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排序方式: 共有149条查询结果,搜索用时 265 毫秒
41.
J. Berton C. Harris Morgan W. Tingley Fangyuan Hua Ding Li Yong J. Marion Adeney Tien Ming Lee William Marthy Dewi M. Prawiradilaga Cagan H. Sekercioglu Suyadi Nurul Winarni David S. Wilcove 《Conservation biology》2017,31(2):394-405
The trade in wild animals involves one‐third of the world's bird species and thousands of other vertebrate species. Although a few species are imperiled as a result of the wildlife trade, the lack of field studies makes it difficult to gauge how serious a threat it is to biodiversity. We used data on changes in bird abundances across space and time and information from trapper interviews to evaluate the effects of trapping wild birds for the pet trade in Sumatra, Indonesia. To analyze changes in bird abundance over time, we used data gathered over 14 years of repeated bird surveys in a 900‐ha forest in southern Sumatra. In northern Sumatra, we surveyed birds along a gradient of trapping accessibility, from the edge of roads to 5 km into the forest interior. We interviewed 49 bird trappers in northern Sumatra to learn which species they targeted and how far they went into the forest to trap. We used prices from Sumatran bird markets as a proxy for demand and, therefore, trapping pressure. Market price was a significant predictor of species declines over time in southern Sumatra (e.g., given a market price increase of approximately $50, the log change in abundance per year decreased by 0.06 on average). This result indicates a link between the market‐based pet trade and community‐wide species declines. In northern Sumatra, price and change in abundance were not related to remoteness (distance from the nearest road). However, based on our field surveys, high‐value species were rare or absent across this region. The median maximum distance trappers went into the forest each day was 5.0 km. This suggests that trapping has depleted bird populations across our remoteness gradient. We found that less than half of Sumatra's remaining forests are >5 km from a major road. Our results suggest that trapping for the pet trade threatens birds in Sumatra. Given the popularity of pet birds across Southeast Asia, additional studies are urgently needed to determine the extent and magnitude of the threat posed by the pet trade. 相似文献
42.
Marion Desquilbet Bruno Dorin Denis Couvet 《Environmental Modeling and Assessment》2017,22(3):185-200
In this paper, we model the supply and demand for agricultural goods and assess and compare how welfare, land use, and biodiversity are affected under intensive and extensive farming systems at market equilibrium instead of at exogenous production levels. As long as demand is responsive to price, and intensive farming has lower production costs, there exists a rebound effect (larger market size) of intensive farming. Intensive farming is then less beneficial to biodiversity than extensive farming is, except when there is a high degree of convexity between biodiversity and yield. On the other hand, extensive farming leads to higher prices and smaller quantities for consumers. Depending on parameter values, it may increase or decrease agricultural producer profits. Implementing “active” land sparing by zoning some land for agriculture and other land for conservation could overcome the rebound effect of intensive farming, but we show that farmers have then incentives to encroach on land zoned for conservation, with higher incentives under intensive farming. We also show that the primary effect of the higher prices associated with extensive farming is a reduction of animal feed production, which has a higher price elasticity of demand, whereas less of an effect is observed on plant-based food production and almost no effect is observed on biofuel production if there are mandatory blending policies. 相似文献
43.
Wienold J Recknagel S Scharf H Hoppe M Michaelis M 《Waste management (New York, N.Y.)》2011,31(3):530-535
The EU RoHS Directive (2002/95/EC of the European Parliament and of the Council) bans the placing of new electrical and electronic equipment containing more than agreed levels of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) flame retardants on the EU market. It necessitates methods for the evaluation of RoHS compliance of assembled electronic equipment. In this study mounted printed circuit boards from personal computers were analyzed on their content of the three elements Cd, Pb and Hg which were limited by the EU RoHS directive. Main focus of the investigations was the influence of sample pre-treatment on the precision and reproducibility of the results. The sample preparation steps used were based on the guidelines given in EN 62321. Five different types of dissolution procedures were tested on different subsequent steps of sample treatment like cutting and milling. Elemental analysis was carried out using ICP-OES, XRF and CV-AFS (Hg). The results obtained showed that for decision-making with respect to RoHS compliance a size reduction of the material to be analyzed to particles ?1.5 mm can already be sufficient. However, to ensure analytical results with relative standard deviations of less than 20%, as recommended by the EN 62321, a much larger effort for sample processing towards smaller particle sizes might be required which strongly depends on the mass fraction of the element under investigation. 相似文献
44.
