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611.
Stephen C. Newbold 《Environmental Modeling and Assessment》2005,10(3):251-263
Most landscape design models have been applied to the problem of maximizing species richness in a network of nature reserves.
This paper describes a combined hydrologic simulation and landscape design model designed to prioritize sites for wetlands
restoration, where the objective is to maximize the amount of nutrients in non-point-source runoff attenuated in the restored
wetlands. Targeted site selection in four small watersheds in the Central Valley resulted in predicted levels of nitrogen
attenuation two to eight times greater than that from maximizing wetland area without consideration of the location of the
restoration sites.
Disclaimer The views expressed in this paper are those of the author and do not necessarily represent those of the US Environmental Protection
Agency. No official Agency endorsement should be inferred. 相似文献
612.
Mathematical Methods for Spatially Cohesive Reserve Design 总被引:1,自引:0,他引:1
Mark D. McDonnell Hugh P. Possingham Ian R. Ball Elizabeth A. Cousins 《Environmental Modeling and Assessment》2002,7(2):107-114
The problem of designing spatially cohesive nature reserve systems that meet biodiversity objectives is formulated as a nonlinear integer programming problem. The multiobjective function minimises a combination of boundary length, area and failed representation of the biological attributes we are trying to conserve. The task is to reserve a subset of sites that best meet this objective. We use data on the distribution of habitats in the Northern Territory, Australia, to show how simulated annealing and a greedy heuristic algorithm can be used to generate good solutions to such large reserve design problems, and to compare the effectiveness of these methods. 相似文献
613.
张仁志 《中国环境管理干部学院学报》2006,16(1):26-29
秦皇岛市2004年总人口为278.26万人,自然增长率为3.78‰,符合计划生育率为98.27%,但出生性别比为109%,2001年全市居民平均期望寿命为75.64岁;2000年全市老龄人口占11.4%,2005年将达到12.95%;2000年全市城镇化比率为41.7%,初中入学率达到99.59%。为实施可持续发展战略,需进一步加强计划生育工作,严格控制出生性别比,进一步提高城镇化水平和教育水平,关注老龄化问题。 相似文献
614.
Lene Hansen Egon Noe Katrine Højring 《Journal of Agricultural and Environmental Ethics》2006,19(2):147-168
The relationship between agriculture and nature is a central issue in the current agricultural debate. Organic Farming has
ambitions and a special potential in relation to nature. Consideration for nature is part of the guiding principals of organic
farming and many organic farmers are committed to protecting natural qualities. However, the issue of nature, landscape, and
land use is not straightforward. Nature is an ambiguous concept that involves multiple interests and actors reaching far beyond
farmers. The Danish research project Nature Quality in Organic Farming has investigated the relationship between nature and organic farming. This article will focus on an expert workshop held
in connection with the project that investigates the way different actors conceptualize nature. Farmers, scientists, and non-governmental
organizations came together to discuss their experiences of nature and expectations of organic agriculture. From this interaction,
it was clear that nature is a contested notion. Different understandings of nature exist within the three groups and there
is disagreement as to whether emphasis should be given to biological qualities, production values, or experiential and aesthetic
perspectives. This complexity provides a challenge to organic farming as well as to the implementation of nature considerations
in general. It illustrates an underlying battle for the right to define nature and nature quality and essentially decide what
organic farmers should work towards. We argue that successful implementation requires organic farmers to carefully consider
what expectations they wish to meet. Optimally it is dependent on a dialog between stakeholder interest groups that allows
for multivocality and pluralism. 相似文献
615.
经过对勃利县的自然生态和地理环境的调查,收集了大量的资料,并根据生态环境的问题,提出了相应的保护对策措施,例如实施天然林保护工程、建立自然保护区、发展生态农业和绿色食品。 相似文献
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619.
协调好人与自然的关系:对1998年水灾的灾害经济学思考 总被引:5,自引:2,他引:3
通过一些数据和实例,得出了我国1998年的水灾既是天灾,又是由人祸酿成的结论。天灾难以完全避免,而人祸却加深加重了天灾,其关键是未能协调好人与自然的关系,招致了大自然对人类的报复。如何变害为利,协调好人与自然的关系,本文从灾害经济学角度提出了一些看法。 相似文献
620.
苏北海州群云台组上段变火山岩富含碱性长石(60-70%)和钾长石(35-60%),黑云母为富铁黑云母,部分火山岩含霓辉石、萤石等.其岩石地球化学特征:高硅(SiO_2>6.41%),富碱(Na_2O+K_2O8.54%).高钾(K_2O4.52%),低铝(Al_2O_311.88%).贫钙、镁(CaO0.25%,MgO0.13%);富Nb、Zr、Y、Zn和Ga等元素;富REE、LREE和Eu强烈亏损.上述特征与世界和福建魁歧、浙江青田、江苏苏州、山东崂山等A型(或碱性)花岗岩的特征一致,为A型火山岩.其连云港市东部分布区是寻找与海相A型火山岩有关的Sn、W、Zn、Ph、Ag(Au)等华前型块状硫化物矿床和热液矿床的重要靶区. 相似文献