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1.
The Belt and Road Initiative(BRI)–a development strategy proposed by China – provides unprecedented opportunities for multi-dimensional communication and cooperation across Asia,Africa and Europe.In this study,we analyse the spatio-temporal changes in cultivated land in the BRI countries(64 in total) to better understand the land use status of China along with its periphery for targeting specific collaboration.We apply FAO statistics and Globe Land30(the world's finest land cover data at a 30-m resolution),and develop three indicator groups(namely quantity,conversion,and utilization degree) for the analysis.The results show that cultivated land area in the BRI region increased 3.73×10~4 km~2 between 2000 and 2010.The increased cultivated land was mainly found in Central and Eastern Europe and Southeast Asia,while the decreased cultivated land was mostly concentrated in China.Russia ranks first with an increase of 1.59×10~4 km~2 cultivated land area,followed by Hungary(0.66×10~4 km~2) and India(0.57×10~4 km`2).China decreased 1.95×10~4 km~2 cultivated land area,followed by Bangladesh(–0.22×10~4 km~2) and Thailand(–0.22×10~4 km~2).Cultivated land was mainly transferred to/from forest,grassland,artificial surfaces and bare land,and transfer types in different regions have different characteristics:while large amount of cultivated land in China was converted to artificial surfaces,considerable forest was converted to cultivated land in Southeast Asia.The increase of multi-cropping index dominated the region except the Central and Eastern Europe,while the increase of fragmentation index was prevailing in the region except for a few South Asian countries.Our results indicate that the negative consequence of cultivated land loss in China might be underestimated by the domestic-focused studies,as none of its close neighbours experienced such obvious cultivated land losses.Nevertheless,the increased cultivated land area in Southeast Asia and the extensive cultivated land use in Ukraine and Russia imply that the regional food production would be greatly improved if China' "Go Out policy" would help those countries to intensify their cultivated land use.  相似文献   

2.
The study of temperature change in major countries of the world since the 1980 s is a key scientific issue given that such data give insights into the spatial differences of global temperature change and can assist in combating climate change. Based on the reanalysis of seven widely accepted datasets, which include trends in climate change and spatial interpolation of the land air temperature data, the changes in the temperature of major countries from 1981 to 2019 and the spatial-temporal characteristics of global temperature change have been assessed. The results revealed that the global land air temperature from the 1980 s to 2019 varied at a rate of 0.320℃/10 a, and exhibited a significantly increasing trend, with a cumulative increase of 0.835℃. The mean annual land air temperature in the northern and southern hemispheres varied at rates of 0.362℃/10 a and 0.147℃/10 a, respectively, displaying significantly increasing trends with cumulative increases of 0.828℃ and 0.874℃, respectively. Across the globe, the rates of change of the mean annual temperature were higher at high latitudes than at middle and low latitudes, with the highest rates of change occurring in regions at latitudes of 80°–90°N, followed by regions from 70°–80°N, then from 60°–70°N. The global land surface air temperature displayed an increasing trend, with more than 80% of the land surface showing a significant increase. Greenland, Ukraine, and Russia had the highest rates of increase in the mean annual temperature;in particular, Greenland experienced a rate of 0.654℃/10 a. The regions with the lowest rates of increase of mean annual temperature were mainly in New Zealand and the equatorial regions of South America, Southeast Asia, and Southern Africa, where the rates were <0.15℃/10 a. Overall, 136 countries(93%), out of the 146 countries surveyed, exhibited a significant warming, while 10 countries(6.849%) exhibited no significant change in temperature, of which 3 exhibited a downward trend. Since the 1980 s, there have been 4, 34 and 68 countries with levels of global warming above 2.0℃, 1.5℃ and 1.0℃, respectively, accounting statistically for 2.740%, 23.288% and 46.575% of the countries examined. This paper takes the view that there was no global warming hiatus over the period 1998–2019.  相似文献   

