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1.
Soil organic carbon (SOC) sequestration and soil redistribution are linked to soil properties, land use, farming system and climate. In a global‐change context, landscape and climate changes are expected and will most probably have impacts on changes in the soil. Soil change was simulated from 2010 to 2100 in an 86‐ha hedgerow landscape under different scenarios of landscape and climate changes. These scenarios combined contrasting land uses, hedgerow networks and climates. Two models were combined to evaluate the impact of these scenarios on soils: LandSoil, a soil redistribution model, and a SOC model based on RothC‐26.3. A soil thickness of 105 cm was considered. The results indicate that the main factor influencing soil degradation was land‐use change: when compared with the baseline business‐as‐usual landscape, the landscape with the most intensive agricultural systems had the greatest soil erosion (+0.26 t ha?1 year?1) and reduced mean SOC stocks (?17 t ha?1 after 90 years). The second significant factor was climate change, followed by hedgerow network density. Sensitivity to climate change differed between landscapes, and the most sensitive were those with continuous winter wheat. The results indicate that a hedgerow landscape is well adapted to protect soil (regarding carbon storage and soil erosion) in a context of climate change. However, this type of landscape is highly sensitive to cropping intensification and should be protected.  相似文献   

2.
For a case study area in the Okhombe catchment in the province of KwaZulu‐Natal, South Africa, a multi‐scale analysis of soil erosion dynamics was performed. At sub‐catchment level, the dynamics of erosional features were investigated by means of aerial photographs. At site level, the changes in soil physical and chemical properties were investigated by means of a fence‐line contrast study. Attention was paid to both surface and subsurface erosion phenomena. The number of erosional features in the study area in 2000 was not substantially different from the number of features in 1945. At sub‐catchment level, an increase in the number of gullies was observed from 1975 to 2000 but this followed a substantial inactivation of most erosional features from 1962 to 1975. Increases in erosional activity in 1962 compared to 1945 were mainly related to abandoned cultivated fields. At site level, a significant decrease in soil C/N ratio was observed within the fenced site within three years. For the same site, total carbon, saturated hydraulic conductivity and bulk density were not significantly different for the topsoil inside the fenced area compared with outside. Subsurface erosion phenomena mainly occur in the communal grazing areas and are mostly related to transitions between permeable and less permeable layers. The complex relationships between soil erosion, land use change and climate might further be understood by involving local people in the development, monitoring and evaluation of alternative types of land use, which is also likely to facilitate future steps in controlled grazing management. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

3.
The interaction between land use/cover change and landscape pattern is pivotal in research concerning global environmental change. This study uses three different Landsat images of 1989, 1998 and 2009 to study the land use/cover and landscape pattern changes in the middle reaches of the Tarim River basin. envi ®, erdas ®, ArcGIS ® and fragstats ® software were used to analyse the land use/cover changes. The objectives of study were to map and study the changes in land use/cover and landscape pattern, and propose some possible factors in making the land use/cover changes from 1989 to 2009. Seven different types of land use/cover are analysed, and the results are listed in tables. From 1989 to 1998, the percentage of farmland, slight–moderate saline land, heavy saline land and water areas have increased; woodland, desert and the undeveloped land have decreased. From 1998 to 2009, farmland, heavy saline land and the undeveloped land have increased; the other types of land use/cover have decreased. The gravity centre of each land use/cover types has shifted. The farthest shifting of the gravity centre was heavy saline land, which occurred between 1989 and 1998. The transformation and changes of land use/covers and landscape occurred more frequently from 1989 to 2009. Other types of land use and land cover changes to saline land have increased, which implied that a serious salinization took place in the Tarim Basin. The results from this study would show the adverse environmental changes (e.g. salinization and desertification) and they can be used for future sustainable management of land resources. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

