Cities and villages are components of a specific organism. Only the sustainable development of two parts can support the prosperous development as a whole. According to the theory of man-earth areal system, urban-rural integrated system and rural regional system are the theoretical bases for entirely recognizing and understanding urban-rural relationship. To handle the increasingly severe problems of "rural disease" in rapid urbanization, accelerating rural revitalization in an all-round way is not only a major strategic plan for promoting the urban-rural integration and rural sustainable development, but also a necessary requirement for solving the issues related to agriculture, rural areas, and rural people in the new era and securing a decisive victory in building a moderately prosperous society in all respects. This study explores the basic theories of urban-rural integration and rural revitalization and analyzes the main problems and causes of rural development in the new era, proposing problem-oriented scientific approaches and frontier research fields of urban-rural integration and rural revitalization in China. Results show that the objects of urban-rural integration and rural revitalization is a regional multi-body system, which mainly includes urban-rural integration, rural complex, village-town organism, and housing-industry symbiosis. Rural revitalization focuses on promoting the reconstruction of urban-rural integration system and constructs a multi-level goal system including urban-rural infrastructure networks, zones of rural development, fields of village-town space and poles of rural revitalization. Currently, the rural development is facing the five problems: high-speed non-agricultural transformation of agriculture production factors, over-fast aging and weakening of rural subjects, increasingly hollowing and abandoning of rural construction land, severe fouling of rural soil and water environment and deep pauperization of rural poverty-stricken areas. The countryside is an important basis for the socioeconomic development in China, and the strategies of urban-rural integration and rural revitalization are complementary. The rural revitalization focuses on establishing the institutional mechanism for integrated urban-rural development and constructs the comprehensive development system of rural regional system, which includes transformation, reconstruction and innovation in accordance with the requirements of thriving businesses, pleasant living environments, social etiquette and civility, effective governance, and prosperity. Geographical research on rural revitalization should focus on the complexity and dynamics of rural regional system and explore new schemes, models and scientific approaches for the construction of villages and towns, which are guided by radical cure of "rural disease", implement the strategy of rural revitalization polarization, construct the evaluation index system and planning system of rural revitalization, thus providing advanced theoretical references for realizing the revitalization of China's rural areas in the new era.

城市与乡村是一个有机体,只有二者可持续发展,才能相互支撑。依据人地关系地域系统学说,城乡融合系统、乡村地域系统是全新认知和理解城乡关系的理论依据。针对日益严峻的“乡村病”问题,全面实施乡村振兴,既是推进城乡融合与乡村持续发展的重大战略,也是破解“三农”问题,决胜全面建成小康社会的必然要求。本文探讨了新时代城乡融合与乡村振兴的基础理论,剖析了乡村发展面临的主要问题,提出了问题导向的中国城乡融合与乡村振兴科学途径及研究前沿领域。结果表明：① 城乡融合与乡村振兴的对象是一个乡村地域多体系统,包括城乡融合体、乡村综合体、村镇有机体、居业协同体,乡村振兴重在推进城乡融合系统优化重构,加快建设城乡基础网、乡村发展区、村镇空间场、乡村振兴极等所构成的多级目标体系。② 中国“三农”问题本质上是一个乡村地域系统可持续发展问题,当前乡村发展正面临主要农业生产要素高速非农化、农村社会主体过快老弱化、村庄建设用地日益空废化、农村水土环境严重污损化和乡村贫困片区深度贫困化等“五化”难题。③ 乡村是经济社会发展的重要基础,城乡融合与乡村振兴战略相辅相成,乡村振兴应致力于创建城乡融合体制机制,推进乡村极化发展,按照产业兴旺、生态宜居、乡风文明、治理有效、生活富裕的要求,构建乡村地域系统转型—重构—创新发展综合体系。④ 乡村振兴地理学研究应着眼于乡村地域系统的复杂性、综合性、动态性,探究以根治“乡村病”为导向的新型村镇建设方案、模式和科学途径,为实现新时代中国乡村振兴战略提供理论参考。

Under new international and domestic situations, scientific analysis of China's cultivated land quantity and its protection ways is of great significance for ensuring national food security and sustainable resources and environment development. This paper analyzes the amount of cultivated land under the constraints of multi-scenario food security within shared social-economic paths (SSPs), using model methods such as cultivated land retention, population forecast, food demand estimation, and yield potential decay. According to the multi-dimensional urgency assessment framework based on productivity characteristics-health status-farming, China's resilience-space for cultivated land protection is delineated by coupling the quantitative boundary control of time series and the regional rules of spatial scale. On the premise of satisfying the assumption of individual basic nutrition security and the constant variables of crop yield conditions, we obtain the following findings. (1) China's multi-scenario cultivated land retention will decline from 2020 to 2100. Existing cultivated land is sufficient to maintain long-term food security, but it barely reaches the critical range of theoretical food security (140 million-159 million hm2) in the short term. (2) The urgency of cultivated land protection in different dimensions presents different distribution characteristics within the nine agricultural zones. The North China Plain and the Middle-lower Yangtze River, which have superior natural conditions suitable for farming, are clusters of high-value plots of comprehensive urgency. (3) The sustainable scenario (SSP1) and the regional conflict scenario (SSP3) represent the minimum and maximum cultivated land retention scenarios under the constraints of food security bottom line. Given the current international situation, China should ensure that the short-term (before 2035) fallow land is not higher than 9.29%. (4) The resilience-space of cultivated land protection delineated based on time and space coupling can be divided into priority protection area, strict control area, rest area, strategic reserve area, comprehensive consolidation area, and special protection area. The flexibility, objectives and tasks of cultivated land protection in different divisions have their priorities. Overall, delineating resilience-space for cultivated land protection facilitates the establishment of spatial planning systems for cultivated land, such as agricultural structure adjustment and fallow policy improvement. This study provide a reference for research on the transformation of China's cultivated land protection system.

