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251.
Brood sex ratio is often affected by parental or environmental quality, presumably in an adaptive manner that is the sex that confers higher fitness benefits to the mother is overproduced. So far, studies on the role of parental quality have focused on parental morphology and attractiveness. However, another aspect, the partner’s behavioral characteristics, may also be expected to play a role in brood sex ratio adjustment. To test this hypothesis, we investigated whether the proportion of sons in the brood is predicted by the level of territorial aggression displayed by the father, in the collared flycatcher (Ficedula albicollis). The proportion of sons in the brood was higher in early broods and increased with paternal tarsus length. When controlling for breeding date and body size, we found a higher proportion of sons in the brood of less aggressive fathers. Male nestlings are more sensitive to the rearing environment, and the behavior of courting males may often be used by females to assess their future parental activity. Therefore, adjusting brood sex ratio to the level of male aggression could be adaptive. Our results indicate that the behavior of the partner could indeed be a significant determinant in brood sex ratio adjustment, which should not be overlooked in future studies.  相似文献   
252.
We performed detrended correspondence analysis (DCA) ordination to compare seven successional seres running in stone quarries, coal mining spoil heaps, sand and gravel pits, and extracted peatlands in the Czech Republic in central Europe. In total, we obtained 1,187 vegetation samples containing 705 species. These represent various successional stages aged from 1 to 100 years. The successional seres studied were more similar in their species composition in the initial stages, in which synathropic species prevailed, than in later successional stages. This vegetation differentiation was determined especially by local moisture conditions. In most cases, succession led to a woodland, which usually established after approximately 20 years. In very dry or wet places, by contrast, where woody species were limited, often highly valuable, open vegetation developed. Except in the peatlands, the total number of species and the number of target species increased during succession. Participation of invasive aliens was mostly unimportant. Spontaneous vegetation succession generally appears to be an ecologically suitable and cheap way of ecosystem restoration of heavily disturbed sites. It should, therefore, be preferred over technical reclamation.  相似文献   
253.
Aluminium (Al) is a key element in critical loadcalculations for forest. Here, we argue for re-evaluating theimportance of Al. Effects of two levels of enhanced Alconcentrations and lowered Ca:Al ratios in the soil solutionin a field manipulation experiment in a mature spruce stand(1996–1999) on tree vitality parameters were tested. Inaddition, Al solubility controls were tested. Various loads ofAl were added to forest plots by means of an irrigationsystem. Potentially toxic Al concentrations and criticalratios of Ca to inorganic Al were established. The ratio of Cato total Al was not a suitable indicator for unfavourableconditions for plant growth. No significant effects on crowncondition, tree growth and fine root production were observedafter three years of treatment. In 1999, foliar Mg content inthe highest Al addition treatment had declined significantly.This agreed with the known response to Al stress of seedlingsin nutrient solution experiments. No support was found forusing the chemical criterion Ca:Al ratio in soil solution,foliar and root tissue as an indicator for forest damage dueto acidification. Al solubility was considerably lower thanimplied by the assumption of equilibrium with gibbsite,particularly in the root zone. The gibbsite equilibrium iscommonly used in critical load models. Substitution of thegibbsite equilibrium with an Al-organic matter complexationmodel to describe Al solubility in soil water may have largeconsequences for calculation of critical loads. The resultsindicate that critical load maps for forests should bereconsidered.  相似文献   
254.
Hydrocarbon deposition and soil microflora as affected by highway traffic.   总被引:3,自引:0,他引:3  
The proximity of a busy highway (90,000 vehicles/day) increased the amount of polycyclic aromatic hydrocarbons (PAHs) in soil at the depth of 5-15 cm from 106 ng/g as a grassland background to 3095 ng/g dry soil at the highway verge (a sum of 10 PAH species). The PAH concentration was related to the distance from the source and exhibited a biphasic character, which is interpreted in terms of bimodal distribution of the exhaust microparticles with different rates of deposition. Similarly, the tendency of benz(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, and indeno(1,2,3-cd)pyrene to decrease their proportion with distance from the highway, in contrast to phenanthrene, fluoranthene, pyrene, benzo(a)pyrene, and benzo(g,h,i)perylene, was attributed to their prevalent localisation on the heavier particle fraction. The abundance of bacteria (8.33 x background) and fungi (3.17 x background) close to the highway is thought to be a consequence of hydrocarbon deposition from the traffic that serves as a significant energetic input into the soil. The elevated concentrations of hydrocarbon substrates, as indicated by PAHs, increased both the absolute and relative numbers of the microbial degraders of diesel fuel, biphenyl, naphthalene, and pyrene. Their maximum numbers at 0.5-1.5 m from the pavement reached 1.3 x 10(4), 1.2 x 10(5), 1.1 x 10(4), and 6.6 x 10(3) colony-forming units (CFU) or infection units per gramme dry soil, respectively. On the other hand, the number of anthracene degraders (1.1 x 10(3) CFU per g dry soil) remained close to the detection limit of the enumeration technique used (0.1-0.2 x 10(3) per g dry soil), consistently with the absence of anthracene and higher linear PAHs in the investigated soil samples. The amounts of persisting PAHs justify artificial inoculation with effective degrader strains in the vicinity of motorways.  相似文献   
255.

