吉林省西部土地开发整理重大工程与苏打盐碱土工程改良

苏打盐碱土改良是世界性的难题。本文从改土工程、水利工程和生物工程的角度,介绍了吉林西部苏打盐碱土的改良经验和成果。同时,提出西部土地开发整理重大工程项目的实施为吉林西部苏打盐碱土改良提供了新的契机。

美国西部土地政策初探

美国政府对西部土地实行的是“公共土地”政策 ,在经历了从邦联到联邦政府的转变之后 ,内容日趋完善。而联邦政府更能适应西部社会的实情 ,及时调整西部土地出售标准 ,不断颁布减轻移民负担的各种经济法规 ,最具代表性的是承认“先购权”原则的实施 ,同时 ,联邦政府对西部土地的综合治理策略也体现了它的远见卓识。由此可知 ,美国政府的西部土地政策是积极可行的 。

邦联国会与美国西部土地政策的制定

人们对美国历史上的邦联国会一直评价不高。但在西部土地立法问题上,邦联国会发挥了主导性作用,充分体现出它作为全国合法性政府在早期国家构建中的地位和能力。此外,邦联国会对西部土地的立法,从法律上确定了新建州"在一切方面均享有与原有诸州平等的地位"的联邦主义建州原则,这是美国日后领土扩张的根本原则。

联邦政府的土地政策与美国西部开发

西部国有土地私有化是美国西部开发的基础和前提 ,也是美国联邦政府开发西部的主要手段。美国独立后 ,联邦政府通过了一系列土地法案 ,将西部土地收归国有 ,再通过出售和赠予等手段将这些土地转为私有。这种处理土地的方式对美国西部开发产生了重要影响 ,促进了美国农业、交通运输业的发展 ,并加快了西部城市化的进程。但是 ,在这一过程中也产生了一些负面影响 ,如土地投机现象和“宅地法”

美国西部土地投机问题的史学争论与理论思考

西部土地投机起源于西部土地的交易与买卖。早在美国殖民时期土地投机已经盛极一时。1785-1935年期间,美国政府把近2/3的国有土地转售、赠送给私人及私营机构。在这特定条件下完成的土地转移与土地交易过程中,土地投机以及土地投机集团自始至终表现了其存在的价值,直接影响了西部的经济结构、文化性格、政治特性,以及社会形象。“没有这一[土地投机]集团,美国边疆[的形成与发展]是很难想像的。

社会转型期吉林西部农村土地法律纠纷的解决路径

随着我国经济发展逐步放缓,我国逐渐步入经济新常态的局面,经济的放缓,出现大量的剩余劳动力。从户籍制度上看,我国有九亿农民,由于近些年来我国经济结构的调整,经济的发展速度放缓,部分产能过剩等诸多方面的原因,大部分农村劳动力开始返乡,着手于农业生产,因为种种因素,农村社会开始出现一系列的农村法律纠纷,而农村法律纠纷的客体复杂化、规模的群体化以及类型的多样化形成的原因是多方面的。在解决纠纷方面,就完全体现了我国解决机制上的缺陷,主要体现在意识形态以及相关的解决制度机制的不完善等方面上。本文主要就吉林西部农村土地法纠纷问题作简要的探讨,以供相关人士参考。

西部农村土地经营权流转法治研究

土地经营权流转是事关农民切身利益,保障国家有限土地资源充分利用,增加国民财富的重要内容。目前我国农村土地经营权流转还存在法制不完善、基层服务能力弱、农民土地流转意愿不强、流转程序比较混乱、农村农业基础设施落后等问题,特别是西部地区。通过实证方法分析西部土地经营权流转存在问题及其产生原因,并从法治角度提出构建新农村土地经营权流转法制体系、完善司法救济制度、完善农民社会保障制度、健全土地流转模式、健全新农村基础设施建设机制等对策。

西部农村土地融资难问题探析

由于西部农村的土地存在地形不规则、融资模式单一等问题,使农村土地难以进行有效融资,遏制了农村经济的发展。针对这一问题,本文在西部农村土地融资现状的基础上,分析了产生的各项原因,并提出了有效对策与措施。希望能够对促进土地资源的合理利用,构建和谐农村金融体制有所帮助。