科学解析中国耕地数量保多少与如何保等问题对保障国家粮食安全与资源环境可持续发展具有重要意义。面向共享社会经济路径（SSPs）的多情景粮食安全底线约束,本文试图利用耕地保有量、人口预测、粮食需求估算、单产提升潜力衰减等模型方法,依据产能特征—健康状态—耕作条件—利用水平的多维度耕地保护紧迫性评估框架,通过耦合时间序列的数量边界控制与空间尺度的区域规则约束刻画出中国的耕地保护弹性空间。在满足个人基本营养安全与作物单产条件干扰变量恒定的假设前提下,研究发现：① 中国多情景耕地保有量在2020—2100年间呈下降态势,现有耕地数量足以维持长期的粮食安全,但短期内则仅勉强达到理论粮食安全的临界区间1.40×10⁸~1.59×10⁸ hm²。② 不同维度耕地保护紧迫性在九大农业区划内呈现差异化分布特征,自然条件优越且适宜耕作的黄淮海平原区与长江中下游地区是综合紧迫性高值地块集聚区域。③ 可持续情景与区域冲突情景分别代表粮食安全底线约束下的最小与最大耕地保有量情景,在当前国际形势下,中国应保证短期（2035年内）可休耕量不高于9.29%。④ 基于时空耦合划定的耕地保护弹性空间可分为优先保护、严格管控、休养生息、战略储备、整治修复和特殊保护6类,不同空间的耕地保护弹性强度、目标与任务各有侧重。整体而言,耕地保护弹性空间的划定思路有助于农业结构调整、休耕政策完善等耕地空间规划体系构建,对中国耕地保护制度转型具有借鉴价值。

It is of great significance to study the spatial and temporal evolution and driving mechanism of multi-cropping rice area to ensure Chinese grain production and security. The Nich index and geo-detector model were used to explore the spatial and temporal dynamics and main influencing factors of one-cropping rice and double-cropping rice planting in Dongting Lake Area from 1987 to 2017. The results show that: (1) In the past 30 years, the proportion of one cropping rice in the hilly area was greater than that in the central plain, and the overall trend was increasing; with a tendency to decrease first and then increase in Wuling district, Yuanjiang city and other places from 2007 to 2017. (2) From 1987 to 2002, the relative development rates of the area of one-cropping rice and double-cropping rice showed a high gradient pattern in the west and low in the east. From 2002 to 2017, one-cropping rice showed a high-low-high banding pattern, while double-cropping rice showed a pattern of high in the north and low in the south. (3) The results of geo-detector models in 1987 and 2017 showed that the effect of effective irrigation area, industrial workers, agricultural workers, and the total output value of agriculture, forestry, animal husbandry and fishery exerted influence on rice area. This research results provide a basis for optimizing the adjustment of rice planting structure.

研究多熟制水稻面积时空演变及驱动机制对保障我国粮食生产和安全具有重要意义。综合运用Nich指数和地理探测器模型,探讨了洞庭湖地区1987—2017年一季稻和双季稻种植面积的时空动态变化及主要影响因素。结果表明：（1）近30年来,位于丘岗山地区的一季稻面积比例大于中部平原地区,整体呈上升的变化趋势;武陵区、沅江市等地在2007—2017年呈先降后升的变化趋势。（2）1987—2002年间一季稻和双季稻面积相对变化率呈西高东低的梯度型变化模式;2002—2017年间一季稻呈高—低—高的条带状变化模式,双季稻呈北高南低的变化发展模式。（3）1987年和2017年地理探测模型结果表明,有效灌溉面积、工业从业人员、农业从业人员、农林牧渔总产值对水稻面积影响程度不断加深。研究结果可为水稻种植结构调整提供参考依据。

Food security is the cornerstone of national economic development and social stability. The increasingly serious problem of cultivated land non-grain conversion intensifies the risk of food insecurity and directly affects the sustainable development of China's social and economic systems. From the perspective of non-grain production of food, this study selected Guangdong Province as the research area and county as the evaluation unit and based on socioeconomic statistics and geospatial data, using Theil index, spatial autocorrelation model, random forest model, principal component analysis, and cluster analysis to examine the spatiotemporal characteristics, influencing factors, and driving types of cultivated land non-grain conversion in 2005 and 2019. The results show that: (1) The non-grain rate of cultivated land in Guangdong Province increased from 48.47% in 2005 to 54.65% in 2019. The non-grain degree of cultivated land had changed from low to moderate, and the spatial differentiation of non-grain rate of cultivated land showed a decreasing trend, especially in the Pearl River Delta area. (2) The spatial distribution of non-grain cultivated land maintained a stable agglomeration state and showed high concentration in the Pearl River Delta area and low concentration in the east wing, west wing, and mountainous sub-regions of the province. (3) Road network density and GDP per square kilometer had significant promoting effects on cultivated land non-grain conversion, while the proportion of labor force in rural primary industry and distance between counties and provincial capital cities were important factors to restrain the cultivated land non-grain conversion. (4) The main driving type of cultivated land non-grain conversion was economy driven (44.63%), mainly distributed in the Pearl River Delta area. This was followed by agriculture supporting type (33.06%), mostly distributed in the mountainous areas. The resource dependency type was the least dominant (22.31%) and was concentrated in the east and west wing sub-regions. This research result is conducive to accurately identify the spatiotemporal characteristics of cultivated land non-grain conversion in Guangdong Province, improve the risk control level of local cultivated land non-grain conversion, and has important theoretical and practical significance for sustainable agricultural development and ensuring regional food security.

粮食安全是保障国家经济发展和社会稳定的基石,日益严峻的耕地非粮化问题加剧了粮食安全风险,直接影响中国社会经济的可持续发展。本文从食物性生产的非粮化角度,选取广东省为研究区域,以县域为评价单元,运用社会经济统计数据及地理空间数据,集成Theil指数、空间自相关模型、随机森林模型、主成分分析和聚类分析等方法,从全省四大区域角度探讨了广东省2005和2019年耕地非粮化的时空演变特征、影响因素及其驱动类型。结果表明：①广东省耕地非粮化率由2005年的48.47%上升至2019年的54.65%,耕地非粮化程度由低度为主转向中度为主,且耕地非粮化利用空间差异呈现缩小态势,以珠三角的演变差异最为显著。②耕地非粮化的空间分布保持稳定的集聚状态,并以珠三角的高高集聚和东翼、西翼、山区的低低集聚为主。③路网密度、地均GDP对耕地非粮化存在显著的推动作用,农村第一产业劳动力占比、各县到省会城市距离是抑制耕地非粮化的重要因素。④耕地非粮化驱动类型以经济驱动型为主(44.63%),主要分布在珠三角;其次是农业支持型(33.06%),大多分布在山区;资源依赖型占比最少(22.31%),集聚在东、西两翼。研究结果有利于精准识别广东省耕地非粮化的时空特征,提升当地耕地非粮化的风险管控水平,对于农业可持续发展以及保证地区的粮食安全具有重要的理论与现实意义。