4.
In this study, we used image‐processing techniques to examine the spatial pattern of land‐use and land‐cover (LULC) change that occurred in the coffee growing area in the Western Ghats of India during the international coffee crisis in the 1990s. The study also ascertains the driving forces of these changes using qualitative research methods that include archival studies and interviews of knowledgeable individuals. We analyzed Landsat Thematic Mapper (TM) for 1991 and Landsat ETM+ for 2002 to quantify LULC. Historical land‐use changes in different land ownership regimes were also analyzed. Global coffee market fluctuations were found to be the major cause of landscape change in the study region. When the global coffee prices increased, more forested areas were cleared for coffee cultivation. Failure of global coffee market forced farmers to convert land from subsistence farming (rice) to short‐period commercial crops like ginger. This also resulted in land degradation in rice paddies. For the farmers in the Western Ghats, LULC decisions are one of the methods used to cope with the vulnerability created due to the international coffee crisis. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

5.
Impacts of land use and climate change on runoff were investigated by studying the runoff in the Yarlung Zangbo River basin, China. Trends in precipitation, mean air temperature, and runoff were analysed by non‐parametric Mann‐Kendall tests. Land‐use changes were examined with land‐use transition matrix and geographic information system tools. Land‐use and climate changes showed several characteristics, including increased reforestation, decreased grassland, retreat of glaciers and increased desertification. Human activity caused great impact, especially within densely populated regions and cities. Reforestation and degradation of grasslands were more frequent than deforestation and cultivation of grasslands. Annual mean air temperature, precipitation and runoff showed increasing trends between 1974 and 2000. The impacts of land use and climate change on runoff had different effects depending on region and season. In the season of freezing, climate change clearly affected runoff within regions that experienced precipitation. Altered evapotranspiration accounted for about 80 per cent of runoff changes, whereas land‐use changes appear to have had greatest impact on runoff changes within regions that have inconsistent relationships between runoff and climate change. It was demonstrated that afforestation leads to increased runoff in dry seasons. It was estimated that glacier snow melt has caused annual runoff to increase at least 6·0 mm/10yr, 2·1 mm/10yr and 1·7 mm/10yr in Regions 1, 3 and 4, respectively, whereas evapotranspiration caused annual runoff to decrease at least 7·4 mm/10yr in Region 2. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

6.
北方农牧交错带界线变迁区的土地利用与景观格局变化   总被引：11，自引：2，他引：9  
交错带是相邻生态系统的边缘交汇带,是陆地生态系统对全球变化和人为干扰响应较为敏感的地段。在全球气候变化和人为干扰的影响下,北方农牧交错带的地理位置和界线不断变迁,界线变迁区的土地利用和景观格局也处于快速的变化之中。该文基于气象和土地利用数据,利用遥感、GIS技术和景观生态学方法,界定了北方农牧交错带及界线变迁区的地理位置,并分析了1986-2000年界线变迁区的土地利用和景观格局时空变化特征。结果显示:(1)北方农牧交错带的西北界、东南界缓冲区土地利用结构变化、不同地类之间的相互转化及土地利用动态度变化存在明显区域差异;(2)西北界、东南界缓冲区景观重心迁移的距离和方向、景观格局变化呈现出不同的特征。  相似文献   

7.
The research community increasingly analyses global environmental problems like climate change and desertification with models. These global environmental modelling studies require global, high resolution, spatially exhaustive, and quantitative data describing the soil profile. This study aimed to develop a pedological approach that takes stock of available legacy and auxiliary data to create a global, 30 arc second soil property database for modelling. The methodology uses the Harmonized World Soil Database and the ISRIC‐WISE 3.1 soil profile database. Auxiliary information at 30 arc second resolution for various landscape properties is used to describe the variation in landscape properties (temperature and precipitation, topography, elevation, land use, and land cover). Complex mapping units of the HWSD were first disaggregated using a digital elevation model and toposequences to generate delineated areas described by a single soil type. Secondly, ranges of soil properties per soil type were determined using the soil profile data. Then a meta‐analysis on a broad literature survey was used to develop a simple model that, based on landscape properties at a particular location, determines the position within these ranges and thus provides an estimation of the local soil properties. Finally, the model was implemented at the global level to determine the distribution of soil properties. The methodology, denominated S‐World (Soils of the world) resulted in readily available, high resolution, global soil property maps that are now available for environmental modelling. © 2016 The Authors Journal of Behavioral Decision Making Published by John Wiley & Sons Ltd.  相似文献   

