共查询到20条相似文献，搜索用时 312 毫秒
1.
While agriculture is expanded and intensified in many parts of the world, decreases in land use intensity and farmland abandonment take place in other parts. Eastern Europe experienced widespread changes of agricultural land use after the collapse of the Soviet Union in 1991, however, rates and patterns of these changes are still not well understood. Our objective was to map and analyze changes of land management regimes, including large-scale cropland, small-scale cropland, and abandoned farmland. Monitoring land management regimes is a promising avenue to better understand the temporal and spatial patterns of land use intensity changes. For mapping and change detection, we used an object-based approach with Superpixel segmentation for delineating objects and a Random Forest classifier. We applied this approach to Landsat and ERS SAR data for the years 1986, 1993, 1999, 2006, and 2010 to estimate change trajectories for this time period in western Ukraine. The first period during the 1990s was characterized by post-socialist transition processes including farmland abandonment and substantial subsistence agriculture. Later on, recultivation processes and the recurrence of industrial, large-scale farming were triggered by global food prices that have led to a growing interest in this region. 相似文献
2.
重庆市武隆县农地流转下农业劳动力对耕地撂荒的不同尺度影响 总被引：12，自引：1，他引：11
在农地流转市场日趋完善的背景下,农户间的耕地流转无疑会缓解因部分农户劳动力不足造成的耕地撂荒现象,但仅从农户尺度上分析难以揭示农业劳动力数量与耕地撂荒间的关系。运用重庆市武隆县17 个乡镇40个自然村的308 份农户调查数据,通过二分类Logistic 回归模型、简单相关和偏相关分析,从农户和村庄两个层次上探讨农业劳动力对耕地撂荒的影响程度及农地流转对两者关系的影响。结果显示：① 农户尺度上亩均农业劳动力对耕地是否撂荒的影响不显著,而在村庄尺度上显著。② 亩均务农劳动力与耕地撂荒规模的偏相关回归分析中,控制耕地流转和不控制流转条件下,农户尺度上两者的偏相关系数和简单相关系数分别为-0.138 和-0.027,前者在1%水平上显著,而后者不显著;村庄尺度上,控制流转和不控制流转的相关系数分别为-0.273 和-0.294,均在5%水平上显著。③ 在农地流转市场较为完善的地区,选择在村庄尺度上进行农业劳动力对耕地撂荒影响分析研究是比较合理的。 相似文献
3.
Cropland abandonment is spreading from developed countries to developing countries such as China. Cropland abandonment in China commonly occurs in mountainous areas due to their specific natural and geographical conditions. However, due to the lack of dependable monitoring methods via medium-high-resolution remote sensing images, the scale of abandoned cropland in many mountainous areas of China is unclear, and the mechanisms driving cropland abandonment have not been clearly identified. To overcome these limitations, we took Zhong County of Chongqing in China as an example, and used Landsat 8 OLI_TIRS remote sensing image data to develop a method for mapping abandoned cropland in mountainous areas based on annual land use change monitoring. At the same time, the ridge regression method was adopted to analyze the factors influencing cropland abandonment. These analyses showed that the cropland abandonment rate in Zhong County of Chongqing was as high as 7.86%, while the overall accuracy of identifying abandoned cropland was as high as 90.82%. Among the social and economic factors that affect cropland abandonment, the rural population, economic development, and livestock husbandry development were the most important ones. At the land parcel scale, large-scale cropland abandonment occurred in areas at elevations above 650 m or with slopes of more than 15°. 相似文献
4.