3.
Yu  Wanhui  Zhang  Lijuan  Zhang  Hongwen  Jiang  Lanqi  Zhang  Ankang  Pan  Tao 《地理学报(英文版)》2020,30(3):439-454
The effects of human activities on climate change are a significant area of research in the field of global environmental change. Land use and land cover change(LUCC) has a greater effect on climate than greenhouse gases, and the effect of farmland expansion on regional drought is particularly important. From the 1910 s to the 2010 s, cultivated land in Songnen Plain increased by 2.67 times, the area of cultivated land increased from 4.92×10~4 km~2 to 13.14×10~4 km~2, and its percentage of all land increased from 25% to 70%. This provides an opportunity to study the effects of the conversion of natural grassland to farmland on climate. In this study, the drought indices in Songnen Plain were evaluated from the 1910 s to the 2010 s, and the effect of farmland expansion on drought was investigated using statistical methods and the Weather Research and Forecasting Model based on UK's Climatic Research Unit data. The resulting dryness index, Palmer drought severity index, and standardized precipitation index values indicated a significant drying trend in the study area from 1981 to 2010. This trend can be attributed to increases in maximum temperature and diurnal temperature range, which increased the degree of drought. Based on statistical analysis and simulation, the maximum temperature, diurnal temperature range, and sensible heat flux increased during the growing season in Songnen Plain over the past 100 years, while the minimum temperature and latent heat flux decreased. The findings indicate that farmland expansion caused a drying trend in Songnen Plain during the study period.  相似文献   

4.
Zhu  Wenbo  Zhang  Jingjing  Cui  Yaoping  Zhu  Lianqi 《地理学报(英文版)》2020,30(9):1507-1522
Regional land use change is the main cause of the ecosystem carbon storage changes by affecting emission and sink process.However,there has been little research on the influence of land use changes for ecosystem carbon storage at both temporal and spatial scales.For this study,the Qihe catchment in the southern part of the Taihang Mountains was taken as an example;its land use change from 2005 to 2015 was analyzed,the Markov-CLUE-S composite model was used to predict land use patterns in 2025 under natural growth,cultivated land protection and ecological conservation scenario,and the land use data were used to evaluate ecosystem carbon storage under different scenarios for the recent 10-year interval and the future based on the carbon storage module of the In VEST model.The results show the following:(1) the ecosystem carbon storage and average carbon density of Qihe catchment were 3.16×107 t and 141.9 t/ha,respectively,and decreased by 0.07×107 t and 2.89 t/ha in the decade evaluated.(2) During 2005–2015,carbon density mainly decreased in low altitude areas.For high altitude area,regions with increased carbon density comprised a similar percentage to regions with decreased carbon density.The significant increase of the construction areas in the middle and lower reaches of Qihe and the degradation of upper reach woodland were core reasons for carbon density decrease.(3) For 2015–2025,under natural growth scenario,carbon storage and carbon density also significantly decrease,mainly due to the decrease of carbon sequestration capacity in low altitude areas;under cultivated land protection scenario,the decrease of carbon storage and carbon density will slow down,mainly due to the increase of carbon sequestration capacity in low altitude areas;under ecological conservation scenario,carbon storage and carbon density significantly increase and reach 3.19×107 t and 143.26 t/ha,respectively,mainly in regions above 1100 m in altitude.Ecological conservation scenario can enhance carbon sequestration capacity but cannot effectively control the reduction of cultivated land areas.Thus,land use planning of research areas should consider both ecological conservation and cultivated land protection scenarios to increase carbon sink and ensure the cultivated land quality and food safety.  相似文献   

