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1.
The vegetation coverage dynamics and its relationship with climate factors on different spatial and temporal scales in Inner Mongolia during 2001-2010 were analyzed based on MODIS-NDVI data and climate data.The results indicated that vegetation coverage in Inner Mongolia showed obvious longitudinal zonality,increasing from west to east across the region with a change rate of 0.2/10°N.During 2001-2010,the mean vegetation coverage was 0.57,0.4 and 0.16 in forest,grassland and desert biome,respectively,exhibiting evident spatial heterogeneities.Totally,vegetation coverage had a slight increasing trend during the study period.Across Inner Mongolia,the area of which the vegetation coverage showed extremely significant and significant increase accounted for 11.25% and 29.13% of the area of whole region,respectively,while the area of which the vegetation coverage showed extremely significant and significant decrease accounted for 7.65% and 26.61%,respectively.On inter-annual time scale,precipitation was the dominant driving force of vegetation coverage for the whole region.On inter-monthly scale,the change of vegetation coverage was consistent with both the change of temperature and precipitation,implying that the vegetation growth within a year is more sensitive to the combined effects of water and heat rather than either single climate factor.The vegetation coverage in forest biome was mainly driven by temperature on both inter-annual and inter-monthly scales,while that in desert biome was mainly influenced by precipitation on both the two temporal scales.In grassland biome,the yearly vegetation coverage had a better correlation with precipitation,while the monthly vegetation coverage was influenced by both temperature and precipitation.In grassland biome,the impacts of precipitation on monthly vegetation coverage showed time-delay effects.  相似文献   

2.
The first-stage of an ecological conservation and restoration project in the Three-River Source Region(TRSR), China, has been in progress for eight years. However, because the ecological effects of this project remain unknown, decision making for future project implementation is hindered. Thus, in this study, we developed an index system to evaluate the effects of the ecological restoration project, by integrating field observations, remote sensing, and process-based models. Effects were assessed using trend analyses of ecosystem structures and services. Results showed positive trends in the TRSR since the beginning of the project, but not yet a return to the optima of the 1970 s. Specifically, while continued degradation in grassland has been initially contained, results are still far from the desired objective, ‘grassland coverage increasing by an average of 20%–40%'. In contrast, wetlands and water bodies have generally been restored, while the water conservation and water supply capacity of watersheds have increased. Indeed, the volume of water conservation achieved in the project meets the objective of a 1.32 billion m~3 increase. The effects of ecological restoration inside project regions was more significant than outside, and, in addition to climate change projects, we concluded that the implementation of ecological conservation and restoration projects has substantially contributed to vegetation restoration. Nevertheless, the degradation of grasslands has not been fundamentally reversed, and to date the project has not prevented increasing soil erosion. In sum, the effects and challenges of this first-stage project highlight the necessity of continuous and long-term ecosystem conservation efforts in this region.  相似文献   

3.
Data show that carbon emissions are increasing due to human energy consumption associated with economic development. As a result, a great deal of attention has been focused on efforts to reduce this growth in carbon emissions as well as to formulate policies to address and mitigate climate change. Although the majority of previous studies have explored the driving forces underlying Chinese carbon emissions, few have been carried out at the city-level because of the limited availability of relevant energy consumption statistics. Here, we utilize spatial autocorrelation, Markov-chain transitional matrices, a dynamic panel model, and system generalized distance estimation(Sys-GMM) to empirically evaluate the key determinants of carbon emissions at the city-level based on Chinese remote sensing data collected between 1992 and 2013. We also use these data to discuss observed spatial spillover effects taking into account spatiotemporal lag and a range of different geographical and economic weighting matrices. The results of this study suggest that regional discrepancies in city-level carbon emissions have decreased over time, which are consistent with a marked spatial spillover effect, and a ‘club' agglomeration of high-emissions. The evolution of these patterns also shows obvious path dependence, while the results of panel data analysis reveal the presence of a significant U-shaped relationship between carbon emissions and per capita GDP. Data also show that per capita carbon emissions have increased in concert with economic growth in most cities, and that a high-proportion of secondary industry and extensive investment growth have also exerted significant positive effects on city-level carbon emissions across China. In contrast, rapid population agglomeration, improvements in technology, increasing trade openness, and the accessibility and density of roads have all played a role in inhibiting carbon emissions. Thus, in order to reduce emissions, the Chinese government should legislate to inhibit the effects of factors that promote the release of carbon while at the same time acting to encourage those that mitigate this process. On the basis of the analysis presented in this study, we argue that optimizing industrial structures, streamlining extensive investment, increasing the level of technology, and improving road accessibility are all effective approaches to increase energy savings and reduce carbon emissions across China.  相似文献   

