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1.
1IN T R O D U C T IO N Since the20th century, ecosystem and even biosphere has been facedwith threat sunder theimpactsofclimate and humankind together(E RICH and ULRIKE , 2002 ; G LADE ,2003 ;O LGERTS etal.,2005 ).Land isan im- portantpartof natureecosyst…  相似文献   

2.
A medium-sized delesseriaceous red alga has been collected from the subtidal area of the northern Huanghai Sea coast. The characteristics of the specimens precludes their being placed in any genus defined by the currently accepted criteria. Tsengiella gen. nov., with T. spinosa sp. nov., as the type and only known species, is created and allied with the Hypoglossum group of-the Delesserioideae (Delesseriaceae, Ceramiales, Rhodophyta).  相似文献   

3.
1INTRODUCTIONCommunity residents form an important part of tourismdestinations and play a crucial role in the protection anddevelopment oftourism resources. The Tourism Agenda21 advocates that the development of tourism industryshouldconsider the interestsofthe host residentsand en-sure long-term viability beneficial towards destinationcommunity (LIU, 2000). Yet in manyinstances tourismdevelopment proves detrimental to host communities(LANKFORD and HOWARD, 1994; LIU and VAR,1986)…  相似文献   

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5.
1INTRODUCTIONUrbanrelationshipaswellasurbansystemhas beenthemostimportantandlastingdirectioninthestudyofur-bangeographysinceCHRISTALLER(1933)putfor-wardthecentralplacetheory.Alongwiththepaceofglobalizationinthe1980s,somepioneer researchessen-sitivelyexpoundedaworldcitysystem,includingworldcity,internationalcity,nationalcity,regionalcityandlocalcity(FRIEDMAN,1986).Lotsofresearchesfo-cusedonthedevelopingmechanismofthebigcitiesandurbansystemnetwork(GU,2000;ZHOU,1997;CUI,1992;HUeta…  相似文献   

6.
It had been demonstrated that individual or protoplasts isolated from Porphyra thallus by enzyme could develop into normal leafy thalli in the same way as monosproes,and that isolated cells develop in different way in liquid and on semi-solid media,The authors observed the ultrastructure of isolated vegetative cells cultured on semi-solid media and compared them with those of monospores and isolated cells cultured in liquid media,The results showed that subcellular struce-tures were quite different among cells in different conditions.In their development,isolated cells on semi-solid media did not show the characteristic subcellular eature of monospore formation ,such as production of fibrous vesicles,Callus-like cells formed on semi-solid media underwent a distinctive modification in cellular organization.They developed characteristic cell inclusions and a special 2-layer cell covering,Golgi bodies,ER ,starch grains,mitochondria,Vaculoes were not commonly found in them.  相似文献   

7.
1INTRODUCTIONDesertification is one of the most serious land degrada-tion, which results in the deterioration of physical, che-mical, and biological characteristics of soils (UNEP, 1992). Soil organic carbon (SOC) was considered to be a key index in evaluation of soil quality, soil degradation and soil C sequestration(SCHLENGSINGER etal., 1990; FENG etal., 2002; WANG etal., 2003). Many researchers have reported the correlations among desertification restoration, soil C s…  相似文献   

8.
The present paper reports 9 species of pontoniine shrimps collected from Hainan IS-land ,South China Sea ,by the Joint Chinese-German Marine Biology Expeditions,in which Peri-climenaeus arabicus (Calman,1939) and Periclimenaeus hecate (Nobili,1904) are recorded for the first time from Hainan Island.  相似文献   

9.
The economic system of mining city is of typical vulnerability characteristics that can be manifested by its high economic sensitivity and lack of response capacity to the gradual depletion of regional mineral resources. Taking Fuxin City of Liaoning Province as a case, this paper established an economic vulnerability assessment method integrating BP neural network with vulnerability index, then carried out an economic vulnerability assessment of Fuxin during 1989–2006. The results indicate that: 1) Affected by the gradual depletion of regional mineral resources, the economic development of Fuxin had kept high economic sensitivity from 1995 to 2001, and the response capacity to cope with and adapt to the impacts of the perturbation of mineral resources was weak and relatively lag. The evolution of economic vulnerability can be divided into three stages: in 1989–1994, the economic vulnerability of Fuxin City decreased slowly; in 1995–2001, the beginning stage of economic transformation, the economic vulnerability of Fuxin City went up rapidly; in 2002–2006, the economic vulnerability of Fuxin City descended and showed a trend to be stable. 2) The influence of economic sensitivity on Fuxin’s economic vulnerability is more evident than that of response capacity. 3) The decreasing supply of mineral resources and the simple industrial structure are main factors leading to the economic sensitivity of Fuxin. 4) The improvement of economic response capacity of Fuxin has typical characteristics of input-driven growth, and external assistance is of great importance to the rapid improvement of economic response capacity of Fuxin. And 5) the change from the simple industrial structure to diversified one of Fuxin is still unaccomplished, and the contribution of non-coal-based industry to local economic development is relatively limited. Foundation item: Under the auspices of Key Program of National Natural Science Foundation of China (No. 40635030), Knowledge Innovation Programs of the Chinese Academy of Sciences (No. KZCX2-YW-342, No. KZCX2-YW-321)  相似文献   

