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1.
Rapid land use change has taken place in many arid and semi-arid regions of China over the past decade, such as in Yellow River Basin. In this paper, changes in the land use pattern of the Yellow River Basin were analyzed using Landsat TM data in 1990, 1995 and 2000. The aim was to improve the understanding of changes in land use with a view to identifying potentially more sustainable systems of land use. Firstly, the mathematical methodology was explored and developed for spatial pattern changes of land use, which include the degree index model of land use dynamic, index model of land use degree, mean center model of land use and transformation model of land use. Based on these models, the changing spatial patterns of land use were calculated and analyzed. During the period 1990–2000, the areas of cropland, built-up land and unused land all increased, the area of cropland increased dramatically by 2917 km2, while the areas of grassland and woodland decreased by 4668 and 33 km2, respectively. Meanwhile, the spatial pattern of land use also experienced a great change. Then the driving factors of land use change were investigated, the governmental policies on eco-environmental protection, population growth and meteorological conditions were the major factors that caused the land use change in the past decade.  相似文献   

2.
This study uses resource‐based measures to explore the evolution of China's demand and supply for food. China's dietary shift from plant to animal‐based foods, induced by its income growth, is likely to impose considerable pressure on agricultural resources. China's demand for food on this measure appears consistent with global trends, while China is an out‐performer on the supply side, producing much more food than its income level and land endowment would predict. China's current per capita income is in a range where consumption growth is high and in excess of production growth, but the gap between supply and demand is likely to diminish as population and per capita consumption growth decelerate. Continuing agricultural productivity growth and sustainable resource management will be important influences on the growth of China's future net import demand for food.  相似文献   

3.
Mexico is a megadiverse country with large agroclimatic diversity and socioeconomic inequality. These two factors result in strong diversity in diets and agricultural systems within the country. In this paper, we assess the impact of Mexican diets and production systems on the per capita land requirements for food. We estimate it for the extremes: from the very basic diet of the poorest share of the population to the affluent diet of the richest share of the population; and for extensive and intensive systems, with irrigation as the indicator of the intensity of the system. We show that the basic diet produced in rainfed systems requires 1620 m2/cap/yr and produced in irrigate systems requires 700 m2/cap/yr. The affluent diet produced in rainfed systems requires 2540 m2/cap/yr and produced in irrigated systems requires 1230 m2/cap/yr. Hence, differences in diets result in a requirement for 80% or 60% more land for an affluent diet; and differences in production systems result in more than twice the amount of land for extensive than for intensive systems. In 2050, it would be possible to feed the entire population with affluent diets only if all the present area of crop land had the productivity of intensive systems. In contrast, it would be possible to feed all people with a basic diet even if all present crop land area had only the productivity of extensive systems.  相似文献   

4.
We analyse food demand patterns of Indonesian households from a resource intensity perspective and quantify the impact of changed demand patterns on the use of three major resource inputs: fossil fuel; land; and water in agricultural production. Using Indonesian Family Life Survey data, 13 major food items (which constitute 70 per cent of food expenditure) are categorised into low, moderate and high resource intensity, and income elasticity and Engel curves are estimated for the period from 1997 to 2007. Our results show that income growth in Indonesia is associated with demand patterns that are more resource intensive. By 2007, per capita requirements of fossil fuel, land and water increased by 42.7 per cent (3.13 MJ), 44.9 per cent (1.24 m2) and 50.4 per cent (2.1 kL), respectively, relative to 1997. The results imply that, at least for Indonesia, changed food demand patterns resulting from economic development will increase the demand for natural resources substantially.  相似文献   

