还原论与农户地理研究

依据科学研究的还原论方法和数学逻辑,分析指出农区经济活动的最基本组织单元是农户。基于地理学、经济学、组织学相关原理,建立了农户地理研究的基本框架。农户地理研究的主要内容包括农户自主发展能力研究、农户区位研究、农户发展环境研究、农户与地理环境相互关系研究。除了单一农户研究之外,农户地理还包括通过正式联系或非正式联系所形成的农户群研究。中国的特殊国情决定了农户在农区经济中的重要地位,农户与地理环境的长期相互作用轨迹及其相互印记又决定了农户地理研究在地理学中的特殊意义。沿着这一方向的研究,有利于建立富有中国特色的经济地理理论。     

贫困山区农户兼业行为及其居民点用地形态——基于重庆市云阳县568户农户调查

贫困山区农户兼业现象普遍,对相关的土地利用活动影响深刻。采用重点与随机抽样、参与式农村评估和景观格局分析等方法,从微观尺度定量分析了云阳县568户农户兼业行为与居民点用地形态变化的相互关系,可为土地利用结构调整、居民点用地整理挖潜提供认识依据。结果表明:(1)云阳县农户兼业现象普遍,依据非农收入与农业收入差、非农劳动投入比重,将农户划分为纯农业型、农业主导型、农工兼具型、非农主导型、非农业型五种兼业类型;(2)老龄和女性人口少、且平均文化水平较高的农户兼业水平最高,人口数量多、分工多元化的农户兼业水平居中;(3)以农业生产为主要生计活动的纯农业型与农业主导型农户,居民点用地规模变化较小,约为180m2,土地利用粗放且多样化程度高,其中,纯农业户圈养与堆棚用地比重较高,农业主导型院坝用地比重较高;(4)农工兼具型农户的居民点用地规模扩大,约为190m2,土地利用集约度得到提高,且多样性下降,堆棚用地弱化,住房用地占主导;(5)逐渐退出农业生产的非农主导型与非农业型农户,居民点用地规模缩减,约为160～130m2,土地集约度较高,多样性下降,居民点中生产性用地比重下降、居住性用地比重上升。研究认为,农村居民点整理挖潜必须与农户的兼业需求相适应。     

基于生计资产量化的农户分化研究——以重庆市沙坪坝区白林村471户农户为例

农户生计资产的配置结构及其空间分布特征决定着农户生计发展的资源优势和空间可能性,依据农户生计资产结构可以准确地识别其分化情景。研究采用＂PRA＋3S＂相结合的方法,以地理坐标为标识码,建立农户属性与地块空间数据相链接的＂农户-土地＂数据库,对农户生计资产配置结构、农户类型划分、农户空间分布特征进行了研究。结果表明：（1）农户生计资产配置结构差异明显,113户农户自然资产产值高于平均值,趋于发展农业生产;108户农户各项资产处于平均水平,主要向兼业发展;250户农户自然资产小于0.1,趋于发展非农生产;（2）依据农户生计发展趋势将其划分为农业多样化发展型（16%）、农业专业化发展型（8%）、兼业化发展型（23%）、非农多样化发展型（31%）、非农专业化发展型（22%）。     

Assessment of land-use and land-cover changes from 1965 to 2014 in Tam Giang-Cau Hai Lagoon,central Vietnam

