首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   8篇
  免费   0篇
  5篇
综合类   2篇
园艺   1篇
  2016年   1篇
  2011年   3篇
  2009年   2篇
  2008年   2篇
排序方式: 共有8条查询结果,搜索用时 15 毫秒
1
1.
We investigated conservation value (CV) related to the quality of spider communities in different non-wooded habitat patches - ranging from arable land to natural grasslands. The study was conducted in two ecologically distinct regions of Hungary: the Hungarian Great Plain and the Buda Hills. We used seven variables to indicate CV which together formed a multi-criteria space of spider community characteristics. These variables were either related to species characters obtained from an extensive background database: abundance and frequency based rarity, specialist status, association to natural habitats; or were calculated for the community at the given patch: species richness, functional diversity and species evenness. Using the variables in an ordination analysis we could establish a gradient of the patches in the multi-criteria space of the spider community characteristics. Position of patches along the first axis of the ordination was taken as the multi-criteria measure of CV. CVs established this way were strongly and positively correlated with an independent botanical CV assessment. We also sought a simpler measure of spider CV by: (a) calculating only one variable out of the seven and using it as a surrogate for the multi-criteria CV measurement; by (b) calculating this variable only for a short time period or (c) for only one spider family. Average abundance based rarity value of the species proved to be the best surrogate of the multi-criteria CV measure for both regions, and it also performed very well when sample size was restricted to two sampling occasions per patch or to a single family. This adds further evidence to, what has been found in other studies, that species rarity is a sensitive and reliable measure of the ecological and conservational status of communities.  相似文献   
2.
This research proposes a more complete, easy and unique method to assess the greening potential of derelict and vacant urban lands in order to prioritize them for reclamation. Greening these lands can convert a problem into an opportunity, assuming that green spaces must fulfill multiple functions, being part of a green infrastructure. The evaluation cover a wide range of criteria that reflect the complexity of the city and consider environmental, ecological, social and economic aspects related to the local urban structure. The criteria were organized into three groups: ecology, stormwater, and community. For each criterion, there are quantitative or qualitative indicators, measured by continuous, binary or multi-categorical parameters converted into numerical values in order to create a ranking score from highest to lowest potential of greening. The city São Bernardo do Campo, in the Metropolitan region of São Paulo, Brazil, was chosen as the case study to apply this method. The city is experiencing a post-industrial process and has few urban green spaces accessible to the community, while there are several empty and abandoned areas. We identified and mapped sixty derelict and vacant lands, of which ten were chosen as samples to evaluate. The results revealed that 40% of evaluated lands have high potential to reclaim into green spaces, 40%, medium potential and 20%, low potential. Nature or vocation as green spaces was also evaluated: 50% of them have social importance, 20%, environmental, and 30% socio-environmental. The vocation is an important information since it identifies some areas that despite their medium-low potential, they should not be rejected due to their social value. The results can drive a preliminary environmental planning decision making, to be applied in any city that faces similar problems of land dereliction, offering support to professionals to prioritize the reclamation of new urban green spaces.  相似文献   
3.
Invasive alien trees and shrubs pose significant threats to biodiversity and ecosystem services in South African fynbos ecosystems. An ambitious initiative, the Working for Water program, commenced in 1995 to reduce the extent and impact of plant invasions. Despite substantial progress, the problem remains immense, and innovative ways of improving the efficiency of control operations are urgently needed. This study sought to develop a robust conceptual framework for effective management of the most important invasive alien plant (IAP) species. Two methods were applied in exploring the complexity of problems, thereby identifying appropriate response strategies. The DPSIR (Driving forces-Pressure-State-Impacts-Responses) framework and the Analytic Hierarchy Process (AHP) tool were used to design a strategy for prioritizing management actions. This strategy considers explicitly the most influential factors that determine the distribution, abundance, spread and impacts of IAPs. Efficient management of IAPs is constrained by multiple interacting environmental and socio-economic factors. Factors related to the fire-prone nature of the ecosystem and the characteristics of the invasive stands emerged as pivotal features for setting spatially-explicit priorities for management. Results of the analyses provide an objective and quantifiable perspective for improving the management efficiency. We conclude that considerable progress in controlling the spread of IAPs in fynbos ecosystems could be achieved by better coordination of management practices and by improving the quality of species distribution data.  相似文献   
4.