4.
Evaluating the effectiveness of protecting nature assets is a vital component of responsive, pro-active management of protected areas. It is important to protect reserves of geological(including fossils) assets as a means to also protect national and natural heritage. At the end of 2013, 2669 protected areas had been established in China and 123 of them are reserves for nature assets. This paper builds an evaluation framework for protection effectiveness of these assets. The current elements and characteristics for effective protection are analyzed, along with an analysis of existing problems so as to construct a scientific approach to protect these assets. The influencing elements and characteristics for effective protection of nature asset reserves are included in an index evaluation system for effective protection in such areas, which contains four parts–target layer, evaluation criteria, evaluation indexes, and evaluation parameters–based on related documents and files. For the target layer, it includes nature asset evaluation and management evaluation. In the end, it is discussed how to build a comprehensive evaluation model and achieve an effective quantitative evaluation.  相似文献   

5.
Global and regional environmental changes such as land use and climate change have significantly integrated and interactive effects on forest. These integrated effects will undoubtedly alter the distribution, function and succession processes of forest ecosystems. In order to adapt to these changes, it is necessary to understand their individual and integrated effects. In this study, we proposed a framework by using coupling models to gain a better understanding of the complex ecological processes. We combined an agent-based model for land use and land cover change(ABM/LUCC), an ecosystem process model(PnET-Ⅱ), and a forest dynamic landscape model(LANDIS-Ⅱ) to simulate the change of forest aboveground biomass(AGB) which was driven by land use and climate change factors for the period of 2010–2050 in Taihe County of southern China, where subtropical coniferous plantations dominate. We conducted a series of land use and climate change scenarios to compare the differences in forest AGB. The results show that:(1) land use, including town expansion, deforestation and forest conversion and climate change are likely to influence forest AGB in the near future in Taihe County.(2) Though climate change will make a good contribution to an increase in forest AGB, land use change can result in a rapid decrease in the forest AGB and play a vital role in the integrated simulation. The forest AGB under the integrated scenario decreased by 53.7%(RCP2.6 + land use), 57.2%(RCP4.5 + land use), and 56.9%(RCP8.5 + land use) by 2050, which is in comparison to the results under separate RCPs without land use disturbance.(3) The framework can offer a coupled method to better understand the complex and interactive ecological processes, which may provide some supports for adapting to land use and climate change, improving and optimizing plantation structure and function,and developing measures for sustainable forest management.  相似文献   

6.
<正> Mercury(Hg)was investigated in bone tissues of skua(Catharacta mac-cormick)and penguin(Pygoscelis adeliae)collected in the maritime Antarctic usingatomic fluorescence spectrometry(AFS)and synchrotron radiation X-ray fluorescence(SR-XRF)method.The total levels of mercury in bone tissues of penguin and skuaare much lower than those in other organs(e.g.,kidney,liver).The toxic effects ofmercury in bone tissues of seabirds in polar region are not known.We have used SR-XRF method to map the distribution of trace levels of mercury in bones.The levels ofmercury are found to be enriched somewhere near the periosteal surface and/or endos-teal surface.The distribution of mercury shows strongly correlation with that of someessential elements and probably poses negative effect on the bone metabolism inferringfrom the relationship of mercury with the other elements.These studies represent afirst step toward understanding the toxic effects of mercury on bone of polar animals bysuggesting the possible microscopic investigation.  相似文献   