Understanding the spatial and temporal variations of cropping systems is very important for agricultural policymaking and food security assessment, and can provide a basis for national policies regarding cropping systems adjustment and agricultural adaptation to climate change. With rapid development of society and the economy, China’s cropping structure has profoundly changed since the reform and opening up in 1978, but there has been no systematic investigation of the pattern, process and characteristics of these changes. In view of this, a crop area database for China was acquired and compiled at the county level for the period 1980-2011, and linear regression and spatial analysis were employed to investigate the cropping structure type and cropping proportion changes at the national level. This research had three main findings: (1) China’s cropping structure has undergone significant changes since 2002; the richness of cropping structure types has increased significantly and a diversified-type structure has gradually replaced the single types. The single-crop types—dominated by rice, wheat or maize—declined, affected by the combination of these three major food crops in mixed plantings and conversion of some of their planting area to other crops. (2) In the top 10 types, 82.7% of the county-level cropping structure was rice, wheat, maize and their combinations in 1980; however, this proportion decreased to 50.7% in 2011, indicating an adjustment period of China’s cropping structure. Spatial analysis showed that 63.8% of China’s counties adjusted their cropping structure, with the general change toward reducing the main food types and increasing fruits and vegetables during 1980-2011. (3) At the national level, the grain-planting pattern dominated by rice shifted to coexistence of rice, wheat and maize during this period. There were significant decreasing trends for 47% of rice, 61% of wheat and 29.6% of maize cropping counties. The pattern of maize cropping had the most significant change, with the maize proportion decreasing in the zone from northeastern to southwestern China during this period. Cities and their surroundings were hotspots for cropping structural adjustment. Urbanization has significantly changed cropping structure, with most of these regions showing rapid increases in the proportion of fruit and vegetables. Our research suggests that the policy of cropping structural adjustment needs to consider geographical characteristics and spatial planning of cropping systems. In this way, the future direction of cropping structural adjustment will be appropriate and scientifically based, such as where there is a need to maintain or increase rice and wheat cropping, increase soybean and decrease maize, and increase the supply of fruit and vegetables.

In recent years, the studies of land circulation are frequently seen in research field, but, up to now, there is still no general judgement on the basic situation of land circulation price in China. Based on the land circulation price data at the provincial level of 2009 and 2017, this paper adopts ESDA method and space econometric model to carry out the analysis of the spatio-temporal evolution and macro differentiation mechanism of land circulation price in China. The results show that land circulation price overall rose 33.28% between 2009 and 2017, but the growth rates were uneven among provinces. In general, the superposition area of the eastern developed regions and the main grain producing areas increased greatly, while the southeast coastal areas and the northwest hinterland increased slowly. Besides, the land circulation price was decreasing from east to west, and presented inverted u-shaped structure from north to south. Moreover, Land circulation price showed a significant "HH-LL" clustering structure among provinces, and with the development of land circulation market, the spillover effect is further strengthened. Finally, spatial econometric analysis shows that the differentiation of land circulation price among provinces in China is mainly affected by regional economic factors. With the development of land circulation market, the role of natural factors is decreasing, while the influence of regional economic factors and cultivated land resources endowment is further strengthened. Based on this study, this paper suggests that we should follow the objective law of spatial differentiation of land circulation price in China, avoid blind price comparison, timely regulate the land circulation price and restrain excessive capitalization of cultivated land.

虽然近年来有关土地流转的研究频繁见诸报端,但至今对中国土地流转价格的基本情况仍缺少总体判断。为此,本文以2009年和2017年2期省域层面的土地流转价格数据为基础,采用ESDA方法和空间计量模型,开展了全国土地流转价格时空演化及宏观分化机制的分析。研究结果表明：2017年土地流转价格较2009年整体上涨,但各省域之间的增幅不均衡,东部发达地区和粮食主产区的叠加区增幅较大,而东南沿海和西北腹地增幅较缓,京沪地区基本持平;土地流转价格在全国尺度上呈现出“东西向递减,南北向U型”的分布格局;土地流转价格在省域之间呈现出显著的“HH-LL”聚类结构,且随着土地流转市场的发展,外溢作用进一步加强;宏观机制分析发现,中国省域间的土地流转价格分化主要受区位经济因素影响,随着土地流转市场的发育,自然因素的作用在减小,而区位经济因素和人地资源禀赋因素的影响则进一步增强。基于研究结果,本文建议,应遵循中国土地流转价格空间分化规律,避免盲目的价格攀比,并适时调控流转价格,抑制土地过度资本化。

In the rapid process of industrialization and urbanization, non-agriculturalization has become one important tendency of Chinese rural evolution, which at the same time indicates obvious spatial heterogeneity. The participatory rural appraisal is employed, which involves 16 typical villages of Yishui County in Shandong Province, to explore the rural non-agricultural differences and its driving factors. In terms of regional differentiation, the livelihood activities of rural households were divided into four types: non-agricultural employment outside the county, non-agricultural employment inside the county, part-time non-agricultural employment inside the county and agricultural production. Then, we quantified the non-agricultural level by estimating the proportion of rural non-agricultural labor, non-agricultural income and non-agricultural time in 2013. On the basis of this estimation, we discussed the spatial differences and driving forces of rural non-agriculturalization in the study area. The results showed that, (1) Non-agricultural level of the villages was between 37.54% and 90.65%, which indicated that non-agriculturalization was a common phenomenon in traditional agricultural regions. Suburban independent non-agricultural villages developed their own industries, while rural households of other villages were employed in non-agricultural industries outside their villages. It is indicated that the study area was underdeveloped in non-agricultural economy. (2) Suburban villages hold the highest non-agricultural level. Food crops dominated villages showed higher level of non-agriculturalization in the regions near town, while economic crops dominated villages showed lower level of non-agriculturalization. In the same geomorphologic region, food crops dominated villages showed higher level of non-agriculturization than economic crops dominated villages. Spatial differentiation of rural non-agriculturalization was remarkable in traditional agricultural regions at the county scale. (3) As the distances to town became shorter, there was a decline in the proportion of non-agricultural employment outside the county (labor, income, and time), and that inside the county was on the rise, and the proportion of part-time non-agricultural employment inside the county showed an inverted "U"-shaped pattern. (4) The driving mechanism showed that economic diffusing efficiency and the regional accessibility were both deeply influencing employment structure of rural labors, which kept the suburban villages at the highest non-agricultural level. Agricultural income and the demand for labor made non-agricultural level of food crops dominated villages higher than that of economic crops dominated villages. As the distances to town became shorter, owing to economic diffusing efficiency and agricultural income increase, food crops dominated villages showed higher level of non-agriculturalization while economic crops dominated villages showed lower level. Non-agricultural differentiation is an important development trend of traditional agricultural regions in East China. Therefore, the authors suggest that the governments should take concrete measures on rural development management that keep consistent with non-agricultural characteristics and its driving mechanism of different villages.