5.
中国耕地供需变化规律研究   总被引:25,自引:1,他引:25  
研究目的:探讨中国城市化 — 工业化用地需求和满足粮食安全的耕地供给之间的消长关系及变化规律,以期为国家土地利用政策提供科学依据。研究方法:首先提出关于最小人均耕地面积(即满足粮食安全的人均耕地需求)和耕地非农化逻辑斯蒂的假设。然后对历年中国耕地的统计数据进行订正,重建1980 — 2006年耕地数据序列。据此计算了同期的最小人均耕地面积和耕地压力指数(反映耕地需求和供给的对比关系),并验证耕地非农化逻辑斯蒂假设。研究结果:保障粮食安全的人均耕地需求数量逐渐降低,耕地压力指数虽先降后升但总体呈下降趋势。中国在基本满足城市化 — 工业化用地需求和生态退耕,因而满足粮食安全需求的耕地供给不断减少,同时人口又不断增加的情况下,粮食安全状况非但没有恶化,反而有所改善;耕地压力指数非但没有加重,反而有所减轻,根本原因在于土地生产率的不断提高。耕地非农化逻辑斯蒂增长过程的推导和证明,显示了两个拐点分别出现在1980年和2050年,前者是从缓慢到加速的转折点;后者是从增长到停滞的转折点,保证粮食安全的耕地供给将趋于稳定。其间还有一个由加速到减缓的拐点将出现在2015年。研究结论:城市化 — 工业化用地需求和粮食安全用地需求可以兼顾。  相似文献   

6.
African countries continue to face deepening food crises that have been accentuated by the global food, energy, and financial crises. This situation is part of a long‐term structural problem: decades of under‐investments in agricultural sector and poor policies of support for smallholder farmers who form the bulk of the farming population. The inability of these farmers to achieve a supply response when commodity prices were high and market access was less of a problem suggests that there are multiple sets of binding constraints that continue to limit the potential of agricultural growth to reduce food security and poverty on the continent. This article reviews some of the historical trends that have hampered the performance of the agriculture sector. In addition, it reviews the impacts of more positive trends that could stimulate agricultural growth in Africa that could change the African agricultural landscape. The article however warns that there are more recent global developments and some continental challenges that could prevent or slow agricultural growth. These include the global financial crisis, public sector investments, inequities in global agricultural development policies, rush for agricultural lands by foreign investors, domestic commercial financing markets, climate change, and emerging carbon markets. The article argues that while opportunities for accelerated growth exists for African agriculture, new sets of policy instruments will be needed to support smallholder farmers to access new agricultural technologies, finance, reduce impacts of climate change, and adopt sustainable land use practices that can allow them to benefit from emerging global carbon markets.  相似文献   

7.
The purpose of this study was to assess the effect of grassland (GL) conversion to cropland (CL) and cropland conversion to forest (FL) and orchard (OL) on soil C and N distribution in dry aggregate size fractions in Nihegou catchment of the southern Loess Plateau, China. Four main land-use changes were analyzed in different agronomic management systems in 2006. The soil is wind-deposited loessial parent materials with a rather homogeneous silty clay loam texture classified as Calcic Cambosols. The GL was long-term over-used grassland. The CL was changed from GL after 33 years tillage with conventional tillage and fertilizer. The FL and OL originated from long-term CL after 23- and 7-year planted, respectively. Samples were taken at soil depths of 0–20 cm and 20–50 cm and were subjected to a physical fractionation process by way of aggregate size. Soil aggregate size fractions, total C and N contents and distributions were determined on all soil samples. Three dry aggregate fractions of very coarse (2.0–0.2 mm), coarse (0.2–0.05 mm) and fine (<0.05 mm) were obtained by shaking and sieving for 20 min. After 33 years of tillage, CL had 22% lower content of very coarse aggregates (2.0–0.2 mm) and 34% higher contents of fine aggregates (<0.05 mm) than GL. FL and OL soils had increased 9% and 10% contents of very coarse aggregates, and decreased 2% and 8% contents of fine aggregates compared to the CL. C and N losses in whole CL soils were 31% and 26% higher than those in GL. However, conversion of land uses from CL to FL (after 23 years) and OL (after 7 years) has increased C and N stocks by 76% and 40% in FL soils and by 66% and 63% in OL soils, respectively. This accessorial C and N stocks were higher in very coarse aggregate fractions (1.10 kg C m−2 and 0.13 kg N m−2 in FL soils, 1.43 kg C m−2 and 0.17 kg N m−2 in OL soils); moreover, the C and N stocks in fine aggregate fraction increased by 8% and 33% in FL soils and by 58% and 69% in OL soils, respectively. This results showed that C and N turnover and loss in aggregate fractions of this silty clay loam soils was very fast. Conversion of land uses from CL to FL and OL has obviously recovered the soil structure, and improved soil quality.  相似文献   