邹永红  谭建林 《安徽农业科学》2011,39(25):15228-15229,15232
[目的]建立基于属性差异度的多属性决策方法并说明其在水稻优选中的应用。[方法]提出属性间贴近度的概念,在此基础上对属性间的差异度进行研究,并对基于属性差异度的权重确定方法进行分析。[结果]得到了1种基于属性差异度的多属性决策方法,并针对水稻优选问题说明了该方法具有应用及可行性。[结论]丰富了多属性决策中属性权重确定的问题,并为科学合理地选择水稻品种问题提供了必要的理论支撑。  相似文献   
5.
Expansion of the global terrestrial protected area system   总被引:2,自引:0,他引:2  
Under the Convention on Biological Diversity, the world’s governments set a goal of protecting 10% of all ecological regions by 2010. We evaluated progress toward that goal for the world’s major terrestrial biomes, realms, and ecoregions. Total land area under any legal protection has increased from previous estimates to 12.9%, a notable achievement, although only 5.8% has strict protection for biodiversity. For biomes, protection ranges from 4% to 25%, with six of 14 biomes still below the 10% level. Geographic patterns of protection have a distinct bias, with higher rates of protection in New World realms than Old World realms. Of the world’s terrestrial ecoregions, half do not meet the 2010 Target and 76% have less than 10% of their area strictly protected. Approximately 13% of ecoregions have no strict protected areas. Recent years have seen an expansion of the protected area network, with an average of 0.13% of the global land area added per year. Most of the expansion since 2003 though has been in Brazil, particularly the Amazon. Without major investments in conservation, spread across the world’s ecosystems, the world will likely miss the 2010 target.  相似文献   
6.
Prioritizing management actions for wildlife conservation is a difficult task due to the large number of problems relative to available conservation resources and uncertainty about the benefits arising from numerous potential management actions. In this study we use a cost-efficiency protocol to evaluate and prioritize eight different management actions for waterbird community in wetlands throughout southeastern Spain. The protocol generated an action priority ranking based on the costs and predicted benefits of the actions in terms of waterbird carrying capacity. Action prioritization outcomes were also evaluated using population viability analysis models for two of the study species. Removal of dead bird carcasses to prevent disease outbreaks was identified as the most cost efficient action. Removing lead pellets from the sediment was the least efficient strategy. Our approach highlights the role of detailed risk assessment as a form of quality control on the simpler prioritization protocols. We recommend a two-step prioritization protocol based on (i) a rapid, usually simpler prioritization approach for the bulk of species or values being managed, and (ii) a more sophisticated risk assessment for a subset of the species of interest for which detailed risk assessments are tractable. This process strikes a balance between sophistication and practicality.  相似文献   
7.
A priority list of 323 plant species was created through a consultative process for ex situ conservation in the recently inaugurated Israel Plant Gene Bank (IGB). The IGB is set up to preserve plant genetic resources and the endangered genetic variability of the Israeli flora. Upon its inauguration, we consulted with the country’s leading plant breeders and botanists in an attempt to create a list of the most important plant species to be included in the initial collections. The list includes crop wild relatives (CWRs), selected according to their contribution to humans: edible plants (grains, vegetables, oil); forage plants; species with potential industrial and biotechnological applications (e.g. spices, medicinal plants, aromatic plants, fibers, dyes), and species with horticultural and forestry potential. We further ranked the species on the basis of assessed values for each of seven characteristics: distribution range in the country; abundance; rarity of the growing habitats; endemism; red number index—representing imminent threat of extinction; availability of samples in Israeli collections, and genetic relationship to cultivated crops. The sum of the assessed values for these seven characteristics was used to group the species on the list into four main prioritized-collection schemes. Statistical analysis indicated that all attributes had similar influence on the collecting prioritization scheme. In general, rare species with low abundance in their growing habitats were ranked in the highest priority group, while highly distributed species were sorted together into a lower priority group. The prioritization scheme will be used to optimize the collection in the IGB with the aim of establishing its collecting activities.  相似文献   
8.
[目的]建立基于属性差异度的多属性决策方法并说明其在水稻优选中的应用。[方法]提出属性间贴近度的概念,在此基础上对属性间的差异度进行研究,并对基于属性差异度的权重确定方法进行分析。[结果]得到了1种基于属性差异度的多属性决策方法,并针对水稻优选问题说明了该方法具有应用及可行性。[结论]丰富了多属性决策中属性权重确定的问题,并为科学合理地选择水稻品种问题提供了必要的理论支撑。  相似文献   
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号