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991.
城市生物多样性问题及保护对策探讨   总被引:5,自引:0,他引:5  
结合秦皇岛市的实际,对城市生物多样性现状和特点、生物多样性保护存在的问题进行了讨论,并提出了城市生物多样性保护的对策。   相似文献   
992.
The introduction of national parks to Scotland represents a significant shift in the evolution of protected area management within the UK. Although the National Parks (Scotland) Act 2000 adopts the established national park aims of conservation and recreation, provisions are also made for advancing notions of sustainable development. This paper provides an assessment of the degree to which the Scottish national park model is likely to enable the realisation of multiple national park objectives. Five key areas are considered for analysis. These relate to management aims, institutional arrangements, implementation, democratic accountability and funding. The evaluation reveals that whilst management provisions have been established in accordance with international sustainable development guidelines, a number of concerns relating to operational processes remain.  相似文献   
993.
To understand a state's incentives to invest in conflict or cooperation over their international rivers, this paper argues that it is necessary to appreciate the relationships a river can create and the national security threat riparians may confront. Rivers impose interdependent and vulnerable relationships, which can compromise a state's ability to respond effectively to floods and droughts, meet its domestic food and energy needs, dredge the river, maintain its drainage systems, and allocate its domestic water budget. The inability to accomplish these tasks can contribute to social, economic, and political losses that may threaten a state's territorial integrity. Regardless of whether a state is upstream or downstream, from these relationships it acquires leverage to manipulate the interdependence and vulnerability to inflict losses on its riparian neighbour. This argument challenges several assumptions within the existing literature, including the belief that a shortage of freshwater is the initial force producing a national security threat and that an upstream–downstream river bequeaths all advantages on the upstream state and leaves the downstream state purely dependent. As the paper shows, riparians confront a more complex relationship than captured by the existing literature.  相似文献   
994.

Problem

In 2006 Texas raised the daytime speed limit for passenger vehicles on segments of I-10 and I-20 from 75 to 80 mph. Methods: Traffic speeds were measured before and 3, 12, and 16 months after the limit was changed. Results: During the 16-month period following the speed limit increase, mean speeds of passenger vehicles on I-20 increased by 9 mph relative to the comparison road, where no speed limit change occurred and traffic speeds declined. On I-10 mean speeds increased by 4 mph relative to the comparison road. Limiting the analysis to the month before the speed limit change and 1 year later, the proportion of drivers exceeding 80 mph was 18 times higher on I-20 and 2 times higher on I-10. Discussion: The smaller speed increases on I-10 may be related to its proximity to the U.S. border with Mexico. Highly visible border patrol activity coincided with posting of the higher speed limit. Long-term monitoring in other states suggests that traffic speeds in Texas are likely to continue to increase. Impact on Industry: The present study adds to the wealth of evidence that increased speed limits lead to increased travel speeds. The primary countermeasures to reduce the risk of speed-related crashes include highly visible police traffic enforcement and the use of speed cameras accompanied by publicity.  相似文献   
995.
Before 2001, the ecological protection area in the Kenting National Park (KTNP), southern Taiwan, was poorly described. In this study, a set of four-year data (2001-2004) of seawater qualities at 19 sampling sites around the Nanwan Bay in the KTNP was used to explore anthropogenic impacts to ecological environment, especially coral reefs. The parameters of water quality were analyzed immediately after collection. The results showed that higher values of nutrients and suspended solids were attributed to the higher run-off around Nanwan Bay. The fluxes of nutrients and suspended solids were consistently correlated to rainfall. Hence, equations were developed to calculate nutrient fluxes and suspended solids by using only rainfall data. Our results show that suspended solids and ammonia were the dominant factors leading to the drop in coral coverage. In summary, the water quality in the intertidal zone of Nanwan Bay has been degraded and required greater attention.  相似文献   
996.