8.
文章通过2004~2013年河南省耕地压力指数的直观数据,分析了2003年以来河南省耕地面积、粮食播种面积、粮食产量及常住人口的动态变化情况,发现河南省2003~2012年耕地压力指数与最小人均耕地面积变化趋势呈现出相同的波动状态,即先呈下降趋势,后在较小的波动中趋于稳定,表明2003~2012年间河南省无明显耕地压力,粮食产量足以满足人口需求。同时,文章利用灰色系统理论与线性回归分析等工具对影响河南省耕地压力指数的粮食单产、实际人均耕地面积等因素的变化进行了GM(1,1)模型的构建、修正及线性回归方程的建立,测算出以后若干年河南省耕地压力指数。研究表明,未来10年河南省耕地压力指数远小于1,耕地供应能力可以满足粮食生产需求。在肥力改善,耕地巨大生产能力得以保持的基础上,优化农业种植结构,退耕还林还草,改善农业生态,甚至开发休闲农业等,都将成为可能。  相似文献   

9.
Pereira HC 《Land use policy》1993,10(3):187-190
Governments have frequently ignored the issue of population consumption exceeding the rates of renewal of natural resources. At the UN Conference on the Environment and Development in Rio de Janeiro, the issue of population growth was ignored in the agenda and action plan. In 1974, the UN World Population Conference suggested population stability would be possible if standards of living were raised. Industrialized nations spent half a century of active interference with the stability of global populations and failed to slow growth. 27 countries, mainly in tropical and subtropical zones, have an average cereal yield of under 1 ton per hectare, when improved seed and basic minimum fertilizer could yield 2 tons per hectare. Efforts to increase yields by the Consultative Group for International Agricultural research in 13 international centers resulted in global annual increases of about 50 million tons of grain (wheat and rice). Rainfed agriculture did not benefit as much because of climatic conditions. Where varieties of triticale, sorghum, millet, groundnuts, chick peas, cowpeas, beans, and cassava have helped increase food production, population growth has outstripped the gains. Agricultural fertilizers have been unfairly blamed for soil nutrient losses. Because of the age structure of population, the expected population growth can only be addressed through development of higher yields, new strains resistant to disease, and fertilizers. Slow release phosphates for tropical soils are needed. Shortages of domestic fuel divert much needed farmyard manure and composted crop residues. About 400 million tons of dung are thus wasted annually; food grain harvests are thus reduced by 14 million tons. About 50% of the 1133 million poorest people will live in Asia and another 25% will live in Sub-Saharan Africa, living on a total degraded area of 1219 million hectares. Imbalance between food supply and population need to be addressed on an effective international scale.  相似文献   

10.
Recent demographic change, mainly characterised by a decreasing and ageing population, is seen as one of the main factors for future land use development in Europe. However, there is still insufficient evidence about the relationship between demographic changes and land use changes since quantitative studies dealing with these interactions are still rare. We aim to fill that gap by presenting the first comprehensive study that investigates statistical relationships and spatial differentiations between demographic and land use change for the whole of Germany. Our study is based on data for the period from 1995/1996 to 2003/2004. The results clearly show that in most growing regions in the West of Germany a correlation was found between land use, natural population growth and net-migration, whereas for land use change in the shrinking regions in the East of Germany economic variables are of noticeable importance. A cluster analysis reveals “gaining” and “shrinking” regions concerning both urbanisation and demographic change. Neither a decreasing nor an ageing population imply reduced land consumption for housing and transportation. Furthermore we found a decreasing settlement population density for almost all German districts regardless of population growth or shrinkage.  相似文献   