Population growth demands sustainable spatial planning strategies for settlements in Uzbekistan, Central Asia, especially in rural areas that are inhabited by approximately 64 percent of the country's population. Where can settlements expand in rural Uzbekistan and does settlement growth affect valuable agricultural land? SPOT-5 data with a resolution of 2.5 m was utilized for mapping building layers and assessing settlement growth between 2006 and 2011 at the example of 53 communities located in the Khorezm province in North-West Uzbekistan. Object based image analysis was conducted, i.e. a multi-scale segmentation for the derivation of building contours, followed by a random forest (RF) classification of the object's spectral and spatial characteristics. A geographical information system (GIS) was used for identifying settlement densification and expansion processes, and for quantifying agricultural land parcels of different soil quality occupied during settlement growth.A calibration routine based on indices of segmentation quality enabled the selection of optimal segmentation parameters. After GIS-based refinements of the RF classification results, the overall accuracy (OA) of the building layers of both years exceeded 95%. The OA of the change map was 92.7%. The results revealed that the building area increased by 20%, whilst settlement expansion amounted to 10% in 2006–2011. Settlements widely expanded in accordance with the existing rules prohibiting the conversion of agricultural land to housing areas. Nevertheless, about 20% of the settlement growth occurred on agricultural production areas, also on those with highly productive soils. The results indicated both, the pressure on land resources for settlement growth and – in face of continuous population growth – an increasing demand for comprehensive spatial planning in rural Uzbekistan. The elaborated methodological approach can be extrapolated to regions throughout Central Asia with similar environmental conditions. 相似文献
5.
For more than 100 years, forest cover in Europe has increased substantially due to afforestation and natural forest expansion. The latter, resulting typically from farmland abandonment and subsequent secondary forest succession, has played a major role in marginal mountain areas and possesses various highly important environmental and economic consequences. In the Polish Carpathians, farmland abandonment is a spatially dispersed, locally specific process because of small farm and land parcel sizes, and its extent in the entire region is not well known. This study aims therefore to map current farmland abandonment in the Polish Carpathians and to identify its spatial determinants. To map farmland abandonment we detected secondary forest succession on abandoned fields using Airborne Laser Scanning (ALS) point clouds and topographic data in 230 sample areas (tiles) distributed throughout the Carpathian communes. To reveal the spatial determinants of current farmland abandonment, we investigated variables describing the accessibility and environmental, land cover, and socioeconomic conditions of communes, using best subset regression modelling. The results showed that 13.9% of agricultural land was abandoned and underwent secondary forest succession in recent decades. Topography (mainly slope gradients) and employment outside of agriculture were the two most important spatial determinants of farmland abandonment. Consequently, a substantial forest expansion may be observed in the coming decades throughout the Polish Carpathians if no counteractions are taken. 相似文献
6.
不同类型农户撂荒及其影响因素研究——以重庆市12 个典型村为例 总被引：20，自引：0，他引：20
近年来,耕地撂荒因与耕地流失及粮食安全紧密联系而备受关注。反映撂荒现状并揭示其影响因素,有利于政府制定科学的政策、规划和计划。现有的研究多将农户作为一个整体,较少考虑到不同类型农户撂荒的差异。以重庆市12 个典型村为例,在农户类型划分的基础上,分析不同类型农户撂荒的差异,运用多元线性回归模型定量分析不同类型农户撂荒的影响因素。研究表明：① 不同类型农户撂荒的差异主要体现在撂荒户数比重、户均撂荒面积、撂荒面积占承包地面积比重随耕作半径的变化情况、撂荒地现状及不同时间段撂荒面积;② 野生动物影响和人均耕地面积是影响不同类型农户撂荒的共同原因。此外,影响基本型农户的因素包括户主外出经历、耕作半径和房屋离集镇距离;影响自然资产型农户的因素包括农业劳动力比重、户主外出经历、地块平均面积和耕地收益;影响人力资产型农户的因素包括家庭人口、非农收入、耕地转出面积和耕作半径。 相似文献
7.
基于多期数据集的中亚五国土地利用/覆盖变化分析 总被引：4，自引：0，他引：4
针对目前中亚地区土地利用变化和分布格局方面的信息相对匮乏,现有资料较为陈旧且零散,无法满足中亚生态与环境变化研究需求的现状,利用全球的UMD, DISCover,GLC2000,GlobCover2005和GlobCover2009的5期土地覆被遥感数据集,提取中亚地区长时间序列土地覆被信息。并针对上述4个土地覆被分类系统无法进行直接对比和变化分析的问题,分别将其综合为4类土地覆被类型：耕地、自然植被、水体和其他,以分析近30 a中亚土地利用/土地覆被变化趋势。中亚土地利用类型多样,草地、裸地、农田、灌丛占绝对优势。自前苏联解体以后,20世纪90年代初至2000年期间,耕地面积大幅度减少,至2010年尽管有所恢复,但仍无法达到20世纪90年代初水平。而自然植被表现出了相反的趋势,这说明在此时间段内,由于社会政治制度的变化和市场经济的建立,耕地发生了较大规模的弃耕,弃耕地通常转换为草地、灌丛等自然植被。近10 a由于社会经济条件的变化,前苏联解体后所弃耕的土地又被收复和重新开发为耕地。90年代初至2000年期间,水体呈现先减少后增加的趋势。利用全球基于多期不同信息源获得的中亚土地覆被数据,尽管分类体系不统一,但均可较好地表征当时地表覆被状况。这在一定程度上弥补了中亚地区土地覆被数据不足的现状。通过对耕地、自然植被、水体及其他土地覆被类型进行大类合并,可基本体现中亚土地覆被的宏观特征和变化趋势。 相似文献
8.