非农化是中国快速工业化、城镇化进程中农村演变的重要趋势,呈现出明显的空间异质性。以山东省沂水县为例,选取16个典型样点村,根据农户就业地域空间差异,将农户就业划分为县域外非农就业、县域非农就业、县域非农兼业和农业生产4类,在此基础上,选取非农就业劳动力、收入和时间比例3个指标研究县域农村非农化程度差异及驱动力。结果表明,沂水县农村非农化程度介于37.54%~90.65%,非农化现象普遍。县域农村非农化程度的总体分布特征为：近郊村最高;随着与城镇的临近,粮食作物主导村提高、经济作物主导村降低;同一地形区内,粮食作物主导村高于经济作物主导村。农村非农分化趋势明显。驱动力研究表明,受县域城镇经济实力、农村到城镇的可达性,农业收益及劳动需求量等的综合影响,不同类型农村劳动力就业结构存在差异,进而导致县域农村非农化程度的差异。研究认为,当前农村非农化普遍,且非农分化明显。政府应根据不同类型农村非农化程度差异的内容及驱动因素,实施差别化的农村发展管理措施。

This paper analyzes characteristics, major driving forces and alternative management measures of land-use change in Kunshan, Jiangsu province, China. The study used remote sensing (RS) maps and socio-economic data. Based on RS-derived maps, two change matrices were constructed for detecting land-use change between 1987 and 1994, and between 1994 and 2000 through pixel-to-pixel comparisons. The outcomes indicated that paddy fields, dryland, and forested land moderately decreased by 8.2%, 29% and 2.6% from 1987 to 1994, and by 4.1%, 7.6% and 8% from 1994 to 2000, respectively. In contrast, the following increased greatly from 1987 to 1994: artificial ponds by 48%, urban settlements by 87.6%, rural settlements by 41.1%, and construction land by 511.8%. From 1994 to 2000, these land covers increased by 3.6%, 28.1%, 23.4% and 47.1%, respectively. For the whole area, fragmentation of land cover was very significant. In addition, socio-economic data were used to analyze major driving forces triggering land-use change through bivariate analysis. The results indicated that industrialization, urbanization, population growth, and China's economic reform measures are four major driving forces contributing to land-use change in Kunshan. Finally, we introduced some possible management measures such as urban growth boundary (UGB) and incentive-based policies. We pointed out that, given the rapidity of the observed changes, it is critical that additional studies be undertaken to evaluate these suggested policies, focusing on what their effects might be in this region, and how these might be implemented.

Currently, the implementation of new type industrialization, new type urbanization and agricultural modernization strategy lacks of a major hand grip and spatial sustain platform, due to long-term existed "dual-track" structure of rural-urban development in China as well as unstable rural development institution and mechanism and backward rural and agricultural infrastructures, which greatly affects the advancement of urban-rural integration development. It is necessary to restructure rural production, living and ecological space by carrying out land consolidation, so as to establish a new platform for building new countryside and realize urban-rural integration development in China. This paper develops the concept and connotation of rural spatial restructuring, i.e., an optimization and adjustment even utterly changing process of rural production, living and ecological space accompanied by rural socio-economic structure reshaping under the pressure of rapid industrialization and urbanization. The connotations of rural spatial restructuring involve three aspects of assembling industrial development, centralizing farmers' living and intensive resources utilization. Based on the effects analysis of industrialization and urbanization on rural production, living and ecological space, this paper also probes the mechanism which push forward rural spatial restructuring by carrying out land consolidation, an important approach to supplying cultivated land, revitalizing the stock land, optimizing rural-urban land, utilizing land intensively, and increasing land productivity. A conceptualization of the models of rural production, living and ecological environment spatial restructuring is analyzed in combination with agricultural land consolidation, hollowed villages consolidation and industrial and mining land consolidation. Finally, the author argues that a "bottom-up" restructuring strategy accompanied by a few "top-down" elements is helpful for smoothly pushing forward current rural spatial restructuring in China. The optimization and restructuring of rural intensive and high-efficient production space, suitable living space with amenity and ecological space with beautiful mountain and clean water will rely on the innovation of regional engineering technology, policy mechanism and mode of rural land consolidation, and more attentions should be paid to rural space, the foundation base and platform for realizing urban-rural integration development.

目前,中国新型工业化、城镇化和农业现代化的推进仍缺乏重要抓手和空间支撑平台,严重影响了城乡一体化发展进程。亟需通过开展农村土地综合整治,重构乡村生产、生活和生态空间,为推进新农村建设和城乡一体化发展搭建新平台。本文在界定了乡村空间重构,即在快速工业化和城镇化进程中,伴随乡村内生发展需求和外源驱动力综合作用下导致的农村地区社会经济结构重新塑造,乡村地域上生产空间、生活空间和生态空间的优化调整乃至根本性变革的过程,及其产业发展集聚、农民居住集中和资源利用集约3 个方面内涵的基础上,分析了工业化和城镇化进程对乡村生产、生活和生态空间的影响;探讨了乡村空间重构的土地整治类型及助推机制;结合农用地整治、"空心村"整治和工矿用地整治提出了乡村生产、生活和生态空间重构的模式与途径,以及依托土地整治的以"自下而上"为主、"自上而下"为辅的乡村空间重构战略。作为城乡一体化发展根基的乡村空间其重要性和基础平台作用应受到足够重视,乡村集约高效的生产空间、宜居适度的生活空间和山清水秀的生态空间的优化重构,有赖于区域农村土地整治工程技术、政策机制与模式的创新。

. Land cover (LC) determines the energy exchange, water and carbon cycle between Earth's spheres. Accurate LC information is a fundamental parameter for the environment and climate studies. Considering that the LC in China has been altered dramatically with the economic development in the past few decades, sequential and fine-scale LC monitoring is in urgent need. However, currently, fine-resolution annual LC dataset produced by the observational images is generally unavailable for China due to the lack of sufficient training samples and computational capabilities. To deal with this issue, we produced the first Landsat-derived annual China land cover dataset (CLCD) on the Google Earth Engine (GEE) platform, which contains 30 m annual LC and its dynamics in China from 1990 to 2019. We first collected the training samples by combining stable samples extracted from China's land-use/cover datasets (CLUDs) and visually interpreted samples from satellite time-series data, Google Earth and Google Maps. Using 335 709 Landsat images on the GEE, several temporal metrics were constructed and fed to the random forest classifier to obtain classification results. We then proposed a post-processing method incorporating spatial–temporal filtering and logical reasoning to further improve the spatial–temporal consistency of CLCD. Finally, the overall accuracy of CLCD reached 79.31 % based on 5463 visually interpreted samples. A further assessment based on 5131 third-party test samples showed that the overall accuracy of CLCD outperforms that of MCD12Q1, ESACCI_LC, FROM_GLC and GlobeLand30. Besides, we intercompared the CLCD with several Landsat-derived thematic products, which exhibited good consistencies with the Global Forest Change, the Global Surface Water, and three impervious surface products. Based on the CLCD, the trends and patterns of China's LC changes during 1985 and 2019 were revealed, such as expansion of impervious surface (+148.71 %) and water (+18.39 %), decrease in cropland (−4.85 %) and grassland (−3.29 %), and increase in forest (+4.34 %). In general, CLCD reflected the rapid urbanization and a series of ecological projects (e.g. Gain for Green) in China and revealed the anthropogenic implications on LC under the condition of climate change, signifying its potential application in the global change research. The CLCD dataset introduced in this article is freely available at https://doi.org/10.5281/zenodo.4417810 (Yang and Huang, 2021).