美国西部开发中的“占地运动”及其法律遗产

“占地运动”是美国西部开发运动的重要一面。其持续时间长,它在某种程度上影响了美国公共土地的法律处置及土地制度;由“占地运动”而出现的“占地法”,扩大了美国私人产权的内容;“占地运动”及相关法律促进了西部土地的流转,提高了西部土地的利用率。这有益于19世纪美国社会经济的发展。

Changes in Land Use and Agricultural Production Structure Before and After the Implementation of Grain for Green Program in Western China–Taking Two Typical Counties as Examples

Soil erosion becomes a serious environmental problem in the world, especially in western China. An effective management practice called the Grain for Green Program(GGP), which was launched in 1999, aims to reduce soil and water loss and alleviate the ecological environment problem in western China. Two typical counties in western China, the Zhongxian(in Chongqing Municipality) and Ansai(in Shaanxi Province) were chosen to evaluate the dynamic changes of land use and agricultural production structure before and after the implementation of the Program in this paper. The results showed that the cultivated land area was reduced by 7.08% from 1989 to 2003. The cultivated land per person was decreased by 8.42% during 1999-2003. Moreover, the stability index of the secondary sector of the economy was increased from 0.91 in the period 1990-1999 to 0.94 in the following ten years. In addition, the stability index of tertiary economic sector increased from 0.88 to 0.92 in Zhongxian county. Meanwhile, the cultivated land area was reduced by 15.48% from 1990 to 1999. The soil erosion modulus was decreased by 33.33% from 1999 to 2006. Also, the stability index of secondary and tertiary economic sectors was 0.86 in the period 1998-2002. However, it decreased by 77% during 2002 to 2007 in Ansai County. These results imply that the Grain for Green Program had different impact on the two regions. Several effective strategies of soil and water conservation have been carried out to ameliorate the sustainable development of ecological environment and economy in these two counties of western China.

Dynamics of Saline-alkali Land and Its Ecological Regionalization in Western Songnen Plain, China

As the important reserve land resources for food production,saline-alkali land should play a significant role to ensure the national food security in the context of global food crisis. The western Songnen Plain is one of main distribution regions of saline-alkali land in China,with great potential in agricultural development. In this study,the extent,transformation,spatial distribution and temporal change of saline-alkali land in the western Songnen Plain during 1954–2005 were investigated by using remote sensing and GIS spatial analysis methods. Saline-alkali land change was detected from a temporal series of topographic maps in 1954,satellite images of Landsat MSS in 1976,Landsat TM/ETM in 1988,2000 and 2005 through artificial visual interpretation. The results indicated a significant expansion in saline-alkali land area and aggravation in salinization. The area of saline-alkali land had increased from 401.48×103 ha in 1954 to 1 097.45×103 ha in 2005. While the ratio of light,moderate and serious salinized land areas changed from 6.72︰2.92︰1.00 to 1.25︰1.06︰1.00 in the study period. Grassland,cropland,swampland and water body were the major land use and land cover types from which saline-alkali land transformed. And the secondary salinization occured mainly in Da′an City,Tongyu County,Changling County,Daqing City,Dorbod Mongolian Autonomous County and Zhaoyuan County. Finally,seven large ecoregions and 14 corresponding sub-ecoregions were delineated out based on spatio-temopral dynamic characteristics of saline-alkali land and geo-relational environmental attributes. According to the results,measures of amelioration and ways of development of saline-alkali land in the western Songnen Plain were put forward.

The Effects of Land Cover Change on Regional Climate over the Eastern Part of Northwest China

A regional climate model （RegCM4） is em- ployed to investigate the impacts of land use/cover change （LUCC） on the climate over the eastern part of Northwest China （ENW） in the periods of 2001 and 2011. The re- sults indicated that the LUCC in ENW, which was char-acterized by desert retreat, reforestation, and farmland expansion, led to significant local changes in surface air temperature （within -0.3℃） and slight regional changes in precipitation （within -15%） in summer. In the desert retreat area, the net absorbed shortwave radiation had a greater influence than evaporative cooling, leading to increases in the daily mean and maximum temperature. Besides, the daily mean and maximum temperatures in- creased in the reforestation area but decreased in the farmland expansion area. As surface albedo showed no significant change in these regions, the temperature in- crease in the reforestation area can be attributed to a decrease in evaporation, while the opposite effect appears to have been the case in the farmland expansion area.