11.
Urban agriculture (UA) can be highly productive in terms of yield per unit area, however productivity is limited by available land and high input requirements. We determined how much of the food supply of Sydney, Australia, could be produced through UA by synthesising yield data from 13 UA gardens with information on labour and key material inputs and using spatial analyses to assess available land area. We modelled three scenarios with varying proportions of available land used for food production; 25 %, 50 % or 75 % of domestic yard space along with street verges and unused land (e.g. vacant lots). Around 15 % of Sydney’s total food supply, or its entire vegetable supply, could be produced through UA under the low range scenario, increasing to 34 % under the highest land use scenario. Under the low range scenario, all necessary irrigation water and organic soil amendments could be obtained from local waste streams, though these sources were insufficient to meet the needs of higher range scenarios. Available labour was a limiting factor in all scenarios, with the entire population being insufficient to meet labour needs required to maintain food production under efficiency and labour investment regimes typical of amateur urban gardeners. Establishing a professionalised UA workforce with greater labour efficiency would be required for managing the available land, however this scenario would likely require changes in public attitudes towards use of private land. These social issues, rather than physical limitations, may be the biggest factors preventing cities like Sydney from obtaining a non-trivial proportion of their food supply from UA.  相似文献   

12.
Land use and land cover changes have complex linkages to climate variability and change, biophysical resources, and socioeconomic driving forces. To assess these land change dynamics and their causes in the Great Plains, we compare and contrast contemporary changes across 16 ecoregions using Landsat satellite data and statistical analysis. Large-area change analysis of agricultural regions is often hampered by change detection error and the tendency for land conversions to occur at the local-scale. To facilitate a regional-scale analysis, a statistical sampling design of randomly selected 10 km × 10 km blocks is used to efficiently identify the types and rates of land conversions for four time intervals between 1973 and 2000, stratified by relatively homogenous ecoregions. Nearly 8% of the overall Great Plains region underwent land-use and land-cover change during the study period, with a substantial amount of ecoregion variability that ranged from less than 2% to greater than 13%. Agricultural land cover declined by more than 2% overall, with variability contingent on the differential characteristics of regional human-environment systems. A large part of the Great Plains is in relatively stable land cover. However, other land systems with significant biophysical and climate limitations for agriculture have high rates of land change when pushed by economic, policy, technology, or climate forcing factors. The results indicate the regionally based potential for land cover to persist or fluctuate as land uses are adapted to spatially and temporally variable forcing factors.  相似文献   

13.
The global land use implications of biofuel expansion have received considerable attention in the literature over the past decade. Model‐based estimates of the emissions from cropland expansion have been used to assess the environmental impacts of biofuel policies. And integrated assessment models have estimated the potential for biofuels to contribute to greenhouse gas (GHG) abatement over the coming century. All of these studies feature, explicitly or implicitly, competition between biofuel feed stocks and other land uses. However, the economic mechanisms governing this competition, as well as the contribution of biofuels to global land use change, have not received the close scrutiny that they deserve. The purpose of this article is to offer a deeper look at these factors. We begin with a comparative static analysis which assesses the impact of exogenously specified forecasts of biofuel expansion over the period: 2006–2035. Global land use change is decomposed according to the three key margins of economic response: extensive supply, intensive supply, and demand. Under the International Energy Agency's “New Policies” scenario, biofuels account for nearly one‐fifth of global land use change over the 2006–2035 period. The article also offers a comparative dynamic analysis which determines the optimal path for first and second generation biofuels over the course of the entire 21st century. In the absence of GHG regulation, the welfare‐maximizing path for global land use, in the face of 3% annual growth in oil prices, allocates 225 Mha to biofuel feed stocks by 2100, with the associated biofuels accounting for about 30% of global liquid fuel consumption. This area expansion is somewhat diminished by expected climate change impacts on agriculture, while it is significantly increased by an aggressive GHG emissions target and by advances in conversion efficiency of second generation biofuels.  相似文献   