8.
Landscape adaptation to climate change requires policies that facilitate species dispersal, to counteract the effects of fragmentation and allow tracking of a species’ ‘climatic niche’. Expanding existing ecological networks is often proposed as a measure to maintain functional connectivity for forest species in multi-functional landscapes.In the next decades, however, such networks will be threatened by climate change through its effects on land use change, as global drivers are likely to have an increasing influence on national land use policy. Evaluation of indirect effects of climate change, on habitat networks, mediated by land use change, is therefore needed. We used an approach integrating climate, soil properties, and landscape resistance to dispersal, the latter estimated using Circuit Theory, to evaluate the vulnerability to land use change of forest habitat networks in Scotland, given two scenarios of land use change. In Scotland a combination of high food prices and improved land capability for agriculture could lead to decreased landscape connectivity for woodland species, especially in the East and South, with potentially large trade-offs between agriculture and woodland connectivity in the case of loss of woodland on prime agricultural land. We suggest that planning of ecological networks needs to account for future land use change. Adaptation and mitigation strategies across multiple sectors should be reconciled. Woodland networks will benefit from minimising creation of new woodlands on future prime agricultural land, the protection of existing patches, and the creation of wide-scale dispersal pathways along climatic gradients, i.e. in the N–S and E–W directions.  相似文献   

9.
We use a simple single‐pool model of soil carbon turnover to evaluate possible explanations for the widespread changes in the organic carbon contents of mineral soils across England and Wales, measured in the National Soil Inventory between 1978 and 2003. We provide a means of quantifying the changes in rates of soil organic carbon decomposition in relation to inputs from vegetation required to explain the results. We find that neither changes in decomposition resulting from the effects of climate change on soil temperature and moisture, nor changes in input, could by themselves account for the overall trends. Past changes in land use and management were more likely explanations. Any climate‐change signal is masked by these other changes.  相似文献   

10.
1962-2010年玛纳斯流域耕地景观的时空变化分析   总被引：7，自引：5，他引：7  
为分析近几十年来玛纳斯流域水资源开发密集开发条件下耕地景观的时空变化,采用1962年、1977年、1989年、2000年和2010年5期遥感影像进行土地利用制图,并针对耕地信息,分别从时间变化过程、类型转化关系、空间格局等方面分析了近50 a来面积变化的时空特征,从气候变化与灌区建设的角度探讨了水资源空间配置与耕地扩张的关系。结果表明:1)近50 a来耕地和建设用地面积持续增加,未利用地、湿地和冰川雪地持续减少,草地在前20年增加、后30年减少;土地利用的变化程度总体上由剧烈逐渐趋于缓和;2)整体上耕地的变化由双向转化期逐渐过渡到单向转入期,草地和未利用地为各期主要转入类型,建设用地和草地为主要转出类型,各期的转入面积远大于转出面积,耕地总面积持续、快速增长。3)耕地扩张的重心由城市周边转向荒漠地区、由上游地区逐渐转移到下游,先后在昌吉、呼图壁、沙湾县、主要河流两岸及北部荒漠地区扩张,耕地景观也由杂乱破碎转的斑块转为成片连续的耕地带,耕地在景观中的优势进一步加强。4)耕地面积的扩张与降水和河川径流量的增加有关,耕地的扩张速度与方向与水库的空间分布及建成时间有明显的相关性,水库及灌渠建成的后一个时段往往会伴随一轮耕地的快速扩张。流域内水资源开发的潜力不足,已不能满足耕地的大规模扩张。适当控制耕地规模、优化用水结构、提高水资源利用效率,是集约化农业发展、生态环境保护的关键。  相似文献   

