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The structure of Enchytraeidae communities of Leucobryo-Pinetum and Peucedano-Pinetum pine forests was analysed. One community-type was registered. Differences in species composition and dominance structure related to regional phytosociological diversity and limiting influence of anthropogenous pressure on community density were observed.
Analysing possibilities of indicating threats of earthworms for protection demands, it was shown that at the current stage of faunistical work it is not possible to choose the most threatened species in the Polish fauna, which could qualify to one of the threat of the European categories. In the case of this group of animals it is not possible basing, on current knowledge, to determine the category of threat. Although, it is assumed that there are four endemic species (e.g. connected with Carpathian Mts) in this group. The criteria stated in the Polish Red Data Book do not apply to oligochaete. Nearly none of the species can be characterized with demanded precision for chosen criteria, because the lack of quantity and quality data. It is only possible to distinguish „groups of non-determined species”, which are treated as „rare species”, but the lack of enough data does not allow to determine to which group they really belong. The determining of factors affecting the habitation of particular species belongs to a group of the least known subjects. A group of factor affecting one particular earthworm species was not considered yet.
The structure of Enchytraeidae communities inhabiting the soil in pine forest stands of various ages situated in Puszcza Białowieska has been analysed. The greatest transformations in Enchytraeidae communities have been observed in younger stands. Older stages of the sere are characterized by stabilization of the communities, which is associated with the establishment of specific soil conditions resulting from humus formation.
An experiment was conducted in plastic pots filled with loamy sand and inserted into the soil. Half of the pots were sown with one species, orchard grass, and half with a mixture of six grass species. Every year at the end of May, half of the pots in each variant was enriched with 300 g DM of earthworm casts per pot. To estimate the abundance of Enchytraeidae, Acarina and Collembola, soil samples were taken three times per season. The abundance of enchytraeids was significantly higher in the orchard grass monoculture and in pots enriched with earthworm casts, especially at high population densities. No unequivocal effect of vegetation and earthworm casts on the Acarina and Collembola density was observed.
The paper describes a field experiment with the application of two biocides: oxytetracycline that reduced bacteria and captan that reduced soil fungi. The purpose of the experiment was to investigate the response of enchytraeid species to the changes of the abundance and activity of the microbial community as part of their food resources. The following variables were recorded: the biomass of microorganisms by the PLFA method, the rate of cellulose decomposition and the numbers and species composition of enchytraeids. No relationship was found between enchytraeids and abundance of microorganisms, but numbers of animals were correlated with changes in soil cellulolytic activity. Both biocides, even the non toxic oxytetracycline, reduced the diversity (H’) of enchytraeid community by increasing the proportion of dominant species. It is suggested that biocides reduced the functional diversity of microorganisms, and this factor had an effect on the enchytraeid populations. The animals responded to the treatment and their community became predominated by the species probably with a broad food spectrum.
24 potworm specles have been found in the forest habitats studied in Puszcza Kampinoska. Species diversitv of Enchytraeidae decreases' with deteriorating trophic and moisture conditions. Potworm communities in alder swamps and mixed forests have a characteristic species cornposition and structure. Linden-oak-hornbeam forests with a variety of habitats present accomrnodate a number ofdistinct potworm communities.
The objective of this paper was to recognize the influence of forest strips planted (as the shelterbelts) in agricultural area, on adjoining cereal fields basing on the distribution and composition of enchytraeid community. Species composition, density and individual size of enchytraeids were estimated in October and April 2003–2005 along two transects: 6 and 11 years old shelterbelts > ecotones > fields (at a distance of 15 and 50 m. from the wood strip) and in two reference sites: large (about 100 ha) forest stand and the field (“control” field) located in deforested area. The results have been compared with the published results of the previous studies made in the same area four years before (1999–2000). Samples were collected with soil corer 10 cm2 in area and 15 cm deep. Ten samples in each site were taken twice a year. Sixteen species were found in total. The range of density and biomass of enchytraeids for all study sites accounted for 1.6 to 15.3 ind.m⁻² and 55 to 956 mg f.wt. m⁻² (i.e.15– 308 mg d.w.) respectively. The lowest density was obserwed in the control field located in the deforested area. However, density and biomass of enchytraeids in the fields accounted for 67% and 47% respectively of those in shelterbelts. Species composition of enchytraeids in the young (2–11 yrs old) forest strips and in the adjacent fields was similar, however different from those in the forest stand and in old (150 yrs) shelterbelt. The response of enchytraeids to grass litter introduced on the soil surface was assessed in the experiment performed in a control field and in the transect of wood strip > field. The 7–10 portions of dried grass Dactylis glomerata (L.), (10 g each) were exposed in each plot for 12 and 18 months. More animals was found in the upper soil layer taken below the exposed litter as well as the density of all enchytraeids and percent share of the dominant genus Enchytraeus increased in the soil after 18 months of litter exposure.
Changes in densities of microorganisms were analysed in Cognetia sphagnetorum Vejd. cultures at normal and low numbers of microorganisms. Different abundance of microorganisms was achieved by using captan and oxytetracycline. During 14 weeks, the following variables were measured: total numbers of bacteria and fungi by plate method, the biomass of microorganisms by PLFA method, content of ions, and activity of acid and alkaline phosphatase and urease. Numbers of enchytraeids increased with numbers of fungi. The presence of animals reduced the activity of soil enzymes and the content of Cl, SO₄, Na, Ca, and Mg ions in soil leacheates. An increase in the content of N-NO₃ and N-NH₄ was not significant.
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