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261.
Linking Theory and Practice for Restoration of Step-Pool Streams   总被引:1,自引:0,他引:1  
Step-pools sequences are increasingly used to restore stream channels. This increase corresponds to significant advances in theory for step-pools in recent years. The need for step-pools in stream restoration arises as urban development encroaches into steep terrain in response to population pressures, as stream channels in lower-gradient areas require stabilization due to hydrological alterations associated with land-use changes, and as step-pools are recognized for their potential to enhance stream habitats. Despite an increasingly voluminous literature and great demand for restoration using step-pool sequences, however, the link between theory and practice is limited. In this article, we present four unique cases of stream restoration using step-pools, including the evolution of the approaches, the project designs, and adjustments in the system following restoration. Baxter Creek in El Cerrito, California demonstrates an early application of artificial step-pools in which natural adjustments occurred toward geomorphic stability and ecological improvement. Restoration of East Alamo Creek in a large residential development near San Ramon, California illustrates an example of step-pools increasingly used in locations where such a channel form would not naturally occur. Construction of a step-pool channel in Karnowsky Creek within the Siuslaw National Forest, Oregon overcame constraints posed by access and the type and availability of materials; the placement of logs allowed natural scouring below steps. Dry Canyon Creek on the property of the Mountains Restoration Trust in Calabasas, California afforded a somewhat experimental approach to designing step-pools, allowing observation and learning in the future. These cases demonstrate how theories and relationships developed for step-pool sequences over the past two decades have been applied in real-world settings. The lessons from these examples enable us to develop considerations useful for deriving an appropriate course of design, approval, and construction of artificial step-pool systems. They also raise additional fundamental questions concerning appropriate strategies for restoration of step-pool streams. Outstanding challenges are highlighted as opportunities for continuing theoretical work.  相似文献   
262.
The environmental performance of the University of Maribor (Engineering Campus) has been assessed on a life cycle basis. The following activities have been considered in the study: the use and operation of lecture theatres (construction and maintenance, heating, lighting and water consumption) and day-to-day consumption of sundries (paper and plastic bottles). The results indicate that the heating and construction of buildings are the ‘hot spots’ in the system, for most environmental impacts. Different waste management options for the plastic and paper, including recycling, incineration and landfill, have also been compared for environmental impacts and economic costs. The option combining 70% recycling, 29% incineration and 1% landfill has been found to be most economically and environmentally sustainable.  相似文献   
263.
The dual goals of the Organic Act of 1916 and Wilderness Act of 1964 are to protect natural resources and provide quality visitor experiences. Park managers need metrics of trail conditions to protect park resources and quality of visitor experiences. A few methods of sampling design for trails have been developed. Here, we describe a relatively new method, spatially balanced sampling, and compare it to systematic sampling. We evaluated the efficiency of sampling designs to measure recreation-related impacts in Rocky Mountain National Park. This study addressed two objectives: first, it compared estimates of trail conditions from data collected from systematic versus spatially balanced sampling data; second, it examined the relationship between sampling precision and sampling efficiency. No statistically significant differences in trail condition were found between the 100-m interval and the spatially balanced datasets. The spatially balanced probability-based dataset was found to be a good estimate of trail conditions when analyses were conducted with fewer sample points. Moreover, spatially balanced probability-based sampling is flexible and allows additional sample points to be added to a sample.  相似文献   
264.
An essential step in the development of products based on biotechnology is an assessment of their potential economic impacts and safety, including an evaluation of the potential impact of transgenic crops and practices related to their cultivation on the environment and human or animal health. The purpose of this paper is to provide an assessment method to evaluate the impact of biotechnologies that uses quantifiable parameters and allows a comparative analysis between conventional technology and technologies using GMOs. This paper introduces a method to perform an impact analysis associated with the commercial release and use of genetically modified plants, the Assessment System GMP Method. The assessment is performed through indicators that are arranged according to their dimension criterion likewise: environmental, economic, social, capability and institutional approach. To perform an accurate evaluation of the GMP specific indicators related to genetic modification are grouped in common fields: genetic insert features, GM plant features, gene flow, food/feed field, introduction of the GMP, unexpected occurrences and specific indicators. The novelty is the possibility to include specific parameters to the biotechnology under assessment. In this case by case analysis the factors of moderation and the indexes are parameterized to perform an available assessment.  相似文献   
265.