Brient L Lengronne M Bertrand E Rolland D Sipel A Steinmann D Baudin I Legeas M Le Rouzic B Bormans M 《Journal of environmental monitoring : JEM》2008,10(2):248-255
In many countries, the presence of cyanobacteria in freshwater bodies used for both drinking water and recreational purposes is under increasing public health attention. Water managers are considering how to implement monitoring that leads to a minimization of the risks incurred by the users of potentially contaminated sites. To address this question, this study involved assessing the performance of a submersible probe for measuring phycocyanin-specific fluorescence as a function of cyanobacterial biomass, with the aim of applying it as a tool for surveillance management. Its advantages and limits compared to more traditional analyses are discussed. The monitoring of cyanobacteria in the water bodies of western France was carried out using a minifluorimeter specific to the fluorescence of phycocyanin, a pigment specific to cyanobacteria. The results are compared with the analyses recommended by the World Health Organisation (chlorophyll a and cell counting). This study based on nearly 800 samples shows a significant correlation between the phycocyanin content and the cyanobacterial biomass, expressed as the number of cells per mL (R2 = 0.73). This submersible probe is simple and rapid to use, making it possible to take into account horizontal and vertical heterogeneities in the proliferation growth. In this way, we are able to detect at an early stage the conditions that could potentially lead to a risk, in order to start sampling. Due to its sensitivity, this tool proves suitable for monitoring aimed at reducing the risks incurred by the users of contaminated sites and launching preventative actions. The use of the phycocyanin probe provides an effective tool to complement traditional analyses of cyanobacterial presence. It is suggested that a surveillance protocol based on phycocyanin concentration can significantly improved the accuracy of the extent of cyanobacterial bloom development in the light of spatial and temporal variabilities associated with these occurrences. 相似文献
45.
Bonny Patrice Desdouits Marion Schaeffer Julien Garry Pascal Essia Ngang Jean Justin Le Guyader Françoise S. 《Food and environmental virology》2020,12(3):274-277
Food and Environmental Virology - Shellfish constitute an important protein source but may be contaminated by viruses from various origins. A study performed on clams collected in Cameroon showed a... 相似文献
46.
Sustaining Visitor Use in Protected Areas: Future Opportunities in Recreation Ecology Research Based on the USA Experience 总被引:4,自引:1,他引:3
Christopher A. Monz David N. Cole Yu-Fai Leung Jeffrey L. Marion 《Environmental management》2010,45(3):551-562
Recreation ecology, the study of environmental consequences of outdoor recreation activities and their effective management,
is a relatively new field of scientific study having emerged over the last 50 years. During this time, numerous studies have
improved our understanding of how use-related, environmental and managerial factors affect ecological conditions and processes.
Most studies have focused on vegetation and soil responses to recreation-related trampling on trails and recreation sites
using indicators such as percent vegetation cover and exposed mineral soil. This applied approach has and will continue to
yield important information for land managers. However, for the field to advance, more attention needs to be given to other
ecosystem attributes and to the larger aspects of environmental conservation occurring at landscape scales. This article is
an effort at initiating a dialog on needed advances in the field. We begin by reviewing broadly generalizable knowledge of
recreation ecology, to separate what is known from research gaps. Then, based on the authors’ perspective of research in the
USA and North America, several research directions are suggested as essential for continued progress in this field including
theoretical development, broadening scale, integration with other disciplines, and examination of synergistic effects. 相似文献
47.
Combining theory and wisdom in pragmatic,scenario-based decision support for sustainable development
Megan Davenport Marion Delport James Nelson Blignaut Tanja Hichert Gerhard van der Burgh 《Journal of Environmental Planning and Management》2019,62(4):692-716
Researchers have increasingly acknowledged the relative strength of ‘hybrid’ approaches to scenario analysis for exploring the futures of coupled human-nature systems. In this paper, we explain, demonstrate, and provisionally evaluate the usefulness of a simple analytical framework, based on five categories of capital assets, as part of a protocol for overcoming the conversion problem in hybrid scenario analysis. Based on a preliminary application of the framework to a case study in South Africa, we suggest that the five capitals framework has the potential to improve expedience and counter the bias against ‘soft’ drivers in hybrid approaches to scenario analysis. However, in light of the methodological trade-off between rigour and expedience, we suggest that future research needs to compare the available protocols for hybrid scenario analysis by weighing up the relative gain in scenario quality versus the relative cost of scenario construction. 相似文献
48.
