干旱区绿洲不同土地利用方式和强度对土壤粒度分布的影响

以干旱区三工河流域下游绿洲作为研究区,应用SPSS数理统计软件,选择12种土地利用系统,采集上层（0～20cm）和下层土壤（20-40cm）样品,分析出不同土地利用系统对土壤粒度分布的影响。研究结果表明：（1）研究区土壤主要由砂和粉砂组成,土地利用系统对砂、粉砂和粘土粒度分布的影响显著,无论上层还是下层,不同土地利用系统土壤砂、粉砂和粘土含量差异明显。（2）绿洲土壤砂含量随着土地种植年限增加有降低的趋势,而粉砂和粘土含量有增加的趋势。在不同的土地利用强度下土壤粒度分布表现出了不同的特征。土地利用强度大的一年生作物和多年生作物土壤粉砂和粘土含量较高。土壤质量得到了逐步改善;而受人类活动干扰较小的土地利用系统土壤砂和粉砂含量高,土壤质地差。说明干旱区绿洲的人类农业活动基本趋于合理。绿洲生态环境正逐步得到改善并持续发展。     

从康雍乾垦殖政策看中国清前期垦荒发展趋势

垦荒作为一种农业生产活动,与国家政策密切相关。在以农业生产为主要经济活动的清代,这种关系尤为密切。因而详尽分析与合理把握有清一代垦殖政策的内涵与取向,是深入了解清代垦荒态势及特征的重要途径。本文通过对康雍乾三朝垦殖政策及措施的比较分析,阐述了我国清前期土地垦辟的历史过程及其时空特征。分析结果认为:康熙朝是以恢复因战乱而凋敝的农业生产为主要目的,雍正朝是处于从恢复农业生产向解决“人多地少”矛盾方向转化的过渡期,而乾隆朝则是以解决“穷民资生”问题为目的;它们反映在垦荒上,即表现为:康熙朝以恢复性垦殖为特征,雍正朝以恢复性垦殖向拓展性垦殖过渡为特征,乾隆朝则是以拓展性垦殖为特征。同时,它们在地域空间及垦殖强度上也表现出明显的差异。     

Soil water property variations in three adjacent land use types in the Rift Valley area of Ethiopia

This study investigated the effects of land use change on infiltration and moisture content of soils in three land use types. A total of 81 soil and core samples (3 replications × 3 treatments × 3 profiles × 3 soil depths) were used to determine parameters that may affect the infiltration properties of soils. The infiltration rate was measured in the field using double-ring infiltrometer with three replicates in each land use type. Results showed that infiltration rates were generally slow in the open grazed and cultivated lands suggesting high potential for runoff, limited percolation, and very low amount of water available in the soil profiles. The accumulated infiltration in soils under cultivation and open-grazing was smaller than the controlled grazing by approximately 57%. Similarly, cultivation and open-grazing had reduced the soil moisture content by 29 and 33%, respectively, compared to the controlled grazing. Surface soil compaction, higher dry bulk density and lower soil organic carbon, appeared to be the principal factors for the low infiltration capacity and moisture content of the soils. Therefore, dry land management, with long term tree cover and well regulated grazing system, is very crucial for the sustainable ecosystem functioning of this environmentally fragile area.     

Soils and Land use on Lithologically Diverse Ophiolitic Alluvia on the Coastal Plain of Palawan,Philippines

The soils on the southeastern coastal plain of Palawan, Philippines are developed on alluvium derived from various lithologies of the Palawan Ophiolitic Complex. There is little lateral mixing of the alluvium. The soil pattern is interpreted as the result of increasing weathering and leaching with age on deposits of different lithological origins. In the ultramafic catchment the younger soils are infertile due to several unfavourable characteristics, including high contents of heavy metals and Mg, deficiencies of P and micro‐nutrients, and impermeability. These soils improve with increased weathering and leaching, and the older soils have better physical and Mg characteristics. In felsic alluvia the reverse is found, and the soils on younger deposits are the most fertile, while the older soils have unfavourable combinations of subsoil compaction, acidity and dominance by aluminium. These patterns are reflected in the current land use, with areas of sparse settlement and cultivation on the less fertile soils on younger ultramafic and older felsic alluvia. These areas have been avoided or abandoned, rather than overlooked, by farmers and cannot be considered as “empty lands”. Their sustainable development will require careful management. Most of the more fertile land is already cultivated.     

