首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
Protected areas are a cornerstone of many conservation approaches, and concepts of pristineness and wilderness are often considered central to protected area designation and management. However, these concepts are rarely explored through a historical lens that captures the philosophies and assumptions underlying protected area designation. In this paper, we aim to improve our understanding of protected area designation and management by reviewing the history of four main conservation approaches: (1) Wilderness conservation and the Yellowstone Model; (2) Wise use and the Game Reserve Model; (3) Wildlife and Biodiversity conservation; and (4) Ecosystem management. Through examination of the history of these Models, we discuss the values, rationale and assumptions behind each approach, and how these interface with protected area designation. In each case, we explore the extent of dependence on concepts of wilderness and pristineness. We also highlight the evolution of alternative criteria for designating protected areas, and ascertain how far these alternative values influence protected area designation and management.
Lindsey GillsonEmail:
  相似文献   

2.
Plants respond to shading through an adaptive syndrome termed shade avoidance. In high-density crop plantings, shade avoidance generally increases extension growth at the expense of yield and can be at odds with the agronomic performance of the crop as a whole. Studies in Arabidopsis are beginning to reveal the essential role phytochromes play in regulating this process and to identify genes underlying the response. In this article, we focus on how phytochrome signaling networks have been targeted in cereal breeding programs in the past and discuss the potential to alter these pathways through breeding and transgenic manipulation to develop crops that perform better under typical high density conditions.  相似文献   

3.
4.
Environmental Biology of Fishes - Reef fish assemblages under fishing pressure generally exhibit a lower fish biomass, abundance, and size structure, which can be counteracted with the creation of...  相似文献   

5.
Influenza viruses continue to pose a severe threat worldwide, causing thousands of deaths and an enormous economic loss every year. The major problem in fighting influenza is the high genetic variability of the virus, resulting in the rapid formation of variants that escape the acquired immunity against previous virus strains, or have resistance to antiviral agents. Every virus depends on its host cell and, hence, cellular functions that are essential for viral replication might be suitable targets for antiviral therapy. As a result, intracellular signaling cascades induced by the virus, in particular mitogen-activated protein kinase pathways, have recently come into focus.  相似文献   

6.
Recent arguments for conventional fisheries management approaches (CFMAs) and against no-take marine protected areas (NTMPAs) are reviewed, i.e. CFMAs are more effective, density-dependent factors will lead to reduced fish stock production in and around NTMPAs, rights-based approaches in combination with CFMAs will be more effective, and natural refuges from fishing already exist. It is concluded that these are largely valid but only from a fisheries management perspective. The arguments of proponents of NTMPAs and those of proponents of CFMAs are considered as contrasting storylines, the divergences between which are based on two key factors: different objectives and different science. In relation to different objectives, it is concluded that the arguments against NTMPAs based on their lack of fisheries management benefits must be considered as only applying to the secondary resource conservation objectives of such designations and not to the primary marine biodiversity conservation objectives. On this basis it is argued that it is counter-productive for NTMPAs to be ‘sold’ on a win–win basis, including their potential to deliver fisheries management benefits, as this detracts from their marine biodiversity conservation objectives and leaves such calls open to arguments that CFMAs are better able to deliver fisheries management objectives. In relation to different science, it is concluded that criticisms of NTMPAs and support for CFMAs implicitly resist the shift from Mode 1 (reductive, intra-disciplinary) to Mode 2 (holistic, trans-disciplinary) science that is inherent in calls for NTMPAs as part of an ecosystem approach. Mode 2 science attempts to accommodate both uncertainty and wider societal values and preferences, and it is argued that arguments for NTMPAs should be more explicitly focussed on this potential. It is difficult, if not impossible and inappropriate, to extend the reductive approach inherent in CFMA analyses to encompass the broader ethical and scientific concerns for the health of marine ecosystems and their component populations and habitats that arguments for NTMPAs reflect. NTMPA proponents might focus on stressing that arguments against such designations and in favour of CFMAs do not encompass such valid concerns, therefore they tell only half of the story.
P. J. S. JonesEmail:
  相似文献   

