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Spatial distribution of nematode fauna was studied in relation to horizontal heterogeneity of a natural tall-sedge fen in north-eastern Poland. Due to vegetation patchiness at scale of several tens centimetres two distinct habitats can be distinguished – “tussocks” and sites “between tussocks”. Nematode fauna in the soil “between tussocks” was different from that of the adjacent “tussocks” sites with respect to total abundance, generic composition and community trophic structure. On the two sampling dates (in spring and summer) significant more nematodes were found in the “tussocks” than “between tussocks”. Nematode communities were more diverse in the “tussocks” than “between the tussocks”, however the differences between two sites were significant only in spring. Each site had its own dominant genera different from the dominant genera of the adjacent site. Spatial pattern of nematodes was dynamic over time and seemed to be highly influenced by seasonal fluctuations of floods, which make the sites “between tussocks” available for nematodes only when floods recede.
Vertical distribution of nematodes down to a depth of 50 cm was studied in a peat, meadow soil in north-eastern part of Poland. The abundance and generic composition of nematode fauna in five soil layers (0-10, 10-20, 20-30, and 40-50 cm) were analysed. It was found that total numbers of nematodes and their generic diversity decreased with increasing soil depth. Out of all nematodes, 65% (in May) and 72% (in September) were found down to a depth of 20 cm. The proportion of nematodes in the deepest studied soil layer (40-50 cm) was the lowest, about 9% in spring samples and only 1.3% in autumn samples. Nematode fauna of the studied site was represented by 43 genera from 27 families. The most common genera in both sampling occasions were Acrobeloides, Aglenchus, Cephalobus, Filenchus, Helicotylenchus, Rotylenchus and Rhabdolaimus. Considerable differences in vertical distribution of some genera were also found. An attempt was made to use some soil characteristics of the studied site in interpretation of the results.
The response of soil nematodes to simulated in spring, summer and autumn periods of warming and drought were studied in a grassland mesocosm experiment. The abundance, diversity and some community parameters of nematodes were analysed at different times after the end of the extreme events – 170 days after the spring treatment, 90 days after the summer treatment and 22 days after the autumn treatment. Among studied parameters the abundance of nematode trophic groups, taxonomic richness and diversity were found to be sensitive to changes in the soil system caused by extremes. Our results showed that warming and drought did not cause predictable shifts in nematode communities. Moreover the extremes’ after-effect was not unidirectional with time. The periods of warming and drought induced a positive or negative long lasting influence on nematodes, and the outcome seems to depend on season, the nematode trophic group or even the nematode taxon.
Nematode colonization and establishment of nematode communities on icefree areas created by the recession of Antarctic glaciers were studied on the Antarctic Specially Protected Area (ASPA) No. 128 (Western coast of Admiralty Bay, King George Island, South Shetlands Islands). Soil samples were taken along three transects marked between sea shore and Ecology Glacier, Baranowski Glacier and Windy Glacier and assigned to four age-class intervals: 0-7, >7– 29, >29–52 and >52 years after the retreat of the glaciers. Changes in nematode communities, in terms of abundance, diversity and trophic structure were related to the duration of the ice-free period. The abundance of nematodes increased with the age of ice-free areas. The highest numbers of nematodes were found on the sites free of ice for more than 52 years. Taxonomic and trophic diversity of nematodes on these sites was also significantly higher in comparison to the rest sites. Nematode communities on the sites from the first three age-class intervals were poor in genera (up to 6 genera) while on the oldest sites in total 16 genera of nematodes were found. A trend of increasing the number of nematode trophic groups along the age classes was also apparent – from community of nematodes belonging to only two trophic groups (bacterial and fungal feeders) on younger ice-free sites to more complex community of nematodes (belonging to five trophic groups), at the oldest sites.
Agricultural practices in organic farming theoretically are supposed to lead to higher diversity and activity of soil organisms, which correlates with the stability or resilience of the soil system. In a 3-year study, we tested that hypothesis by comparing the nematode abundance, genera composition and community structure in the soil of winter wheat crop under organic and conventional management. We found the soil type to be a stronger predictor for the total nematodes abundance than the farming system itself. In both systems nematode densities were higher in the sandy than in the clayey soil. Total abundance of nematodes was significantly higher in the organic than conventional farm only in sandy soil and only in the autumn. Significantly more plant feeders was observed in organic than in the conventional crops regardless the soil type. In the clayey soil more bacterial feeders were found in the conventional farm, while in the sandy soil — in the organic one. Nematode generic richness was higher in the organic (a range of 15–35 genera) than in the conventional crops (a range of 15–29) on most sampling dates. Higher generic diversity (H') in the organic crop than in conventional was found for total nematodes in the clayey soil, and for hyphal feeders in sandy soil. H' for plant feeders were higher under organic than conventional system in both types of soil. In both farming systems bacterial feeding genera (Rhabditis, Panagrolaimus, Cephalobus and Acrobeloides) dominated in the communities. Plant feeders and omnivores were found among dominant genera only in the clayey soil, first under both systems, the latter only in the organic crops. The evaluation based on the ecological indices such as Maturity Index, Plant Parasite Index, Enrichment and Structure Index, and ratios between nematode trophic groups, showed that nematode communities under both farming systems most of the time were low matured and the soil food webs strongly disturbed.
Data on the density and the body mass of a single community of soil fauna were collected and metabolic rates were calculated from the literature data to test some predictions of the metabolic theory of ecology on the local scale. Part of the results are in accordance with the theory: power functions were found between the metabolic rate and the body mass, and between the density and the body mass. These two relationships have opposite exponents inducing that total population energy use is independent of the body mass. However, the exponents of the relationships were significantly different from the predicted values of |3/4|. The metabolic rate - body mass relationships yielded an exponent >0.8, while the density - body mass relationships yielded an exponent <-0.85. Our results indicate that the metabolic theory of ecology does not hold at the local level. Few studies have been carried out on the local scale and further analysis is required to validate this controversial but promising theory.
The list of species of the plant parasitic nematodes presented in this paper (133 species belonging to 14 families) is based on the results of faunistic research conducted in the Wielkopolska region by Polish nematologists up until the year 2010, and the results obtained from the project “Elaboration of Innovative Methods for Rapid Identification of Nematodes Causing Damage to the Economy” managed by the Museum and Institute of Zoology of the Polish Academy of Sciences. During the two years of the project (2010-2011) we found 21 species of nematodes which had not yet been reported in the list of species from the Wielkopolska region. Two of them were reported for the first time in Poland.
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