This study integrates the use of multi-source and multi-resolution remote sensing, topographic and field-based datasets to quantify land-use and land-cover (LULC) changes along a coastal stretch of Thua Thien Hue Province (central Vietnam). The LULC change analysis involves the Tam Giang-Cau Hai lagoon, the largest lagoon system in Southeast Asia, which is running nearly 70 km along the coast and having about 22,000 ha of water surface.The LULC change analysis was performed by computer-aided visual interpretation for 5 years (1965, 1989, 2000, 2006 and 2014) using satellite imagery from LANDSAT MSS, TM, ETM+ and 8, ASTER and SPOT5. National topographic maps were also used for the 1965 and 2000 years.To adequately represent the LULC features and peculiarities of central Vietnam coastal areas, an adapted CORINE Land Cover nomenclature was used where new 3rd and 4th level classes were adopted. Due to their intrinsic relative high spatial and radiometric resolution, SPOT5 images from 2006 were assumed as a reference for interpretation keys and first delineation. Changes were mapped by editing those vectors representing features which underwent LULC change prior or after 2006. Spatial and temporal changes were analyzed by post-classification approach and validated by ground truth information. High detail object-based classification was finally performed to infer the capability of medium spatial resolution imagery for extracting cadastral scale pond maps. The accuracy of classification was checked by a polygon by polygon comparison with an existing aquaculture facility inventory.Five LULC maps were obtained by applying a legend of 21 classes including two newly defined: “Aquaculture ponds” and “Mangrove forest”. The overall classification accuracy of the LULC map is 85% while the KHAT statistics 0.81 for the year 2006. Accuracy of the object-based aquaculture facilities classification is 84% or better for the SPOT5 imagery and 47.9% for the ASTER imagery. The study provides a synoptic LULC representation for the largest lagoon system of Southeast Asia and delivers quantitative estimates of main changes occurred during the last 50 years. Moreover, it reveals the adaptability of the CORINE Land Cover method outside European environment. Finally, SPOT5 provides good results to map aquaculture features at cadastral scale, even if in some circumstances (e.g. tidal areas), the integration with higher spatial resolution multispectral sensors should be envisaged.     

武陵山片区城镇化的农户生计响应及影响因素研究——基于3个典型乡镇355户农户调查数据的分析

基于3个典型乡镇355户农户的调查数据考察武陵山片区农户的城镇化生计响应发现：① 农户生计响应是“城乡连续体”的“人业地”关系重构中乡村聚落的决策单元对城镇聚落吸附与扩散效应的综合反应,受宏观环境、外部条件和家庭因素的影响;② 区域性中心城市郊区、革命老区红色旅游景区和县城近郊特色农业种植区周边农户的生计综合响应、生计空间响应和生计产出响应依次递减,但生计资本和生计方式响应及各维度的响应强度排序不一致;③ 城乡二元体制的演变与新型城镇化战略、乡村振兴战略动态地规制与诱导农户,使其生计响应与国家阶段性战略目标相适应。地形平缓、距离县城较近、经济发展水平较高以及区域性中心城市郊区休闲驱动型城镇化对应于更广维度和更高强度的农户生计响应。收入来源以经商、务工为主,家庭成员中有小孩或老人,有较高教育程度家庭成员以及社会资本较高的农户,其生计响应的维度更广且强度更高。     

近30年来三江源地区土地覆被与宏观生态变化特征

利用1970年代中后期MSS图像和1980年代末、2004年以及2008年三期TM图像并结合野外调查,获得三江源地区四期土地覆被空间数据集,提出了土地覆被转类指数和土地覆被状况指数,以表征该区域生态变化的趋势。通过计算土地覆被转类途径和幅度、土地覆被转类指数和土地覆被状况指数,分析青海三江源地区1970年代中后期以来土地覆被时空变化特征及其反映的宏观生态状况变化。结果表明:三江源地区近30年平均土地覆被状况指数为38.20,土地覆被状况为4级,其中黄河流域最好,其次为澜沧江流域,长江流域最差;三江源地区土地覆被转类,在1970s~1990s和1990s~2004年两个时段,均主要以高生态级别向低生态级别转移为主,2004~2008年时段,主要以低生态级别向高生态级别转移为主;由土地覆被状况指数变化率和土地覆被转类指数,可以反映出近30年来三江源地区土地覆被和宏观生态状况,总体上经历了变差(1970s~1990s时段土地覆被状况指数变化率Zc为-0.63,土地覆被转类指数LCCI为-0.58)—显著变差(1990s~2004时段Zc为-0.94,LCCI为-1.76)—略有好转(2004~2008时段Zc为0.06,LCCI为0.33)的变化过程。这一变化过程前、中期主要受到气候变化和草地载畜压力共同驱动的影响,后期则叠加了生态建设工程的驱动作用。     

