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61.
Although induced plant responses to herbivory are well studied as mechanisms of resistance, how induction shapes community interactions and ultimately plant fitness is still relatively unknown. Using a wild tomato, Solanum peruvianum, native to the Peruvian Andes, we evaluated the disruption of pollination as a potential ecological cost of induced responses. More specifically, we tested the hypothesis that metabolic changes in herbivore-attacked plants, such as the herbivore-induced emission of volatile organic compounds (VOCs), alter pollinator behavior and consequentially affect plant fitness. We conducted a series of manipulative field experiments to evaluate the role of herbivore-induced vegetative and floral VOC emissions as mechanisms by which herbivory affects pollinator behavior. In field surveys and bioassays in the plants' native habitat, we found that real and simulated herbivory (methyl jasmonate application) reduced attractiveness of S. peruvianum flowers to their native pollinators. We show that reduced pollinator preference, not resource limitation due to leaf tissue removal, resulted in reduced seed set. Solitary bee pollinators use floral plant volatiles, emitted in response to herbivory or methyl jasmonate treatment, as cues to avoid inflorescences on damaged plants. This herbivory-induced pollinator limitation can be viewed as a general cost of induced plant responses as well as a specific cost of herbivory-induced volatile emission. 相似文献
62.
Julien Saada Olivier Parant Sylvie Kessler Jacqueline Aziza Marie France Sarramon 《黑龙江环境通报》2006,26(1):9-10
Congenital splenic cyst (CSC) is a rare condition, and only a few cases with prenatal diagnosis and no associated malformation have been reported. Spontaneous regression is possible in case of mild CSC (under 40 mm), but enlargement or secondary complications may lead to surgical treatment. We report, herein, two cases of isolated mild CSC with complete spontaneous postnatal regression. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
63.
64.
Jean Bogner Riitta Pipatti Seiji Hashimoto Cristobal Diaz Katarina Mareckova Luis Diaz Peter Kjeldsen Suvi Monni Andre Faaij Qingxian Gao Tianzhu Zhang Mohammed Abdelrafie Ahmed R T M Sutamihardja Robert Gregory 《Waste management & research》2008,26(1):11-32
Greenhouse gas (GHG) emissions from post-consumer waste and wastewater are a small contributor (about 3%) to total global anthropogenic GHG emissions. Emissions for 2004-2005 totalled 1.4 Gt CO2-eq year(-1) relative to total emissions from all sectors of 49 Gt CO2-eq year(-1) [including carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and F-gases normalized according to their 100-year global warming potentials (GWP)]. The CH4 from landfills and wastewater collectively accounted for about 90% of waste sector emissions, or about 18% of global anthropogenic methane emissions (which were about 14% of the global total in 2004). Wastewater N2O and CO2 from the incineration of waste containing fossil carbon (plastics; synthetic textiles) are minor sources. Due to the wide range of mature technologies that can mitigate GHG emissions from waste and provide public health, environmental protection, and sustainable development co-benefits, existing waste management practices can provide effective mitigation of GHG emissions from this sector. Current mitigation technologies include landfill gas recovery, improved landfill practices, and engineered wastewater management. In addition, significant GHG generation is avoided through controlled composting, state-of-the-art incineration, and expanded sanitation coverage. Reduced waste generation and the exploitation of energy from waste (landfill gas, incineration, anaerobic digester biogas) produce an indirect reduction of GHG emissions through the conservation of raw materials, improved energy and resource efficiency, and fossil fuel avoidance. Flexible strategies and financial incentives can expand waste management options to achieve GHG mitigation goals; local technology decisions are influenced by a variety of factors such as waste quantity and characteristics, cost and financing issues, infrastructure requirements including available land area, collection and transport considerations, and regulatory constraints. Existing studies on mitigation potentials and costs for the waste sector tend to focus on landfill CH4 as the baseline. The commercial recovery of landfill CH4 as a source of renewable energy has been practised at full scale since 1975 and currently exceeds 105 Mt CO2-eq year(-1). Although landfill CH4 emissions from developed countries have been largely stabilized, emissions from developing countries are increasing as more controlled (anaerobic) landfilling practices are implemented; these emissions could be reduced by accelerating the introduction of engineered gas recovery, increasing rates of waste minimization and recycling, and implementing alternative waste management strategies provided they are affordable, effective, and sustainable. Aided by Kyoto mechanisms such as the Clean Development Mechanism (CDM) and Joint Implementation (JI), the total global economic mitigation potential for reducing waste sector emissions in 2030 is estimated to be > 1000 Mt CO2-eq (or 70% of estimated emissions) at costs below 100 US$ t(-1) CO2-eq year(-1). An estimated 20-30% of projected emissions for 2030 can be reduced at negative cost and 30-50% at costs < 20 US$ t(-) CO2-eq year(-1). As landfills produce CH4 for several decades, incineration and composting are complementary mitigation measures to landfill gas recovery in the short- to medium-term--at the present time, there are > 130 Mt waste year(-1) incinerated at more than 600 plants. Current uncertainties with respect to emissions and mitigation potentials could be reduced by more consistent national definitions, coordinated international data collection, standardized data analysis, field validation of models, and consistent application of life-cycle assessment tools inclusive of fossil fuel offsets. 相似文献
65.
