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One of the characteristic features of forestry work is its seasonality. Most of forestry work comprises simple activities not requiring any special preparation from the workers who do it. However, the current state of forest technology makes it possible to perform many operations, using machines and technical equipment. In Poland, the type of work that is used most often is manual work. It is still relatively cheap and available. Most of the companies providing services for forest management departments just use this simplest form of performing tasks and hire so-called seasonal employees to perform them. Thanks to this solution, the costs of keeping employees in the event there is a seasonal fall in demand for their services, is eliminated. The principal purpose of the research undertaken is to propose technological and organizational solutions that would diminish the impact of natural seasonality of forestry work on the level and structure of employment in the forestry service companies. The initial analyses show that by increasing the degree of work mechanization the demand for employees performing tasks in a forest management department may be reduced even by several tens of persons per month.
The aim of this paper is a statistical verification of seasonality phenomenon and calculation of seasonal factors of sold production of furniture in Poland. The work has been prepared on the basis of monthly data from Central Statistical Office for the years 2005-2014. The occurrence of seasonal fluctuations has been determined on the basis of statistical knowledge, using Kruskal-Wallis test. The increase of sold production of furniture occurs in March, September, October and November of each year as a result of seasonality. While, in July the value of sold production of furniture is lower by approximately 14% than the average sub-period, as the result of seasonality.
The seasonal diet of pine marten Martes martes (Linnaeus, 1758) in southern boreal Sweden was studied by analyses of scats and digestive tract contents collected over a 6-year period. The diet was diverse; whereas microtines was the single most important food category, also shrews, hares, birds, insects, and berries were frequently consumed. The diet of pine marten varied seasonally but the consumption of small mammals (microtines and shrews) and hares was relatively stable over the year, and may be regarded as a year-round staple for marten. The winter diet differed from most other Fennoscandian studies in that it contained more berries and insects, and less squirrels and cervids. This may be explained by the general lack of snow, and by the dense marten population, during the years of the study. Among birds passerines were most frequent; tetraonids were consumed mainly in winter. The food niche was broadest in winter and decreased over summer.
The definition of the wildcat Felis silvestris Schreber, 1775 in Scotland is conten­tious, in light of long-term interbreeding with domestic cats F. catus Linnaeus, 1758. Two morphological groupings (Group 1 and Group 2) have previously been proposed to explain the variation found in wild-living cats in Scotland, with Group 1 cats closest to wildcats and Group 2 cats to domestic cats. Data from the reproductive tracts of 185 wild-living cat carcasses and evidence of reproductive activity in 31 live cats were analysed in order to compare reproductive activity between the morphological groups, and in relation to seasonality and existing data on wildcats and domestic cats. For males, Group 2 cats had a greater mean relative testes size than Group 1 cats. Estimated from corpora lutea, there was a suggestion that Group 1 females showed more seasonality in oestrous than Group 2 cats. In all wild-living cats, the mean litter size was 4.3 and estimated birth dates were throughout the year, but least in winter. A high number of pseudopregnancies were recorded. The results were consistent with the hypothesis that Group 2 cats are closer to domestic cats. However, the variation observed in the sample of wild-living cats reported here, suggested that reproduction was neither strictly seasonal nor outside the range observed in some feral cat popu­lations.
The paper contains the results of eight-year-long studies on the runoff of nitrates from heavy soils used as croplands. The runoffs of nitrates from a drainage catchment and a catchment drained with ditches were compared. The drainage system was found to carry away twice as much water, with a five-fold higher concentration of nitrates and 20-fold higher load of nitrates, than the system of ditches. High runoff of nitrates (22 kg ha-1 annually) from the soils drained by drains was distributed quite evenly throughout the year, with maximum peaks in March and June. Nitrate runoff through the system of ditches was low (1.15 kg ha-1 annually), reaching maximum peaks in March and April (62% of the load), but disappearing in the summer.
Small insectivores and rodents, despite similarities in body size and attributes scaling to body size, exhibit significant differences in other properties, including many life history traits. In this article major differences between life history traits of the two taxa are reviewed, with an indication of contrasting selection pressures related to somewhat different body size, as well as to differences in metabolic rates, diet and exposure to predation. Additionally, since the life history differences between small mammals are particularly well pronounced in highly seasonal habitats, the winter ecology of shrews and rodents is compared. Finally, the two different reproductive strategies typical for soricine shrews and small nonhibernating rodents, are presented. In conclusion, it is proposed that the reproduction delayed to the second calendar year of life in shrews is the result of selection for traits ensuring successful survival in winter, a period that is more perilous for shrews than for rodents. In rodents, in contrast, opportunistic reproduction is the most prominent characteristic which also helps to maximize their reproductive output. This ability for high reproduction seems to be the main antipredatory measure selected for in rodent evolution.
The genus Grillotia Guiart, 1927 is cosmopolitan in its distribution and the type-species, G. erinaceus (van Beneden, 1858), has been relatively well studied. However, this study provides infection indices of Grillotia erinaceus from southern and northern Black Sea whiting Merlangius merlangus for the first time. The specimens of Grillotia erinaceus were obtained from subserosa of the anterior oesophagus, stomach, pyloric caeca, liver, ovaries and mesenterium of whiting caught by commercial fishing vessels off Sinop, Turkey and off Balaklava, Ukraine. Fish were examined during the period from May 2011 to April 2012. Prevalence and mean intensity values in 268 fish collected off Sinop in the Black Sea were 18.66% and 1.82 ± 0.16 parasites per infected fish, respectively. In Ukrainian 166 whiting samples collected off Balaklava in the Black Sea, however, G. erinaceus plerocercus infection prevalence was 10.24% and mean intensity 1.71 ± 0.75 parasites per infected fish. Infection parameters were also determined at both sampling sites in relation with host length, sex and season.
On the basis of monthly averaged satellite data, this study examined how the annual cycle of the Baltic Sea surface temperature (SST) varied spatially and temporally during the period 1986–2005. We conclude that there are two main thermal seasons in the Baltic Sea separated only by short transitional periods – spring lasting about one month, and autumn lasting two months. Generally speaking, summer covers the part of the year from June to October with the highest monthly mean SST in August. Winter, with a minimum monthly mean SST in February in shallow waters or in March in deeper areas, lasts from December to April. As a result of climate changes over the Baltic Sea region, strong positive trends in SST occur in the summer months. In consequence, the period with extremely high sea surface water temperatures has become slightly longer in the central Baltic. In the last decade winter changes in SST display zero or even negative tendencies. The investigated period was characterized by an annual increase in mean temperatures of about 0.03–0.07◦C. However, the rates of monthly mean SST changes were sometimes more than three times as high.
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