Abstract: Logging is considered the most important threat to species in boreal forests. In contrast to eastern Canada, where most boreal forests remain largely untouched, in Fennoscandia it is possible to assess the cumulative, long-term effects of intensive forestry on wildlife. But harvesting of stands is rapidly changing Canadian boreal forests, which represent an important proportion of the world's boreal forests. We show that Fennoscandia and eastern Canada present striking similarities in terms of forest-age structure, natural-disturbance regime, and structure of bird assemblages, and we provide an assessment of the long-term effects of forestry on eastern Canadian birds of the boreal forest. We used life-history traits from habitat, nesting site, and geographical range to calculate an index of sensitivity to changes induced by modern forestry for boreal species of each region. Tropical migrants commonly found in eastern Canadian boreal forests have life-history traits that are not threat factors in relation to changes caused by modern forestry. Therefore, the general belief that tropical migrants in North America are more sensitive to landscape changes than those in Europe may not hold for species found in the boreal coniferous forests of eastern Canada. Nine Fennoscandian species present high levels of sensitivity, and at least eight eastern Canadian species are of similar concern. In both regions, most of the sensitive species are resident cavity nesters. Given the important similarities between the two regions, the northern expansion of commercial forestry in eastern Canada is likely to result in the significant decline of several resident species, as has occurred in Fennoscandia. 相似文献
Goal, scope, and background Arsenic contamination in groundwater creates severe health problems in the world. There are many physiochemical and biological
methods available for remediation of arsenic from groundwater. Among them, microbial remediation could be taken as one of
the least expensive methods, though it takes longer treatment time. The main objective of this research was to study the improvement
on remediation by addition of some essential ion salts such as Mn and Fe.
Materials and methods
Staphylococcus aureus, Bacillus subtilis, Klebsiella oxytoca, and Escherichia coli were taken as model microbes from Dhulikhel, 30 km east from Kathmandu, Nepal.
Results and discussion Microbes used in this study showed different abilities in their removal of As(III) with and without addition of Mn and Fe
salts. The trend of remediation increased with time. S. aureus was found to be the best among the microbes used. It showed almost 100% removal after 48-h culture, both with and without
Fe and Mn salts. Rate of removal of As increased with addition of Fe and Mn for all microbes. Removal efficiency was found
to increase by about 32% on average after addition of salts in 24-h cultures of S. aureus. 相似文献
Recently, computer, mobile phone and Internet use has increased. This study aimed to determine the possible relation between self-reported wrist and finger symptoms (aches, pain or numbness) and using computers/mobile phones, and to analyze how the symptoms are specifically associated with utilizing desktop computers, portable computers or mini-computers and mobile phones. A questionnaire was sent to 15,000 working-age Finns (age 18–65). Via a questionnaire, 723 persons reported wrist and finger symptoms often or more with use. Over 80% use mobile phones daily and less than 30% use desktop computers or the Internet daily at leisure, e.g., over 89.8% quite often or often experienced pain, numbness or aches in the neck, and 61.3% had aches in the hips and the lower back. Only 33.7% connected their symptoms to computer use. In the future, the development of new devices and Internet services should incorporate the ergonomics of the hands and wrists. 相似文献
Novel catalytic adsorbent (ruthenium on carbon) was employed for the treatment of pulp mill effluent in the presence of hydrogen peroxide. Mathematical model and optimization of the process regarding the most favorable COD (%), TOC (%) and color (%) removal rates was developed and performed with experimental design taking into account catalytic adsorption process kinetics. As the initial experimental design, 3(3-1) half-fractional factorial design (H-FFD) was accomplished at two levels to study the significance of the main effects, such as catalytic adsorbent (g l(-1)) and hydrogen peroxide (ppm) concentrations using the response surface methodology (RSM). Finally, a four factor-three coded level central composite design (CCD) with 28 runs was performed in order to fit a second-order polynomial model. Validation of the model was accomplished by different criteria including coefficient of determination and the corresponding analysis of variance. The achieved removal rates for TOC (up to 75%), COD (up to 73%) and color (up to 68%) were observed for the defined optimal conditions: 1g l(-1) of ruthenium on carbon, 7 ppm of hydrogen peroxide, pH = 4 and ambient temperature. The proposed method benefited significantly improved TOC, COD and color removal efficiency, regenerability and reusability of the catalytic adsorbent and unaltered initial pH of an effluent in comparison to traditional adsorption or oxidation processes. 相似文献
Urban air pollution has emerged as an acute problem in recent years because of its detrimental effects on health and living conditions. The research presented here aims at attaining a better understanding of phenomena associated with atmospheric pollution, and in particular with aerosol particles. The specific goal was to develop a form of air quality modelling which can forecast urban air quality for the next day using airborne pollutant, meteorological and timing variables.Hourly airborne pollutant and meteorological averages collected during the years 1995–1997 were analysed in order to identify air quality episodes having typical and the most probable combinations of air pollutant and meteorological variables. This modelling was done using the Self-Organising Map (SOM) algorithm, Sammon's mapping and fuzzy distance metrics. The clusters of data that were found were characterised by statistics. Several overlapping Multi-Layer Perceptron (MLP) models were then applied to the clustered data, each of which represented one pollution episode. The actual levels for individual pollutants could then be calculated using a combination of the MLP models which were appropriate in that situation.The analysis phase of the modelling gave clear and intuitive results regarding air quality in the area where the data had been collected. The resulting forecast showed that the modelling of gaseous pollutants is more reliable than that of the particles. 相似文献
Inbreeding depression is a relative decline in fitness in offspring of related parents. The magnitude of inbreeding costs
varies among taxa and may increase under stressful conditions. Inbreeding tolerance is expected to be low and selection for
inbreeding avoidance intense when both sexes invest substantially in shared offspring like in nuptial gift-giving butterflies.