北京典型行业微区位选址比较研究——以北京企业管理服务业和汽车制造业为例

以微观企业数据为基础,采用核密度空间平滑和条件逻辑选择模型等方法,重点关注企业在城市内部微观尺度下的区位选择,并对北京典型现代服务业和制造业区位选择的差异进行对比分析。结果表明：① 北京中小型制造企业倾向于在集聚区分布,符合马歇尔式产业集群的特征,而服务业则是大型企业更倾向于集中布局;② 尽管微观尺度下多样化和上下游产业链对现代服务业和制造业依然有重要影响,但是与宏观尺度下不同的是对于现代服务业来说过度多样化并不利于其发展,对于制造业来说区域专业化劳动力规模而非专业化程度更为重要;③ 政府对地铁等公共设施布局选址将对现代服务业的微观区位产生重要影响。     

北京平原区地表质地特点与土地风沙化

本文是在实地调查研究及采集大量样品分析的基础上, 对北京平原区地表质地进行对比分析, 结果是: 延庆盆地地表以含石砾为特点; 北京平原区的广大河间冲积, 淤积区以粉壤质为主, 沙土主要分布在温榆河、潮白河及永定河流域, 以永定河流域占面积最大且比较集中; 风沙化土地的分布地域, 基本和沙土的分布地域一致, 只是由于沙质地表为主的地区, 因风沙长期作用及不合理的开垦利用, 加强了风沙活动强度, 地表细粒物质进一步被吹失, 地表相应粗化。     

中国地面交通线路密度的空间差异及变化

运用标准差、变差系数对我国三大地带及地带间地面交通线路密度的绝对差、相对差进行测度,发现三大地带内部及地带间交通线路密度的相对差和绝对差都很大且存在继续扩大的趋势。区位熵大于1的省域集中在东部,区位熵按东、中、西三大地带呈优势递减。地面交通线路密度与多数经济、社会因子的相关性都很强,与城市化水平的正相关性最强,与第一产业产值比重、工业化水平及第二产业产值比重呈负相关。主成分回归分析表明:三大主成分与地面交通线路密度具有很强的线性关系,各因子的作用大小不同。针对地面交通线路密度与城市化水平、第一产业产值比重、工业化水平及第二产业产值比重等典型影响因素的正、负相关性,探讨其成因。     

Scenarios of land system change in the Lao PDR: Transitions in response to alternative demands on goods and services provided by the land

Sudden and gradual land use changes can result in different socio-ecological systems, sometimes referred to as regime shifts. The Lao PDR (Laos) has been reported to show early signs of such regime shifts in land systems with potentially major socio-ecological implications. However, given the complex mosaic of different land systems, including shifting cultivation, such changes are not easily assessed using traditional land cover data. Moreover, regime shifts in land systems are difficult to simulate with traditional land cover modelling approaches. A novel simulation approach was employed that focused on simulating changes in land systems rather than focusing on land cover. With the CLUmondo model we simulated three scenarios of potential developments between the years 2010 and 2030 assuming different degrees of international market integration and sustainable growth objectives. Although all scenarios show a decline of shifting cultivation systems, the respective orientation of markets and land governance resulted in strongly different land change trajectories. The land system changes are strongly location dependent and different trajectories are found in different parts of the country. Some scenarios show clear elements of land sparing with intensification of land management in the valleys and re-growth of forest on sloping land. Other scenarios show elements of enhanced multi-functionality. The approach addressed methodological challenges in simulating land system regime shifts and complex mosaic landscapes while accounting for societal demands for different types of goods and services from land systems. The land systems approach allows a nuanced representation of different types of forests and agricultural systems such as shifting cultivation and commercial agricultural plantations. Simulation results contribute to a debate about desired future land use on the national scale including its environmental and socio-economic implications.     

Perspectives on Alaskan Agriculture

Abstract

Agriculture in Alaska is apparently declining in both absolute and relative terms, yet new land is still being brought into use and agricultural scientists continue to introduce improved varieties of crops and methods of cultivation. In an attempt to reconcile sometimes conflicting evidence, the present article reviews data for recent crop years and analyzes the circumstances under which farming exists. In the light of contemporary socioeconomic trends and the overwhelming disadvantages of the Alaskan setting, and in view of the fact that agricultural production is not critical to the needs of the state, further decline seems most likely. There are several factors, however, including those of perceived human values, institutional support, high prices of certain imported commodities, and above all the feasibility of part-time farm operation, that may contribute to a continuing although limited agricultural use of land.     