Daniel A. Marion Jonathan D. Phillips Chad Yocum James Jahnz 《Journal of the American Water Resources Association》2019,55(6):1425-1442
Factors influencing sediment availability are assessed and erosion rates are quantified for an off‐highway vehicle (OHV) trail system in the Ouachita Mountains of Arkansas. As of May 2012, the Wolf Pen Gap trail system included 77.0 km of "trails" which consist of county roads; open and closed Forest Service roads; and open and closed OHV trails. For a given trail length, the sediment volume available to be eroded is determined by bare trail width and sediment depth. Four condition types are defined that group trail sections based on statistically different trail widths or depths. Trail construction method appears to influence sediment availability differences more than erosion potential (as indexed by trail slope gradient and length). The range for annual trail erosion rates is estimated as 75 and 210 tonne/ha/yr. The high and low rates are obtained using two independent methods. The 210 tonne/ha/yr rate is computed from mean sediment capture at 30 sediment traps installed for 0.5–1.0 year. The 75 tonne/ha/yr rate is computed assuming all available trail sediment measured in a one‐time sampling is eroded over the next year. We argue in support of this assumption and suggest both rate values may be conservative. Trail erosion rates and sediment trap observations indicate frequent trap cleanout will be needed to continue sediment capture from All Terrain Vehicle trails. 相似文献
49.
Marion L. East Heribert Hofer Wolfgang Wickler 《Behavioral ecology and sociobiology》1993,33(6):355-370
In East Africa, spotted hyenas live in large clans in a highly structured society dominated by females. A clan is a fission-fusion society where members are often solitary or in small groups. Spotted hyenas have a ritualized greeting during which two individuals stand parallel and face in opposite directions. Both individuals usually lift their hind leg and sniff or lick the anogenital region of the other. The unique aspect of greetings between individuals is the prominent role of the erect penis in animals of both sex. Female spotted hyenas have fused outer labiae and a pseudo-penis formed by the clitoris which closely resembles the male penis and can be erected. During greetings subordinates signalled submission with gestures which were not necessarily reciprocated by the dominant participant. Asymmetries were most pronounced in greetings between adult females where the probability of asymmetries increased with the divergence in rank between partners. Greetings between adult females and males were uncommon and restricted to males above median rank, principally the alpha male. Models of primate affiliative behavior assume that benefits derived from social relationships with different individuals are not equal and that individuals are selected to maximize the benefits they receive from social relationships with others. The observed distribution of greetings between partners of different rank matched the predictions of these models. An examination of non-adaptive hypotheses on the evolution of the pseudo-penis demonstrated that the conventional scenario linking (initial) virilization of female genitalia with selection for female dominance does not explain either the initial virilization, nor the evolution of the pseudo-penis to its current form and use. We sketch a new scenario that links (1) initial virilization to the occurrence of neonatal siblicide amongst members of a twin litter, and (2) costs of maintenance, pseudo-penile control over copulation and male submission. Our analysis confirms previous adaptive hypotheses on the function of the pseudo-penis in greetings and suggests new hypotheses to account for hitherto unexplained features.
Correspondence to: M.L. East 相似文献
50.
Brigitte Simon-Bouy Agnès Taillandier Delphine Fauvert Isabelle Brun-Heath Jean-Louis Serre Carmen G. Armengod Martin G. Bialer Michèle Mathieu Jacques Cousin David Chitayat Jan Liebelt Barbara Feldman Marion Gérard-Blanluet Stefani Körtge-Jung Cath King Hannele Laivuori Martine Le Merrer Sarju Mehta Christina Jern Saba Sharif Fabienne Prieur Gabriele Gillessen-Kaesbach Andreas Zankl Etienne Mornet 《黑龙江环境通报》2008,28(11):993-998