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181.
Abstract: Many of the skills and resources associated with botanic gardens and arboreta, including plant taxonomy, horticulture, and seed bank management, are fundamental to ecological restoration efforts, yet few of the world's botanic gardens are involved in the science or practice of restoration. Thus, we examined the potential role of botanic gardens in these emerging fields. We believe a reorientation of certain existing institutional strengths, such as plant‐based research and knowledge transfer, would enable many more botanic gardens worldwide to provide effective science‐based support to restoration efforts. We recommend botanic gardens widen research to include ecosystems as well as species, increase involvement in practical restoration projects and training practitioners, and serve as information hubs for data archiving and exchange.  相似文献   
182.

More knowledge on the composition of aqueous extracts of broiler litter amended for Water Soluble P (WSP) reduction would help to understand how amendments work. We measured pH, concentrations of Ca, Mg, Fe, Al, Cu, Mn, Zn, Molybdate Reactive P (MRP), and Dissolved Unreactive P (DUP) in water extracts of broiler litter treated with aluminum sulfate (ALS), ferrous sulfate (FES), ferric chloride (FEC), and gypsum (GYP) at 0, 5, 15, and 25% w/w. In order to study the effects of acidification, the same properties were measured in aqueous extracts of broiler litter suspensions that were titrated to end-points 3, 4, or 6 with 0.5N HCl. Concentrations of MRP, DUP, Ca and Mg, were 61%, 53%, 3.8 times, and 2.6 times greater in extracts from suspensions acidified to pH 6 than at the original pH of 8.9. ALS, FES, and FEC reduced pH, and showed similar effects on WSP concentrations, which were greater than with GYP. The magnitude of the reductions in WSP by ALS, FES, and FEC is uncertain because the actual amount of WSP immobilized cannot be determined. This is because of two opposite effects: 1) Through adsorption, soluble aluminum and iron remove phosphates from solution, and 2) Through acidification, iron and aluminum compounds release phosphates to solution.  相似文献   
183.
Risk compensation denotes offsetting behavioral responses to safety improvements. Theoretical arguments suggest that, when drivers are required to drive safer cars or drive in a safer manner, they will tend to increase their driving speed or drive in some other risky manner.

The purpose of this paper is to review critically the theory and evidence on risk compensation. Our general conclusion is that the application of risk compensation theory, especially to some types of regulations, is questionable, and the empirical support for significant offsetting behavior is weak. Specifically—(1) the role of limitations in processing information is not appreciated, especially regarding risk perceptions and the learning component associated with new regulations; (2) the types of regulations and types of driving behavior are not adequately distinguished; and (3) the empirical studies haves mixed results and are subject to important limitations.  相似文献   
184.
When populations decline in response to unfavorable environmental change, the dynamics of their population growth shift. In populations that normally exhibit high levels of variation in recruitment and abundance, as do many amphibians, declines may be difficult to identify from natural fluctuations in abundance. However, the onset of declines may be evident from changes in population growth rate in sufficiently long time series of population data. With data from 23 years of study of a population of Fowler's toad (Anaxyrus [ = Bufo] fowleri) at Long Point, Ontario (1989–2011), we sought to identify such a shift in dynamics. We tested for trends in abundance to detect a change point in population dynamics and then tested among competing population models to identify associated intrinsic and extrinsic factors. The most informative models of population growth included terms for toad abundance and the extent of an invasive marsh plant, the common reed (Phragmites australis), throughout the toads’ marshland breeding areas. Our results showed density‐dependent growth in the toad population from 1989 through 2002. After 2002, however, we found progressive population decline in the toads associated with the spread of common reeds and consequent loss of toad breeding habitat. This resulted in reduced recruitment and population growth despite the lack of significant loss of adult habitat. Our results underscore the value of using long‐term time series to identify shifts in population dynamics coincident with the advent of population decline. Efectos de una Planta Invasora sobre las Dinámica Poblacional de Sapos  相似文献   
185.