Dynamic Changes of the Bush Encroachment in Low Altitude Area of Ethiopia

Bush encroachment is widely distributed in arid and semi-arid regions, and it has a serious impact on livestock production, especially in Africa where livestock is a primary source for the livelihoods of many people. In this study, methods of supervised classification and decision tree classification, and indexes of a land use change significance index (Ci) and a single land use dynamic degree, were applied to remote sensing imagery of Ethiopia for 1986-2016. The results show the dynamic characteristics of grassland bush encroachment in low altitude areas (pastures <1500 m above sea level) of Ethiopia in the 30 year period studied. The results revealed several interesting features of this phenomenon. (1) The area of bush encroachment showed an increasing trend, with a maximum of 3.74×10³ km² in 2003, which represented 68.97% of the total area, and declined slightly from 2003~2016. (2) Among classification types, the area of severe shrub grassland was the largest, accounting for 28.36-49.10% of the total area, while the area of moderate bush encroachment accounted for 9.77-16.68%, and slight bush encroachment accounted for 5.52-7.57%. (3) The expansion rate of shrubby grassland was 0.74% for the 30 year period, while the average annual expansion rate was 2.16% for the 8 years from 1995-2003. (4) Forest land and grassland were the two main land use types of shrub grassland transformation in low altitude areas and bush encroachment changed large amounts of forest land into grassland due to shrub grassland management. The results of this study provide basic data for revealing the impacts of development processes on subsequent bush encroachment and can inform better management for the sustainable development of grasslands in low altitude systems.     

山区农户耕地利用集约度及其影响因素——以重庆市12个典型村为例

耕地利用集约度对粮食安全、生态环境和耕地保护有深刻影响。利用重庆市酉阳县、武隆县、巫山县3个县12个典型村972份有效农户调查样本,基于货币额衡量生产成本,对比分析不同类型农户的耕地利用集约度差异,同时综合价值形态指标与实物形态指标对其内部结构进行分析比较,然后运用多元线性回归模型定量分析不同类型农户内部耕地利用集约度的影响因素,以期为政府制定山区农业发展政策与措施提供科学依据。研究表明:1不同类型农户的耕地利用集约度及其内部结构存在较大差异,劳动集约度、资本集约度与耕地利用集约度基本呈现自然资产型人力资产型基本型缺失型的关系;2研究区正经历着农村劳动力快速转移过程,农户生计多样化显著,但生计多样化并不一定意味着耕地集约度的降低;3农业生产补贴和经济作物播种面积比重对自然资产型农户有显著的正向影响,故农业发展政策应集中在提高农业生产补贴和调整农业产业结构方面,前提是继续采取有效措施改善农村交通水利等基础设施,建立农业发展的平台。     

贫困山区农户人力资本对生计策略的影响研究——以四川省凉山彝族自治州为例

人力资本是构建农户生计的关键要素,从人力资本视角探讨农户生计选择对于推动农户生计转型、实现乡村振兴具有重要意义。论文以西南贫困山区四川省凉山彝族自治州为案例区,采用2018年508个农户样本数据,应用回归模型,估算了人力资本对农户生计策略的影响。结果表明：人力资本是山区农户生计选择的重要影响因素,不同类型人力资本对农户生计策略的影响不同,且具有明显的空间差异。教育文化、健康状况对非农生计策略的选择具有正向影响,且高山区>二半山区>河谷区,健康状况对河谷区农户生计选择影响不显著;非农技能培训对非农生计策略选择具有显著的正向影响,且高山区>二半山区>河谷区;农业技能培训对非农生计策略选择具有负向影响,且高山区<二半山区<河谷区,但其对高山区农户生计选择并不显著;青壮年劳动力倾向于选择非农生计,务农人口老龄化问题严峻,高山区表现最为突出,二半山区次之,河谷区较不明显。最后,根据研究结论,探讨了人力资本、劳动力转移与乡村发展之间辩证关系及相关政策建议。     

Local level rainfall and temperature variability in drought-prone districts of rural Sidama,central rift valley region of Ethiopia

