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1.
中国耕地整理潜力测算方法研究综述   总被引:11,自引:0,他引:11  
对中国耕地整理潜力测算方法研究现状及趋势进行了分析。结果表明,耕地整理潜力测算已由数量潜力向数量、质量和生态并重发展,但目前耕地整理潜力分级的主要依据是新增耕地面积和产能提升潜力,且主要通过调查已实施典型整理项目确定新增耕地系数和产能提升目标状态,科学依据不足。亟需通过多学科理论和实践融合,科学确定产能目标状态,建立统一的多因素耕地整理潜力评价指标体系和测算模型,为耕地整理潜力测算提供科学依据。  相似文献   

2.
中国土地整理分区研究进展与展望   总被引:4,自引:0,他引:4  
合理划分土地整理区,明确不同区域土地整理的类型与方向,是制定土地整理标准和技术措施的基础,也是编制土地整治规划的基础。分析了包括土地整理功能分区、土地整理工程类型分区和土地整理潜力分区在内的中国土地整理分区研究新进展,探讨了目前研究中存在的问题和今后研究的主要方向。  相似文献   

3.
随着我国城镇化水平的提高,农村居民点用地与耕地、城市建设用地的矛盾日益突出.在综述农村居民点土地整理研究现状的基础上,结合国家农村建设用地标准对德州市农村居民点用地潜力进行了测算,对居民点土地整理的效益进行了评价,并对德州市合村并居中农村居民点土地整理提出了建议.  相似文献   

4.
西藏自治区土地资源的适宜性评价与利用   总被引:4,自引:0,他引:4  
本文综合评价了西藏自治区土地资源的适宜性及其质量.阐明了影响土地资源潜力发挥的主要限制因素,分析了土地资源利用现状、存在问题和开发潜力。并在此基础上、提出了西藏自治区土地资源合理开发利用的方向、对策和措施。  相似文献   

5.
土地集约利用潜力测算方法初探   总被引:5,自引:0,他引:5  
土地集约利用潜力测算研究是充分挖掘城市土地利用潜力的基础。概述了现有土地集约利用潜力测算方法并进行了分析,针对现有测算方法存在的不足提出了改进的正多边形法,运用改进的正多边形法能动态地反映土地集约利用程度、各指标的均衡性与协调性,以及挖潜潜力的方向。土地集约利用潜力测算研究能使土地集约利用评价的成果更好运用于实践。  相似文献   

6.
区域土地利用的社会效益及其时空特征研究   总被引:1,自引:0,他引:1  
土地利用的社会效益是社会经济可持续发展的基础。从用地公平、居民生活质量、社会公平和社会保障等四个方面构建土地利用社会效益评价指标体系,采用AHP法、变异系数法和综合评价模型对湛江市土地利用的社会效益进行了评价,并分析了其时空特征。结果表明,1996-2006年湛江市土地利用的用地公平性较高且变化较小,而居民生活质量、社会公平性和社会保障功能都有不同程度的提高,土地利用的社会效益明显增加;2006年土地利用社会效益以遂溪县最高、徐闻县最低。分析了土地利用社会效益的主要影响因素,并提出了相应的对策措施。  相似文献   

7.
我国农村居民点整理潜力测算方法研究进展   总被引:8,自引:0,他引:8  
农村居民点整理是我国农村土地整理的重要内容之一,已成为当前土地整理工作的重要组成部分,引起众多学者的关注。在阅读大量相关文献资料的基础上,结合近年来我国农村居民点整理研究现状,针对其中的农村居民点整理潜力及其测算方法这一技术问题进行了简要综述,并就存在的问题及未来的发展趋势进行了探讨。该研究不但有助于农村居民点整理工作的开展,而且可完善其理论研究。  相似文献   

8.
耕地整理潜力评价   总被引:7,自引:0,他引:7  
耕地整理的作用随着社会经济发展和人口增长显得日益重要.耕地整理的潜力评价作为整理基础工作,目前缺乏统一的评价指标体系.依据耕地整理目标和潜力评价的原则,以实践工作为基本,指出评价工作应从单一指标过渡到多指标综合考虑,提出耕地潜力评价体系应包括增加耕地系数、耕地产出提高率、投入产出比、林地面积比重提高率等方面,以期在评价工作中做到社会效益、经济效益和生态环境效益的统一.  相似文献   