Both the food production value on arable land and the structure of food crop cultivation have impacted on national food security. Therefore, exploring changes in their spatial and temporal coupling patterns can help us to understand their relationships and to further improve food security. In this research, we took provincial-level regions in China as the object, and based on an in-depth interpretation of the connotation of the grain-to-arable value ratio and cropping structure, Simpson's index model, coupling coordination model and spatial auto-correlation are comprehensively used to study the spatial and temporal evolution patterns of grain-to-arable value ratio and cropping structure in the study area from 2004 to 2020, and the spatial and temporal dynamics between them in different regions are revealed in consequence. The results show that: (1) The spatial distribution of the grain-to-arable value ratio in all the provincial-level regions from 2004 to 2020 shows a double-decreasing characteristic, one from north to south and the other from west to east; (2) The spatial pattern of cropping structure shows a Hu-Huanyong-line-ridge in terms of spatial distribution, where Northeast, North and East China witness a significant decrease in crop diversity; (3) The degree of coupling coordination between the grain-to-arable value ratio and cropping structure is found between barely coupled and coordinated and highly coupled and coordinated, showing regular spatial clustering characteristics. In the central, western and northeastern China, there is a high-high concentration with matching advantage; in the southeast coastal region, there is a low-low concentration for matching improvement; and the overall distribution presents a pattern of high in the northeast and central regions, and low in the southeast. The study believes that, based on the heterogeneous characteristics of the spatial concentration and diffusion of factors, the synergistic evolution of food quality and diversity on arable land should be encouraged according to the local conditions, so as to promote the harmonious development of food structure and efficiency.

耕地粮食产出价值与种植结构均深刻影响着国家粮食安全，探讨耕地粮食产出价值与种植结构的时空耦合变化，可理清两者关系，助力粮食安全保障能力的提升。本文以中国省级行政单元为研究对象，在深刻解读粮耕价值比和种植结构内涵的基础上，综合利用Simpson指数、耦合协调度模型和空间自相关等方法，分析2004—2020年中国粮耕价值比和种植结构耦合时空演化，以揭示其时空动态关系。结果表明：① 2004—2020年各省份粮耕价值比空间分布特征表现为“由北向南”和“由西向东”的双重递减态势；② 种植结构空间格局呈现由“胡焕庸线”沿线区域向两侧递减的空间分布形态，东北、华北和华东地区多样性递减明显；③ 粮耕价值比与种植结构耦合协调度介于勉强耦合协调与高度耦合协调之间，表现为规律性空间集聚，中西部及东北地区呈高高集聚，具有“匹配性优势”，东南沿海地区呈低低集聚，有待“匹配性改良”，总体表现为：“东北、中部高，东南部低”的态势。本文认为应依据要素空间集聚和扩散的分异特征，因区施策引导耕地粮食品质化与多元化协同演进，促进粮食结构与效益匹配发展。

Under new international and domestic situations, scientific analysis of China's cultivated land quantity and its protection ways is of great significance for ensuring national food security and sustainable resources and environment development. This paper analyzes the amount of cultivated land under the constraints of multi-scenario food security within shared social-economic paths (SSPs), using model methods such as cultivated land retention, population forecast, food demand estimation, and yield potential decay. According to the multi-dimensional urgency assessment framework based on productivity characteristics-health status-farming, China's resilience-space for cultivated land protection is delineated by coupling the quantitative boundary control of time series and the regional rules of spatial scale. On the premise of satisfying the assumption of individual basic nutrition security and the constant variables of crop yield conditions, we obtain the following findings. (1) China's multi-scenario cultivated land retention will decline from 2020 to 2100. Existing cultivated land is sufficient to maintain long-term food security, but it barely reaches the critical range of theoretical food security (140 million-159 million hm2) in the short term. (2) The urgency of cultivated land protection in different dimensions presents different distribution characteristics within the nine agricultural zones. The North China Plain and the Middle-lower Yangtze River, which have superior natural conditions suitable for farming, are clusters of high-value plots of comprehensive urgency. (3) The sustainable scenario (SSP1) and the regional conflict scenario (SSP3) represent the minimum and maximum cultivated land retention scenarios under the constraints of food security bottom line. Given the current international situation, China should ensure that the short-term (before 2035) fallow land is not higher than 9.29%. (4) The resilience-space of cultivated land protection delineated based on time and space coupling can be divided into priority protection area, strict control area, rest area, strategic reserve area, comprehensive consolidation area, and special protection area. The flexibility, objectives and tasks of cultivated land protection in different divisions have their priorities. Overall, delineating resilience-space for cultivated land protection facilitates the establishment of spatial planning systems for cultivated land, such as agricultural structure adjustment and fallow policy improvement. This study provide a reference for research on the transformation of China's cultivated land protection system.

科学解析中国耕地数量保多少与如何保等问题对保障国家粮食安全与资源环境可持续发展具有重要意义。面向共享社会经济路径（SSPs）的多情景粮食安全底线约束,本文试图利用耕地保有量、人口预测、粮食需求估算、单产提升潜力衰减等模型方法,依据产能特征—健康状态—耕作条件—利用水平的多维度耕地保护紧迫性评估框架,通过耦合时间序列的数量边界控制与空间尺度的区域规则约束刻画出中国的耕地保护弹性空间。在满足个人基本营养安全与作物单产条件干扰变量恒定的假设前提下,研究发现：① 中国多情景耕地保有量在2020—2100年间呈下降态势,现有耕地数量足以维持长期的粮食安全,但短期内则仅勉强达到理论粮食安全的临界区间1.40×10⁸~1.59×10⁸ hm²。② 不同维度耕地保护紧迫性在九大农业区划内呈现差异化分布特征,自然条件优越且适宜耕作的黄淮海平原区与长江中下游地区是综合紧迫性高值地块集聚区域。③ 可持续情景与区域冲突情景分别代表粮食安全底线约束下的最小与最大耕地保有量情景,在当前国际形势下,中国应保证短期（2035年内）可休耕量不高于9.29%。④ 基于时空耦合划定的耕地保护弹性空间可分为优先保护、严格管控、休养生息、战略储备、整治修复和特殊保护6类,不同空间的耕地保护弹性强度、目标与任务各有侧重。整体而言,耕地保护弹性空间的划定思路有助于农业结构调整、休耕政策完善等耕地空间规划体系构建,对中国耕地保护制度转型具有借鉴价值。