11.
自1997年中国三峡大坝成功截流以来，对库区土地利用和景观格局产生复杂影响。该文采用遥感技术和景观格局评价方法对奉节和巫山两个移民大县在1998年到2000年的土地利用变化进行监测研究。在大江截流后一年半时间内，该区域22.9%土地利用发生了变化，表明移民安置工作速度显著加快。新开发用地变化最为明显，增加4800.8 hm2，扩展626.6%。 而耕地面积则减少了18567.9 hm2，下降约27.6%。这些土地利用变化导致区域景观发生了变化。斑块密度增大了29.5%，连通度下降了13.9%，表明移民安置导致区域景观进一步破碎化。景观形状指数上升了17.7%，斑块形状进一步复杂和不规则。研究结果表明土地利用变化并未按照移民安置规划有序进行，应进一步控制新开发用地扩展速度和范围，对不适合农业用地的新开发用地及时进行退耕还林草工作。  相似文献   

12.
土地利用景观格局反映环境特征及社会经济发展模式,可为资源开发和环境保护提供参考。应用1988年、2000年和2009年遥感数据,通过遥感信息提取、景观格局指标和转移矩阵计算,研究西藏曲水—桑日地区土地利用时空演变特征。结果表明:1988—2009年,研究区土地利用时空演变显著,各地类均发生转移,转移面积约占总面积的6%,灌木林、滩地、沙地和草地变化较大;耕地和沙地面积先增后降,建筑用地和工矿用地持续增长,高山湖泊面积总体减少;平均斑块面积增加,斑块密度减小,蔓延度先增后减,边缘密度、总边界长度和散布与并列指数先减后增;地类破碎度增加,有林地、建筑用地和工矿用地边缘密度增加;耕地、滩地、沙地和有林地平均斑块面积先增后减;滩地和湖泊散布与并列指数减小,工矿用地增大。该结果对土地资源保护具有重要意义。  相似文献   

13.
Adoption of input‐responsive varieties enhanced food production during the second half of the 20th century. However, even bigger challenges lie ahead because of the growing societal demands. For example, the global population of 7.2 billion in 2013 is projected to reach 9.2 billion by 2050 and stabilize at 10 billion by 2100. The growing and increasingly affluent population, with preference towards more and more meat‐based diet, is likely to jeopardize the finite, fragile, and dwindling soil and water resources which are already under great stress in densely populated countries in Asia and elsewhere. Economic growth and increase in gross domestic product also lead to generation of waste or by‐products, along with contamination and eutrophication of water resources. International trade in food/feed products also involves transfer of virtual water, which is a serious issue when water‐scarce countries export virtual water to water‐endowed countries. The problem is confounded by the present and future climate change driven by the growing energy demands of the carbon civilization. Thus, adaptation to climate change represents both a threat and an opportunity for sustainable development. Adaptive strategies must be sustainable socially and environmentally and advance the Millennium Development Goals, while buffering agroecosystems against extreme climate events (e.g., pedologic, agronomic, and ecologic drought). Thus, recognizing and addressing the water‐soil‐waste nexus is important to achieving climate‐strategic agriculture. Sustainable intensification of agroecosystems, producing more per unit consumption of essential resources, must consider judicious management of hydrological and biogeochemical cycles (C, N, P, S). The soil C pool must be managed and enhanced to offset anthropogenic emissions, and mitigate/adapt to the climate change. The pace of adoption of recommended land use and soil‐/plant‐/animal‐management practices can be kept at par with advances in scientific knowledge through continuous dialogue between scientists on the one hand and policy makers / land managers on the other to translate research data into policy and action plans.  相似文献   

14.
Landsat images acquired in 1987, 1999 and 2008 were selected to evaluate land use and land cover changes in three different ecological zones in the Republic of the Sudan: savannah (North Kordofan), semi‐desert (River Nile) and desert (Northern State). Maps of soil, vegetation and non‐photosynthetic material were built by spectral mixture analysis using endmembers spectra derived from images. Multitemporal comparison techniques were then applied to vegetation and soil maps to estimate the long‐term land degradation/re‐growth dynamics and to emphasize land cover variation over time and in space. Multitemporal comparisons have shown that site‐specific interactions between natural processes, climate variation and human activity played a pivotal role in land use and land cover change. In savannah, human activities strongly affected degradation phenomena. Expansion of villages triggered a change in land use and mismanagement of the natural resources, mainly caused by deforestation to supply wood for domestic uses. The degradation then promoted sand encroachment and dune migration. On average, 48% of the total area was subjected to medium (25–50%) and high (50–75%) land degradation. Differently, climatic constraints drove increasing degradation processes in semi‐desert and desert zones. The phenomenon was particularly severe in the desert zone. In each site, an inversion of the general trend was due to a land use change where forestry or agricultural projects were established, partly sustained in savannah by the positive rainfall trend of the last two decades. Site‐specific strategies that take into account the interactions of the driving factors at local scale are thus necessary to combat land degradation. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