14.
A high level of fragmentation of farmland ownership is an important underlying cause of land degradation and, at the same time, an obstacle to sustainable land management. This study makes the first-ever analysis of long-term trends in the rate of fragmentation. Our study covers the period from the earliest stages of the current form of ownership patterns at the end of the 18th century until the present day. On the basis of significant predictors that have been identified (initial fragmentation, population growth, historical development of inheritance laws and of the land market, natural soil fertility and landscape type), we go on to project probable developments for the period from 2016 to 2045. A total of 102,984 land parcels in 56 cadastral units in the territory of Czechia have been analysed on the basis of data from four years (1785, 1840, 1950, 2015). Our study considers the development of two basic indicators of fragmentation – Mean Parcel Size and Number of Owners per 100 ha. The Mean Parcel Size has decreased over a period of 230 years from 1.08 ha to 0.64 ha, at a mean rate of −0.26% year−1. During the same period, the Number of Owners per 100 ha has risen from 17.50 to 79.66, at a mean rate of 0.61% year−1. A detailed analysis of the development trends confirms significant spatial variability and also time variability of the rates of the two indicators. The analysis also shows their mutual complementarity: growth in the rate of one of the indicators is usually accompanied by a drop in the other. The general trend that we project for the territory of Czechia in the upcoming 30 years is that there will be further diminution of the physical size of land parcels (continuing fragmentation of land parcels) accompanied by a reduction in the Number of Owners (defragmentation of land ownership).  相似文献   

15.
Creating private property rights and establishing land markets were fundamental to the historical development of capitalism in the Global North and remain at the centre of capitalist development in the Global South. This article contributes to debates about these processes by analysing the relationship between land markets and indigenous peoples in Highland Ecuador. Building on Karl Polanyi's concept of fictitious commodities, it elaborates a new concept that makes an analytical distinction between the activation and development of land markets. The former refers to the occasional participation of actors in markets to secure land, whereas the latter relates to the establishment and expansion of markets that regulate the distribution and value of land through market prices. Focusing on indigenous land struggles in the late 20th century, this article shows that the activation of land markets created opportunities for indigenous peasants to secure land, whereas the development of land markets closed them down. Social and class differentiation among the highland indigenous population increased through this contradictory process. The article connects this historical analysis to recent developments in Ecuador to contribute to empirical and theoretical debates about contemporary land struggles and agrarian change elsewhere in the Global South.  相似文献   

16.
Soil is a natural resource essential to human welfare by virtue of its numerous crucial functions. In the past, soil has been taken for granted because of its widespread, albeit finite, availability. However, now that world's population is projected to exceed ten billion before the end of this century, soil is increasingly perceived as a precious commodity. Consequently, soil is increasingly under pressure by rich private investors and governments within the poorest countries to satisfy appetites for food production and biofuel. A case study is used to explore the plausibility of soil being considered as ‘brown gold’. Based on the comparison of land use maps, we estimated the value in terms of resource from raw material, carbon sink and virtual calories of the productive soil lost during the period 2003–2008 in the Emilia-Romagna Plain, one of the most productive areas of Italy. More than fifteen thousand hectares of cropland underwent land use change – in particular urbanization – over the 6-year period with an implied loss of crop production potential equivalent to the daily calorific requirement of more than 440,000 people. Taking into account that Italy is no longer self-sufficient in food production, such a loss appears to be strategically significant. Perhaps more importantly, urbanization and soil sealing has had negative ramifications on environmental sustainability, on both local and broad scales, with increased consumption of public funds. A logical framework of the socio-economic impact of land use change has been compiled and is presented as a possible example of a policy relevant approach to managing productive soils as a finite resource.  相似文献   

17.
合肥市人口-耕地-粮食系统的可持续发展研究   总被引:1,自引:0,他引:1  
根据1980—1999年合肥市耕地、人口、粮食等资料,定量分析在城市化快速发展下耕地的数量变化、质量状况和耕地减少的形式以及人口、粮食的变化,并用回归法分析它们的变化趋势。研究认为在2005年、2010年合肥市食物保障能力分别在97%和95%;提出提高粮食产量的对策和实现途径,为合肥市在实行城市可持续发展的同时,做好耕地—人口—粮食系统生产发展决策、提供科学依据。  相似文献   