Impact of human activities on soil respiration: A review

Soil respiration is one of the primary fluxes of carbon between soils and the atmosphere.It is produced by rhizosphere respiration and soil microbial respiration.Soil respiration is not only affected by environmental factors,but also changes with the hu-man-induced disturbances of ecosystems.Land-use,the measures of land management,the pollution of soil,and so on can affect soil respiration and change the soil efflux.According to some research,the authors summed up their impacts on soil respiration by human activities through land-use changes and land-management measures among agroecosystem,grassland ecosystem,and for-est ecosystem.The results showed that (1) when adding fertilization to farmland,the soil respiration will increase;(2) fenced land can decrease soil respiration,while soil respiration in the grazed land at a grassland ecosystem will decline with the increasing of grazing intensity;(3) with grassland fertilization;farmland cultivation;fire,fertilization,and cutting of forest,conflicting results were found in the changes of soil respiration.Perhaps plant species,site condition,and measurement season can lead to different results on soil respiration.     

LAND QUALITY AND LAND ALIENATION ON THE DRY FARMING FRONTIER

From 1900 to 1920 the land alienation process in the northern Great Plains was primarily influenced by location, not land quality, in a railroad-dominated settlement pattern. Homesteaders in Sheridan County, MT and Bowman County, ND generally did not settle on the best lands first and assessed the productive acreage on their claims inaccurately. In peripheral locations, homesteaders who perceived soil resources correctly took the higher quality lands first. Evidence suggests abandonment was most likely on poorer soils, least likely on the best soils. Inability to perceive soil capability exacerbated an unstable situation that, with drought, led to out-migration.     

Exploring spatio-temporal variations of habitat loss and its causal factors in the Shenzhen River cross-border watershed

Understanding the mechanisms that underlie habitat loss is fundamental to nature conservation. Habitat loss and its related factors are location dependent, but their spatial variations across geographical space are poorly understood. This research attempts to explore the spatio-temporal variations of human and biophysical factors of habitat loss in the Shenzhen River watershed, a border region shared by the Hong Kong Special Administrative Region (SAR) and Shenzhen in China. Habitat loss was quantified through the comparison of historical land cover maps in 1988/1998/2008, derived from the Landsat imagery. The different degree of habitat loss is further considered by referring to loss of ecosystem services during habitat alteration or destruction processes. In order to examine how influencing factors change with space, the model of geographically weighted regression (GWR) was employed. The GWR model was proved to be effective in revealing a spatially varying relationship, and has better performance compared with the global regression model. The results also provided the detailed site information of the different roles of the related factors across the different locations. Various factors, especially the human-related ones, played a significant role in determining both the “rate” and “location” of habitat loss, and the influences also varied during the entire study period. These results could provide comprehensive information for future habitat conservation and cross-border watershed management.     

长春市耕地动态变化及其驱动力分析

利用1988~2007年统计数据和土地详查与变更调查资料,分析了长春市19a间耕地总量动态变化情况,并在此基础上运用主成分分析进一步探讨了影响长春市耕地变化的主要驱动因素。结果表明:①1988~2007年长春市耕地数量总体呈下降趋势;②经济发展是长春市耕地数量变化的主要驱动因素;③主成分分析中各因子的因子载荷除林牧渔业占农林牧渔业总产值为0.575外,其他均大于0.9;④耕地产出率与林牧渔业占农林牧渔业总产值的比例因子载荷相对较高。影响长春市耕地总量动态变化的驱动因子可归纳为社会经济发展、人口增长、农业科技进步三大因素。     

1960-2010 年贵州省喀斯特山区陡坡土地利用变化

基于GIS 与RS技术, 以贵州省喀斯特山区坡度大于25°的区域为研究对象, 利用1960 年1:50000 地形图、1990 年Landsat TM遥感影像以及2010 年的环境减灾卫星(HJ-1A/1B)影像, 解译获取1960、1990、2010 年3 个时间点的土地利用数据, 并结合贵州省水文地质图、坡度图进行陡坡土地利用变化分析。结果表明:①1960-1990 年的30 年间, 有林地、灌木林、水体呈减少趋势, 其中灌木林减少的最多, 其次是有林地;而草地、建设用地、裸岩和耕地呈持续增长趋势, 其中草地增加的最多, 其次是耕地。②1990-2010 年的20 年间, 灌木林、裸岩、耕地呈减少趋势, 其中耕地减少的最多;而有林地、疏林地、草地、水体呈增长趋势, 其中疏林地增加的最多。③随坡度增加覆盖比例呈降低趋势的土地利用类型为有林地、疏林地、水体、建设用地和耕地;随坡度增加覆盖比例呈增加趋势的土地利用为灌木林、草地和裸岩。     

金衢盆地退化红砂土在不同利用方式下肥力逆转特征

以浙江省金衢盆地为例 ,探讨了我国南方山间盆地广泛分布的退化红砂土的特征 ,研究了退化红砂土在人为参与下土壤肥力的逆转及其与利用方式的关系 ,分析了各种利用方式下红砂土肥力性质的演变特征。     

