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991.
992.
广东梅县松口镇是岭南四大古镇之一,享有文化之乡、华侨之乡、山歌之乡的美誉。作为历史的产物和反映历史文化与民族习俗沉淀的千年古镇,其不但是稀缺的,而且是不可再生的。松口古镇文化是一种"活着"的文化,为保护文化的多样性和促进当地经济的发展,松口古镇应在加强保护的同时,科学、合理、适度地开发,突出"客味"和"乡土味",塑造客家文化旅游精品,促进古镇可持续发展,以期达到与旅游开发的和谐共生。 相似文献
993.
根据张掖市黑河流域湿地所处的生态区域、湿地成因和受干扰因素的影响程度及湿地过程的自然特征,同时,还考虑到研究区湿地资源的利用涉及多个部门和多个利益主体,提出了张掖市黑河流域湿地分层保护管理模式;根据张掖市黑河流域湿地研究现状,提出张掖市黑河流域湿地科学研究内容及研究方向,为西北干旱半干旱区内陆河流域湿地研究与保护提供示范和参考。 相似文献
994.
995.
黄河三角洲滨海湿地的生物多样性特征及保护对策 总被引:7,自引:0,他引:7
黄河三角洲滨海湿地具有以下生物多样性特点;不同类型的湿地中生物多样性差别显著;生物的态适应类型复杂;生物区系的地理分布成分有一定规律性;资源性动植物物种多;国家重点保护物种和濒危物种多。受自然因素和人为因素的影响,黄河三角洲滨海湿地出现了天然湿地面积减小、土壤盐渍化程度加重、湿地生态服务功能退化、湿地生物多样性水平下降等问题。为了保护黄河三角洲滨海湿地的生物多样性,提出了加强黄河三角洲自然保护区的基础设施建设、实施湿地生态恢复工程、建设黄河三角洲高效生态经济区、加强宣传教育以提高全民生物多样性保护意识、加强黄河三角洲湿地科学研究等对策。 相似文献
996.
997.
耕地资源是一种稀缺的公共资源,耕地保护是社会主义新农村建设的要务,是经济社会可持续发展的关键,是我国粮食安全的重要保障。在介绍我国耕地保护问题理论和现状的基础上,将耕地保护问题产生的原因归结为市场失灵,政府失败,法律制度的不完善及与经济发展、生态建设等的矛盾,并从制度层面提出了相应的对策建议。认为我国耕地保护应建立一个多元的管理体系,需要在耕地保护时引入公共管理的理念,利用“第三部门”来保护耕地。 相似文献
998.
The northeast region is one of the principal mire distribution regions in China. According to the process of peat formation and accumulation , middle geomorphology type controlling water source supplement and the plant cover, 2 types, 10 subtypes and 27 mire bodies are divided. The mire area decreases gradually from north to south. There is more peat mire in the mountain and there is mainly gley mire without peat in the plain. The paper also explains the mire types in the principal mire distribution region and the utilization of mire in the fields of agriculture, forest, animal husbandry. The mire is a wetland ecosystem. It can reserve a lot of water, adjust rivers, humidify air. Thereby , attention must be paid to protecting ecological balance in the process of reclaiming mire and the mire protection. 相似文献
999.
Sydney T. Bacchus Douglas D. Archibald George A. Brook Kerry O. Britton Bruce L. Haines Stephen L. Rathbun Marguerite Madden 《水文研究》2003,17(9):1785-1809
Pond‐cypress (Taxodium ascendens Brong.) is a dominant canopy species in depressional wetlands of the south‐eastern Coastal Plain. Unsustainable withdrawals from the karst Floridan aquifer system have caused premature decline and death of pond‐cypress trees, presumably owing to altered hydroperiods (which alter the flow of water and nutrients in trees). There has been no scientifically based means to determine sustainable yield from this regional aquifer system or to detect early stages of physical/ecological damage associated with groundwater mining and aquifer storage and recovery (ASR, which also can alter natural hydroperiods). In this study, the relationship between visual symptoms (indicators) of stress or premature decline, and spectral reflectance was evaluated using dried, milled branch tips collected from natural stands of mature pond‐cypress. Depressional systems evaluated represented four of the six aquifer system subregions where subsurface perturbations from groundwater mining: (i) were presumed not to be occurring (reference wetlands); (ii) may be occurring but are not documented; and (iii) have been confirmed. Sampled trees were assigned to one of three stress classes (1, no/minimal; 2, moderate; 3, severe) based on the visual indicators. Partial least squares–linear discriminant analysis of second derivative spectral transformations in the visible/shortwave near‐infrared (NIR) region (400–1100 nm) and the NIR region (1100–2500 nm) was used to evaluate the samples in assigned classes. Class 1 samples were discriminated from combined class 2 and 3 samples in the NIR region with 100% and 97% accuracy for consecutive winter sample periods (before bud‐break). The percentage of correctly classified samples in this spectral region was lower (85%) for summer samples (full leaf‐out). Second‐derivative models for the NIR region developed from the winter data sets predicted assigned classes for alternate winter's samples with an accuracy of 97% and 100%. High correlation between spectral reflectance of dried, milled branch tips collected from mature pond‐cypress in winter and visual indicators of premature decline suggests in situ pond‐cypress are hydroecological indicators of anthropogenic subsurface hydroperiod perturbations. This approach provides objective means for early detection of unsustainable aquifer yield and adverse impacts from ASR activities in the south‐eastern Coastal Plain. Used in conjunction with hydrological monitoring and modelling, the hydroecological indicators should provide the means with which sustainable yield in the south‐eastern Coastal Plain can be achieved and maintained. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
1000.
This paper discusses numerical methods for modelling cathodic protation (CP) using Boundary ElementMethods(BEM) for CP design analysis in comparision with the traditional methods and presentsseveral mathematical models (for CP design in 3-D infinite area) solvable by using BEM withmicrocomputer. 相似文献