7.
Geological disasters not only cause economic losses and ecological destruction, but also seriously threaten human survival. Selecting an appropriate method to evaluate susceptibility to geological disasters is an important part of geological disaster research. The aims of this study are to explore the accuracy and reliability of multi-regression methods for geological disaster susceptibility evaluation, including Logistic Regression(LR), Spatial Autoregression(SAR), Geographical Weighted Regression(GWR), and Support Vector Regression(SVR), all of which have been widely discussed in the literature. In this study, we selected Yunnan Province of China as the research site and collected data on typical geological disaster events and the associated hazards that occurred within the study area to construct a corresponding index system for geological disaster assessment. Four methods were used to model and evaluate geological disaster susceptibility. The predictive capabilities of the methods were verified using the receiver operating characteristic(ROC) curve and the success rate curve. Lastly, spatial accuracy validation was introduced to improve the results of the evaluation, which was demonstrated by the spatial receiver operating characteristic(SROC) curve and the spatial success rate(SSR) curve. The results suggest that: 1) these methods are all valid with respect to the SROC and SSR curves, and the spatial accuracy validation method improved their modelling results and accuracy, such that the area under the curve(AUC) values of the ROC curves increased by about 3%–13% and the AUC of the success rate curve values increased by 15%–20%; 2) the evaluation accuracies of LR, SAR, GWR, and SVR were 0.8325, 0.8393, 0.8370 and 0.8539, which proved the four statistical regression methods all have good evaluation capability for geological disaster susceptibility evaluation and the evaluation results of SVR are more reasonable than others; 3) according to the evaluation results of SVR, the central-southern Yunnan Province are the highest sus-ceptibility areas and the lowest susceptibility is mainly located in the central and northern parts of the study area.  相似文献   

8.
Comparative study of LUCC between Fujian and Taiwan provinces could be a good case for study because of their geographical proximities and historical, cultural similarities. Fujian and Taiwan had gone through and currently are in different economic development stages. Taiwan is in the stage of post-industrialization and Fujian is in the intermediate stage of industrialization. By using the official statistics, changes of built-land in Fujian and Taiwan were analyzed in details. The results showed that these two provinces seemed to have the same characteristics of built-land changes, i.e., accelerating development, and concentrated distribution on both sides of the Taiwan Straits, forming a pattern with the economic layout of two sides acting in cooperation with eath other. If comparing different industrialized areas in Fujian with industrialized stages in Taiwan, it is clear that these two provinces seemed to have the same characteristics of synthesized index of built-land change (Lc), i.e., which is from stabilization or comparative stabilization at the initial stages of industrialization to high ex- pansion at the intermediate stages of industrialization, then followed by low consumption at later stages of industrialization, but the Lc of the initial and the later stages of industrialization in Taiwan were slightly higher than those in Fujian. The results from comparison on relevant indexes have shown: The industrial structure changing rate of Fujian is actually higher than that of built-land in Taiwan, but its using efficiency of regional built-land is also obviously lower than that in Taiwan in the intermediate and later stages of industrialization of Fujian. The major driving forces of the built-land changes in both provinces were analyzed in Causal Models of Path Analysis, and its result indicated that the difference in built-land changes of the two provinces is closely related to their economic development stages and industrial structure. Countermeasure for the realization of sustainable utilization of built-land in Fujian put forward in this article is to strengthen its intension and tap the latent power.  相似文献   

9.
Analyzing the information on benthic organisms and geochemistry, obtained from the Chinese First Expedition on Antarctic Ocean and its succeeded works and comparing with that of other oceans, this paper shows that in the circumstances of the researched area benthic organisms are rich. However, the prodsperity of the organisms is limited below 5-10 cm of the profiles in which the environment is mainly dominated by sulfate reducing reaction. On the condition of low temperature in Antarctic Ocean, the solubility of carbonates is higher than that of other latitudes of oceans, but the concentration of calcium in overlying water and pore water of the benthic environment is not higher than that in other oceans, which results in the difficulty for the crustaceas and mollusks to obtain sufficient calcium carbonate to form their solid shell as well as to bring about the lower ratios of these animals both in abundance and biomass in the researched ocean. Futhermore, there is a positive relationship between the dis  相似文献   