Food is one of the basic human needs. Achieving food security is one of the important goals of “The 2030 Agenda for Sustainable Development”. However, there is lack of system review of mutual influence between safeguarding food security and global climate change. Accordingly, this paper reports a critical review of the existing researches related to interactions between ensuring food security and global climate change. Effects of global climate change on the food system, impacts of ensuring food security on global climate change and adapting food security strategies against global climate change were systematically reviewed. The results indicated that, firstly, global climate change had increased uncertainty in the food system which had great impact on China’s food production. Secondly, demand for food was one of the main drivers of global climate change, and the reconfiguration of crop production elements exacerbated global climate change. Thirdly, a synthetic approach is required for food security adaption strategies against global climate change, specifically, in the micro-level promoting technological progress and scientific management, in the meso-level strengthening resources and environment protection, and in the macro-level adhering to the laws of market and improving food policy system. Moreover, under the background of global climate change, research on ensuring food security presents two major trends: one is the change from single discipline, one dimension and single means into multi-disciplinary, multi-scale, multi-factor, comprehensive and integrated approach; the other is to turn a high-carbon food system into a low-carbon and high-efficient food system.

粮食是人类生存的基础,保障粮食安全是“2030年可持续发展议程”的重要目标之一。论文基于粮食系统视角,从全球气候变化对粮食系统的作用、保障粮食安全对全球气候变化的影响,以及应对全球气候变化的粮食安全适应性策略出发,揭示粮食安全与全球气候变化的相互作用,系统梳理全球气候变化下的中国粮食安全问题。研究结果表明：1）全球气候变化导致粮食系统不确定性增加,且对中国粮食生产的影响加剧;2）粮食需求是全球气候变化的主要驱动力,粮食生产要素的重新配置加剧了全球气候变化;3）多尺度有机结合应对全球气候变化保障粮食安全需在微观上“藏粮于技”实现提质增效,在中观上“藏粮于地”注重生态建设,在宏观上坚持市场为主导完善粮食政策体系。全球气候变化背景下,保障粮食安全研究呈现从单一学科、单一维度、单一手段向依靠多学科开展多尺度、多要素、系统综合集成研究保障粮食安全转变,从高碳粮食系统向低碳高效粮食系统转变的趋势。

Spatial stratified heterogeneity is the spatial expression of natural and socio-economic process, which is an important approach for human to recognize nature since Aristotle. Geodetector is a new statistical method to detect spatial stratified heterogeneity and reveal the driving factors behind it. This method with no linear hypothesis has elegant form and definite physical meaning. Here is the basic idea behind Geodetector: assuming that the study area is divided into several subareas. The study area is characterized by spatial stratified heterogeneity if the sum of the variance of subareas is less than the regional total variance; and if the spatial distribution of the two variables tends to be consistent, there is statistical correlation between them. Q-statistic in Geodetector has already been applied in many fields of natural and social sciences which can be used to measure spatial stratified heterogeneity, detect explanatory factors and analyze the interactive relationship between variables. In this paper, the authors will illustrate the principle of Geodetector and summarize the characteristics and applications in order to facilitate the using of Geodetector and help readers to recognize, mine and utilize spatial stratified heterogeneity.

空间分异是自然和社会经济过程的空间表现,也是自亚里士多德以来人类认识自然的重要途径。地理探测器是探测空间分异性,以及揭示其背后驱动因子的一种新的统计学方法,此方法无线性假设,具有优雅的形式和明确的物理含义。基本思想是：假设研究区分为若干子区域,如果子区域的方差之和小于区域总方差,则存在空间分异性;如果两变量的空间分布趋于一致,则两者存在统计关联性。地理探测器q统计量,可用以度量空间分异性、探测解释因子、分析变量之间交互关系,已经在自然和社会科学多领域应用。本文阐述地理探测器的原理,并对其特点及应用进行了归纳总结,以利于读者方便灵活地使用地理探测器来认识、挖掘和利用空间分异性。

Cultivated land abandonment has a profound impact on China's food security. Taking the main grain producing areas in China as an example and based on the identification of the distribution of abandoned land, this paper measured the spatial distribution pattern of abandoned land, established the mediating effect model of cultivated land abandonment, and explored the influence mechanism of cultivated land abandonment on regional grain yield. The results showed that: (1) The area of abandoned cultivated land in the main grain producing areas of China was 4.0553 million hectares, with a rate of 5.85%; the distribution of abandoned land presented a T-shaped pattern, mainly concentrated in the Northeastern Heilongjiang, Northwestern Jilin and Southern Inner Mongolia. (2) Cultivated land abandonment had a significant negative impact on the grain yield of the main grain producing areas. In 2017, these areas lost a farmland production potential of 13.3915 million tons, and the loss of grain output was as high as 22.656 million tons, accounting for 4.69%; Inner Mongolia was the most affected region. (3) Grain sown area, farmland production potential, and agricultural technology input all played an intermediary role, and their regression coefficients were -0.194, -0.025 and 0.006, respectively. (4) We should follow the trend of urban-rural integration and agricultural-rural development, strengthen the input of modern agricultural production factors and policy support in major grain producing areas, and construct the flexible mechanism of spatial transformation between grain production and cultivated land fallow to ensure food security in China.

耕地撂荒严重地影响着我国的粮食安全。以我国粮食主产区为研究区域,在识别撂荒地分布的基础上,测度了撂荒地空间分布格局,并建立耕地撂荒中介效应模型,探究了耕地撂荒对区域粮食产量的影响机制。结果表明：（1）中国粮食主产区耕地撂荒规模为405.53万hm²,撂荒率约为5.85%;空间上撂荒地规模分布呈“T”字形空间格局,黑龙江东北部、吉林西北部以及内蒙古南部地区为撂荒地主要集聚区。（2）耕地撂荒对于粮食主产区粮食产量具有显著负向影响,2017年我国粮食主产区因耕地撂荒损失的农田生产潜力达到1339.15万t,损失的粮食产量高达2265.6万t,损失比例达4.69%;内蒙古自治区成为粮食产出损失量和损失比例最大的地区。（3）粮食播种面积、农田生产潜力和农业技术投入均发挥了部分中介作用,系数分别为-0.194、-0.025和0.006。（4）应遵从城乡融合以及农业农村发展态势,强化粮食主产区农业生产现代要素投入与政策扶植,构建粮食生产—耕地休耕空间转换弹性机制,保障我国粮食安全。

Urban expansion often occurs on croplands. However, there is little scientific understanding of how global patterns of future urban expansion will affect the world's cultivated areas. Here, we combine spatially explicit projections of urban expansion with datasets on global croplands and crop yields. Our results show that urban expansion will result in a 1.8-2.4% loss of global croplands by 2030, with substantial regional disparities. About 80% of global cropland loss from urban expansion will take place in Asia and Africa. In both Asia and Africa, much of the cropland that will be lost is more than twice as productive as national averages. Asia will experience the highest absolute loss in cropland, whereas African countries will experience the highest percentage loss of cropland. Globally, the croplands that are likely to be lost were responsible for 3-4% of worldwide crop production in 2000. Urban expansion is expected to take place on cropland that is 1.77 times more productive than the global average. The loss of cropland is likely to be accompanied by other sustainability risks and threatens livelihoods, with diverging characteristics for different megaurban regions. Governance of urban area expansion thus emerges as a key area for securing livelihoods in the agrarian economies of the Global South.