Abstract:  Applying the ecosystem services concept to conservation initiatives or in managing ecosystem services requires understanding how environmental impacts affect the ecology of key species or functional groups providing the services. We examined effects of river impoundments, one of the leading threats to freshwater biodiversity, on an important ecosystem service provided by large tropical rivers (i.e., artisanal fisheries). The societal and economic importance of this ecosystem service in developing countries may provide leverage to advance conservation agendas where future impoundments are being considered. We assessed impoundment effects on the energetic costs of fisheries production (embodied energy) and commercial market value of the artisanal fishery of the Paraná River, Brazil, before and after formation of Itaipu Reservoir. High-value migratory species that dominated the fishery before the impoundment was built constituted a minor component of the contemporary fishery that is based heavily on reservoir-adapted introduced species. Cascading effects of river impoundment resulted in a mismatch between embodied energy and market value: energetic costs of fisheries production increased, whereas market value decreased. This was partially attributable to changes in species functional composition but also strongly linked to species identities that affected market value as a result of consumer preferences even when species were functionally similar. Similar trends are expected in other large tropical rivers following impoundment. In addition to identifying consequences of a common anthropogenic impact on an important ecosystem service, our assessment provides insight into the sustainability of fisheries production in tropical rivers and priorities for regional biodiversity conservation .  相似文献   
186.
Abstract: Because habitat loss due to urbanization is a primary threat to biodiversity, and land‐use decisions in urbanizing areas are mainly made at the local level, land‐use planning by municipal planning departments has a potentially important—but largely unrealized—role in conserving biodiversity. To understand planners’ perspectives on the factors that facilitate and impede biodiversity conservation in local planning, we interviewed directors of 17 municipal planning departments in the greater Seattle (Washington, U.S.A.) area and compared responses of planners from similar‐sized jurisdictions that were “high” and “low performing” with respect to incorporation of biodiversity conservation in local planning. Planners from low‐performing jurisdictions regarded mandates from higher governmental levels as the primary drivers of biodiversity conservation, whereas those from high‐performing jurisdictions regarded community values as the main drivers, although they also indicated that mandates were important. Biodiversity conservation was associated with presence of local conservation flagship elements (e.g., salmonids) and human‐centered benefits of biodiversity conservation (e.g., quality of life). Planners from high‐ and low‐performing jurisdictions favored different planning mechanisms for biodiversity conservation, perhaps reflecting differences in funding and staffing. High performers reported more collaborations with other entities on biodiversity issues. Planners’ comments indicated that the term biodiversity may be problematic in the context of local planning. The action most planners recommended to increase biodiversity conservation in local planning was public education. These results suggest that to advance biodiversity conservation in local land‐use planning, conservation biologists should investigate and educate the public about local conservation flagships and human benefits of local biodiversity, work to raise ecological literacy and explain biodiversity more effectively to the public, and promote collaboration on biodiversity conservation among jurisdictions and inclusion of biodiversity specialists in planning departments.  相似文献   
187.
Despite the high profile of amphibian declines and the increasing threat of drought and fragmentation to aquatic ecosystems, few studies have examined long‐term rates of change for a single species across a large geographic area. We analyzed growth in annual egg‐mass counts of the Columbia spotted frog (Rana luteiventris) across the northwestern United States, an area encompassing 3 genetic clades. On the basis of data collected by multiple partners from 98 water bodies between 1991 and 2011, we used state‐space and linear‐regression models to measure effects of patch characteristics, frequency of summer drought, and wetland restoration on population growth. Abundance increased in the 2 clades with greatest decline history, but declined where populations are considered most secure. Population growth was negatively associated with temporary hydroperiods and landscape modification (measured by the human footprint index), but was similar in modified and natural water bodies. The effect of drought was mediated by the size of the water body: populations in large water bodies maintained positive growth despite drought, whereas drought magnified declines in small water bodies. Rapid growth in restored wetlands in areas of historical population declines provided strong evidence of successful management. Our results highlight the importance of maintaining large areas of habitat and underscore the greater vulnerability of small areas of habitat to environmental stochasticity. Similar long‐term growth rates in modified and natural water bodies and rapid, positive responses to restoration suggest pond construction and other forms of management can effectively increase population growth. These tools are likely to become increasingly important to mitigate effects of increased drought expected from global climate change. Papeles de las Características del Fragmento, Frecuencia de Sequía y Restauración en las Tendencias a Largo Plazo de un Anfibio Ampliamente Distribuido  相似文献   
188.