Spatially non-stationary relationships between urban residential land price and impact factors in Wuhan city,China

Land price plays an important role in guiding land resource allocation for urban planning and development, particularly in big cities of fast developing countries where infrastructures and populations change frequently. Therefore, detecting spatially implicit information in the spatial pattern of relationships between land price and related impact factors is critical. Geographically weighted regression (GWR) analysis was conducted in this study for the purpose in Wuhan, China, by using a 10-year panel data set of residential land price. Based on twelve factors in three aspects (land attributes, location factors and neighborhood attributes), an evaluation index system of resident land price was established. The spatial distributions of estimated coefficients and pseudo t-values of three major explanatory variables (floor area ratio, distance to nearest center business district (CBD) and distance to nearest lake), obtained from GWR analysis, indicated that their relationships of the impact factors with land price are spatially non-stationary. The positive impact of floor area ratio on land price is more significant in highly developed areas than in less developed areas. Conversely, the negative impact of distance to nearest CBD on land price is larger in highly developed areas than in less developed areas. Moreover, wealthier dwellers may be willing to pay a higher price for a good lake view (especially views of small lakes), but infrastructure barriers (near some large lakes) cause negative effect. The outputs of this study, which provide detailed information on the relationships between land price and impact factors in local areas, are promising for urban planners to scientifically evaluate land price and make area-specific strategies.     

乡村振兴村庄类型识别与振兴策略研究——以山西省长子县为例

乡村振兴战略是新时代破解“三农”问题、实现农业农村现代化的重大战略部署。坚持乡村差异性与发展分化原则,科学识别乡村类型、明晰乡村振兴导向,对于编制区域乡村振兴规划与分类施策具有重要的现实意义。村域尺度是乡村振兴战略的基本尺度,但囿于微观尺度统计数据与基础资料的缺乏,亟需构建一套科学合理、简便易行的乡村类型识别方法体系。论文简要解析了影响村庄分布、演进与发展潜力的关键因素,据此构建乡村振兴村庄类型识别指标体系,并按照“自然因素→振兴潜力→发展现状→资源基础”的逻辑思路逐级识别乡村主导类型。结果表明：① 自然因子限制了村落的基本格局与演变方向,经济区位决定了村落的发展潜力与转型能力,二者在村落演进与乡村振兴中起到决定性作用;② 从农户视角看,村落的空间区位效能是否适应农户生产生活需求和生计方式,决定了农户居住场所是否发生空间迁移,并通过闲置废弃宅基地得到呈现;③ 将长子县村庄识别为城郊融合型、集聚提升型、传统农业型、特色保护型、搬迁撤并型5类,结合不同的乡村振兴模式提出相应的发展导向与振兴策略,以期为乡村振兴分类施策提供决策参考。     

中国土地利用变化及其影响的空间建模分析

通过 GIS建模 ,本文分析了我国土地利用的变化与其影响因子之间的相互作用关系 ,并着重对耕地的变化及其空间分布进行了模拟。研究发现 ,土地利用的变化主要是自然与经济因素综合作用的结果 ,并且区分不同的规模尺度与不同的区域类型 ,将对提高土地利用空间变化模型的精度有着重要的影响。     

AGRICULTURAL EXPANSION IN NORTHERN ALBERTA

ABSTRACT. Since the early 1980s some 40,000 acres of forested land have been cleared and placed under cultivation by Mennonite farmers near the small town of La Crete in northern Alberta's Peace River district. This incipient agriculture has been accompanied by dramatic increases in road building and home construction and by the establishment of churches and schools. The principal force behind the acquisition of land has been a desire of families to have homes in rural areas where they can enjoy lifestyles based on traditional Mennonite values. Because most new farmers cannot earn a living in the district from agriculture alone, they must rely on the wood industries to supplement their incomes. Demand is building for the province to open still more land, but disagreements between the government and the Mennonite community about the most appropriate location for developing new farms has put further expansion on hold until the conflict can be resolved.     

西北干旱区不稳定耕地概念与分类研究——以新疆昌吉州为例

厘清西北干旱区不稳定耕地的资源清单对于维持区域生态平衡至关重要.当前,全国对不稳定耕地的定义和分类比较笼统,难以突出西北干旱区不稳定耕地的特征.本文阐明了西北干旱区不稳定耕地的概念,并根据不稳定因素构建了分类体系.同时以昌吉州为例,分析不稳定耕地的数量、质量与空间分布.结果表明:①昌吉州不稳定耕地面积为14.56万hm...