18.
Historically, land use in Britain has been shaped by the environment's capacity to provide energy as well as food, water and shelter. Over the next decades, energy will again become a major driver in land cover change as we seek to capture the necessary energy to replace fossil fuels, reduce environmental damage and substitute for insecure supplies. Britain was one of the first places to exploit fossil fuels extensively, initially coal, and it has the potential to generate considerable amounts of renewable energy from tides, waves, the wind, biomass and sunlight. The UK Government's policy is to develop a suite of technologies that will provide a resilient supply without compromising its economy or its international commitments to environmental protection.This paper examines the three major terrestrial options for renewable energy and assesses each by successively filtering them for feasibility, achievability and practicality incorporating existing developments, designation and public opinion. Technology and opinion are dynamic, so the outputs need to be viewed as indicative of alternative scenarios rather than as fixed forecasts. Implications for changes in the energy supply infrastructure needed to match the new supply chains are highlighted.The demand for energy depends on the demographic profile (population size, age distribution, lifestyle and expectations) and on economic activity. Here total demand is predicted using the UK Energy Research Centre's Energy 2050 model, which uses linear programming to balance economics and environmental capacity by major demand sectors in five-year time steps. The core model often generates challenging results.  相似文献   

19.
After the GATT agreements in 1986, which removed the existing external protection on wine market, and with demand developing towards a qualitative level, the European wine sector has been subjected to a continuous transformation to accomplish that main objective. To give producers the chance to bring production into line with market developments and to allow the sector to become permanently competitive, the European Commission established the Council Regulation (EC) No. 1493/1999) on the common market organization in wine, later adopted in the 2003 CAP reform. Among other measures, this regulation finances the restructuring of a large part of present vineyards by adopting new farming systems (EC Council Regulation No. 1227/2000), supporting actions as soil preparation, which includes land levelling and terracing. Traditional vineyard areas in Mediterranean mountain environments, with subsistence agriculture and farming systems based on man and animal labour, have taken advantage of the new market opportunities in the wine sector and of this policy as well, and have changed to a market-oriented farming strategy. It has involved the construction of terraces on hillslopes using heavy machinery with the objective of crop mechanization, which has supposed important changes in soils and landscape. An example of this situation is the Priorat region (Catalonia, NE Spain), where vineyards have been cultivated on hillslopes by human and animal labour since the 12th century. Since the early 1990s the region has been undergoing major changes arising from new wine market opportunities and later by vineyard conversion and restructuring EU policy, which subsidizes up to 50% of the cost. In this paper we consider two aspects of the changes that modern farming systems are causing in the region: (a) land use changes after the coming into practice of the EU vineyard restructuring policy and (b) terrain morphology changes due to land terracing and related geomorphological effects. The results show high terracing rates (22.6–36.1 ha year−1) in the study period (1998–2006), accompanied by huge land movements (a cutting rate of about 5475 m3 ha−1). Bad design of terraces has led to the collapse of benches and borders, affecting about 3.5% of the newly planted area. These effects question the suitability of the EU CAP for vineyard restructuring in Mediterranean mountain environments, revealing that although farmers comply with environmental protection requirements, CAP support is not accomplishing the objectives for which was conceived: the protection of the environment by the reduction of impacts of the agricultural activities.  相似文献   

20.
This paper provides an original accounting of changes in livestock production efficiency per livestock category in historical perspective and connects livestock consumption with land requirements and virtual land trade. We use France as a demonstration study and account for productivity changes in terms of energy. Feed rations composition are reconstructed per livestock production and feed crop group over time to account for changes in land use in relation to dietary changes. Land requirements for consumption in France dropped by 28% over the study period besides an increase by 35% of the human population and by 53% of the livestock consumption. The two-fold increase in agricultural productivity is due, for half, to energy conversion efficiency improvements and for half to agricultural yields. Overall, the livestock energy conversion efficiency increased by 45% from 1961 to 2010, poultry gained 84%, pork 17%, sheep&goat 67% and cattle 27%. The feed share of oilcrops and cereals in animal rations doubled against a drop by 35% of feed from pastures. Virtual land imports for oilcrops in relation to livestock consumption in France today amount to 0.9 million ha against a maximum of 1.9 million ha in 1979. Besides its dependence on oilcrops imports, the French livestock sector displays net virtual land exports ranging from about 2.5–5.3 million ha per year over the study period. Gross virtual land trade is today five times higher than the net virtual trade. The difference highlights the share of circular product loops in increasingly integrated agricultural markets at the international scale.  相似文献   

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