10.
中国城市绿色发展效率时空演变特征及影响因素   总被引:1,自引:3,他引:1  
To resolve conflicts between development and the preservation of the natural environment,enable economic transformation,and achieve the global sustainable development goals(SDGs),green development(GD)is gradually becoming a major strategy in the construction of an ecological civilization and the ideal of building a"beautiful China",alongside the transformation and reconstruction of the global economy.Based on a combination of the concept and implications of GD,we first used the Slacks Based Model with undesirable outputs(SBM-Undesirable),the Theil index,and the spatial Markov chain to measure the spatial patterns,regional differences,and spatio-temporal evolution of urban green development efficiency(UGDE)in China from 2005 to 2015.Second,by coupling natural and human factors,the mechanism influencing UGDE was quantitatively investigated under the framework of the human-environment interaction.The results showed that:(1)from 2005 to 2015,the UGDE increased from 0.475 to 0.523,i.e.,an overall increase of 10%.In terms of temporal variation,there was a staged increase,with its evolution having the characteristics of a"W-shaped"pattern.(2)The regional differences in UGDE followed a pattern of eastern>central>western.For different types of urban agglomeration,the UGDE had inverted pyramid cluster growth characteristics that followed a pattern of"national level>regional level>local level",forming a stable hierarchical scale structure of"super cities>mega cities>big cities>medium cities>small cities".(3)UGDE in China has developed with significant spatial agglomeration characteristics.High-efficiency type cities have positive spillover effects,while low-efficiency cities have negative effects.Different types of urban evolution processes have a path dependence,and a spatial club convergence phenomenon exists,in which areas with high UGDE are concentrated and drive low UGDE elsewhere.(4)Under the framework of regional human-environment interaction,the degree of human and social influence on UGDE is greater than that of the natural background.The economic strength,industrial structure,openness,and climate conditions of China have positively promoted UGDE.  相似文献   

11.
In this paper we analyze daily mean, minimum, and maximum temperature data collected at 119 meteorological stations over five regions of China during the period 1951-2010. The series of minimum, maximum, and mean temperatures from each climatic region have similar signatures, but there are differences among the five regions and the countrywide average. The results indicate that the periods of faster warming were not synchronous across the regions studied: warming in northeast China and Tibet began in 1986, while in central-east, southeast, and northwest China the warming emerged in 1995. Furthermore, central-east and northwest China, and Tibet, have warmed continuously since 2000, but the temperature has decreased during this period in southeast China. We evaluated the evolution of these temperature series using a novel nonlinear filtering technique based on the concept of the lifetime of temperature curves. The decadal to secular evolution of solar activity and temperature variation had similar signatures in the northeast, southeast, and northwest re- gions and the average across the whole country, indicating that solar activity is a significant control on climate change over secular time scales in these regions. In comparison with these regions, the signatures were different in central-east China and Tibet because of regional differences (e.g., landforms and elevation) and indirect effects (e.g., cloud cover influencing the radiation balance, thereby inducing climate change). Furthermore, the results of wavelet analysis indicated that the El Nino Southem Oscillation (ENSO) has had a significant impact on climate change, but at different times among the regions, and these changes were most probably induced by differing responses of the atmospheric system to solar forcing.  相似文献   

12.
Tropical forests have been recognized as having global conservation importance. However,they are being rapidly destroyed in many regions of the world. Regular monitoring of forests is necessary for an adaptive management approach and the successful implementation of ecosystem management. The present study analyses the temporal changes in forest ecosystem structure in tribal dominated Malkangiri district of Orissa,India,during 1973-2004 period based on digitized forest cover maps using geographic information system (GIS) and interpretation of satellite data. Three satellite images Landsat MSS (1973),Landsat TM (1990) and IRS P6 LISS III (2004) were used to determine changes. Six land cover types were delineated which includes dense forest,open forest,scrub land,agriculture,barren land and water body. Different forest types were also demarcated within forest class for better understanding the degradation pattern in each forest types. The results showed that there was a net decrease of 475.7 km2 forest cover (rate of deforestation = 2.34) from 1973 to 1990 and 402.3 km2 (rate of deforestation = 2.27) from 1990 to 2004. Forest cover has changed over time depending on a few factors such as large-scale deforestation,shifting cultivation,dam and road construction,unregulated management actions,and social pressure. A significant increase of 1222.8 km2 agriculture area (1973-2004) clearly indicated the conversion of forest cover to agricultural land. These alterations had resulted in significant environmental consequences,including decline in forest cover,soil erosion,and loss of biodiversity. There is an urgent need for rational management of the remaining forest for it to be able to survive beyond next decades. Particular attention must be paid to tropical forests,which are rapidly being deforested.  相似文献   