5.
The Qilian mountain area was examined for using the Logistic-CA-Markov coupling model combined with GIS spatial analyst technology to research the transformation of LUCC, driving force system and simulate future tendency of variation. Results show that:(1) Woodland area decreased by 12.55%, while grassland, cultivated land, and settlement areas increased by 0.22%, 7.92%, and 0.03%, respectively, from 1986 to 2014. During the period of 1986 to 2000, forest degradation in the middle section of the mountain area decreased by 1,501.69 km~2. Vegetation cover area improved, with a net increase of grassland area of 38.12 km~2 from 2000 to 2014.(2) For constructing the system driving force, the best simulation scale was 210m×210m. Based on logistic regression analysis, the contribution(weight) of composite driving forces to land use and cover change was obtained, and the weight value was more objectively compared with AHP and MCE method.(3) In the natural scenarios, it is predicted that land use and cover distribution maps of Qilian mountain area in 2028 and 2042, and the Lee-Sallee index test was adopted. Over the next 27 years(2015–2042), farmland, woodland, grassland, settlement areas show an increasing trend, especially settlements with an obvious change of 0.56%. The area of bare land will decrease by 0.89%. Without environmental degradation, tremendous structural change of LUCC will not occur, and typical characteristic of the vertical zone of the mountain would remain. Farmland and settlement areas will increase, but only in the vicinity of Qilian and Sunan counties.  相似文献   

6.
近10年洞庭湖区土地利用变化时空特征   总被引：4，自引：0，他引：4  
The research on the land use/cover change is one of the frontiers and the hot spots in the global change research. Based on the Chinese resource and environment spatial-temporal database,and using the Landsat TM and ETM data of 1990 and 2000 respectively, we analyzed the spatial-temporal characteristics of land use/cover changes in the Dongting Lake area during the last decade. The result shows that during the last ten years there were three land-use types that had changed remarkably. The cultivated land decreased by 0.57% of the total cultivated land. The built-up land and water area expanded, with an increase of 8.97% and 0.43% respectively. The conversion between land use types mostly happened among these three land-use types, especially frequently between cultivated land and water area. The land-use change speed of land-use type is different. Three cities experienced the greatest degree of land-use change among all the administrative districts, which means that the land use in these cities changed much quickly. The following changed area was the west and south of the Dongting Lake area. The slowest changed area is the north and east area.  相似文献   

7.
Earth is always changing.Knowledge about where changes happened is the first step for us to understand how these changes affect our lives.In this paper,we use a long-term leaf area index data(LAI) to identify where changes happened and where has experienced the strongest change around the globe during 1981-2006.Results show that,over the past 26 years,LAI has generally increased at a rate of 0.0013 per year around the globe.The strongest increasing trend is around 0.0032 per year in the middle and northern high latitudes(north of 30°N).LAI has prominently increased in Europe,Siberia,Indian Peninsula,America and south Canada,South region of Sahara,southwest corner of Australia and Kgalagadi Basin;while noticeably decreased in Southeast Asia,southeastern China,central Africa,central and southern South America and arctic areas in North America.  相似文献   

8.
The aim of this study is to establish several important factors representing land use intensification in cultivated land(denoted by CII), using a multi-dimensional approach to achieve realistic and practical cultivated land use policies in China. For this reason, the theoretical framework was first built to explain the changes of land use intensification in the cultivated land, and then the variables and index were further developed for the purpose of characterizing the dynamic trends and driving forces of the land use intensification in the cultivated land at the provincial level. The study results indicate that the extent of CII significantly increased during the period of 1996 to 2008, due to the extensive use of fertilizers, machinery and pesticide, increased labor and capital input, and intensified land use. Moreover, the principal component regression results show that the productivity of cultivated land, economic benefits of cultivated land, labor productivity, and land use conversion are the main factors affecting the village development. The first three factors play a positive role, while the last one has a negative effect on the land use intensification in the cultivated land. According to these results, the main policies for sustainable intensification in cultivated land are proposed. First, the sustainable pathways for intensification should be adopted to reduce the unsustainable uses of chemical fertilizer, agricultural chemicals, etc. Second, the conditions for agricultural production should be further improved to increase the cultivated land productivity. Third, it is very necessary and helpful for improving labor productivity and land use efficiency from the viewpoint of accelerated the cultivated land circulation. The last step is to positively affect the production activities of peasants by means of reforming the subsidy standards.  相似文献   