The extensive alteration of the earth's land cover during the anthropocene had widespread, and in some cases unknown, effects on terrestrial and atmospheric conditions and processes. Predicting future changes to the earth system therefore mandate a future-predicting framework of land use dynamics. However while future-predicting earth surface and atmospheric models tend to explicitly incorporate projected climatic conditions they all but ignore or overly simplify land use dynamics. As most surface and atmosphere dynamics models use gridded input datasets, and land use is a highly spatially-dynamic phenomena, a need clearly arise for spatially explicit representation of future land use dynamics. While a number of such datasets exists at regional and country scales, no fully gridded future-predicting global land use model and database has been reported to date. Here we present the Global Land Use Dynamics Model (GLUDM), a gridded and temporally explicit agricultural land use predictor. GLUDM calculates the relative area of a land use category (e.g. cropland) in each grid-cell by generating unique regression coefficients in each grid-cell based on local historic trends and global population dynamics. Spatial expansions or abandonment of agricultural land is simulated by propagating excesses or deficiencies in agricultural areas between neighboring grid-cells. This spatial connectivity is restricted by topographic, latitudinal and urban characteristics. A validation analysis shows that GLUDM corresponds well to observed land use distribution. GLUDM-predicted global cropland area dynamics between 2005 and 2100 are described herein. Globally, 18% increase in cropland area is predicted between 2005 and 2050 which corresponds very well to previous estimations. Following 2050, a general decrease in cropland area is predicted. The results reveal new insights about global cropland dynamics, demonstrating, for example, that changes in its spatial distribution will be highly heterogeneous, at both micro and macro scales, in some locations worldwide. 相似文献
9.
耕地撂荒研究进展与展望 总被引：35，自引：5，他引：35
20世纪后半叶以来许多发达国家发生明显的耕地撂荒现象,并逐渐演变为全球性土地利用现象,深刻地改变了广大农村地区土地景观.本文以"土地利用变化--驱动机制--环境效应--政策响应"的框架系统梳理耕地撂荒主要研究进展.研究表明:① 全球耕地撂荒仍主要发生在欧美发达国家,但发展程度的区域差异很大;② 社会经济要素变化是耕地撂荒最主要驱动力,务农机会成本上升等原因引起的耕地边际化是撂荒发生的根本原因,而劳动力析出是造成耕地撂荒的直接原因;③ 耕地撂荒与否,撂荒程度以及撂荒地空间分布受村镇,农户,地块三个尺度的自然条件,劳动力特征,农业生产条件和区域社会经济条件等多方面因素的综合影响;④ 生态环境效应是当前撂荒效应研究的焦点,但该效应是以积极还是消极为主仍存争议;⑤ 增加农业补贴是当前减缓耕地撂荒的主要措施,但并非唯一和最合理的措施.未来,快速城镇化进程将促使中国耕地撂荒现象愈演愈烈,所以当前研究有待加强,本文认为应加强大范围耕地撂荒信息提取和监测,撂荒趋势预测和风险评估,社会经济效应评估及政策设计等方面研究. 相似文献
10.