基于土地非农化与经济发展阶段耦合规律的理论分析,应用承载力模型,开展了2008年环渤海地区县域土地非农化适度性的评价和土地适度非农化阈值的界定。结果表明:①受区域土地资源禀赋与经济社会需求的影响,经济社会发展对非农建设用地的需求与建设用地供给之间呈现为正反双向的"S"型曲线,两者之间的耦合变化规律以工业化完成阶段最为显著;②工业化初期至后期阶段土地非农化趋势表现为缓慢增长,土地适度非农化阈值为10.0%~17.5%;③工业化与城镇化驱动作用强度决定着土地非农化规模的区域差异。因地制宜、科学调控土地非农化进程是区域可持续发展的重要保障。

With the implementation of rural vitalization strategy, China has stepped into a critical period with the dramatic changes of urban-rural relations and the accelerating transformation development of rural territorial system. Scientifically understanding the research progress of urban-rural relation theory and evolution rule is of great significance for boosting rural vitalization, narrowing urban-rural disparity, adjusting urban-rural structure and optimizing urban-rural patterns. This paper elaborates the research progress of urban-rural relations and rural development in China from the dimensions of economy, society, ecology and culture based on the review of foreign urban-rural relations and the characteristics of domestic rural development, as well as the evolution of urban-rural relation. Furthermore, prospect of research focus or key fields in the future were given. Firstly, transforming the development idea from productivism oriented to post-productivism oriented and attaching importance to the multiple values of rural areas should be emphasized. Therefore, it is necessary to carry out intensive studies about the mechanism, regional path selection and development mode of rural vitalization based on the theory of rural multiple function transition. Understanding the relationship of different functions is essential for dealing with rural decline and realizing the comprehensive vitalization. Meanwhile, we should focus on the mechanism and format of rural vitalization based on different territorial types. Against the context of rural-urban integrated development, we should promote the supply-side reform and activate the forces of socio-economic growth in underdeveloped areas. As for the developed rural areas, the “hybridity” should be emphasized and further studies should be conducted. In some rural areas, the phenomenon of the hybridity of development agents, the combination of production space and living space, the mixture of rurality and modernism have emerged. Accordingly, more emphasis should be placed on the heterogeneity and diversity in the process of rural restructuring. Secondly, with the emergence of new factors or new technologies, we should focus on the new morphology of rural development, such as characteristic towns, rural complex and “Taobao village”. In recent years, China's rural areas have undergone intensive restructuring motivated by e-commerce, which has triggered a new wave of rural rejuvenation. But how e-commerce affects rural development and the characteristics of this process are still unclear, and this is important for understanding the urban-rural relations under the context of informatization. Thirdly, the mechanism and format of urban-rural spatial restructuring should be emphasized. From the perspective of urban-rural interaction, the theory of urban-rural network may be practical and meaningful for optimizing the spatial distribution of infrastructure construction and industrial development. Lastly, creating or improving the theory and improving the path of rural vitalization according to the national conditions are meaningful for realizing the strategy.

随着乡村振兴战略的实施,我国已经进入城乡关系变革及乡村发展快速转型的关键时期。科学认知国内外城乡关系理论发展和演变规律对实施乡村振兴战略、缩小城乡差距、调整城乡结构和优化城乡格局具有重要意义。本文在系统梳理国外城乡关系理论及我国乡村发展与城乡关系演进的阶段性特征的基础上,从经济、社会、生态及文化的视角阐述了我国乡村发展与城乡关系研究的相关进展,并在此基础上探讨了未来重点的研究领域和方向。乡村发展思维应由生产主义导向转向后生产主义,关注乡村多元价值,深化基于乡村多功能转型理论的乡村振兴机制、区域路径与模式研究;在科技迅速发展,新事物新因素大量涌现的新时代,应关注特色小镇、田园综合体、民宿及乡村电子商务等新兴乡村转型发展形态的形成机制;同时,基于不同地域类型的乡村振兴的机制与模式研究也应得到重视,结合国际乡村地理学前沿,深入开展发达地区乡村的混杂性研究。广泛的城乡空间重构进程对乡村地区产生剧烈的影响与挑战,对于乡村振兴视角下城乡空间重构的动力机制与模式的研究仍需持续关注;根据我国的特殊国情,创新适合我国基本国情与发展实际的乡村振兴理论与实现路径,推动城乡融合发展。

With urbanization and industrialization, cultivated land in hilly regions of China has been gradually marginalized. Abandoned cultivated lands have ranged from inferior sloping land and extended to high-quality terraces. The abandonment of terraces will lead to a series of social and ecological problems, especially with large-scale abandonment. Therefore, the degree and spatial distribution of terrace abandonment should be evaluated scientifically to address the issue of abandonment as well as its effects. This study investigated the extent of terrace abandonment in China via a questionnaire sampling method. Based on 560 village questionnaires from 329 counties in China, the scale of terrace abandonment was calculated and the spatial heterogeneity characteristics and primary reasons for terrace abandonment were further analyzed. Study results showed that: (1) The phenomenon of terrace abandonment was observed throughout China, occurring in 54% of all the villages investigated; 9.79% of the total terraced areas have been abandoned. (2) The degree of terrace abandonment showed a spatial pattern of "high in the south and low in the north". The degree of terrace abandonment was higher in the southern hilly mountains, and the middle and lower reaches of the Yangtze River was the most serious. (3) The primary factors related to terrace abandonment were found to be labor migration, the degree to which terraces have been mechanized, irrigation conditions, and farming traffic conditions. Measures that include improving the degree of terrace mechanization should be enacted to address the problem of terrace abandonment. An orderly "conversion of cropland" could be applied to poor-quality terraces. Changing the planting structure, strengthening new agricultural infrastructure, and encouraging circulation and large-scale operations are options that could be applied to good-quality terraces.