Reducing the impact of drought and famine remains a challenge in sub‐Saharan Africa despite ongoing drought relief assistance in recent decades. This is because drought and famine are primarily addressed through a crisis management approach when a disaster occurs, rather than stressing preparedness and risk management. Moreover, drought planning and food security efforts have been hampered by a lack of integrated drought monitoring tools, inadequate early warning systems (EWS), and insufficient information flow within and between levels of government in many sub‐Saharan countries. The integration of existing drought monitoring tools for sub‐Saharan Africa is essential for improving food security systems to reduce the impacts of drought and famine on society in this region. A proactive approach emphasizing integration requires the collective use of multiple tools, which can be used to detect trends in food availability and provide early indicators at local, national, and regional scales on the likely occurrence of food crises. In addition, improving the ability to monitor and disseminate critical drought‐related information using available modern technologies (e.g., satellites, computers, and modern communication techniques) may help trigger timely and appropriate preventive responses and, ultimately, contribute to food security and sustainable development in sub‐Saharan Africa.  相似文献   
266.
Sandy beaches are the prime sites for human recreation and underpin many coastal economies and developments. In many coastal areas worldwide, beach recreation relies on the use of off-road vehicles (ORVs) driven on the shore. Yet, the use of ORVs is not universally embraced due to social conflicts with other beach user groups and putative environmental consequences of vehicle traffic on sandy shores. Such ecological impacts of ORVs are, however, poorly understood for endobenthic invertebrates of the intertidal zone seawards of the dunes. Consequently, this study quantified the degree to which assemblages of intertidal beach invertebrates are affected by traffic. The study design comprised a series of temporally replicated spatial contrasts between two reference sites (no ORVs) and two beaches with heavy ORV traffic (in excess of 250,000 vehicles per year) located in South-East Queensland, Australia. Macrobenthic assemblages on ORV-impacted beaches had significantly fewer species at substantially reduced densities, resulting in marked shifts in community composition and structure. These shifts were particularly strong on the middle and upper shore where vehicle traffic was concentrated. Strong effects of ORVs were detectable in all seasons, but increased towards the summer months as a result of heavier traffic volumes. This study provides clear evidence that ORVs can have substantial impacts on sandy beach invertebrates that are manifested throughout the whole community. Demonstrating such an ecological impact caused by a single type of human use poses a formidable challenge to management, which needs to develop multi-faceted approaches to balance environmental, social, cultural, and economic arguments in the use of sandy shores, including management of “beach traffic.”  相似文献   
267.
This study explored the public perceptions of mobile telecommunications development – new landscape elements installed to deliver new technology – in a protected area. It examined: (1) the perceived landscape impacts of such development; (2) the importance attached to the socio-economic value of mobile telecommunications; and (3) the factors underlying the perceived landscape impacts of mobile telecommunications development. A postal questionnaire survey was conducted in the Peak District National Park, England with 420 respondents drawn from National Park residents and visitors, urban dwellers and members of environmental organisations. The study suggests that: (1) there was a prevailing antipathy towards the landscape impacts of mobile telecommunications development in the National Park; (2) apart from emergency uses, the other socio-economic benefits of mobile telecommunications technology were thought to be relatively unimportant in the National Park; and (3) rather than socio-demographic characteristics, it was respondents' understandings of protected areas' needs for the technology and potential health risks that had significant effects on the perceived landscape impacts. Overall, this study suggests that the significance of National Park landscapes is respected by the public, even when setalongside the convenience of modern technology, which has substantial implications for landscape planning and management in protected areas.  相似文献   
268.