9.
Changes in rice production in Southern China are crucial to national food security. This study employed Landsat images to map the distributions of paddy rice-cropping systems in Southern China in 1990 and 2015. The impact of rice multiple cropping index changes on grain production capacity was then evaluated. Three important results were obtained for the 1990 to 2015 study period. First, the multiple cropping index for rice decreased from 148.3% to 129.3%, and 253.16×10~4 ha of land area was converted from double-cropping to single-cropping rice, termed "double to single". The area with the most dramatic changes is in the Middle-Lower Yangtze Plain. The rice-cropping system distribution in Southern China showed a change from north to south with double-cropping rice shrinking and single-cropping rice expanding. Second, the "double to single" conversion led to a reduction of 6.1% and 2.6% in rice and grain production, respectively. Hunan and Jiangxi Provinces, located in the main rice producing areas, and Zhejiang, which has shown better economic development, exhibited large reductions in rice production due to the "double to single" conversion, all exceeding 13%. Third, the grain production capacity of converted "double to single" paddy fields is equivalent to that of 223.3 × 10~4 ha of newly reclaimed cultivated land, which is 54% of the total newly cultivated land reclaimed through the 2001–2015 land consolidation project. It is also 1.7 times the target goal for newly cultivated land in the national land consolidation plan for 2016–2020. Making full use of the converted "double to single" paddy fields can save 167.44 billion yuan in newly reclaimed cultivated land costs. Therefore, instead of pursuing low-quality new arable land, it is better to make full use of the existing high-quality arable land. Based on these results, the government should change the assessment method for cultivated land balance, and incorporate the sown area increased by improving the multiple cropping index into the cultivated land compensation indicator.  相似文献   

10.
Explicitly identifying the spatial distribution of ecological transition zones(ETZs) and simulating their response to climate scenarios is of significance in understanding the response and feedback of ecosystems to global climate change. In this study, a quantitative spatial identification method was developed to assess ETZ distribution in terms of the improved Holdridge life zone(iHLZ) model. Based on climate observations collected from 782 weather stations in China in the T0(1981–2010) period, and the Intergovernmental Panel on Climate Change Coupled Model Intercomparison Project(IPCC CMIP5) RCP2.6, RCP4.5, and RCP8.5 climate scenario data in the T1(2011–2040), T2(2041–2070), and T3(2071–2100) periods, the spatial distribution of ETZs and their response to climate scenarios in China were simulated in the four periods of T0, T1, T2, and T3. Additionally, a spatial shift of mean center model was developed to quantitatively calculate the shift direction and distance of each ETZ type during the periods from T0 to T3. The simulated results revealed 41 ETZ types in China, accounting for 18% of the whole land area. Cold temperate grassland/humid forest and warm temperate arid forest(564,238.5 km~2), cold temperate humid forest and warm temperate arid/humid forest(566,549.75 km~2), and north humid/humid forest and cold temperate humid forest(525,750.25 km~2) were the main ETZ types, accounting for 35% of the total ETZ area in China. Between 2010 and 2100, the area of cold temperate desert shrub and warm temperate desert shrub/thorn steppe ETZs were projected to increase at a rate of 4% per decade, which represented an increase of 3604.2, 10063.1, and 17,242 km~2 per decade under the RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively. The cold ETZ was projected to transform to the warm humid ETZ in the future. The average shift distance of the mean center in the north wet forest and cold temperate desert shrub/thorn grassland ETZs was generally larger than that of other ETZs, with the mean center moving to the northeast and the shift distance being more than 150 km during the periods from T0 to T3.In addition, with a gradual increase of temperature and precipitation, the ETZs in northern China displayed a shifting northward trend, while the area of ETZs in southern China decreased gradually, and their mean center moved to high-altitude areas. The effects of climate change on ETZs presented an increasing trend in China, especially in the Qinghai-Tibet Plateau.  相似文献   