Ecosystem service delivery in Karst landscapes： anthropogenic perturbation and recovery

Covering extensive parts of China, Karst landscapes are exceptional because rapid and intensive land use change has caused severe ecosystem degradation within only the last 50 years. The twentieth century intensification in food production through agriculture has led to a rapid deterioration of soil quality, evidenced in reduced crop production and rapid loss of soil. In many areas, a tipping point appears to have been passed as basement rock is exposed and 'rocky desertification' dominates. Through the establishment of the "Soil processes and ecological services in the karst critical zone of SW China"(SPECTRA)Critical Zone Observatory(CZO) we will endevaour to understand the fundmental processes involved in soil production and erosion, and investigate the integrated geophysical-geochemical-ecological responses of the CZ to perturbations. The CZ spans a gradient from undisturbed natural vegetation through human perturbed landscapes.We seek to understand the importance of heterogeneity insurface and below-ground morphology and flow pathways in determining the spatial distribution of key stocks(soil,C, vegetation, etc.) and their control on ecosystem service delivery. We will assess the extent to which the highly heterogeneous critical zone resources can be restored to enable sustainable delivery of ecosystem services. This paper presents the CZO design and initial assessment of soil and soil organic carbon stocks and evidence for their stability based on caesium-137(^(137) Cs) data.

Land Use Regionalization of Rural Settlements in China

This paper compartmentalizes regional land use of rural settlements in China by employing a hierarchical clustering method.The statistic data are sourced from the National Bureau of Statistics of China(NBSC) and the data of land use change from the Ministry of Land and Resources of China(MLRC).The population of rural settlement decreases from the southeast to the northwest of China and the density of rural settlement decreases from the east to the west of China.Land-use scale of rural settlement,the proportion of one-storey houses and the average household area decrease from the north to the south of China.The ratio of area of cultivated land to rural settlement is high in the northeast and southwest of China but low in the southeast of China.The land use regionalization of rural settlement can be divided into four regions,namely:the northern region of China,Qinghai-Tibet,Yunnan-Guizhou,and the middle and eastern region of China.The northern region of China and the middle and eastern region of China can be further divided into nine sub-regions:Xinjiang,Northeast China,Ningxia and Inner Mongolia,North China,the south of the Changjiang(Yantze) River and Sichuan Basin,Jiangsu-Shanghai,South China,the Loess Plateau,and Guangxi.In consideration of the significant regional differences,it is proposed that different policies should be implemented regarding the utilization and management of rural settlements.

Remote sensing classification of western Sierra Leone using landsat TM and ETM+

The study examines the changes of land cover/use resources for the period under investigation.An unsupervised vegetation classification is being performed that provides five distinctive classes and thus assesses these changes in five broad land cover classes-high/moist forests,forest regrowth,mixed savanna,bare land/ grass and water.The remote sensing images used in this work are both images of TM and ETM+in different time periods(1986 to 2001)to determine land cover/use changes.A fairly accuracy report is recorded after performing the unsupervised classification,which shows vegetation has been depleted for over the years.Changes created are mostly human and to a lesser extent environment.Human activities are mainly encroachment thus altering the landscape through activities such as population growth,agriculture,settlements,etc.and environment due to some perceive climatic changes.This vegetation classification highlights the importance to acquire and publish information about the country's partial vegetation cover and vegetation change including vegetation maps and other basic vegetation influencing factors,leading to an understanding of its evolution for a period.