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。

Cropland abandonment has increasingly occurred in China, which potentially affects national food and ecological security. This study collected existing publications focusing on cropland abandonment. Then, we extracted the key characteristics of cropland abandonment events, including time, location, magnitude, and driving force. The meta-analysis was carried out on these items to disclose the spatio-temporal pattern and main drivers of cropland abandonment in China in the last three decades. We found that there were a total of 163 counties in which cropland abandonment occurred according to the existing literature. These counties were mostly located in southern China and, in particular, exhibited a pattern of a T-shape on 90 degree anticlockwise rotation. The vertical axis exhibited a north-south belt across southeastern Gansu Province, eastern Sichuan Province, Chongqing, western Guizhou Province, and northern Yunnan Province. The horizontal axis exhibited a west-east belt along the middle to lower reaches of the Yangtze River across southern Hubei Province, northern Hunan Province,w and central to southern Anhui Province. In the provinces of Hunan, Sichuan, and Anhui, cropland abandonment can be found in 24, 23, and 21 counties, respectively; in Hubei, Chongqing, Fujian, Gansu, and Yunnan provincial-level areas, there are more than 10 counties with cropland abandonment. The formation of the “T” structure underwent two stages. Before 2010, there were 102 counties with cropland abandonment that mainly existed along the middle to lower reaches of the Yangtze River, where the horizontal axis occurred. Since 2010, there have been 63 counties with cropland abandonment, mostly existing in the north-south belt from southeastern Gansu to northern Guizhou, where the vertical axis occurred. The spatio-temporal patterns of cropland abandonment events matched well with the labor emigration from agriculture in the context of regional economic development and industrial restructuring. The low economic efficiency of agriculture and the shortage of agricultural labor are two common drivers leading to cropland abandonment in 86% and 78% of counties, respectively.

当前耕地撂荒已成为一种日益普遍的土地利用变化现象,对粮食安全和生态环境具有重要影响。为揭示1992-2017年中国耕地撂荒的时空特征及驱动机制,采用集成分析的思路,对县（市）域尺度撂荒的研究成果进行了汇总梳理,从中提取撂荒时间、位置、规模（程度）、成因等信息,并进行了荟萃分析。结果发现：1992-2017年全国范围内有撂荒记录的县（市）共165个,主要分布于南方,集中分布区呈逆时针旋转90°的“T”字型,纵轴自北至南贯穿甘肃东南部、四川东部、重庆境内,直至贵州西部和云南北部;横轴位于长江中下游地区,自西向东贯穿湖北、湖南、安徽、江西。其中,湖南、四川、安徽有撂荒记录的县（市）数量较多,分别为24个、23个、21个,其次是湖北、重庆、福建、甘肃、云南,均超过10个。“T”字型结构的形成经历两个阶段,大致以2010年为界,此前有撂荒记录的县（市）为102个,集中分布于沿长江中下游的东西向带状区域,形成横轴;此后新增63个县（市）,集中分布于自甘肃东南部至贵州西部和云南北部地区的南北向带状区域,形成纵轴。撂荒格局的形成过程与区域经济发展和产业结构调整背景下的农业劳动力析出基本同步。农业收益低和劳动力不足分别是86%和78%的县（市）撂荒形成的共性因素。

Taking counties as the basic unit, this paper establishes the evaluation index system of farmland functions from the dimensions of economy, society and ecology, adopts the method combining entropy weighting and multiple correlation coefficient weighting to determine the weights, and calculates the farmland function indices of each county. Subsequently, the spatio-temporal characteristics of farmland functions evolution were analyzed and the coupling relationships between the sub-functions were explored based on the coupling coordination model, simultaneously, the dynamic mechanism of farmland functions evolution was quantitatively probed by applying the spatial econometric regression analysis method in this research. Major conclusions were drawn as follows: (1) The farmland economic function generally presented a declining trend during 1990-2010. Especially, the function is strengthened in underdeveloped and agriculture dominated counties, and weakened continuously in developed areas on contrary; 60.29% of the counties decrease in farmland social function, whereas some counties, which are mostly located in the north of Zhengzhou, the west of Dezhou and Cangzhou, Yantai and Weihai, have experienced an obvious increase; The dramatic decline of farmland ecological function has occurred around Beijing, Tianjin and Jinan. Areas located in northern Henan Province and central Shandong Province has witnessed an increase of ecological function. (2) There is a significant spatial difference in the coupling degree and coordination degree of the sub-functions, and the decoupling phenomenon gradually highlights. The changes of social function and ecological function lag behind those of economic function in developed areas, but they are highly coupled in some underdeveloped areas. (3) The evolution of farmland functions in the Huang-Huai-Hai Plain resulted from the comprehensive effects of regional basic conditions and external driving factors. Furthermore, the transition of population and industry in the process of urbanization and industrialization plays a decisive role in evolution intensity and direction of farmland sub-systems including economy, society and ecology. According to the results above mentioned, agricultural modernization, industrialization and promoting the transformation of traditional agriculture should be regarded as an important engine driving the sustainable development of Huang-Huai-Hai Plain. In view of regional differentiation characteristics of farmland functions evolution, differentiated and diversified farmland use and management modes should be implemented from developed urban areas to underdeveloped traditional agricultural areas.

本文以县域为基本研究单元,从经济、社会及生态三个维度构建了耕地功能评价指标体系,分析了黄淮海平原耕地功能演化的时空特征,利用耦合动态度模型探讨了耕地功能间耦合关系的演变。在此基础上,利用空间计量模型,对耕地功能演化的驱动机制进行了定量分析。研究结果表明：① 1990-2010年间,冀中南及豫东地区部分欠发达县市耕地经济功能明显增强,发达的城市群及其腹地受工业化及城镇化影响较大,耕地经济功能持续下降;60.29%的县域单元耕地的社会功能下降,增强区主要集聚于郑州北部、德州及沧州西部、烟台、威海等区域;生态功能变化在空间格局上基本形成了以豫北、山东中部山地丘陵区为核心的增长区以及以环京津、环济南地区为核心的持续下降区。② 黄淮海平原耕地经济、社会及生态功能的耦合度及协调度空间差异显著,且退耦化现象日渐突出;经济发达地区耕地的社会及生态功能演化速率普遍滞后于经济功能。③ 黄淮海平原耕地的功能演化是区域本底因素与外部驱动因素综合作用的结果;城镇化与工业化进程中人口、产业的转型对耕地经济、社会及生态功能演化的强度及方向起决定性作用。并指出：黄淮海平原应激活农业现代化、产业化发展动力,促进传统农业的转型升级,充分考虑耕地功能演化的区域分异特征,实行由发达城市地区到欠发达传统农区的差异化、多元化的耕地多功能利用与管理模式。