11.
Land use/cover change is an important theme on the impacts of human activities on the earth systems and global environmental change. National land-use changes of China during 2010–2015 were acquired by the digital interpretation method using the high-resolution remotely sensed images, e.g. the Landsat 8 OLI, GF-2 remote sensing images. The spatiotemporal characteristics of land-use changes across China during 2010–2015 were revealed by the indexes of dynamic degree model, annual land-use changes ratio etc. The results indicated that the built-up land increased by 24.6×10~3 km~2 while the cropland decreased by 4.9×10~3 km~2, and the total area of woodland and grassland decreased by 16.4×10~3 km~2. The spatial pattern of land-use changes in China during 2010–2015 was concordant with that of the period 2000–2010. Specially, new characteristics of land-use changes emerged in different regions of China in 2010–2015. The built-up land in eastern China expanded continually, and the total area of cropland decreased, both at decreasing rates. The rates of built-up land expansion and cropland shrinkage were accelerated in central China. The rates of built-up land expansion and cropland growth increased in western China, while the decreasing rate of woodland and grassland accelerated. In northeastern China, built-up land expansion slowed continually, and cropland area increased slightly accompanied by the conversions between paddy land and dry land. Besides, woodland and grassland area decreased in northeastern China. The characteristics of land-use changes in eastern China were essentially consistent with the spatial govern and control requirements of the optimal development zones and key development zones according to the Major Function-oriented Zones Planning implemented during the 12 th Five-Year Plan(2011–2015). It was a serious challenge for the central government of China to effectively protect the reasonable layout of land use types dominated with the key ecological function zones and agricultural production zones in centraland western China. Furthermore, the local governments should take effective measures to strengthen the management of territorial development in future.  相似文献   

12.
We initially estimated the cropland area at county level using local historical documents for the Songnen Plain(SNP)in the 1910s and 1930s.We then allocated this cropland area to grid cells with a size of 1 km×1 km,using a range of cultivation possibilities from high to low;this was based on topography and minimum distances to rivers,settlements,and traffic lines.Cropland areas for the 1950s were obtained from the Land Use Map of Northeast China,and map vectorization was performed with Arc GIS technology.Cropland areas for the1970s,1980s,1990s,2000s,and 2010s were retrieved from Landsat images.We found that the cropland areas were 4.92×104 km~2 and 7.60×10~4 km~2,accounting for 22.8%and 35.2% of the total area of the SNP in the 1910s and 1930s,respectively,which increased to 13.14×10~4 km~2,accounting for 60.9%in the 2010s.The cropland increased at a rate of 1.18×10~4km~2 per decade from the 1910s to 1970s while it was merely 0.285×10~4 km~2 per decade from the 1970s to 2010s.From the 1910s to 1930s,new cultivation mainly occurred in the central SNP while,from the 1930s to 1970s,it was mainly over the western and northern parts.This spatially explicit reconstruction could be offered as primary data for studying the effects of changes in human-induced land cover based on climate change over the last century.  相似文献   

13.
The shapes of the urban lakes in Wuhan city have been strongly influenced by the rapid industrialization and urbanization experienced in recent decades.Based on topographic maps and remote sensing images,the temporal and spatial changes of East Lake,Wuhan city,over the past two decades were analyzed.The landscape shape index(LSI)and centroid method were applied to analyze the evolution of lake morphology and its causes.Several key results were obtained.(1)The surface area of East Lake decreased sharply by 2.13 km2 from 1995 to 2005,and slightly by 1.00 km2 from 2005 to 2015.The shoreline length of East Lake displayed a continuous trend of decline during the study period:The length reduced by 21.89 km from 1995 to 2005,and by 0.67 km from 2005 to 2015.The LSI values,7.04(1995),6.46(2005),and 6.28(2015),displayed an accelerated downward trend,indicating a reduction of complexity in East Lake and the intensification of manual interventions in the water body.(2)The changes to East Lake displayed a clear temporal and spatial heterogeneity.The centroid of East Lake moved northeast from 1995 to 2005 and southeast from 2005 to 2015.(3)The reduction in the area of East Lake was mainly affected by human activities.A lake area of about 4.8 km2 was converted to other land uses during 1995-2005,most of which was unused land,whereas from 2005 to 2015,0.43 km2 of the lake area was converted into built-up land,and 0.25 km2 was converted into other land uses.The reduction in area was caused by infrastructure construction by the government,the development of the real estate industry,illegal construction by villagers,and the development of scenic spots for tourism.The driving forces of this reduction included Wuhan's growing population,and the rapid development of the economy and urbanization between 1995 and 2015,which has resulted in a large demand for land.Finally,a formation mechanism model was constructed by analyzing the causes of East Lake's morphological evolution.  相似文献   