10.
1INTRODUCTION Since the 1750s, promoted by Industry Revolution and the rapid development of science and technology, large-scale urbanization swept over the world. So far, it isestimatedthatmorethan60%oftheriversin the world have been experienced high levels of human modifica- tion (ALLAN, 1995). River systems have now become oneofthemostdeeplyhuman-affectedecosystemsinthe earth. To approach the impact ofhuman activitieson riv- ersystem as a multidiscipline topic has been a focus of res…  相似文献   

11.
Introduction Rocky desert is a distinguishing phenomenon in China’s subtropical karst region, and it is caused by serious soil erosion, large areas of bedrocks protruding above soil, or alternatively large amount of gravels piling up in the field, leading to reduction or complete loss of soil productivity. This is a form of surface soil deterioration similar to desert (WANG 2002, WANG et al. 2004). Now the rocky desert is being expanded at an astonishing speed, and now it accounts for 30 …  相似文献   

12.
Numerous Quaternary deposits are existed in the mountainous areas of Southwest China,especially in the transition zone between the QinghaiTibet Plateau and the Sichuan Basin, where strong tectonic movements and frequent climatic changes increase the potential landslides. The possible deformation and failure process of potential landslides and their impacts on the surrounding environment are important research topics. Field investigation and monitoring indicate that the Qingliu landslide in Xiame...  相似文献   

13.
Residential expansion is gaining more and more attention from government authorities and urban planners.However,most of the current urban models focus heavily on presenting economic,political and ecological objectives of urban development,while seldom taking the effects of human behavior into consideration.Multi-agent systems for land use/cover change(MAS/LUCC),which mainly concern the behavioral effects of stakeholders on the processes of land use/cover change,are promising to fill the gap.This article,based on the concepts of MAS/LUCC model,con-structs a multi-agent system for residential expansion model(MAS/RE)through the analysis of the behavior of gov-ernment authorities and households.The model takes complex human actions into account,namely urban master plan-ning,planning review and approval,policies of traffic,economy and environment,location and allocation choices of the households and their interrelationships.Taking Hongshan District of Wuhan City,Hubei Province as an illustration,the model is implemented on Arc/info platform to simulate residential expansion between 1996 and 2002.The study result shows that the model is suitable for understanding the process of residential expansion with the effects of human actions,and is especially effective for its capacity in presenting spatio-temporal and behavioral complexity.Therefore,the model can be a reference for policy-making for government authorities and urban planners.  相似文献   

14.
1INTRODUCTIONMajorcharacteristicsofurbanizationinclude:ur-banconstructioniscontinuouslyspreading,thedemandforurbanlanduseisrapidlyswelling,andalotofa-griculturallandisconvertingintonon-agriculturalland.Whenthesecharacteristicsarereflectedinurbansys-tem,thedevelopingspeedsofbigcitiesandsupercitiesarequickening(CHEN,1999).Basedonthecondi-tionofmarket,landresourcebearsthreetypesofvalueswhicharerespectivelysocialvalue,economicvalueandecologicalvalue.Theexternalexpressiv…  相似文献   

15.
The goal of land consolidation in China is still to develop agricultural production. The study of landscapeeffects of land consolidation projects (LCPs) faces many difficulties because of the lack of government's interest anddata. This paper, taking Tianmen City of Hubei Province in Central China as an example, presents a methodology foranalyzing landscape effects of LCPs by GIS and Fragstats3.3. It describes landscape effects with indexes of PatchDensity (PD), Largest Patch Index (LPI), Landscape Shape Index (LSI), Interspersion and Juxtaposition Index (IJI),Aggregation Index (AI), and Shannon's Diversity Index (SHDI), showing more regular shape, simpler structure andless habitat diversity after LCPs. It computes ten landscape indexes of four categories of patches including CultivatedLand, Road, Water Channel, and River and Pond. The indexes show that 1) cultivated land becomes more fragmentalin patch area, less irregular in patch shape and more concentrated in block; 2) the transport capacity of roads and irri-gation and drainage capacity of water channels have been improved; 3) the landscape change of river and pond can besummarized as decreasing scale, more regular shape, reducing connectivity and diversity of the class. LCPs can facili-tate agricultural production as well as protect cultivated land and food security. However, it is doubted that the increaseof cultivated land from LCPs results from the reducing in landscape diversity of water area.  相似文献   

16.
The goal of land consolidation in China is still to develop agricultural production. The study of landscape effects of land consolidation projects (LCPs) faces many difficulties because of the lack of government's interest and data. This paper, taking Tianmen City of Hubei Province in Central China as an example, presents a methodology for analyzing landscape effects of LCPs by GIS and Fragstats3.3. It describes landscape effects with indexes of Patch Density (PD), Largest Patch Index (LPI), Landscape Shape Index (LSI), Interspersion and Juxtaposition Index (IJI), Aggregation Index (AI), and Shannon's Diversity Index (SHDI), showing more regular shape, simpler structure and less habitat diversity after LCPs. It computes ten landscape indexes of four categories of patches including Cultivated Land, Road, Water Channel, and River and Pond. The indexes show that 1) cultivated land becomes more fragmental in patch area, less irregular in patch shape and more concentrated in block; 2) the transport capacity of roads and irrigation and drainage capacity of water channels have been improved; 3) the landscape change of river and pond can be summarized as decreasing scale, more regular shape, reducing connectivity and diversity of the class. LCPs can facilitate agricultural production as well as protect cultivated land and food security. However, it is doubted that the increase of cultivated land from LCPs results from the reducing in landscape diversity of water area.  相似文献   

