys are climatic enclaves and an integrated approach that combines rehabilitation of degraded ecosystems and socio-economic development should be adopted if the overall goal of sustainable development of dry valleys is to be achieved. Promotion of niche-based cash crops, rural energy including hydropower, solar energy, biogas and fuelwood plantation is recommended as the priority activities.
基金the Foundation of National Key Science and Technology Program (2011BAD31B03)the National Natural Science Foundation of China (41001163)+1 种基金Western Light Western Doctor of CAS, the international cooperation program of Sichuan province (2013HH0016)CAS West Action: Experimental and Demonstrational study on soil and water losses and non-point pollution in the Three Gorges (KZCX2-XB3-09)
文摘Soil erosion becomes a serious environmental problem in the world, especially in western China. An effective management practice called the Grain for Green Program(GGP), which was launched in 1999, aims to reduce soil and water loss and alleviate the ecological environment problem in western China. Two typical counties in western China, the Zhongxian(in Chongqing Municipality) and Ansai(in Shaanxi Province) were chosen to evaluate the dynamic changes of land use and agricultural production structure before and after the implementation of the Program in this paper. The results showed that the cultivated land area was reduced by 7.08% from 1989 to 2003. The cultivated land per person was decreased by 8.42% during 1999-2003. Moreover, the stability index of the secondary sector of the economy was increased from 0.91 in the period 1990-1999 to 0.94 in the following ten years. In addition, the stability index of tertiary economic sector increased from 0.88 to 0.92 in Zhongxian county. Meanwhile, the cultivated land area was reduced by 15.48% from 1990 to 1999. The soil erosion modulus was decreased by 33.33% from 1999 to 2006. Also, the stability index of secondary and tertiary economic sectors was 0.86 in the period 1998-2002. However, it decreased by 77% during 2002 to 2007 in Ansai County. These results imply that the Grain for Green Program had different impact on the two regions. Several effective strategies of soil and water conservation have been carried out to ameliorate the sustainable development of ecological environment and economy in these two counties of western China.
文摘The ecotourism is a combination of popularizing ecological, scientific knowledge and increasing the nation's awareness of protection of nature. Therefore, it is a better form for national forest parks and nature reserves to fully publicize the necessity of environmental protection. The combination of ecology with tourism is the current world-developing tendency.
文摘To build the artificial forest ecosystem is the major eco-economic development model in the watershed of Miyun Reservoir. It is very important to evaluate the benefits of those ecosystems. Emergy theories are very helpful for us to establish a science-based assessment framework. Emergy evaluation of the artificial forest ecosystems in the watershed of Miyun Reservoir is used to asses the relative values of several ecological functions (sometimes called ecosystem services) and main ecosystem storages (sometimes called natural capital). The main driving energies, internal processes and storages are evaluated. The main functions, including transpiration, GPP and infiltration, are evaluated, which are 609em$/ha/yr, 6,245em$/ha/yr and 340em$/ha/yr respectively. The total values of major environmental services are 4,683em$/ha/yr in the artificial forest ecosystem. The main storages of natural capital including live biomass, soil moisture, organic matter, underground water and landform are estimated, which are 112,028em$/ha, 9em$/ha, 40,718em$/ha, 34em$/ha and 6,400,514em$/ha respectively. The largest value is landform, which accounts for 97.7% of these calculated total emdollar values. The concept of replacement value is explored using the emergy values of both ecosystem services and natural capital. The total calculated replacement values are 302,160em$/ha.
基金supported by the National Institute of Allergy and Infectious Diseases (NIAID contract HHSN266200700005C)European Research Project SARS-DTV (contract no: SP22-CT-2004)
文摘Zoonotic transmissions of emerging pathogens from wildlife to human have shaped the history of mankind. These events have also highlighted our poor understanding of microorganisms circulated in wild animals. Coronaviruses and astroviruses,which can be found from a wide range of mammals,were recently detected in bats. Strikingly,these bat viruses are genetically highly diverse and these interesting findings might help to better understand the evolution and ecology of these viruses. The discoveries of these novel bats viruses not only suggested that bats are important hosts for these virus families,but also reiterated the role of bats as a reservoir of viruses that might pose a zoonotic threat to human health.
文摘Seeking water and earning their livelihoods is the natural selection of human beings.Like other rivers on the earth,the Yangtze River is the birthplace of human civilization and survival.As an ecosystem,the Yangtze River Basin is evolving under the influences of natural factors and human activities.Because of soil erosion,pollution and human activities,the imbalance of secondary environment is exacerbated and the ecological environment has become more vulnerable,so it is urgent to mitigate and prevent the ecological crisis.The practice has proved that implementation of engineering measures is an effective way to improve the ecological environment.The Three Gorges Project (TGP) has a flood control storage capacity of 22.15 billion m 3,effectively storing the flood water upstream of Yichang,and protects 15 million people and 1.5 million hm 2 farmland.Furthermore,the project can prevent or slow down the sedimentation and shrinkage of the lakes in the middle Yangtze River such as Dongting Lake;with an average annual power generation of about 90 billion kW· h,it can significantly reduce the emissions of harmful gas like CO 2.In general,the construction of TGP is conducive to the ecological and environmental protection in the Yangtze River Basin and China,even the world.
基金Project(NS2013091)supported by the Basis Research Fund of Nanjing University of Aeronautics and Astronautics,China
文摘Path planning and formation structure forming are two of the most important problems for autonomous underwater vehicles(AUVs) to collaborate with each other.In this work,a dynamic formation model was proposed,in which several algorithms were developed for the complex underwater environment.Dimension changeable particle swarm algorithm was used to find an optimized path by dynamically adjusting the number and the distribution of the path nodes.Position relationship based obstacle avoidance algorithm was designed to detour along the edges of obstacles.Virtual potential point based formation-keeping algorithm was employed by incorporating dynamic strategies which were decided by the current states of the formation.The virtual potential point was used to keep the formation structure when the AUV or the formation was deviated.Simulation results show that an optimal path can be dynamically planned with fewer path nodes and smaller fitness,even with a concave obstacle.It has been also proven that different formation-keeping strategies can be adaptively selected and the formation can change its structure in a narrow area and restore back after passing the obstacle.