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Adult individuals of Dendrobaena octaedra (Savigny 1826) were collected in three differently polluted mixed oak-pine forests (Pino-Quercetum): the most polluted near Olkusz, the moderately polluted Niepołomice Forest (both Southern Poland) and the relatively unpolluted Kampinoska Forest (Central Poland). In the laboratory established was culture of parent (P) generation was established and the laid cocoons were incubated to obtain F₁ generation. The culture was carried out till death of the last individual of F₁ generation (4 years). Every month individuals and cocoons were extracted from the soil, weighed and replaced into new soil. Individuals collected in the Olkusz forest had a higher cadmium concentration in their bodies (89.4±26.3 mg·kg⁻¹) than those from the Niepołomice Forest (16.7± 11.8 mg·kg⁻¹) and the Kampinoska Forest (8.7±4.0 mg·kg⁻¹). Individuals originating from the Olkusz forest (P generation) in the laboratory culture accumulated more cadmium than individuals from other populations. The above phenomenon was not found in their offspring ( F₁ generation). The present experiment clearly shows that cadmium in low doses decrease the reproduction (cocoon production, mass of produced cocoons, reproductive allocation) and survival (mean survival time, median survival time). Cadmium more negatively affeted reproduction and survival of animals cultured in laboratory and originating from unpolluted forest than those from heavily polluted forest. The observed higher heritable tolerance (higher reproduction, better survival) to cadmium in heavily polluted forest population seems to be the evidence of adaptation of D. octaedra to life in polluted environment.
Earthworm functioning and temperature regime are among the most important biotic and abiotic factors of soil environment; their combined action on soil nematode activities has not been studied. In a 4-month laboratory experiment, effects of the epigeic earthworm Dendrobaena octaedra on a succession of nematode community in litter of a mid-European birch/oak forest were tested in the gradient of an increase of diurnal temperature fluctuations from 0℃ (constant 15℃; T₁₅) to 10℃ (daily range between 10° and 20℃; T₁₀₋₂₀) and 20℃ (daily range between 5° and 25℃; T₅₋₂₅). Earthworm and temperature effects were measured as differences in nematode community respiration rates between the experimental treatments. Nematode respiration rates were calculated on the basis of body size/weight/O₂ consumption relationships for individual species. Nematode community was dominated by bacterial feeders and changed in a characteristic successional pattern which, however, was markedly modified by temperature regime and earthworm activities. Dominant nematode taxa revealed specific patterns of temporal dynamics in connection with their responses to temperature and earthworm presence. Thus, metabolic activity of Plectus acuminatus was strongly reduced by D. octaedra but did not react to variation of temperature regime. In contrast, activity of Panagrolaimus sp. significantly responded to temperature but not to earthworm presence, whereas Pl. thornei reacted to both factors separately and in combination. Ceratoplectus armatus was stronger affected by earthworm presence then by temperature; Tylocephalus auriculatus showed the opposite pattern. The variety of responses may explain the coexistence of several taxonomically related (Plectidae) and trophically similar species within the dominant group. Both earthworm presence and increase of the range of diurnal temperature fluctuations strongly affected the net of interspecific correlations within the nematode community. Earthworms strongly reduced total activities of nematode community at any temperature regime. T₁₅ regime showed markedly lower level of cumulative nematode respiration than both fluctuating regimes, irrespective of earthworm presence. In conclusion, combined effects of earthworms and temperature regime drastically changed patterns of relationships within the nematode litter community. The results of the experiments may have implications for the perspectives of global warming events at the study site: it is suggested that the ultimate vector of the changes in litter environment might be directed towards the conditions of the treatment [T₁₅ regime; earthworms present], with the corresponding trends in the development of the litter nematode community.
Species composition, density and biomass of Lumbricidae were studied in soils of a several years old midfield shelterbelt, an adjacent arable field (maize, wheat) and an ecotone situated between both ecosystems in two years (1999, 2000) in spring, summer and autumn. The lowest density and biomass of Lumbricidae was found in the field. The only species present there was Aporrectodea caliginosa: mean density 0.9 ind m⁻² and biomass 0.7 g m⁻². Three species were found in soils of the shelterbelt and the ecotone - A. caliginosa, Dendrobaena octaedra and Lumbricus terrestris. Two species dominated in biomass and density; L. terrestris occurred sporadically and its biomass and density were low. The average density and biomass in soils noted in 1999 were 58 ind m⁻² and 15 g m⁻², respective values for the ecotone were 73 ind m⁻² and 24 g m⁻². In the next year a nearly twofold increase of density (the shelterbelt - 144 ind m⁻², ecotone - 159 ind m⁻² was noted and similar increase of biomass in shelterbelt soils (31 g m⁻²). A. caliginosa, depending on site and time, contributed to 35-76% to the density and in 68-93% to the biomass of the community, D. octaedra - in 22-64% and 7-30%, respectively. Apart from biomass in the first study year, no significant differences between the shelterbelt and the ecotone were found in both density and biomass of the earthworm community.
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