Abstract: The mandate to increase endangered salmon populations in the Columbia River Basin of North America has created a complex, controversial resource‐management issue. We constructed an integrated assessment model as a tool for analyzing biological‐economic trade‐offs in recovery of Snake River spring‐ and summer‐run chinook salmon (Oncorhynchus tshawytscha). We merged 3 frameworks: a salmon‐passage model to predict migration and survival of smolts; an age‐structured matrix model to predict long‐term population growth rates of salmon stocks; and a cost‐effectiveness analysis to determine a set of least‐cost management alternatives for achieving particular population growth rates. We assessed 6 individual salmon‐management measures and 76 management alternatives composed of one or more measures. To reflect uncertainty, results were derived for different assumptions of effectiveness of smolt transport around dams. Removal of an estuarine predator, the Caspian Tern (Sterna caspia), was cost‐effective and generally increased long‐term population growth rates regardless of transport effectiveness. Elimination of adult salmon harvest had a similar effect over a range of its cost estimates. The specific management alternatives in the cost‐effective set depended on assumptions about transport effectiveness. On the basis of recent estimates of smolt transport effectiveness, alternatives that discontinued transportation or breached dams were prevalent in the cost‐effective set, whereas alternatives that maximized transportation dominated if transport effectiveness was relatively high. More generally, the analysis eliminated 80–90% of management alternatives from the cost‐effective set. Application of our results to salmon management is limited by data availability and model assumptions, but these limitations can help guide research that addresses critical uncertainties and information. Our results thus demonstrate that linking biology and economics through integrated models can provide valuable tools for science‐based policy and management.  相似文献   
189.
The effect of vehicle fleet mass on car crash fatalities was estimated, using a new mathematical model to isolate vehicle mass from related factors like size, stiffness and inherent protection. The model was based on fatality risk data, impact speed, fleet mass distribution, and collision probabilities. The fleet mass distribution was changed over 15 years to (a) a homogeneous fleet of 1300 kg cars, (b) a bimodal fleet of 600 and 1600 kg cars, and (c) a 300 kg lighter fleet.

Occupant and collision partner fatality risks were estimated for the new fleets. The new fleets were achieved by various strategies, and the average fatality rate was calculated after and during the transition to the new fleet.Occupant fatality risk decreased and partner risk increased as occupants changed to a heavier car. The average fatality rate was 59% higher after the transition to a bimodal fleet mass, and 11 % lower for a homogeneous fleet. A 300 kg lighter fleet had a 8% higher fatality rale, but the strategy influenced the number of fatalities accumulated during the transition. The safest strategy to attain the lighter fleet was to reduce the mass of the heaviest cars first.

It was concluded that vehicle fleet mass significantly affects traffic safety. Downsizing consequences can be compensated for by improving inherent vehicle protection or reducing impact speed. The fatalities during downsizing can be limited by choosing an appropriate strategy.  相似文献   
190.
Abstract. The factors leading to the presumed extinction of Trilepidea adamsii (Cheesem) Tiegh., an endemic New Zealand mistletoe, are discussed Although several factors are involved, including habitat loss, overcollecting, reduced seed dispersal, and browsing by the brush tailed possum (Tri-chosurus vulpecula Kerr.), interactions among these factors appear to have been particularly important in this extincion. Possums, introduced from Australia last century, probably expanded too late to have had a major impact on Trilepidea adamsii except perhaps at the very end, but they do seriously jeopardize the long term survival of several other plant species in New Zealand. Trilepidea adamsii illustrates the range of factors, and their interactions, that can lead to the extinction of a species.  相似文献   
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