耕地撂荒研究进展及启示 总被引：2，自引：1，他引：1
本文运用文献计量方法对1992-2019年在Web of Science数据库中发表的耕地撂荒领域的910篇文献进行总量和关键词分析,并根据关键词领域从耕地撂荒监测与制图、驱动力与影响因素、效应评估与权衡三个方面进行主题综述。研究发现:(1)目前撂荒耕地的提取与制图渠道以农户调研与遥感技术为主,结合空间信息的NDVI时间序列撂荒地提取方法具有较高精度;(2)从作用程度、来源、属性三个维度对耕地撂荒的驱动力和影响因素进行归纳,发现耕地边际化是耕地撂荒的根本驱动力,劳动力析出是耕地撂荒的直接驱动力,社会经济因素是主要驱动力;(3)耕地撂荒的环境效应具有空间异质性,时空差异、景观环境、气候、耕种、地形特征均会对耕地撂荒的环境效应起决定作用;耕地撂荒效应权衡主要集中在生态系统服务功能和价值领域,但相关空间背景的作用往往被忽略。在系统梳理现有文献的基础上,本文从开展全国层面的撂荒耕地调查、开展多尺度的撂荒驱动力研究、结合国情开展撂荒效应权衡研究等方面对未来耕地撂荒研究进行展望。 相似文献
11.
《Applied geography (Sevenoaks, England)》2006,26(3-4):175-191
This paper examines effects of postsocialist reforms on land cover and land use through a case study from South-eastern Albania. The paper uses satellite data to measure changes in land cover between 1988 and 2003, draws on a village survey to assess changes in local land-use practices, and examines shifts in the determinants of land cover through seemingly unrelated regressions at the village level. The results show a high incidence of cropland abandonment especially in lower-lying areas closer to markets. Socio-economic factors have emerged as new determinants of spatial variation, suggesting a growing influence of market principles on land use. 相似文献
12.
在城镇化和工业化的驱动下,中国丘陵山区耕地逐渐被边际化,耕地撂荒范围也迅速从劣质的坡耕地延展至优质的梯田,大规模梯田撂荒将会引发一系列社会和生态效应,科学评估中国山区梯田的撂荒程度及空间分布将有助于有效地应对耕地撂荒问题。本文通过全国抽样调查的方式对中国梯田的撂荒程度进行了调查,利用获取的中国329个县的560份村问卷测算了中国梯田撂荒规模,并进一步分析了梯田撂荒空间分异特征及驱动因素。结果显示：(1)全国梯田撂荒现象分布广泛,发生梯田撂荒的村庄占总调查村庄的比例为54%,撂荒面积占梯田总面积的比例达到9.79%;(2)梯田撂荒程度呈现“南高北低”的特征,南方丘陵山区较为严重,尤以长江中下游地区为最;(3)梯田撂荒的主要因素可归结为农业劳动力外出务工、梯田耕作机械化程度、灌溉条件、耕作交通条件等。减缓梯田撂荒,应因区精准施策,提高梯田区机械化水平等措施具有普适性,针对质量较差的梯田,可有序“退耕”,对于质量较好的梯田,可采用调整种植结构、加强农业基础设施建设、鼓励流转与规模经营等方式。 相似文献
13.
劳动力非农转移对农户耕地撂荒的影响 总被引：3，自引：0，他引：3
以福建省长汀县农区为研究区域,依据1978-2008年社会统计资料和农户调查数据,构建农业劳动力非农转移对农户耕地撂荒影响的多项式回归分析模型,采用社会统计和比较分析方法,研究长汀县农业劳动力非农转移对于农户耕地撂荒的影响．结果表明：近30年来,长汀县农业劳动力非农转移与农户耕地撂荒之间存在非线性关系,即自改革开放至20世纪90年代中后期,农业劳动力非农转移程度虽逐渐提高,而农户耕地开垦面积却呈现上升趋势;但自2000年以来,农户从耕地净开垦转向耕地净撂荒,农业劳动力非农转移推动着农户耕地撂荒面积的不断增加．同时发现,与外出务工以及本地雇佣劳动相比,从事传统农业较高的务农机会成本是农户耕地撂荒的根本原因,也是农业劳动力非农转移对耕地撂荒产生影响的主要中介． 相似文献
14.