15.
The aim of this study was to assess the consequences of feasible land‐use change in Great Britain on GHG emissions mainly through the gain or loss of soil organic carbon. We use estimates of per‐area changes in soil organic carbon (SOC) stocks and in greenhouse gas (GHG) emissions, coupled with Great Britain (GB) county‐level scenarios of land‐use change based on historical land‐use patterns or feasible futures to estimate the impact of potential land‐use change between agricultural land‐uses. We consider transitions between cropland, temporary grassland (<5 yr under grass), permanent grass (>5 yr under grass) and forest. We show that reversion to historical land‐use patterns as present in 1930 could result in GHG emission reductions of up to ca. 11 Mt CO2‐eq./yr (relative to a 2004 baseline), because of an increased permanent grassland area. By contrast, cultivation of 20% of the current (2004) permanent grassland area for crop production could result in GHG emission increases of up to ca. 14 Mt CO2‐eq./yr. We conclude that whilst change between agricultural land‐uses (transitions between permanent and temporary grassland and cropland) in GB is likely to be a limited option for GHG mitigation, external factors such as agricultural product commodity markets could influence future land‐use. Such agricultural land‐use change in GB could have significant impacts on Land‐use, Land‐Use Change and Forestry (LULUCF) emissions, with relatively small changes in land‐use (e.g. 5% plough out of grassland to cropland, or reversion of cropland to the grassland cover in Nitrate Vulnerable Zones of 1998) having an impact on GHG emissions of a similar order of magnitude as the current United Kingdom LULUCF sink. In terms of total UK GHG emissions, however, even the most extreme feasible land‐use change scenarios account for ca. 2% of current national GHG emissions.  相似文献   

16.
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17.
World energy consumption increased from 11.5 EJ in 1860 to 463 EJ in 2005, and is projected to be 691 EJ in 2030 and 850 EJ in 2050. The principal driver of such a drastic surge in energy demand is the increase in world population which was merely 1 billion in 1800, 1.6 billion in 1900, 6.0 billion in 2000, and is projected to be 7.5 billion in 2030 and 9.2 billion in 2050 before stabilizing at ≈10 billion by 2100. Heavy reliance on fossil‐fuel consumption has increased atmospheric CO2 abundance from 280 ppm in 1750 to 383 ppm in 2008 and is increasing at ≈2 ppm (4.2 Pg) per year along with the attendant threat of climate disruption. Similar to the close link between energy use and atmospheric chemistry, there also exists a close link between food insecurity and climate change through degradation of soils and desertification of the ecosystems. Global annual per capita cereal consumption increased from 267 kg in 1950, peaked at 339 kg in 1985, and decreased to 303 kg by 2000. In the quest for identifying alternate sources of energy, world production of bioethanol (mostly from corn grains in USA and sugarcane in Brazil) was 65 billion L, and that of biodiesel was 13 million Mg (t) (55% in EU countries) in 2008. Conversion of lignocellulosic biomass, using crop residues or establishing energy plantations, has severe constraints of the additional requirements for land area, water, and plant nutrients. Removal of crop residues for energy and other uses has severe adverse impacts on soil quality and agronomic productivity. Yet, globally average crop yields must be increased by 60% to 120% between 2000 and 2050 for meeting the needs of increase in population and change in dietary habits. Meeting demands of the growing world population and rising aspirations necessitate serious and objective considerations of change in food habits (to a more vegan diet), improvement in energy‐use efficiency, increase in crop yield per unit area and input, restoration of degraded soils and ecosystems, widespread adoption of recommended soil and crop practices, and identification of non‐C fuel sources.  相似文献   