9.
分析粮食与耕地资源态势,研究省域土地整理区域差异与对策,为合理制定土地整理规划目标、确保粮食安全提供科学依据.研究结果表明,四川耕地质量差,耕地后备资源贫乏,人地矛盾日益尖锐,粮食安全保障问题日益凸显.为确保粮食安全,经济较发达、人地矛盾尖锐的成都平原区和盆地丘陵区应以农村居民点和农地整理为主,加强中低产田土改造,从深度上挖掘耕地资源潜力,提高耕地粮食综合生产能力;经济较落后的川西南山地区、盆周山地区和川西北高山高原区,土地整理应与退耕还林、治水治沙相结合,改善生态环境,搞好灾后土地整理复垦规划,加强土地整理复垦工作.全省应重点抓好成都平原区农村居民点整理、川南喀斯特地貌农地和炼磺污染地整理、攀西地区土地复垦开发重点工程,以及地震灾区土地整理复垦、生态恢复与重建.  相似文献   

10.
综合调查分析大连市炮台开发区土地集约利用现状,建立土地集约利用评价指标体系,利用特尔斐法确定指标权重,进而计算土地集约利用度,并分别从扩展潜力、结构潜力、强度潜力、管理潜力四个方面计算土地集约利用强度。综合分析土地集约利用度与土地集约利用潜力强度计算结果表明,炮台开发区土地集约度分值达到86.16%,土地集约利用水平较高,土地利用强度潜力较小。未来土地利用潜力主要为扩展潜力,不存在管理潜力,从而对炮台开发区未来发展土地集约利用提出相应建议与措施。  相似文献   

11.
Fire and logging in nutrient-poor temperate forests with certain ericaceous understory plants may convert the forests into heaths. The process of disturbance-induced heath formation is documented by using examples ofCalluna in western Europe,Kalmia in Newfoundland, andGaultheria (salal) in coastal British Columbia. In a cool, temperate climate, rapid vegetative growth ofCalluna, Kalmia, and salal following disturbance results in increasing organic accumulation (paludification), nutrient sequestration, soil acidification, and allelochemicals. These are thought to be the main reasons to conifer regeneration failure in disturbed habitats. If continuation in forest is a land-use objective, then temperate forests with an ericaceous understory should not be logged unless effective silvicultural methods are devised to control the ericaceous plants and restore forest regeneration. Preharvest vegetation control may be considered as an option. Failure to control the understory plants may lead to a long-term vegetation shift, from forest to heathland, particularly in nutrient-poor sites. Successful methods of controllingKalmia andGaultheria, however, have yet to be developed. While theKalmia- andGaultheria- dominated heathlands are undesirable in Canada and the Pacific Northwest, a wide range ofCalluna heathlands of western Europe are being conserved as natural and seminatural vegetation.  相似文献   

12.
In water stressed regions, water managers are exploring new horizons that would help in long‐range streamflow forecasts. Oceanic‐atmospheric oscillations have been shown to influence streamflow variability. In this study, long‐lead time streamflow forecasts are made using a multiclass kernel‐based data‐driven support vector machine (SVM) model. The extended streamflow records based on tree ring reconstructions were used to provide a longer time series data. Reconstructed data were used from 1658 to 1952 and the instrumental record was used from 1953 to 2007. Reconstructions for oceanic‐atmospheric oscillations included the El Niño‐Southern Oscillation, Pacific Decadal Oscillation, Atlantic Multidecadal Oscillation, and North Atlantic Oscillation. Streamflow forecasts using all four oscillations were made with one‐year to five‐year lead times for 21 gages in the western United States. This is the first study that uses both instrumental and reconstructed data of oscillations in SVM model to improve streamflow forecast lead time. SVM model was able to provide “satisfactory” to “very good” forecasts with one‐ to five‐year lead time for the selected gages. The use of all the oscillation indices helped in achieving better predictability compared to using individual oscillations. The SVM modeling results are better when compared with multiple linear regression model forecasts. The findings are statistical in nature and are expected to be useful for long‐term water resources planning and management.  相似文献   