7.
The prospect for successful biocontrol using immunocontraception is threatened if there is adaptation to the vaccine through natural selection of individuals that are genetically resistant to the contraceptive agent. To assess this possibility we examined the literature and found that little relevant data are available for any species on the appropriate trait, fertility variation among immunized individuals, or about appropriate population and genetic parameters influencing the likelihood of a selection response. Some data are available on variation in antibody response to immunocontraceptives, but the relationship between antibody response and fertility levels is poorly documented. The antibody response data indicate low heritability for this trait suggesting that fertility levels of contraceptive-resistant individuals will also have a low heritability. Slow evolution of contraception resistance might therefore be anticipated. The absence of information about relevant parameters makes the construction of quantitative models premature. We discuss factors in particular need of investigation if predictions about resistance evolution are to be made. These include: 1. the genetic basis of fertility retention, 2. the proportion of the population resistant to the contraceptive agent and how this is affected by gene flow from refuge populations, 3. the genetically-based fitness tradeoffs of resistant individuals that often accompany selection, 4. cross-generation effects that can thwart the effects of selection, and 5. the efficiency of delivery of the contraceptive agent. An understanding of the above for particular species, and the development of appropriate divergently acting multiple vaccines that can be used in temporal rotation or in mixtures, should facilitate the development of management options to minimize resistance evolution.  相似文献   

8.
The last decade has seen growing concern at the uncertain effectiveness of most fisheries assessment and management approaches as reflected by trends in global landing statistics published by FAO. These imply full exploitation of the majority of fishery resources and a serious overcapitalization of fleets at the global level. Projected increases in demand, future prices for fisheries products, and impacts of growing world populations on the ecosystem all require an urgent search for improved management frameworks.Improved management of fisheries requires, first, an understanding of the axioms and working assumptions underlying the current approaches and how these evolved in response to regional or local conditions and target species. This should promote integration of methodologies which better reflect local situations and can be expressed in the form of one or more working paradigms. These paradigms should incorporate ecosystem considerations, including environmental fluctuations and socio-economic factors. They should not assume that current production levels are independent of natural fluctuations and human impacts and should recognize the dangers of maintaining open access to marine resources throughout their seasonal cycle, life history and distribution range.Wide-use management paradigms incorporating explicit user rights, participatory management and inputs from a variety of disciplines and stakeholders are becoming popular, but must operate within a hierarchy of pre-negotiated responses to pre-specified limit reference points so that social and economic options are not lost because conservation issues have not been given precedence.Academic and research institutions could aid the management process by more participation, by promoting interdisciplinary teamwork with stakeholders and by breaking down excessive specialization and regionalization within fisheries studies. On the management side, the key elements for improving the situation seem to be consultative management frameworks that explicitly incorporate watchdog functions and implement precautionary approaches to management. Risk-averse strategies are appropriate but, given the high level of uncertainty that managers face with natural systems, fail-safe management with redundancy, both in the data sources they rely on for fishery performance and in the management measures applied, seem appropriate.For near-shore resources, governments could consider partly devolving management responsibility to appropriate levels in society, involving coastal communities, individual use rights and other vehicles for allocating access. Changing emphasis of modern technology from fisheries exploitation to improved management will be one aspect of successful future management systems, perhaps incorporating geotemporally defined access rights to near-shore and shelf resources.Recent international agreements, including the formal ratification of the Law of the Sea, show that governments are prepared for more ecologically appropriate approaches. The key stake of the fisheries industry in sustainable fisheries development needs supporting, particularly for developing countries, now the major source of aquatic marine products. High priorities for management of marine resources are rebuilding depleted resources and restoring habitats, with concern for maintaining genetic and ecological diversity. There will be a need to consider impacts of global trade on conservation of resources for future generations, if proper management is to be maintained in the face of growing demand.International agreements of relevance to future management paradigms which are compatible with the Law of the Sea Convention (and each other), include Agenda 21 of UNCED, the Biodiversity Convention, the UN Agreement on Straddling Fish Stocks and Highly Migratory Fish Stocks, the Compliance Agreement and the FAO Code of Conduct for Responsible Fisheries. Such agreements, ratified or now open for signature, provide a comprehensive basis for future customary law that can assist authorities in constructing appropriate management frameworks. Current concern remains with application of these agreements in international waters, where limited access as required for proper management still has not been established.  相似文献   

9.
10.
Active or passive immunization against the beta-amyloid peptide (Abeta) has been proposed as a method for preventing and/or treating Alzheimer's disease (AD). In addition to lowering brain Abeta and amyloid burden in transgenic mouse models of AD, a beneficial effect of immunization on previously characterized memory impairment(s) has also been reported in these mice. Whether these preclinical data will predict efficacy in AD patients remains to be seen. A clinical trial of active immunization (vaccination) was halted, owing to a serious adverse event (meningoencephalitis), raising questions about the safety of this approach. Two recent reports suggest that immunotherapy-based approaches to treating and preventing AD will require careful antigen and antibody selection, to maximize efficacy and minimize serious adverse events. However, given the potential efficacy of this approach, we believe that immunotherapy for AD should not be prematurely abandoned.  相似文献   