ABSTRACT

The purpose of this study is to examine local level spatiotemporal rainfall and temperature variability in drought-prone districts of rural Sidama, Central Rift Valley region of Ethiopia. The study used 129 gridded monthly rainfall and temperature data of 32 years (1983–2014). The gridded rainfall and temperature records were encoded into GIS software and evaluated through different statistical and geospatial techniques. Mann-Kendal rank test and F distribution tests were used to test temporal and spatial statistical significance, respectively, of the data. The analysis revealed that Belg and Kiremt are the main rainfall seasons, constituting 81% of the annual rainfall. Although annual, Kiremt, and Belg rainfall amounts appear to have decreased over time, the decreasing trend is statistically significant only for Belg rainfall records. On the other hand, rainfall standard anomaly results indicated seven droughts of different magnitudes: one extreme, two severe, and four moderate. The study also revealed increasing temperature trends over the years under consideration that are statistically significant. The findings of this study on rainfall contradict other findings obtained around the study area. Thus, climate change adaptations need to focus on location-specific climate data analysis so that the intended adaptive interventions can be successful.     

农牧交错区农村居民点土地利用形态演变——以内蒙古自治区阿鲁科尔沁旗为例

以农牧交错区的阿鲁科尔沁旗为例,选取7个典型村,运用参与式农村评估(PRA)、GIS与遥感技术相结合的方法,探讨农牧交错区农村居民点土地利用形态特征及其与农牧户生计的关系。结果表明：①半农半牧型农村居民点由纯牧型农村居民点演变而来。人口增加导致人地矛盾突出和草原开垦耕种,农牧户生计策略转为畜牧业和种植业结合,农村居民点向半农半牧型转变;②半农半牧型农村居民点内部用地类型逐渐多样化。从改革开放前居民点内部以农村宅基地占主导,到改革开放后居民点内部公共设施用地、商服用地、工矿仓储用地迅速扩大;③由于农牧户生计活动的多样化和非农化,农村宅基地内部不但包括居住用地(住房),还包括生产性用地和生产辅助性用地（如牲畜的棚圈、菜园和粮草仓库等）。研究认为,半农半牧型农村居民点人均居民点用地和户均宅基地都远大于国家规定的用地标准,是与半农半牧的生产方式和生计需求紧密相关的。     

Population Pressure,Deforestation, and Land Degradation: A Case Study from the Dominican Republic

Population pressure, deforestation, and land degradation are major ecological concerns in developing countries. This research investigates causal linkages among interrelated physical and social processes in a case study conducted within the Plan Sierra resource management region of the Cordillera Central, Dominican Republic. Results of bivariate regression analysis, based on a sample of 450 traditional hillslope farms, support a linear relationship between population pressure and deforestation at two spatial scales. However, the strength of the relationship between population pressure and forest cover change decreases over a twenty-year time frame. Results also confirm a positive relationship between deforestation and land degradation. This case study contributes to an understanding of the precise nature of these relationships at sub-national scales of analysis.     

Quantifying successional land cover after clearing of tropical rainforest along forest frontiers in the Congo Basin

State-of-the-art impact-modeling studies in environmental and climatological sciences require detailed future deforestation scenarios that allow forest to be replaced by a mosaic of multiple successional land-cover types, rather than the simple conversion of forest to a single land-cover type, such as bare soil or cropland. Therefore, not only the amount and location of forest removal has to be known (as is typically provided by scenarios), but also knowledge about the successional land-cover types and their relative areal proportions is needed. The main objective of this study was to identify these successional land-cover types and quantify their areal proportions in regions deforested during the past 37 years around the city of Kisangani, D.R. Congo. The fallow vegetation continuum was categorized in different stages, adapted from existing classifications. Ground-truth points describing the present-day vegetation were obtained during a field campaign and used for supervised and validated land-cover classification of these categories, using the Landsat image of 2012. Areal proportions of successional land-cover types were then derived from the resulting land-cover map. The second objective of this study was to relate these areal proportions to time since deforestation, which is expected to influence fallow landscapes. Landsat images of 1975, 1990, and 2001 were analyzed. Present-day mature tree fallow is less abundant on areas deforested during 1975–1990. The relative areal proportions were used to refine a deforestation scenario and apply it to existing data-sets of LAI and canopy height (CH). Assuming a simple conversion of forest to cropland, the deforestation scenario projected a reduction of grid-cell-averaged CH from 25.5 to 7.5 m (within deforested cells), whereas the refined scenarios that we propose show more subtle changes, with a reduced CH of 13 m. This illustrates the importance of taking successional land cover correctly into account in environmental and climatological modeling studies.     