The rural economic situation in China-with a living standard mostly at subsistence level-lags far behind the prosperous development in the cities and coastal areas. To balance this disequilibrium, comprehensive concepts and endeavors are necessary keeping in view all-not just economic-interests and needs that contribute to lively rural identities. In this context the role of agriculture, where still 50% of the Chinese population are working, will be newly defined, and sustainability concepts can help to find a readjusted position within the Chinese economy focusing on environmental health and food safety as main targets of political and other supporting measures. Within the SUCCESS project, a Concept of Sustainable Agriculture was developed and it drafts one conceivable relation between the exposure to natural resources and economy and tries to find new answers to the broad range of rural challenges in China. It is a qualitative model and, therefore, not always fully applicable, but in the concrete situation of villages, it shows possible directions of sustainability-oriented development by considering the typical local potentials. In the Chinese context that means identifying the different functions of agriculture-the well-known and the hidden-to make them explicit for the Chinese public and therewith to give them new significance. The article is based on a 3-years study within the EU-China Project SUCCESS with field research in four Chinese rural communities. It analyzes the agricultural sustainability potential of these selected villages against the background of massive structural changes within the next 20 years in rural China. Starting from the current agricultural reality, based on a qualitative analysis of the actual situation, local potentials and needs towards sustainable production and marketing are identified, and possible functions of the Chinese agriculture are formulated for the future.  相似文献   
269.
A study was conducted in southern Ethiopia to evaluate the nutrient status on smallholder farms with respect to land use class (garden, grassland, and outfield) and slope position (upper, middle, and lower). Soil physical and chemical properties were quantified using soil samples collected at two depths (0–15 and 15–30 cm). Available phosphorous was significantly different among the three land use classes. However, organic carbon and total nitrogen were lower in the outfield compared to the garden and grass land but not significantly different. The lower than expected nutrient status of the garden and grassland, which receive almost all available organic supplements, was attributed to the overall low availability of these inputs. Similarly, pH and cation exchange capacity were not significantly different among the different land use classes. However, the sum of the exchangeable cations was significantly higher in the garden compared to the outfields. Comparison at landscape level revealed that the sand fraction was significantly greater, whereas the silt fractions were significantly smaller, on the lower slopes relative to the middle slopes. Moreover, the organic carbon, total nitrogen, cation exchange capacity, Ca, and Mg values were significantly less on lower slopes than upper and middle slopes. Perhaps this is because of leaching and the effect of deposition of coarser sediments from the prevailing gully system. Overall, the fertility of the soil was adequate for supporting smallholder farming, but consideration must be given to reducing pressure on the land resources, addressing erosion problems, and providing a line of credit for purchasing inputs.  相似文献   
270.
Worldwide, the ecological condition of streams and rivers has been impaired by agricultural practices such as broadscale modification of catchments, high nutrient and sediment inputs, loss of riparian vegetation, and altered hydrology. Typical responses include channel incision, excessive sedimentation, declining water quality, and loss of in-stream habitat complexity and biodiversity. We review these impacts, focusing on the potential benefits and limitations of wood reintroduction as a transitional rehabilitation technique in these agricultural landscapes using Australian examples. In streams, wood plays key roles in shaping velocity and sedimentation profiles, forming pools, and strengthening banks. In the simplified channels typical of many agricultural streams, wood provides habitat for fauna, substrate for biofilms, and refuge from predators and flow extremes, and enhances in-stream diversity of fish and macroinvertebrates.Most previous restoration studies involving wood reintroduction have been in forested landscapes, but some results might be extrapolated to agricultural streams. In these studies, wood enhanced diversity of fish and macroinvertebrates, increased storage of organic material and sediment, and improved bed and bank stability. Failure to meet restoration objectives appeared most likely where channel incision was severe and in highly degraded environments. Methods for wood reintroduction have logistical advantages over many other restoration techniques, being relatively low cost and low maintenance. Wood reintroduction is a viable transitional restoration technique for agricultural landscapes likely to rapidly improve stream condition if sources of colonists are viable and water quality is suitable.  相似文献   
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