13.
中国东北地区林地面积变化的动态模拟   总被引:1,自引:0,他引:1  
There is plenty of forests in Northeast China which contributes a lot to the conservation of water and land resources, produces timber products, and provides habitats for a huge number of wild animals and plants. With changes of socio-economic factors as well as the geophysical conditions, there are dramatic changes on the spatial patterns of forest area. In this sense, it is of great significance to shed light on the dynamics of forest area changes to find the underlining reasons for shaping the changing patterns of forest area in Northeast China. To explore the dynamics of forest area change in Northeast China, an econometric model is developed which is composed of three equations identifying forestry production, conversion from open forest to closed forest and conversion from other land uses to closed forest so as to explore the impacts on the forest area changes from demographic, social, economic, location and geophysical factors. On this basis, we employ the Dynamics of Land System (DLS) model to simulate land-use conversions between forest area and non-forest cover and the land-use conversions within the sub-classes of forest area for the period 2000–2020 under business as usual scenario, environmental protection scenario and economic growth scenario. The simulation results show that forest area will expand continuously and there exist various kinds of changing patterns for the sub-classes of forest area, for example, closed forest will expand continuously and open forest and shrub will decrease a little bit, while area of other forest will keep intact. The research results provide meaningful decision-making information for conserving and exploiting the forest resources and making out the planning for forestry production in the Northeast China region.  相似文献   

14.
Gao  Jiangbo  Zuo  Liyuan 《地理学报(英文版)》2021,31(1):111-129
A clear understanding of the relationships among multiple ecosystem services(ESs) is the foundation for sustainable urban ecosystem management. Quantitatively identifying the factors that influence ES trade-offs and synergies can contribute to deepening ES research, from knowledge building to decision making. This study simulated soil conservation, water yield and carbon sequestration in Beijing, China, from 2015–2018. The spatial trade-offs and synergies of these three ESs within the five major river basins in Beijing were explored using geographically weighted regression. Furthermore, geographical detector was applied to quantitatively identify the driving mechanism of the environmental factors for the ES trade-offs and synergies. The results show the following:(1) the spatial relationships between soil conservation and water yield, as well as between water yield and carbon sequestration, were mainly trade-offs. There was a spatial synergy between soil conservation and carbon sequestration.(2) Regarding the spatial trade-off/synergy between soil conservation and water yield in Beijing, the dominant influencing factor was temperature/elevation, and the dominant interactions of the spatial trade-off and synergy between these two ESs in Beijing and the Chaobai River Basin are all manifested in the superposition of precipitation and potential evapotranspiration, temperature, and elevation.(3) Topographic factors were the dominant factors influencing the spatial relationship between soil conservation and carbon sequestration in Beijing and its five major river basins. As a result of the distribution of water systems and hydrological characteristics of the basins, differences were observed in the effects of different combinations of interaction factors on the spatial relationship between these two ESs in different basins.(4) Temperature had the strongest explanatory power in terms of the spatial trade-offs and synergies between water yield and carbon sequestration. The interactions between precipitation and temperature and between precipitation and elevation were the dominant interactions affecting the spatial relationship between water yield and carbon sequestration in Beijing. Overall, the explanatory power of influencing factors on the trade-offs and synergies and the degree of interaction between factors coexist in different basins with consistency and differences. Therefore, understanding the quantitative characteristics of basin-scale spatial trade-offs and synergies between ESs is important for ecosystem management and the promotion of synergy in different basins.  相似文献   