三工河流域两种农田景观的差异及其成因 总被引：2，自引：0，他引：2
从宏观与微观视角,对比分析三工河流域两种经营模式下的农田景观特征,探讨形成这两种景观的原因。得出以下结论:①三工河流域农田扩张过程中,1989-1999年地方的农田增长起主导作用,1999-2007年兵团的农田扩张比地方更为明显,地方与兵团农业发展中的灌溉技术差距是决定两地农田规模扩张差异的主要原因;②土地使用制度的不同导致地方农田表现出小斑块、高密度的特点,而兵团农田则具有大斑块、低密度的特点;③兵团作物种植受宏观调控影响显著,这与地方农户自主选择作物种植类型不同,由此两地农田内部景观格局也形成一定的差异;④撂荒地这一特殊农田景观在地方与兵团也存在差异,兵团撂荒地是地方的2.49倍,主要以连片形式分布于绿洲边缘与荒漠戈壁相邻的区域,地方的撂荒地分布较为零散。 相似文献
15.
基于CiteSpace软件国内外撂荒地研究进展与述评 总被引：1，自引：0，他引：1
基于Web of Science(WOS)和CNKI数据库中以撂荒地为研究主题的文献数据,借助CiteSpace软件对国内外撂荒地研究学科、作者、内容、热点、进程进行梳理,进而对撂荒地成因、机制、影响进行分析。了解国内外撂荒地研究历程和研究现状,并总结遏制土地撂荒的具体措施和办法,期待为中国撂荒地研究提供指引。结果表明：① 国内外学者对撂荒耕地的关注不尽相同,国外学者多研究撂荒地的形成机制,国内学者则侧重揭示耕地撂荒现象。农用地撂荒是国外的研究热点,撂荒政策、模型模拟和遥感技术运用是国内的研究热点。② 国内外撂荒地研究的发展历程有所差别,各阶段呈现出不同的研究特征。③ 撂荒地研究中国内外学者在成因、机制、影响、举措等方面有共识。建议学者采用地理空间大数据、流数据、遥感影像数据等,对撂荒地的时空模拟、趋势推演、风险评估等开展研究;探寻不同资源禀赋和社会经济背景下撂荒的驱动和演变规律,总结演化过程;提出自然-社会-经济等科学化、系统化的研究方法,丰富研究内容和成果;并开展村镇级小尺度案例研究,为理论深化和方法创新提供支撑,进而为小尺度区域的撂荒地生态修复与治理提供理论支撑和案例借鉴。 相似文献
16.
Reducing topsoil salinity and raising carbon stocks through afforestation in Khorezm, Uzbekistan 总被引：3，自引：0，他引：3
C. Hbirkou C. Martius A. KhamzinaJ.P.A. Lamers G. WelpW. Amelung 《Journal of Arid Environments》2011,75(2):146-155
Agricultural mismanagement of irrigated drylands results in severe soil degradation. Afforestation is an option for ameliorating such degraded land. We evaluated the impact afforestation has on the topsoil (0-20 cm) of salinized degraded cropland in regards to salinity, aggregate stability, and soil organic carbon (SOC) stocks in Uzbekistan, Central Asia. The effects of tree plantations established under either furrow or drip irrigation were studied four years following afforestation and two years after irrigation ceased. For comparative study we also sampled fallow land, land with 80 years of tree growth, natural forest, desert ecosystems, and paddy rice fields. Initial furrow irrigation showed to be most effective in improving soil fertility after four years of afforestation; the respective plantations of Populus euphratica and Ulmus pumila showed significant levels of reduced soil salinity and increased aggregate stability and improved SOC stocks. The comparison of the long-term afforested land with the short-term equivalent suggested a C sequestration rate of 0.09-0.15 t C ha−1 year−1. The SOC stocks of the long-term afforestation site exceeded those of the native forest. Hence, a rehabilitation of salt-affected cropland is feasible following the conversion into occasionally irrigated tree plantations, although it takes decades to reach steady-state conditions. 相似文献
17.
This paper quantitatively analyzes the utilization efficiency of agricultural resources in Central Asia by calculating the consumption coefficient of the main resources, including arable land, water and fertilizers. The results of these investigations reveal the following:(1)The average consumption coefficients of cultivated land resources in Central Asia are much higher than the world average value of up to 7.74 m~2/kg, which is 3.6 times that of China, suggesting that the cultivated land resource consumption coefficient of cultivated land resource utilization efficiency is low in the Central Asian region.(2) Up to 80% of available water resources are used for agriculture irrigation. The average agricultural water consumption in Central Asia is about 9.43 m~3/kg, or nearly 9.3 times the average value elsewhere in Asia, indicating that agricultural water use efficiency in this region is very low and water resources are wasted.(3) The fertilizer consumption coefficient in Central Asia is 0.035 kg/kg, which is close to the world average, but the utilization efficiency of fertilizer is relatively high. Therefore, in the future development of agriculture, Central Asia should pay more attention to the management of agricultural water resources in order to improve the utilization efficiency of these resources as well as that of arable land. 相似文献
18.