This is especially true for increasing mating rate for inbreeding avoidance as nuptial feeding decreases net costs of mating
for females. We explored implications of inbreeding in the nuptial gift-giving green-veined white butterfly, Pieris napi. Compared to outbred ones, partially inbred (F = 0.25) eggs and neonate larvae had 25% lower hatching success and 30% lower survival until adult eclosion, respectively.
Inbreeding was also associated with small size. Yet, the magnitude of inbreeding depression was independent of larval conditions.
A lack of assortative mating and mating durations independent of mating type suggest that neither females nor males discriminate
close relatives (r = 0.5) as mates. Indicative of a postcopulatory mechanism to avoid inbreeding, female remating intervals decreased following
incestuous matings. Such a plastic response may affect the level of postcopulatory sexual selection as female remating interval
(time between successive matings) is necessarily negatively correlated with mating rate (matings per unit time) and mating
frequency (lifetime number of matings), and precopulatory mate choice appeared insignificant. Moreover, incest-induced shift
in the phenotype towards the adaptive peak may contribute to the evolution of female mating rates, although alternative explanations
for polyandry besides material benefits have rarely been invoked when nuptial feeding is involved. 相似文献
Objective: The aim of the study was to compare the safety effects of studded and unstudded winter tires based on fatal road accidents.
Methods: The data included 958 road accidents involving a passenger car or van that occurred in Finland from November to March between 1997 and 2012.
Results: Comparing the proportions of winter tire type in accidents and in general traffic showed that the overall effect of tire type on the number of accidents was not significant, although studded tires reduced fatal accidents by 10–15%. Compared to unstudded tires, studded tires reduced accidents significantly only on bald ice in 2005–2012. Drivers using unstudded tires were more experienced and their profession was more frequently related to driving. In addition, the vehicle age was lower for vehicles with unstudded tires. On the other hand, the state of repair was less pertinent for unstudded than for studded tires. These confounding factors offset their effects to some degree.
Conclusions: The risk of fatal road accidents in winter between studded and unstudded tires does not differ significantly. However, the accident risk has recently been substantially higher on bald ice for unstudded than for studded tires. The magnitude of this risk difference is difficult to determine without specific information on exposure by road surface. 相似文献
A case of early-onset, severe spinal muscular atrophy is reported. Normal fetal breathing movement patterns and heart rate accelerations were observed in spite of the severe hypotonia evident at birth. 相似文献
Ozone induces characteristic symptoms in the chloroplasts of the needles of several coniferous species. Chloroplasts are (1) reduced in size and (2) the stroma is electron dense. Moreover, (3) these chloroplast alterations are more pronounced in the outer mesophyll cell layers and in the upper side of the needle compared to the inner layers and lower side. The syndrome, including the three symptoms (1)-(3), is found in the green needles of Scots pine and Norway spruce not only in the experimental fumigations, but also in mature trees in the field, and has potential for diagnosis of ozone stress. For sound ozone diagnostics all three symptoms must be present in the samples studied. The symptoms in relation to needle anatomy and physiology is discussed, and recommendations for sampling and analysis are given. 相似文献
Toxic cyanobacterial blooms, dominated by Nodularia spumigena, are a recurrent phenomenon in the Baltic Sea during late summer. Nodularin, a potent hepatotoxin, has been previously observed
to accumulate on different trophic levels, in zooplankton, mysid shrimps, fish as well as benthic organisms, even in waterfowl.
While the largest concentrations of nodularin have been measured from the benthic organisms and the food web originating from
them, the concentrations in the pelagic organisms are not negligible. The observations on concentrations in zooplankton and
planktivorous fish are sporadic, however. A field study in the Gulf of Finland, northern Baltic Sea, was conducted during
cyanobacterial bloom season where zooplankton (copepod Eurytemora affinis, cladoceran Pleopsis polyphemoides) and fish (herring, sprat, three-spined stickleback) samples for toxin analyses were collected from the same sampling areas,
concurrently with phytoplankton community samples. N. spumigena was most abundant in the eastern Gulf of Finland. In this same sampling area, cladoceran P. polyphemoides contained more nodularin than in the other areas, suggesting that this species has a low capacity to avoid cyanobacterial
exposure when the abundance of cyanobacterial filaments is high. In copepod E. affinis nodularin concentrations were high in all of the sampling areas, irrespective of the N. spumigena cell numbers. Furthermore, nodularin concentrations in herring samples were highest in the eastern Gulf of Finland. Three-spined
stickleback contained the highest concentrations of nodularin of all the three fish species included in this study, probably
because it prefers upper water layers where also the risk of nodularin accumulation in zooplankton is the highest. No linear
relationship was found between N. spumigena abundance and nodularin concentration in zooplankton and fish, but in the eastern area where the most dense surface-floating
bloom was observed, the nodularin concentrations in zooplankton were high. The maximum concentrations in zooplankton and fish
samples in this study were higher than measured before, suggesting that the temporal variation of nodularin concentrations
in pelagic communities can be large, and vary from negligible to potentially harmful. 相似文献