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31.
Parental investment theory predicts that parental effort should be related to the reproductive value of the current brood. This depends on both the number of young and the survival prospects of each of them. Thus parents may provide more care to larger broods either because of (1) the direct effect of brood size per se on reproductive value (the “brood size” hypothesis) or because (2) past mortality, reflected in current brood size, predicts future mortality of the brood and hence its reproductive value (the “brood success” hypothesis). Earlier studies have not attempted to distinguish between these alternatives. We tested the hypotheses in the precocial, nidifugous common goldeneye Bucephala clangula, a species with uniparental female care. Maternal effort was measured as the time spent by the female in rearing the brood. We found that brood size itself is not associated with maternal effort, but that females modify their maternal effort according to the mortality already experienced by the brood, supporting the prediction of the brood success hypothesis. We also found that brood mortality varied considerably between broods and that previous mortality predicts future mortality within broods, basic assumptions of the brood success hypothesis. Received: 30 January 1996 / Accepted after revision: 27 October 1996  相似文献   
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We evaluated performance of species distribution models for predictive mapping, and how models can be used to integrate human pressures into ecological and economic assessments. A selection of 77 biological variables (species, groups of species, and measures of biodiversity) across the Baltic Sea were modeled. Differences among methods, areas, predictor, and response variables were evaluated. Several methods successfully predicted abundance and occurrence of vegetation, invertebrates, fish, and functional aspects of biodiversity. Depth and substrate were among the most important predictors. Models incorporating water clarity were used to predict increasing cover of the brown alga bladderwrack Fucus vesiculosus and increasing reproduction area of perch Perca fluviatilis, but decreasing reproduction areas for pikeperch Sander lucioperca following successful implementation of the Baltic Sea Action Plan. Despite variability in estimated non-market benefits among countries, such changes were highly valued by citizens in the three Baltic countries investigated. We conclude that predictive models are powerful and useful tools for science-based management of the Baltic Sea.  相似文献   
35.
Recent survey results for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, dioxins) in Baltic Sea sediments from Finland, Sweden and Denmark were merged with previously published Baltic Sea data. Regional distribution of concentration levels, differences in congener patterns, and temporal changes in sediment profiles were examined. One of the main objectives was to study if any major point sources for different PCDD/F congeners could be identified on a regional scale, based on sediment records. The survey confirmed the impact of chlorophenol production derived highly chlorinated PCDF-congeners on the total toxicity in sediments in the Gulf of Finland near the Kymijoki river estuary. Signatures of other point sources or combined point sources pertinent to specific industry branches or particular production processes (such as pulp bleaching, vinyl chloride production, thermal processes) may be discerned. However, the findings did not support any of the known point sources significantly influencing those congeners that are most abundant in Baltic herring and salmon. Instead, regional distributions in the Baltic Sea indicate that atmospheric deposition may act as a major source for those congeners and especially for 2,3,4,7,8-PeCDF. There were clear indications of declines in levels in sediment in some areas, but generally the levels of highly chlorinated PCDD/Fs on the northern coast of the Gulf of Finland were still high when compared with other areas of the Baltic Sea. Major areas with data gaps cover the south-eastern and eastern coastal regions of the Baltic Proper and the southern Gulf of Finland.  相似文献   
36.
This paper presents the mass, energy and material balances of a solid recovered fuel (SRF) production process. The SRF is produced from commercial and industrial waste (C&IW) through mechanical treatment (MT). In this work various streams of material produced in SRF production process are analyzed for their proximate and ultimate analysis. Based on this analysis and composition of process streams their mass, energy and material balances are established for SRF production process. Here mass balance describes the overall mass flow of input waste material in the various output streams, whereas material balance describes the mass flow of components of input waste stream (such as paper and cardboard, wood, plastic (soft), plastic (hard), textile and rubber) in the various output streams of SRF production process. A commercial scale experimental campaign was conducted on an MT waste sorting plant to produce SRF from C&IW. All the process streams (input and output) produced in this MT plant were sampled and treated according to the CEN standard methods for SRF: EN 15442, EN 15443. The results from the mass balance of SRF production process showed that of the total input C&IW material to MT waste sorting plant, 62% was recovered in the form of SRF, 4% as ferrous metal, 1% as non-ferrous metal and 21% was sorted out as reject material, 11.6% as fine fraction, and 0.4% as heavy fraction. The energy flow balance in various process streams of this SRF production process showed that of the total input energy content of C&IW to MT plant, 75% energy was recovered in the form of SRF, 20% belonged to the reject material stream and rest 5% belonged with the streams of fine fraction and heavy fraction. In the material balances, mass fractions of plastic (soft), plastic (hard), paper and cardboard and wood recovered in the SRF stream were 88%, 70%, 72% and 60% respectively of their input masses to MT plant. A high mass fraction of plastic (PVC), rubber material and non-combustibles (such as stone/rock and glass particles), was found in the reject material stream.  相似文献   
37.