18.
With ever intensifying land use, land degradation is becoming an increasingly important issue around the world, especially in China. This paper evaluates the extent and underlying causes of rangeland degradation on the Qinghai‐Tibet Plateau in China through a comprehensive review of the literature. Diverse forms and differing intensities of rangeland degradation have been reported in several regions of the Plateau. Rangeland degradation is particularly severe in South Qinghai, North Tibet and the Qaidam Basin. Anthropogenic activities, especially changing land use practices, are identified as the primary force driving rangeland degradation. Dissimilar to climate change‐induced degradation, such anthropogenic degradation is a rather short‐term process altering the abiotic properties of the underlying soil. On the basis of these findings, we assessed the prospects of rehabilitating degraded rangeland to productive uses. Different measures are proposed to rehabilitate rangelands that have been degraded by different mechanisms. Reduction in grazing intensity is prescribed to rehabilitate reversibly degraded rangelands. Targeted human intervention in the forms of selective planting of grasses and artificial seeding, in conjunction with ecological and biological control of the plateau rodent population, is recommended to rehabilitate ‘irreversibly’ degraded rangelands. Our studies suggest it is very difficult or even impossible to rehabilitate new assemblage of species which appear as a result of climate change. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

19.
The Mediterranean region has been regarded as a critical hotspot for desertification due to the impact of soil degradation, the land‐use changes and the climate variations. Few large‐scale studies have been devoted to analyse trends in land sensitivity to desertification in the northern Mediterranean basin. The present paper contributes to this deserving issue by quantifying the level of land sensitivity to desertification in Italy at seven points between 1960 and 2010 at a fine spatial scale. The approach used followed the Environmentally Sensitive Area scheme that assesses changes in four key themes (climate, soil, vegetation and land management) related to land degradation processes. Italian land was classified into four levels of sensitivity to desertification (non‐affected, potentially affected, fragile and critical) according to the Environmentally Sensitive Area framework. Interestingly, although land surface area classified as ‘fragile’ and ‘critical’ grew homogeneously in Italy between 1960 and 1990, the increase observed in the most recent time period was spatially clustered and contributed to reverse the polarisation in ‘structurally vulnerable’ and ‘non‐affected’ regions observed in Italy. The paper discussed these trends in the light of socioeconomic changes that occurred in Italy after World War II. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

20.
Land‐use dynamics in drylands are complex processes. In the context of a typical agropastoral village in northwestern Syria Im Mial, the effects of demographic and social changes, reduced soil productivity, changes in agricultural technologies and historical events on land use and land productivity are examined. Decreasing yields, mainly the result of reduced fallow periods and low investments in the land, and the deterioration of the grazing resources are the two main signs of the loss of land productivity in the area. The growing population forces the villagers to practise continuous rainfed barley cultivation with no or only occasional fallow, and without any application of plant nutrients. Also, technological changes, from the use of donkey ploughs and hand harvesting to less labour‐intensive and time‐consuming cultivation practices with tractors and combine harvesters, and the increased importance of stubble in the livestock diet have contributed to the reduction of the fallow periods. The villagers attribute the yield decreases mainly to the low rainfall in the area. The high rainfall variability discourages the fallowing of fields because continuous cultivation maximizes the chances for good harvests in years with high rainfall. There is also an expansion of cultivation into the less fertile and sloping traditional grazing areas. Population growth, increased numbers of livestock and the expansion of cultivated land into grazing areas has also put pressure on the grazing resources of the village. The possession of livestock is seen as a sign of wealth and the villagers aim to have large flocks of animals. For them, livestock is also an important means for investment of cash earned from off‐farm work, which is the main source of income for most of the households in the village. There is a recent trend of increasing levels of crop‐livestock integration with less free grazing that produces higher return to the land users. This may also have a positive effect on the restoration and conservation of the degraded natural traditional grazing grounds. The stabilization and productive use of the land resources in this dry environment requires the combined and interdisciplinary effort from both the land‐users and the policy‐makers. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

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