14.
Land cover change affects surface radiation budget and energy balance by chang- ing surface albedo and further impacts the regional and global climate. In this article, high spatial and temporal resolution satellite products were used to analyze the driving mechanism for surface albedo change caused by land cover change during 1990-2010. In addition, the annual-scale radiative forcing caused by surface albedo changes in China＇s 50 ecological regions were calculated to reveal the biophysical mechanisms of land cover change affecting climate change at regional scale. Our results showed that the national land cover changes were mainly caused by land reclamation, grassland desertification and urbanization in past 20 years, which were almost induced by anthropogenic activities. Grassland and forest area decreased by 0.60% and 0.11%, respectively. The area of urban and farmland increased by 0.60% and 0.19%, respectively. The mean radiative forcing caused by land cover changes during 1990-2010 was 0.062 W/m2 in China, indicating a warming climate effect. However, spatial heterogeneity of radiative forcing was huge among different ecological regions. Farmland conversing to urban construction land, the main type of land cover change for the urban and suburban agricultural ecological region in Beijing-Tianjin-Tangshan region, caused an albedo reduction by 0.00456 and a maximum positive radiative forcing of 0.863 WIm2, which was presented as warming climate effects. Grassland and forest conversing to farmland, the main type of land cover change for the temperate humid agricultural and wetland ecological region in Sanjiang Plain, caused an albedo increase by 0.00152 and a maximum negative radiative forcing of 0.184 W/m2, implying cooling climate effects.  相似文献   

15.
Land cover change affects surface radiation budget and energy balance by changing surface albedo and further impacts the regional and global climate. In this article, high spatial and temporal resolution satellite products were used to analyze the driving mechanism for surface albedo change caused by land cover change during 1990–2010. In addition, the annual-scale radiative forcing caused by surface albedo changes in China's 50 ecological regions were calculated to reveal the biophysical mechanisms of land cover change affecting climate change at regional scale. Our results showed that the national land cover changes were mainly caused by land reclamation, grassland desertification and urbanization in past 20 years, which were almost induced by anthropogenic activities. Grassland and forest area decreased by 0.60% and 0.11%, respectively. The area of urban and farmland increased by 0.60% and 0.19%, respectively. The mean radiative forcing caused by land cover changes during 1990–2010 was 0.062 W/m2 in China, indicating a warming climate effect. However, spatial heterogeneity of radiative forcing was huge among different ecological regions. Farmland conversing to urban construction land, the main type of land cover change for the urban and suburban agricultural ecological region in Beijing-Tianjin-Tangshan region, caused an albedo reduction by 0.00456 and a maximum positive radiative forcing of 0.863 W/m2, which was presented as warming climate effects. Grassland and forest conversing to farmland, the main type of land cover change for the temperate humid agricultural and wetland ecological region in Sanjiang Plain, caused an albedo increase by 0.00152 and a maximum negative radiative forcing of 0.184 W/m2, implying cooling climate effects.  相似文献   

16.
In order to advance land use and land cover change(LUCC) research in Nepal, it is essential to reconstruct both the spatiotemporal distribution of agricultural land cover as well as scenarios that can explain these changes at the national and regional levels. Because of rapid population growth, the status of agricultural land in Nepal has changed markedly over the last 100 years. Historical data is used in this study, encompassing soils, populations, climatic variables, and topography. Data were revised to a series of 30 m grid cells utilized for agricultural land suitability and allocation models and were analyzed using a suite of advanced geographical tools. Our reconstructions for the spatiotemporal distribution of agricultural land in Nepal reveal an increasing trend between 1910 and 2010(from 151.2 × 10~2 km~2 to 438.8 × 10~2 km~2). This expanded rate of increase in agricultural land has varied between different eco, physiographic, and altitudinal regions of the country, significantly driven by population changes and policies over the period of this investigation. The historical dataset presented in this paper fills an existing gap in studies of agricultural land change and can be applied to other carbon cycle and climate modeling studies, as well as to impact assessments of agricultural land change in Nepal.  相似文献   