Protected areas (nature reserves) cover 0.7% of the land area in southern Finland (162,000 km2), which belongs to the south- and mid-boreal coniferous forest zones. The value of these areas in preserving land birds was studied on the basis of quantitative censuses. The numbers of bird pairs were estimated in nature reserves and in the whole of southern Finland, and the significance of the reserves was evaluated based on how large a proportion of the total population in southern Finland was found in them. Forest habitat generalists and species of coniferous forests occurred in protected areas as expected by the proportion of these areas in southern Finland. Specimens of these species groups comprise two thirds of all the country's land birds. Species of old-growth forests and open peatlands clearly preferred protected areas, whereas species of bushes, and lush and deciduous forest were scarcer in protected areas than elsewhere in southern Finland. The latter fertile habitats are poorly represented in protected areas, even though due to their disappearance or alteration elsewhere several species confined to these habitats have declined and are even threatened. Drainage of open peatlands and clearcutting of old-growth forests has caused a decrease in the area of these habitats in southern Finland during the past decades. Therefore, protected areas have a high significance in preserving bird species preferring these habitats. Protected areas are particularly important for decreased species of old-growth forests, such as the Three-toed Woodpecker Picoides tridactylus and the Siberian Jay Perisoreus infaustus , as about 10% of their total population in southern Finland was estimated to breed in protected areas. The future protection of both old-growth and deciduous forests is important if we are to preserve bio-diversity of land birds in Finland.  相似文献   
38.
Many studies have suggested various kinds of forest policies, management planning and practices to help forests adapt to climate change. These recommendations are often generic, based mostly on case studies from temperate countries and rarely from Africa. We argue that policy and management recommendations aimed at integrating adaptation into national forest policies and practices in Africa should start with an inventory and careful examination of existing policies and practices in order to understand the nature and extent of intervention required to influence the adaptation of forest ecosystems to climate change. This paper aims to contribute to closing this gap in knowledge detrimental to decision making through the review and analysis of current forest policies and practices in Burkina Faso and Ghana and highlighting elements that have the potential to influence the adaptation of forest ecosystems to climate change. The analysis revealed that adaptation (and mitigation) are not part of current forest policies in Burkina Faso and Ghana, but instead policies contain elements of risk management practices which are also relevant to the adaptation of forest ecosystems. Some of these elements are found in policies on the management of forest fires, forest genetic resources, non-timber resources, tree regeneration and silvicultural practices. To facilitate and enhance the management of these elements, a number of recommendations are suggested. Their implementation will require experienced and well-trained forestry personnel, financial resources, socio-cultural and political dimensions, and the political will of decision makers to act appropriately by formulating necessary policies and mainstreaming adaptation into forest policy and management planning.  相似文献   
39.
Corruption and forest concessions   总被引:3,自引:0,他引:3  
We examine how corruption impacts a central government's application of concession policy instruments consisting of royalty rates, concession size, environmentally sensitive logging levels, and enforcement. Harvesters have incentives to illegally log by taking more volume than is allowed, high grading through removal of only the highest valued and best formed trees, and shirking environmentally sensitive logging requirements, all of which reduce public goods produced from native tropical forests. Corruption is introduced through logging inspectors who can be bribed by harvesters to avoid fines associated with illegal logging. Both the theory and a simulation are used to compare policy design under corruption and no corruption.  相似文献   
40.
The frequency, strength and sources of long-range transport (LRT) episodes of fine particles (PM2.5) were studied in southern Finland using air quality monitoring results, backward air mass trajectories, remote sensing of fire hot spots, transport and dispersion modelling of smoke and chemical analysis of particle samples (black carbon, monosaccharide anhydrides, oxalate, succinate, malonate, SO42?, NO3?, K+ and NH4+). At an urban background site in Helsinki, the daily WHO guideline value (24-h PM2.5 mean 25 μg m?3) was exceeded during 1–7 LRT episodes per year in 1999–2007. The 24-h mean maximum concentrations varied between 25 and 49 μg m?3 during the episodes, which was 3–6 times higher than the local mean concentration (8.7 μg m?3) in 1999–2007. The highest particle concentrations (max. 1-h mean 163 μg m?3) and the longest episodes (max. 9 days) were mainly caused by the emissions from open biomass burning, especially during springs and late-summers in 2002 and 2006. During the period 2001–2007, the satellite remote sensing of active fire hot spots and transport and dispersion modelling of smoke indicated that approximately half of the episodes were caused partly by the emissions from wildfires and/or agricultural waste burning in fields in Eastern Europe, especially in Russia, Belarus and Ukraine. Other episodes were mainly caused by the LRT of ordinary anthropogenic pollutants, e.g. from energy production, traffic, industry and wood combustion. During those ‘other episodes’, air masses also arrived from Eastern Europe, including Poland. The highest concentrations of biomass-burning tracers, such as monosaccharide anhydrides (levoglucosan + mannosan + galactosan) and K+, were observed during open biomass-burning episodes, but quite high values were also measured during some winter episodes due to wood combustion emissions. Our results indicate that open biomass burning in Eastern Europe causes high fine particle concentration peaks in large areas of Europe almost every year.  相似文献   
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