13.
Urban ecological systems: scientific foundations and a decade of progress   总被引:9,自引:0,他引:9  
Urban ecological studies, including focus on cities, suburbs, and exurbs, while having deep roots in the early to mid 20th century, have burgeoned in the last several decades. We use the state factor approach to highlight the role of important aspects of climate, substrate, organisms, relief, and time in differentiating urban from non-urban areas, and for determining heterogeneity within spatially extensive metropolitan areas. In addition to reviewing key findings relevant to each state factor, we note the emergence of tentative "urban syndromes" concerning soils, streams, wildlife and plants, and homogenization of certain ecosystem functions, such as soil organic carbon dynamics. We note the utility of the ecosystem approach, the human ecosystem framework, and watersheds as integrative tools to tie information about multiple state factors together. The organismal component of urban complexes includes the social organization of the human population, and we review key modes by which human populations within urban areas are differentiated, and how such differentiation affects environmentally relevant actions. Emerging syntheses in land change science and ecological urban design are also summarized. The multifaceted frameworks and the growing urban knowledge base do however identify some pressing research needs.  相似文献   

14.
Urban gardens are important sources of sustenance for communities with limited access to food. Hence, this study focuses on food production in gardens in the Toledo metropolitan area in Northwest Ohio. We administered surveys to 150 garden managers from November 2014 to February 2015 in our attempt to better understand how neighbourhood racial composition and poverty levels are related to staffing and voluntarism, food production and distribution, the development of infrastructure, and the adoption of sustainability practices in urban gardens. The results from 30 gardens are presented in this paper. We used Geographic Information Systems to map the gardens and overlay the map with 2010 census data so that we could conduct demographic analyses of the neighbourhoods in which the gardens were located. Though the gardens were small – two acres or less – up to 46 varieties of food were grown in a single garden. Gardens also operated on small budgets. Food from the gardens was gifted or shared with friends, family, and neighbourhood residents. Gardens in predominantly minority neighbourhoods tended to have fewer institutional partners, less garden infrastructure, and had adopted fewer sustainable practices than gardens in predominantly White neighbourhoods. Nonetheless, residents of predominantly minority and high-poverty neighbourhoods participated in garden activities and influenced garden operations. Volunteering and staffing were racialised and gendered.  相似文献   

15.
Collisions with deer and other large animals are increasing, and the resulting economic costs and risks to public safety have made mitigation measures a priority for both city and wildlife managers. We created landscape models to describe and predict deer-vehicle collision (DVCs) within the City of Edmonton, Alberta. Models based on roadside characteristics revealed that DVCs occurred frequently where roadside vegetation was both denser and more diverse, and that DVCs were more likely to occur when the groomed width of roadside right-of-ways was smaller. No DVCs occurred where the width of the vegetation-free or manicured roadside buffer was greater than 40 m. Landscape-based models showed that DVCs were more likely in more heterogeneous landscapes where road densities were lower and speed limits were higher, and where non-forested vegetation such as farmland was in closer proximity to larger tracts of forest. These models can help wildlife and transportation managers to identify locations of high collision frequency for mitigation. Modifying certain landscape and roadside habitats can be an effective way to reduce deer-vehicle collisions.  相似文献   

16.
Manganese entering impounded water will undergo a cyclic transformation. Oxidation precipitates manganese from top waters. At the bottom of the lake, biological activity will render manganese soluble by both intracellular as well as extracellular activity. The study was made to demonstrate that biological reduction and transformation, organometallic complexation, together with the presence of carbon dioxide and the lowering of pH all have some effect on the solubility of manganese. Dissolved manganese may be brought back to top waters during the lake overturn and therefore deteriorates the water quality.  相似文献   