Land cover change along the Qinghai-Tibet Highway and Railway from 1981 to 2001

Based on the NOAA AVHRR-NDVI monthly data from 1981 to 2001, the spatial distribution and dynamic change of land cover along the Qinghai-Tibet Highway and Railway were studied. The results of the analytical data indicate that the NDVI values in July, August and September are rather high during a year, and a linear trend by calculating NDVI of each pixel computed based on the average values of NDVI in July, August and September were obtained. The results are as follows: 1) Land cover of the study area by NDVI displays high at two sides of the area and low in the center, and agriculture area > alpine meadow > alpine grassland > desert grassland. 2) In the study area, the amount of pixels with high increase, slight increase, no change, slight decrease and high decrease account for 0.29%, 14.86%, 67.61%, 16.7% and 0.57% of the whole area, respectively. The increase of land cover pixels is mainly in the agriculture and alpine meadow and the decrease pixels mainly in the alpine grassland, desert grassland and hungriness. Grassland and hungriness contribute to the decrease mostly and artificial land and meadow contribute to the increase mostly. 3) In the area where human beings live, the changing trend is obvious, such as the valleys of Lhasa River and Huangshui River and area along the Yellow River; in the high altitude area with fewer people living, the changing trend is relatively low, like the area of Hoh Xil. 4) Human being’s behaviors are a key factor followed by the climate changes affecting land cover.     

Vulnerability and adaptation to climate-related fire impacts in rural and urban interior Alaska

This paper explores whether fundamental differences exist between urban and rural vulnerability to climate-induced changes in the fire regime of interior Alaska. We further examine how communities and fire managers have responded to these changes and what additional adaptations could be put in place. We engage a variety of social science methods, including demographic analysis, semi-structured interviews, surveys, workshops and observations of public meetings. This work is part of an interdisciplinary study of feedback and interactions between climate, vegetation, fire and human components of the Boreal forest social–ecological system of interior Alaska. We have learned that although urban and rural communities in interior Alaska face similar increased exposure to wildfire as a result of climate change, important differences exist in their sensitivity to these biophysical, climate-induced changes. In particular, reliance on wild foods, delayed suppression response, financial resources and institutional connections vary between urban and rural communities. These differences depend largely on social, economic and institutional factors, and are not necessarily related to biophysical climate impacts per se. Fire management and suppression action motivated by political, economic or other pressures can serve as unintentional or indirect adaptation to climate change. However, this indirect response alone may not sufficiently reduce vulnerability to a changing fire regime. More deliberate and strategic responses may be required, given the magnitude of the expected climate change and the likelihood of an intensification of the fire regime in interior Alaska.     

1981-2001年青藏公路和铁路沿线土地覆被变化

1 Introduction Land cover change may result in extremely profound influence on regional water circulation, environmental quality, bio-diversity, and the productivity and adaptive capacity of land ecosystem. Meanwhile, it is an important factor affecting r…     

人口老龄化对乡村发展影响研究进展与展望

人口老龄化是人类发展进程中一个重要的人口现象,研究人口老龄化对乡村发展的影响并探讨相应对策具有重要意义。本文首先分析了乡村人口老龄化特征及原因,随后从生产、生活、生态三个视角梳理了人口老龄化对乡村生产要素投入、农业生产、社会保障、乡村治理、消费结构、土地利用变化和生态空间等方面影响的研究进展。在此基础上提出今后应结合产业兴旺、生态宜居、乡风文明、治理有效、生活富裕的乡村振兴战略总体要求,从生态环境—经济发展—社会发展三个维度开展乡村人口老龄化的影响与适应相关研究,重点研究方向有：①基于人口流动视角的乡村人口老龄化对生态系统服务价值的影响;②乡村人口老龄化空间差异及其对农业现代化的影响;③应对人口老龄化的乡村振兴路径。     

黄河流域NDVI/土地利用对蒸散发时空变化的影响

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