17.
Based on GIS and statistical methods, with the help of searching historical literatures and calculating the landscape indices, the land use changes of Qian‘an County in both spatial and temporal aspects from 1945 to 1996 has been analyzed in this paper. And the driving forces of land use changes and their ecological effects are discussed too. The main findings of this study are as follows: (1) Land use changed greatly in Qian‘an during 1945-1996, characterized by a decrease in grassland, wetland and water bodies, and an increase in cultivated land, saline-alkali land, and the land for housing and other construction purposes. Grassland decreased by 175,828.66 ha, and cultivated land increased by 102,137.23 ha over the half century. Accordingly, the main landscape type changed from a steppe landscape to a managed agricultural ecosystem. (2) Results of correlation analysis show that the land use change in the study area was mainly driven by the socioeconomic factors. (3) The ecological effects of land use change in the area are characterized by serious salinization, degression of soil fertility and the weakening, of landscaoe suitability.  相似文献   

18.
Based on GIS and statistical methods, with the help of searching historical literatures and calculating the landscape indices, the land use changes of Qian'an County in both spatial and temporal aspects from 1945 to 1996 has been analyzed in this paper. And the driving forces of land use changes and their ecological effects are discussed too. The main findings of this study are as follows: (1) Land use changed greatly in Qian'an during 1945-1996, characterized by a decrease in grassland, wetland and water bodies, and an increase in cultivated land, saline-alkali land, and the land for housing and other construction purposes. Grassland decreased by 175,828.66 ha, and cultivated land increased by 102,137.23 ha over the half century. Accordingly, the main landscape type changed from a steppe landscape to a managed agricultural ecosystem. (2) Results of correlation analysis show that the land use change in the study area was mainly driven by the socioeconomic factors.　(3) The ecological effects of land use change in the area are characterized by serious salinization, degression of soil fertility and the weakening of landscape suitability.  相似文献   

19.
The G-WADI network by UNESCO promotes the global capacity for management of water resources in arid and semi-arid areas. The primary aim has been to build a comprehensive global network to promote regional and international cooperation so as to increase knowledge and improve management practices through the sharing of information. The G-WADI objectives and achievements of the past 10 years are reviewed. A number of key initiatives have been implemented––the formation of five regional networks, the creation of a central G-WADI web site, promotion of near-real-time rainfall distribution software enhanced by the inclusion of satellite based precipitation estimations, as well as workshop and web-based activities on chemical and isotopic tracers and on rain water harvesting. Two workshops on surface and on groundwater modeling, supported by publications have been held in India and China. The Asian G-WADI network remains very active, but activities in the other three regions are developing (Africa, Arab Region, Latin America and the Caribbean).  相似文献   

20.
21世纪初中国土地利用变化的空间格局与驱动力   总被引：33，自引：15，他引：18  
Land use and land cover change as the core of coupled human-environment systems has become a potential field of land change science (LCS) in the study of global environmental change. Based on remotely sensed data of land use change with a spatial resolution of 1 km × 1 km on national scale among every 5 years, this paper designed a new dynamic regionalization according to the comprehensive characteristics of land use change including regional differentiation, physical, economic, and macro-policy factors as well. Spatial pattern of land use change and its driving forces were investigated in China in the early 21st century. To sum up, land use change pattern of this period was characterized by rapid changes in the whole country. Over the agricultural zones, e.g., Huang-Huai-Hai Plain, the southeast coastal areas and Sichuan Basin, a great proportion of fine arable land were engrossed owing to considerable expansion of the built-up and residential areas, resulting in decrease of paddy land area in southern China. The development of oasis agriculture in Northwest China and the reclamation in Northeast China led to a slight increase in arable land area in northern China. Due to the "Grain for Green" policy, forest area was significantly increased in the middle and western developing regions, where the vegetation coverage was substantially enlarged, likewise. This paper argued the main driving forces as the implementation of the strategy on land use and regional development, such as policies of "Western Development", "Revitalization of Northeast", coupled with rapidly economic development during this period.  相似文献   

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