15.
Overgrazing has been considered one of the maj or causes that trigger shrub encroachment of grassland. Proliferation of shrubs in grassland is recognized as an important indicator of grassland degradation and desertification. In China, various conservation measures, including enclosures to reduce livestock grazing, have been taken to reverse the trend of grassland desertification, yet shrubs have been reported to increase in the grasslands over the past decades. In late 2007, we set up a 400-m-by-50-m exclosure in a long-term overgrazed temperate grassland in Inner Mongolia, with the ob- jective to quantify the spatiotemporal relationship between vegetation dynamics, soil variables, and grazing exclusion. Soil moisture was continuously monitored within the exclosure, and cover and aboveground biomass of the shrubs were measured inside the exclosure in 2007, 2009, 2010, 2012, and 2013, and outside the exclosure in 2012 and 2013. We found the average shrub cover and biomass significantly increased in the six years by 103 % and 120%, respectively. The result supported the hypothesis that releasing grazing pressure following long-term overgrazing tends to trigger shrub invasion into grassland. Our results, limited to a single gradient, suggest that any conservation measures with quick release of overgrazing pressure by enclosure or other similar means might do just the opposite to accelerate shrub en- croachment in grassland. The changes in vegetation cover and biomass were regressed on the temporal average of the soil moisture content by means of the generalized least square technique to quantify the effect of the spatial autocor- relation. The result indicates that the grass cover and biomass significantly increased with the top, but decreased with the bottom layer soil moisture. The shrub cover and biomass, on the other hand, decreased with the top, but increased with bottom soil moisture, although the regression coefficients for the shrubs were not statistically significant. Hence this study supports the two-layered soil model which assumes grasses and shrubs use belowground resources in dif- ferent depths.  相似文献   

16.
洞庭湖区的泥沙淤积效应   总被引:4,自引:1,他引:3  
According to a long series of measured sediment data, the sedimentation effects of the Dongting Lake Area (DLA) were studied in light of the relationship between sedimentation characteristics and resources and environment. The result shows that the long-term deposi- tion and the impact of human activities have led to a cycle of the evolution of sedimentation pattern, resulting in sediment disaster effects and resources effects in the DLA. The main features are as follows: 1) The water beach, silt beach, lake marsh beach, reed beach and other types of beach shaped by sedimentation effects constitute the main body of the giant lake system. 2) The disaster chains are induced, i.e., sedimentation → marshland expansion and reclamation → flood function decline, fish resource depletion, biodiversity reduction dis- aster chain, sedimentation → marshland expansion → floods, water pollution disaster chain, sedimentation → marshland floating vegetation rising → schistosomiasis, rodents virulence disaster chain, sedimentation → flood embankment bursting → land desertification disaster chain. 3) Sedimentation has created about 98.13×104hm2 of land in the past 55 years. Ra-tional development and utilization of marshland resources have produced tremendous eco- nomic benefits.  相似文献   

17.
To understand the status of public awareness on wetland conservation in China,1237 people from 8 provinces or municipality were interviewed by questionnaire.After analysis of the results,88.5%of the interviewees know the word ’wetland’.TV and radio is the main tool for them to get information.More than two thirds of the respondents mainly learn the information on wetland conservation through TV and radio.There are still big gaps among different people in understanding wetland.Only 13.3%of the respondents give a completely right answer on question ’which areas are wetlands’.Most of the respondents cited lakes,marshes and rivers as wetlands,but more than half of them do not regard beaches,reservoirs,paddy fields and fish ponds as wetlands.Most of the people cited wetlands can provide such functions as water conservation,climate regulation,protecting wildlife,removing pollution, but know little about other functions such as flood control,provisioning of aquatic products,and soil retention, and much less about the cultural functions such as recreation,and inherited folk culture.Except for wastewater discharge, nearly half of the general public knows little about other threats of the wetland,while most of the people do not believe that artificial aquaculture will cause threats to the wetland areas.Public awareness on wetland conservation in China needs to be improved.Most of the respondents cited that TV,radio and internet are the most effective ways to publicize information on wetland conservation.More than two thirds of the respondents mainly learn the information on wetland conservation through TV and radio,while 38.0%of the respondents mainly through internet. Specifically,for farmers/fishermen,posters/picture albums can benefit them more than the internet;the undergraduates also expect to learn wetland mainly through posters/picture albums;while for the primary and middle school students, the school education is another valuable source of publicity in addition to TV and radio.Strengthen cooperation with TV stations and broadcasting stations are the best way to raise public awareness of wetland conservation. The authors suggest to strength cooperation with media on wetland conservation,conduct wetland conservation education in middle and primary schools and communities;organize experts and professionals to write books and teaching materials needed for popularizing science,basic education and staff training;develop an internet-based CEPA network system on wetland conservation;conduct public awareness activities in communities,focusing on females in rural areas;build public awareness and education system,improve the public’s awareness on wetland conservation,create good social environment for conserving wetlands.  相似文献   

