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Many species react negatively to forest fragmentation. If this process also decreases the abundance of forest predators we expect that birds’ broods in small forest patches would be preyed upon only by predators that penetrate from the matrix while broods in larger patches would be also attacked by predators specifically associated with forests. We tested the hypothesis that an increase in forest patch size leads to an increase in predator pressure on nests. Studies were conducted in Central Poland, in an agriculturally dominant area with 6% forest cover and highly fragmented woodlots. Artificial nests were placed along transects from the forest edge to the center of the woodlot. Three patch sizes were chosen for the experiment: small (< 20 ha), medium (30–50 ha) and large (> 120 ha). One quail egg was placed in each nest. All transects were checked after 13– 14 days. The highest predation level was found in medium-sized patches, the lowest – in the largest patches. We found a reverse edge effect on nest predation in the largest patches, i.e. a decreased predation risk closer to the forest/matrix border. When comparing our results with other studies, it seems that the manner of classifying forest size significantly affects the results obtained. This may explain the differences in the results of many authors studying this phenomenon.
The results of previous studies have shown high breeding values of Beskidian spruce. The aim of the study was to assess the genetic structure of seventeen Norway spruce provenances from the Beskidy Mts. tested in IPTNSIUFRO 1964/68 experiment in Krynica, which survived after massive wind damage on the plots. Polymorphism of five isozyme systems encoded in five loci was determined. The highest value of genetic diversity parameters: mean number of alleles per locus and observed heterozygosity was noted for progeny of spruce from the Eastern Beskidy Mts. (Na = 1.47, Ho = 0.15), and the lowest – for the provenance from the Western Beskidy Mts., Babia Góra massif and the Beskid Sądecki Mts. (Na = 1.27, Ho = 0.12). Mean genetic distance between analyzed spruce provenances was equal to 0.027.
Обосновано использование разработанной авторами программы для расчетов полученных данных определения удельной теплоты сгорания для твердого и жидкого топлива при калориметрических исследованиях. Усовершенствованная форма отчета эксперимента позволяет облегчить анализ хода расчетов данных.
The objective of the study was to elucidate correlations between meadow plant species, the content of some biogenic elements in groundwater, sward harvesting frequency and the level of the groundwater table at the beginning and at the end of a growing season. An adequate choice of species grown in organic soil may be of particular significance for nutrient management and prevention of water eutrophication due to biogenic elements. A lysimeter experiment was conducted on peat-muck soil. The chemical composition of groundwater sampled underneath the rhizosphere of P. pratensis, Ph. pratense and L. perenne was assessed in several years. Two fixed levels of the groundwater table were maintained in the lysimeters: 50 and 90 cm below the ground surface. Grass was harvested three or five times during a growing season. The content of nitrate-nitrogen and ammonium-nitrogen, phosphorus, potassium, calcium, sodium and magnesium was determined in the analysed groundwater. The results showed significant variation in the mean (over the research period) content of selected mineral components (except for phosphate ions) in the piezometer water collected under the rhizosphere of specific grass species. The species L. perenne absorbed mineral components most effectively. The highest concentration of the majority of the components studied was found in water beneath the rhizosphere of P. pratensis. Significantly higher concentrations of calcium, magnesium, sodium, phosphorus, nitrate-nitrogen (but not ammonium-nitrogen) and potassium were found in water in the springtime. The biogenic element content found in objects with a three-cut harvesting regime was lower than in waters underneath grasses harvested five times. Regardless of the species and harvesting frequency, a significantly higher content of specific cations and anions in piezometer water was found in objects with a lower level of the groundwater table.
I show that a Natterer's bat (Myotis nattereri) was operantly conditioned to echo cues from a large object; in this case a round bowl full of mealworms. In a subsequent choice experiment the bat preferred the empty, round bowl over an unknown, quadratic bowl filled with prey. I suggest that the quick but transient learning of cues indicating prey rich habitat patches might be adaptive for bats hunting in cluttered environments, where they can often not directly detect prey using echolocation. Therefore, it might be an additional foraging strategy of some gleaning bats to search for specific structural cues indicating a high probability of prey being present.
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