Monitoring land use change in the Badia transition zone in Jordan using aerial photography and satellite imagery 总被引：1，自引：0，他引：1
Detection of land use change makes a valuable contribution to the planning and monitoring of drylands. Land use changes at four sites within the Badia transition zone of Jordan were investigated and quantified over the period from 1953 to 1992 using black and white aerial photographs and SPOT PAN satellite imagery digitally merged with Landsat TM. Land use interpretation was checked in the field, and analysed using a Geographical Information System (GIS). Results indicated that land use changes have altered the character of the selected study sites. The important land use changes were from rangeland to rain-fed cultivation, irrigated fields and urban settlements. The increased agricultural activity was reflected in the land use maps through the 39-year period with the appearance of irrigated fields between 1978 and 1992. The land use changes are mainly attributed to the high population growth rate in Jordan and in the Badia, socio-economic change amongst Beduoin and farmers, the land tenure system and to a minor extent environmental factors. 相似文献
19.
This paper quantitatively analyzes the utilization efficiency of agricultural resources in Central Asia by calculating the consumption coefficient of the main resources, including arable land, water and fertilizers. The results of these investigations reveal the following: (1) The average consumption coefficients of cultivated land resources in Central Asia are much higher than the world average value of up to 7.74 m2/kg, which is 3.6 times that of China, suggesting that the cultivated land resource consumption coefficient of cultivated land resource utilization efficiency is low in the Central Asian region. (2) Up to 80% of available water Central Asia is about 9.43 m3/kg, or nearly 9.3 times the average value elsewhere in Asia, indicating that agricultural water use efficiency in this region is very low and water resources are wasted. (3) The fertilizer consumption coefficient in Central Asia is 0.035 kg/kg, which is close to the world average, but the utilization efficiency of fertilizer is relatively high. Therefore, in the future development of agriculture, Central Asia should pay more attention to the management of agricultural water resources in order to improve the utilization efficiency of these resources as well as that of arable land. 相似文献
20.
Crop diversity (e.g. the number of agricultural crop types and the level of evenness in area distribution) in the agricultural systems of arid Central Asia has recently been increased mainly to achieve food security of the rural population, however, not throughout the irrigation system. Site-specific factors that promote or hamper crop diversification after the dissolvent of the Soviet Union have hardly been assessed yet. While tapping the potential of remote sensing, the objective was to map and explain spatial patterns of current crop diversity by the example of the irrigated agricultural landscapes of the Fergana Valley, Uzbekistan. Multi-temporal Landsat and RapidEye satellite data formed the basis for creating annual and multi-annual crop maps for 2010–2012 while using supervised classifications. Applying the Simpson index of diversity (SID) to circular buffers with radii of 1.5 and 5 km elucidated the spatial distribution of crop diversity at both the local and landscape spatial scales. A variable importance analysis, rooted in the conditional forest algorithm, investigated potential environmental and socio-economic drivers of the spatial patterns of crop diversity. Overall accuracy of the annual crop maps ranged from 0.84 to 0.86 whilst the SID varied between 0.1 and 0.85. The findings confirmed the existence of areas under monocultures as well as of crop diverse patches. Higher crop diversity occurred in the more distal parts of the irrigation system and sparsely settled areas, especially due to orchards. In contrast, in water-secure and densely settled areas, cotton-wheat rotations dominated due to the state interventions in crop cultivation. Distances to irrigation infrastructure, settlements and the road network influenced crop diversity the most. Spatial explicit information on crop diversity per se has the potential to support policymaking and spatial planning towards crop diversification. Driver analysis as exemplified at the study region in Uzbekistan can help reaching the declared policy to increase crop diversity throughout the country and even beyond. 相似文献