18.
基于空间模型的全球粮食安全评价   总被引:3,自引:1,他引:2  
This paper presents a scenario-based assessment of global future food security. To do that,the socio-economic and climate change scenarios were defined for the future and were linked to an integrated modeling framework. The crop yields simulated by the GIS-based Environmental Policy Integrated Climate (EPIC) model and crop areas simulated by the crop choice decision model were combined to calculate the total food production and per capita food availability,which was used to represent the status of food availability and stability. The per capita Gross Domestic Product (GDP) simulated by IFPSIM model was used to reflect the situation of food accessibility and affordability. Based on these two indicators,the future food security status was assessed at a global scale over a period of approximately 20 years,starting from the year 2000. The results show that certain regions such as South Asia and most African countries will likely remain hotspots of food insecurity in the future as both the per capita food availability and the capacity of being able to import food will decrease between 2000 and 2020. Low food production associated with poverty is the determining factor to starvation in these regions,and more efforts are needed to combat hunger in terms of future actions. Other regions such as China,most Eastern European countries and most South American countries where there is an increase in per capita food availability or an increase in the capacity to import food between 2000 and 2020 might be able to improve their food security situation.  相似文献   

19.
As an effective solution for protecting the underlying permafrost and preventing roadway damages, the block-rock embankment(BRE) has been widely used on the Qinghai–Tibet Railway, Qinghai–Tibet Highway, and Ching–Hong Road;and it will be promoted for other roadways in the future. To evaluate the adaptability of BRE, the catastrophe-progression method was adopted for the evaluation. By analyzing the factors affecting the stability of BRE and utilizing engineering experience, we were able to establish the mathematical model and divide the adaptability of BRE into five grades. After the verifying analysis of 28 practical engineering examples, the evaluation results are broadly in line with practical application effects. Therefore, the adaptability of BRE can be evaluated and predicted more accurately with this evaluation model.  相似文献   

20.
Landform classification is commonly done using topographic altitude only.However,practice indicates that locations at a same altitude may have distinctly different landforms,depending on characteristics of soils underneath those locations.The objectives of this study were to:1) develop a landform classification approach that is based on both altitude and soil characteristic;and 2) use this approach to determine landforms within a watershed located in northern Ordos Plateau of China.Using data collected at 134 out of 200 sampling sites,this study determined that D10(the diameter of soil particles 10% finer by weight) and long-term average soil moisture acquired in 2010,which can be estimated at reasonable accuracy from remote sensing imagery,can be used to represent soil characteristics of the study watershed.Also,the sampling data revealed that this watershed consists of nine classes of landforms,namely mobile dune(MD),mobile semi-mobile dune(SMD),rolling fixed semi-fixed dune(RFD),flat sandy land(FD),grassy sandy land(GS),bedrock(BR),flat sandy bedrock(FSB),valley agricultural land(VA),and swamp and salt lake(SW).A set of logistic regression equations were derived using data collected at the 134 sampling sites and verified using data at the remaining 66 sites.The verification indicated that these equations have moderate classification accuracy(Kappa coefficients > 43%).The results revealed that the dominant classes in the study watershed are FD(36.3%),BR(27.0%),and MD(23.5%),while the other six types of landforms(i.e.,SMD,RFD,GS,FSB,VA,and SW) in combination account for 13.2%.Further,the landforms determined in this study were compared with the classes pre-sented by a geologically-based classification map.The comparison indicated that the geo-logically-based classification could not identify multiple landforms within a class that are de-pendent upon soil characteristics.  相似文献   

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