17.
ABSTRACT: Mathematical models for predicting watershed surface flow responses are available, most of which are elaborate nonlinear numerical surface and channel flow models linked with infiltration models. Such models may be used to make predictions for ungaged areas, assuming an acceptable fitting of the model to the topography and roughness of the real system. For some application purposes, these models are impractical because of their complexity and expensive computer solutions. A procedure is developed that uses a complex model of an ungaged area to derive a simpler parametric nonlinear system model for repetitious simulation with input sequences. The predicted flow outputs are obtained with the simpler model at significant savings of money and time. The procedures for constructing a complex kinematic model of a 40 acre (161,880 m2) reference watershed and deriving the simpler system model are outlined. The results of predictions from both models are compared with a selected set of measured events, all having essentially the same initial conditions. Peak discharges ranged from 3 to 118 ft3/sec (0.085 to 3.34 m3/sec), which includes the largest event of record. The inherent limitations of lumped systems models are demonstrated, including the bias caused by their inability to model infiltration losses after rainfall ceases. Computer costs and times for the models were compared. The derived simple model has a cost advantage when repeated use of a model is required. Such an applications hydrologic model has an engineering tradeoff of reduced accuracy, and lumping bias, but is more economical for certain design purposes.  相似文献   

18.
The SPARROW (SPAtially Referenced Regression on Watershed attributes) model was used to simulate annual phosphorus loads and concentrations in unmonitored stream reaches in California, U.S., and portions of Nevada and Oregon. The model was calibrated using de‐trended streamflow and phosphorus concentration data at 80 locations. The model explained 91% of the variability in loads and 51% of the variability in yields for a base year of 2002. Point sources, geological background, and cultivated land were significant sources. Variables used to explain delivery of phosphorus from land to water were precipitation and soil clay content. Aquatic loss of phosphorus was significant in streams of all sizes, with the greatest decay predicted in small‐ and intermediate‐sized streams. Geological sources, including volcanic rocks and shales, were the principal control on concentrations and loads in many regions. Some localized formations such as the Monterey shale of southern California are important sources of phosphorus and may contribute to elevated stream concentrations. Many of the larger point source facilities were located in downstream areas, near the ocean, and do not affect inland streams except for a few locations. Large areas of cultivated land result in phosphorus load increases, but do not necessarily increase the loads above those of geological background in some cases because of local hydrology, which limits the potential of phosphorus transport from land to streams.  相似文献   

19.
Water treatment residuals (WTR) can reduce runoff P loss and surface co-application of P-sources and WTR is a practical way of land applying the residuals. In a rainfall simulation study, we evaluated the effects of surface co-applied P-sources and an Al-WTR on runoff and leacheate bioavailable P (BAP) losses from a Florida sand. Four P-sources, namely poultry manure, Boca Raton biosolids (high water-soluble P), Pompano biosolids (moderate water-soluble P), and triple super phosphate (TSP) were surface applied at 56 and 224kgPha(-1) (by weight) to represent low and high soil P loads typical of P- and N-based amendments rates. The treatments further received surface applied WTR at 0 or 10gWTRkg(-1) soil. BAP loss masses were greater in leachate (16.4-536mg) than in runoff (0.91-46mg), but were reduced in runoff and leachate by surface applied WTR. Masses of total BAP lost in the presence of surface applied WTR were less than approximately 75% of BAP losses in the absence of WTR. Total BAP losses from each of the organic sources applied at N-based rates were not greater than P loss from TSP applied at a P-based rate. The BAP loss at the N-based rate of moderate water-soluble P-source (Pompano biosolids) was not greater than BAP losses at the P-based rates of other organic sources tested. The hazards of excess P from applying organic P-sources at N-based rates are not greater than observed at P-based rates of mineral fertilizer. Results suggest that management of the environmental P hazards associated with N-based rates of organic materials in Florida sands is possible by either applying P-sources with WTR or using a moderate water-soluble P-source.  相似文献   

20.
The interactions between humans, animals and the environment have shaped human values and ethics, not only the genes that we are made of. The animal rights movement challenges human beings to reconsider interactions between humans and other animals, and maybe connected to the environmental movement that begs us to recognize the fact that there are symbiotic relationships between humans and all other organisms. The first part of this paper looks at types of bioethics, the implications of autonomy and the value of being alive. Then the level of consciousness of these relationships are explored in survey results from Asia and the Pacific, especially in the 1993 International Bioethics Survey conducted in Australia, Hong Kong, India, Israel, Japan, New Zealand, The Philippines, Russia, Singapore and Thailand. Very few mentioned animal consciousness in the survey, but there were more biocentric comments in Australia and Japan; and more comments with the idea of harmony including humans in Thailand. Comparisons between questions and surveys will also be made, in an attempt to describe what people imagine animal consciousness to be, and whether this relates to human ethics of the relationships. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

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