Abstract Copper treatment, muscle and liver accumulate a great amount of copper ions. The higher concentration of copper ions in the organism caused an elevated level of metallothionein. Copper induced the synthesis of metallothionein, mostly in the livers. In gel chromatography heat stable low molecular weight protein certain coming from the destruction of high molecular weight proteins could be observed. On the effect of higher copper ion concentration in the liver, the level of the metallothionein bound to copper (as related to total protein bounded to copper) was decreased. This phenomenon shows the weaker affinity of apothionein to copper, compared to other proteins.

Follows copper sulphate treatment, every measured blood serum parameter was changed. GOT activity rose to 130% and the GPT to 300% of control. LDH activity increased, too. According to this, the anaerobic way became preferred in glucose metabolism. On the effect of copper sulphate stress the blood serum glucose concentration was higher than the control value.  相似文献   
256.
Developing countries are often most impacted by climate change. While the work of international environmental organizations has received considerable public and academic attention, local environmental non-governmental organizations (ENGOs) also play a key role in assisting local populations adapt to the changing environment and develop in a sustainable manner. Drawing on data from semi-structured interviews with rural Malians, and using a local ENGO [the Mali-Folkecenter Nyetaa (MFC)] as a case study, this paper begins by describing how rural Malians perceive climate change is impacting their lives, and how the MFC attempts to address these impacts with their programs in the communities. The paper then illustrates the unique advantages of local ENGOs, both in their holistic approach and their integration in the communities, to working with the local population, relative to the approach taken by larger NGOs in this field. It concludes by proposing that a key new avenue for the international community to meet its developmental and environmental goals could be to support the work of local ENGOs through, for example, existing carbon markets.  相似文献   
257.
Modifications to ecosystems often lead to externalities that can be assigned an economic value and traded in ecosystem service markets. One such value may include the provisioning of nest sites for organisms that would otherwise be ousted from the surrounding cultural landscape, such as the sand martin (Riparia riparia), small passerine utilizing river bank rippings when available. The studied sand martin population was initially characterized as relying heavily on human activities for habitat, as extensive river regulation caused the relocation of 97% of Czech sand martins to man-made habitats, most commonly sandpits and gravel-sandpits. The socioeconomic changes and strict implementation of the EIA law had further detrimental effects on this species, which already adjusted to the human-dominated landscape, ousting it for a second time from its key nesting habitats, causing closure 86% of sandpits with only occasional quarrying and closure of 47% of those with regular small-scale regular quarrying. Meanwhile, large-scale quarries remained nearly unaffected. Conversion of any actively quarried site to that with vertical slopes present, but with quarrying absent, led to the progressive disappearance of sand martin colonies in 73% of sandpits with ceased occasional quarrying and in 87% of sandpits with ceased regular small-scale quarrying. The sharp decrease in the number of nest-sites of a bird protected by law is a gloomy result of the hypertrophied business regulation (EIA is estimated to cost € 970 million annually in the E.U. alone) aimed, paradoxically, to support the environment.  相似文献   
258.

The sustainable production and use of small-scale biogas energy are required to ensure clean household energy access in developing countries, including the Sub-Saharan Africa (SSA) region. This is influenced by market risks, which can be identified as political, economic, social, technical, legal, and environmental (PESTLE). This study examines peer-reviewed and grey literature for the period from 2000 to 2020 to identify the PESTLE constraints and assess their impact on the sustainable development of the technology in the SSA region. The production of biogas with small-scale plants is commonly done by rural and peri-urban households. Results show that economic constraints are the most dominant and reducing at a slow pace. This is followed by political constraints, which have received much attention in the last two decades. Despite the policy improvements, broader national bioenergy policies and interventions are still to make significant gains, especially in the Central African region. In order of significance, the Southern, East, and West Africa regions have made greater progress in reducing the constraints. To achieve the sustainable development of the technology, there is a need to further address the PESTLE constraints at national and regional levels. This study partly deduces that the unsustainable production, use, and inadequate regulation of the small-scale biogas sector are delaying its transition in the SSA region.

  相似文献   
259.
Environmental Science and Pollution Research - This article delves into the factors that may influence radon flux, such as soil properties and weather conditions, on the example of two experimental...  相似文献   
260.
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