17.
Extreme and prolonged rainfall in the Tunka Ridge caused several debris flows in the vicinity of the Arshan village(Siberia, Russia) on June 28, 2014. These debris flows, in spite of similar geological conditions, had different velocity, peak discharge and alluvial fan volume values. The flow velocity was from 3.5 m/s to 19.6 m/s, the peak discharge ranged from 63 m3/s to 13566 m3/s, and the alluvial fan volume varied from 4.13×103 to 8.45×105 m3. Such a great range of values is due to the morphometric parameters of the debris flow basins. The article deals with the influence of morphometric parameters of debris flow basins, such as the basin area, the average slope, Melton ratio, relief ratio on the debris flow velocity, peak discharge and volume of alluvial fans. In this debris flow event the average values of slope angle and total basin relief of the debris flow basins did not affect the values of debris flow velocity, peak discharge and alluvial fan volume. The highest correlations were observed with the debris flow basin area that was connected with the water inflow volume into the debris flow basins during the rainfall. The unequal water distribution among debris flow basins also had an impact on the debris flow velocity, peak discharge and volume of alluvial fans.  相似文献   

18.
Agrarian system is well adapted in Himalayan eco-system. Hence, the people have adopted the traditional subsistence cereal farming and it becomes the main stay of Himalayan people. About 80 percent of the workable force is attached with agriculture and its allied practices, according to the census of 1991. Although, horticultural farming runs parallel with agriculture, its proportion in terms of land is quite less, resulted in a negligible place in the economy of the region. Human resources, mainly men are attached with national security after recruitment in Army. While, women play a vital and integrated role in maintaining the workable potential in the field of agriculture and are known as backbone of economy. An animal resource implies foremost and wider part in agricultural system and economy as well Water resources are unutilized yet, while almost all the major rivers of our country are originated from and flowing through this region. Increasing population causes forest resources depletion. The economy of the region is rested either on ‘traditional cereal farming‘ or ‘money order based‘ development, which could not take place due to its remoteness from the main streams of the country. The impactof modern technology with innovation in agricultural system remains impracticable due to unwillingness of people in one hand and on the other hand, adversege ographical conditions like topography, climate etc. which could not permit the uses of modern innovation in the field of agriculture. As for infra-structurally, this region is lacked behind, due to its inaccessibility. While, this region is bestowed with numerous rivers, many places for tourists and pilgrims, and huge forest resources. They might be used evenly in thedevelopment processes. The practice of tourism will help for the further development, particularly, in the wake of the newly born state, Uttaranchal. The present paper aims to evaluate the present potentiality of resources and their balanced utilization in the Pindar Basin. A precise study has been done on resource utilization, ecology and environment with keeping view in mind that more or less exploitation of resources could not influence the environment and the economy of the region.  相似文献   

19.
Since World War Ⅱ, many oil and gas fields have been found in ancient organic reef carbonate sediments all over the world. As reservoirs, the reef deposits have excellent conditions for the formation and preservation of oil and gas. To provide guidelines for the prospecting of oil and gas resources in ancient organic reefs, sedimentologists have made comprehensive studies on the  相似文献   

20.
The impact of land-use on distributed groundwater recharge and discharge in the western Jilin (WJ) was analyzed in this study. WJ is a transitional, semi-arid zone with a fragile, hydrological closed ecosystem in the Songhua River Basin (SRB). The research tool includes a seamlessly linked MODFLOW, WetSpass, the Seepage packages, and ArcGIS. The model calibration showed good agreement between simulated water table elevation and measured water table depths, while predicted groundwater discharge zones showed strong correlations with field occurrences of drainage systems and wetlands. Simulated averages for distributed recharge, water table elevation and groundwater drawdown were 377.42mm/yr, 194.43m, and 0.18m respectively. Forest vegetation showed the highest recharge, followed by agricultural farmlands, while open-water and other drainage systems constituted groundwater exit zones. When present land-use conditions were compared with the hypothetical natural pre-development scenario, an overall loss of groundwater recharge (24.09mm/yr) was observed, which for the project area is 18.05 × 108m3. Groundwater abstraction seemed to be the cause of water table drawdown, especially in the immediate vicinities of the supply wells. An important issue of the findings was the ability of the hypothetical forest vegetation to protect, and hence sustain aquifer reserves and dependent ecosystems. The profound data capture capability of ArcGIS makes it particularly useful in spatio-temporal hydroecological modeling. Biography: Moiwo Juana PAUL (1967–), male, a native of Sierra Leone of West Africa, Ph.D. candidate, specialized in wetland ecology.  相似文献   

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