66.
Noncrop areas such as hedgerows in agricultural landscapes can perform several ecological and agronomic functions (e.g., habitat,
movement corridors, windbreak, etc.), but their dynamics and drivers of changes are often poorly known. We conducted a study
in three agricultural landscapes of southern Quebec, Canada, to assess and compare the spatial and temporal (1958–1997) dynamics
of three hedgerow networks in relation to geomorphic conditions (marine, glacial, and mixed deposit) and land-use changes.
Hedgerow networks were mapped and described in terms of their structure (density, degree of connectivity, and presence of
trees or shrubs) and their relationship to other components of the landscape (connection to woodland). Relationships were
assessed in time and space using nonparametric correlation, Mantel test, and principal components analysis (PCA). Results
show significant differences between hedgerow structure for the three landscapes and distinct temporal and spatial dynamics
that can be related to changes in management practices and agricultural policies. On marine deposits, increases in hedgerow
density did not always correspond to an increase in their degree of connectivity, suggesting a possible reduction in network
quality. On glacial deposits, hedgerow density declined following abandonment of agricultural land, but rather than disappearing,
these linear structures were integrated into adjacent brush or forested areas. Our analysis reveals the complex spatial and
temporal dynamics of the hedgerow networks and highlights the need to take into account spatial attributes such as connectivity
and connection to woodland to evaluate more accurately overall network quality. 相似文献
67.
Carl F. Meyer Andre B. Corbeau 《Journal of the American Water Resources Association》1974,10(3):426-439
ABSTRACT: This paper describes the techniques of factor and discriminant analyses to isolate and quantify the statistical differences between firms located on flood plains and those located off flood plains. The research effort described consists of three segments: data collection, isolation of potential classification variables, and the determination of the appropriate discriminant functions to classify a given fm as either on or off the flood plain. Significant classification functions are developed for both manufacturing and commercial establishments, whose arguments include dollar sales volume, total shipping cost, total employee cost, dollar valuations on the building and inventories, all on an annual basis, and the square footage of the site. 相似文献
68.
Andre Deppermann Markus Blesl Ole Boysen Harald Grethe David Bruchof 《Mitigation and Adaptation Strategies for Global Change》2016,21(5):743-759
Over the past decade, the relationship between agricultural and energy markets has strengthened. Traditional energy sources have been increasingly replaced by energy from biomass, and this trend is expected to continue into the future. Consequently, an assessment of the efficiency of bioenergy policies requires a comprehensive analysis of both agricultural and energy markets. The objective of this paper is to analyze the impacts of two detailed European Union (EU) greenhouse gas (GHG) emission mitigation policies on the utilization of biomass for energy production and the implications for agricultural prices and trade. The consequences of a policy-induced shift from consumption of fossil to renewable energy are assessed under full consideration of interrelations between the energy and agricultural sectors. To this end, we combine an energy system model and an agricultural sector model by establishing a consistent interface between them. Depending on the ambition of the GHG emission reduction scenarios, the results indicate significant price increases. Furthermore, the increase in European demand for energy crops is to a substantial degree covered by additional imports. These results highlight that GHG emission mitigation policies enacted in a large economy like the EU cannot be considered without accounting for indirect effects in the rest of the world. They put the efficiency and also the effectiveness of such policies in general into question. 相似文献
69.
70.
Bercovitch FB Widdig A Trefilov A Kessler MJ Berard JD Schmidtke J Nürnberg P Krawczak M 《Die Naturwissenschaften》2003,90(7):309-312
In many mammalian species, male reproductive success appears to climb sharply at young adulthood, form a brief plateau during prime ages, and decline among older animals, a pattern often attributed to reduced physical condition with ageing. However, solid evidence to either substantiate or refute this profile among nonhuman primates is lacking. Here, we combine a decade of genetic analysis of paternity among free-ranging rhesus macaques, Macaca mulatta, with information about body condition in order to evaluate how changes in morphology might govern age-specific reproduction among males. We show that age-specific reproductive success traverses the same life history profile as found in other mammals, but reductions in reproductive output with advanced age were associated with reduced chances of survivorship rather than accompanied by diminished body condition. We demonstrate that variance in male age at onset of reproduction is three times greater than variance in female age at onset of reproduction. We provide the first evidence from primates that age-specific reproductive output among males is not a consequence of age-related changes in body condition, but reflects social and demographic factors. 相似文献