11.
12.
13.
Taking into consideration that the immune response following infection promotes the expansion of lymphocyte clones that are essentially non-specific, ensuring both parasite evasion and persistence inside the host, what would be the major consequences of this polyclonal response to the development of immunopathology? We favor the hypothesis that the polyclonal B cell responses triggered by the infection is responsible of the host susceptibility and is a major contributor to the maintenance of a progressive disease. In particular, the activation of B cells by parasite mitogens would contribute to the class determination of T cell responses and to the inhibition of macrophages - target cells for parasite multiplication and also responsible for parasite clearance. We also envisage that the activation of T cells by parasite 'superantigens', and the ensuing energy and deletion of these cells, processes that are frequently observed, would contribute for the immunosuppression as well as to parasite escape and persistence in the host. We had concentrated our efforts on the study of the non-specific aspects of the immune response following Trypanosoma cruzi infection. We aimed at finding new strategies to modulate and control the mechanisms leading to both the immunosuppression and the development of chronic auto-immunity leading to rational vaccine approaches against parasite infection and immunopathology.  相似文献   

14.
15.
The phytopathogenic bacterium Pseudomonas syringae can suppress both pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity (ETI) by the injection of type III effector (T3E) proteins into host cells. T3Es achieve immune suppression using a variety of strategies including interference with immune receptor signaling, blocking RNA pathways and vesicle trafficking, and altering organelle function. T3Es can be recognized indirectly by resistance proteins monitoring specific T3E targets resulting in ETI. It is presently unclear whether the monitored targets represent bona fide virulence targets or guarded decoys. Extensive overlap between PTI and ETI signaling suggests that T3Es may suppress both pathways through common targets and by possessing multiple activities.  相似文献   

16.
Using data of the Red Data Book of European Butterflies we establish the species–area relationship (S = 8.5 A0.23) and the endemics–area relationship (S = 0.5 A0.18) of European butterflies. Applying confidence limits as tools for the identification of hotspot countries we show that in the case of butterflies hotspots of endemism and hotspots of overall species richness do not coincide. We introduce plots of residuals from species–area relationships shifted upwards by the 95% confidence limits of the intercept (α-values) as a new tool for identifying and ranking of hotspots.  相似文献   

17.
18.
19.
Estimates of minimum areas required for effective biodiversity conservation differ substantially. Scientific reserve design and placement procedures indicate that between 30 and 75% of any region may be required to sample biodiversity features. These estimates do not routinely incorporate measures for sampling viable populations of species or explore the area requirements of sampling viable populations of species assemblages. To determine the area requirements for sampling viable populations of a herbivore assemblage, spatially explicit abundance data from the Kruger National Park, South Africa, were analyzed. Area requirements were consistently above 50% and were unaffected by selected target population sizes. In addition, area requirements appeared to be insensitive to selection unit size (analytical grain), habitat quality, the coarseness of the land classification system used or the presence of low-density species. Thus, traditional conservation area targets of 10–15% appear inadequate for representing viable populations of a herbivore assemblage from African savanna regions. This suggests that conservation targets of at least 50% of land classification units may represent a more appropriate conservation rule of thumb, or alternatively, that the use of data independent conservation targets may need to be abandoned.  相似文献   

20.
The Sustainable Use of Pesticides Directive (2009/128/EC), part of the EU Thematic Strategy for Pesticides, requires Integrated Pest Management (IPM) to be actively promoted. A key objective is to give greater priority to non-chemical methods of plant protection to reduce the impact of pesticides on human health and the environment. Integrated Weed Management (IWM) can be considered part of IPM, and many non-chemical methods are available. For example, a recent review of methods for control of Alopecurus myosuroides (black-grass) in winter wheat found the following mean annual levels of control: ploughing 67%; delayed drilling 37%; fallowing 70%; higher seed rates 30%; competitive cultivars 27%. In comparison with herbicides these efficacy levels are mediocre, and A. myosuroides would be classified as resistant (R) or moderately resistant (MR) to all these methods if the criteria used by the Chemicals Regulation Directorate in the UK for assigning ratings to herbicide efficacy were used. It is, therefore, not surprising that farmers are reluctant to embrace IWM and continue to place greater.reliance on herbicides as a more reliable and cost effective method of weed control. While non-chemical methods will not replace herbicides on most farms, reduced reliance on herbicides will be necessary both for practical (increasing resistance, lack of new herbicides) and political reasons (complying with EU legislation). Farmers will use nonchemical control methods when they have a major weed problem, and have no alternative, but they must be encouraged to adopt IWM at an earlier stage. Research into IWM must be relevant and practical, and not simply conducted as some sort of 'academic' exercise. More effective knowledge transfer is vital, and this is a challenge due to the decline in independent, state funded, advisory services in many European countries. The question arises; is it possible to achieve reductions in pesticide use by simply promoting non-chemical methods of weed control, or will statutory limits on pesticides be needed to achieve this goal?  相似文献   

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