In 1990, grazing was introduced in a section of Meijendel, a coastal sand dune system near The Hague, The Netherlands. After five years an evaluation was made of the effects of grazing on vegetation development. Three transects were established, two in grazed areas and one in an ungrazed area. Field survey data were classified by means of TWIN-SPAN, ordinated with Detrended Correspondence Analysis and the resulting vegetation types interpreted according to Westhoff & den Held (1969). All associations were found in both the grazed and the ungrazed areas, but at the subassociation and variant level some communities appeared to be restricted to the grazed area. These variants were five grassland variants characterized by disturbance indicators such asSenecio sylvaticus andCynoglossum officinale. The total number of plant species in the 19 permanent plots, which had been observed to have been decreasing since 1960, showed a considerable increase after the introduction of horses and cows in 1990. A marked decrease in the cover ofCalamagrostis epigejos andCarex arenaria since 1990 was evident, while in some plots species such asRibes rubrum andViburnum opulus increased considerably. A series of false-colour aerial photographs were used to compare vegetation structure in the three transects between 1990 and 1995. In the grazed area the tall grass vegetation had almost totally disappeared, whereas the areas of open sand. sand with moss and lichens, and low grass vegetation had increased and the pattern had become more fine-grained. In the ungrazed area the area covered by low grass vegetation had increased at the expense of the area of sand with moss and lichens and the pattern had become more coarse-grained.  相似文献   
997.
/ This review will trace the evolution of beyond boundary/buffer zone thinking and policy responses in the US National Park Service (NPS); address buffer zone science, benefits, and limitations; examine pertinent legal and social concerns; highlight some agency attempts to create buffer zone-like areas; and propose highlights of a protected area strategy, with buffer zones and corridors as one component. Some findings follow. The need to expand national parks to accommodate large ungulate movement began in the late 1800s, but the recognition that such land was also needed to thwart human impacts such as poaching surfaced in the 1930s. External park buffer zone recommendations by 1930s park scientists were not implemented, and other related adopted policy forgotten, supporting the belief that great insight can be discovered in forgotten institutional history. Buffer zones can remedy some impacts but not others, but their benefits are multiple and underappreciated. The science of buffer zones is very immature and deserves more attention. A present primary obstacle to creating park buffer zones and connecting corridors is a social climate opposing federal initiatives that may intrude on the rights of private landowners. Some proactive NPS bufferlike activity examples are reviewed, but there were none where permanent, complete, effective nonlegislated park buffer zones, derived from nonfederal property, circumscribed large natural area parks. The need for buffer zones and corridors may be a symptom of inadequate regional planning. Options to create buffer zones from private and federal land are outlined. A comprehensive, overall protected area strategy must include more than just buffer zones, with highlights provided. Because optimal regional planning for US national parks is now thwarted by land-use politics, American society must soon decide what is most crucial to future well-being. KEY WORDS: Buffer zone; Reserve; Boundary; Policy; Planning  相似文献   
998.
999.
长白山区中国林蛙资源及其保护与增殖   总被引:4,自引:0,他引:4  
中国林蛙主要产于我国的长白山区,具有较高的经济价值。本文根据近年来的生产实践和调查研究资料,着重介绍了吉林省长白山区的中国林蛙养殖生物学特征,提出了在该区的资源保护途径与增殖措施  相似文献   
1000.
长白山自然保护区森林生态系统间接经济价值评估   总被引:166,自引:1,他引:165  
使用市场价值法、影子工程法、机会成本法和替代花费法等对长白山自然保护区森林牛态系统的功能价值进行了经济评估评价结果表明,保护区总的生态功能价值为176465.94万元,其中活立木生产量价值10777.43万元,涵养水源价值69741.2万元,保护土壤减少侵蚀的价值2307.02万元,固碳以减缓温室效应的价值87716.6万元,林分持留N、P、K分价值4338.88万元,降解SO2和防治病虫害价值1584.73万元  相似文献   
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