Lead and Mercury Contamination Assoc=atea with Artisanal Gold Mining in Anka, Zamfara State, North Western Nigeria： The Continued Unabated Zamfara Lead Poisoning

A total of 24 soil samples were collected from areas around Artisanal Gold and associated Pb-Zn-Cu sulfide mining and mineral processing sites in the Anka mining district of Zamfara State, NW Nigeria. The samples were geochemically analyzed with the main objective of assessing the degree of Pb and Hg pollution in the environment resulting from the mining and mineral ore processing activities in the mining district and to consider the effect on human health. The assessment of the degree of pollution or toxicity was based on the Igeo （index of geoaccummulation） and EF （enrichment factor） where the former gives a quantitative pollution class with respect to the quality of the medium analyzed, while the latter differentiates between metals originating from anthropogenic activities and those from natural processes. The geochemical results show that the concentrations of Pb and Hg especially at the mineral processing sites significantly exceed the established thresholds （4,152 ppm and 12.92 ppm respectively）. The calculated EF values for both Pb and Hg revealed that the soils from the entire mining district are extremely enriched in these elements, essentially originating from the anthropogenic activities （EF= 〉〉 40）. Lead and Mercury are toxic heavy metals with documented long-lasting adverse human health effects. These calls for efficient bioremediation measures for the removal of Pb and Hg from the contaminated soils that take into account the geochemical peculiarities of the mining district.

Efects of Cropland Cover Changes on Regional Climate over Western China Based on Simulations with RegCM3

The impacts of land cover changes on regional climate with RegCM3. Sensitivity experiments were conducted by in Shaan-Gan-Ning （SGN） in western China were simulated replacing crop grids with different new land cover types in the key area of SGN, where the returning cropland to tree/grass project has been carried out since 1999. The modified new land cover types include desert, forest, shrub and grass. They represent degraded, improved, and maintained vegetation cover with natural canopy in the key area. Results from three individual case studies show that the land cover change causes changes in temperature and terrestrial water variables especially within the key area, while changes in precipitation are found for a larger area. The strongest changes appear where the cropland is degraded to bare soil, leading to increasing temperature and decreases in rainfall, evaporation and soil water. Opposite changes occur when cropland changed into forests, especially with strong increases in soil water. When cropland changed to grass and shrub land, the climatic changes are closer to those with forest cover. This shows the importance of improving and maintaining the vegetation in SGN for the ecosystem and regional climate.

Relationships between Soil Depth and Terrain Attributes in a Semi Arid Hilly Region in Western Iran

Soil depth generally varies in mountainous regions in rather complex ways.Conventional soil survey methods for evaluating the soil depth in mountainous and hilly regions require a lot of time,effort and consequently relatively large budget to perform.This study was conducted to explore the relationships between soil depth and topographic attributes in a hilly region in western Iran.For this,one hundred sampling points were selected using randomly stratified methodology,and considering all geomorphic surfaces including summit,shoulder,backslope,footslope and toeslope;and soil depth was actually measured.Eleven primary and secondary topographic attributes were derived from the digital elevation model(DEM) at the study area.The result of multiple linear regression indicated that slope,wetness index,catchment area and sediment transport index,which were included in the model,could explain about 76 % of total variability in soil depth at the selected site.This proposed approach may be applicable to other hilly regions in the semi-arid areas at a larger scale.

Numerical Modeling of Shallow Water Table Behavior with Lisse Effect

Air entrapment is an important consideration in environments with shallow water tables and sandy soil, like the condition of highly conductive sandy soils and flat topography in Florida, USA. It causes water table rises in soils, which are significantly faster and higher than those in soils without air entrapment. Two numerical models, Integrated Hydrologic Model (IHM) and HYDRUS-1D (a single-phase, one-dimensional Richards′ equation model) were tested at an area of west central Florida to help further understanding the shallow water table behavior during a long term air entrapment. This investigation employed field data with two modeling approaches to quantify the variation of air pressurization values. It was found that the air pressurization effect was responsible at time up to 40 cm of water table rise being recorded by the observation well for these two models. The values of air pressurization calculated from IHM and HYDRUS-1D match the previously published values. Results also indicated that the two numerical models did not consider air entrapment effect (as the predictive parameters remain uncertain) and thus results of depth to water table from these models did not compare to the observations for these selected periods. Incorporating air entrapment in prediction models is critical to reproduce shallow water table observations.