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1

Nematofauna of the shelterbelts in the agricultural landscape

Wasilewska L.

Polish Journal of Ecology

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2004

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Vol. 52, nr 2

99-113

EN

Trophic structure, number and density of taxa, generic diversity, and maturity indices were compared for soil nematode communities inhabiting a 170-year-old shelterbelt, 6-year-old shelterbelt, and a maize field adjacent to the younger shelterbelt. The study was conducted in an area of long-term research near Turew (Wielkopolska Region, West Poland). Sampling sites in the crop field were located at distances of 0.5 m, 10 m and 50 m from the younger shelterbelt. In the soil of shelterbelts more taxa occurred in comparison with the cropland, the index of generic diversity was higher, the dominance of nematodes of the class Secernentea (r-strategists s.l.) over Adenophorea (K-strategists s.l.) was lower, community maturity indices and bacterivore maturityindex were higher, and the ratio of plant parasite index to maturity index was lower, providing evidence for a more advanced stage of succession in the shelterbelts. In the maize field, fungivorous and plant feeding nematodes predominated, with a strong dominance of one of the taxa pathogenic to plants (Pratylenchus). The effect of 6-year old shelterbelt on nematode community in maize crop field was observed in the field part closes to the shelterbelt.

2

Post-drainage secondary succession of soil nematodes on fen peat meadows in Biebrza Wetlands, Poland

Wasilewska L.

Polish Journal of Ecology

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2002

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Vol. 50, nr 3

269-300

EN

After the drainage of fens and their permanent use as meadows, peat-forming process is being replaced by moorshing (mucking) process (mineralization and humification of peat), and then by turf-forming process. Secondary succession of soil nematodes was examined by using the chronosequence of meadow sites (period I: 1978-1983) and also by analysing the same sites 15-17 years later (period II: 1994-1997). The analysis was focused on the taxa (genera) of nematodes and on 19 to 29 parameters describing the community as total density, density of trophic groups, diversity indices and maturity indices. The pattern of successional changes was obtained for periods from 2 to 117 years after drainage. Natural not-drained fens were used for comparison. Soil structure and soil processes occuring over the time considered can be characterized as follows: soil moisture (by weight) 80-52% total soil porosity 90-77%, bulk density 0.16-0.44 (to 0.92) g cm^-3, total C content in soil 47-7% total N content in soil 4.4-0.5%, ranges in the sequence from Mt I (poorly moorshified soils) to Mt III (strongly moorshified soils). In natural fens, soil moisture was 80%, soil porosity 90%, bulk density 0.15-0.35 g cm^-3, and peat-forming processes (Pt) were continued. As compared with natural fens, drainage and management of fens was associated with increasing density of total nematodes and their components such as bacterivores, fungivores, facultative plant feeders, obligate plant feeders, omnivores, and predators. In drained fens the density of nematodes declined with succession with the exception of omnivores. The increase in the density of omnivores was positively correlated with the number of years after drainage (r=0.48, P<0.01). The indices of taxa diversity and maturity indices were postively correlated with years after drainage (P<0.001-0.05). In natural fens, ranges of density of all trophic groups were lower, and maturity indices higher than in drained peat meadows. The The mechanisms driving the first stage of succession in nematode communities (until about 30 years after the drainage of fens) seem to be tolerance to the droughts and to the excess of nitrogen what was accompanied with higher density of herbivores (mainly Paratylenchus). In later stages, interspecific competition is likely to play a more important role. Also a statistically significant relation was found of some taxa and parameters to peat type.

3

The effect of macroarthropods patrolling soil surface on soil nematodes : a field experiment in a mown meadow

Wasilewska L.

Polish Journal of Ecology

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2000

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Vol. 48, nr 4

327-338

EN

A field experiment was designed to estimate the effect of soil surface patrolling by macroarthropods on organic matter content in soil. One of the components of this experiment was the soil nematode community - density, trophic and dominance strukture, the diversity and maturity indices. These parameters were compared between two types of mesocosms: accessible and inaccessible to macroarthropods. The experiment was performed under natural environmental conditions and did not reduce the diversity of the biota characteristic of the ecosystem. Most parameters of nematodes did not vary significantly between mesocosms. Differences between mesocosms observed over the 5-month period of each of the two experiments (1992 and 1993) concerned mainly, bacterivorous nematodes and, within this trophic group, colonizers. The densities of the taxon Rhabditis s.l. were statistically higher in the mesocosms accessible to macroarthropods, and the proportion of colonizers (r-strategists s.l.) among bacterivorous nematodes was also higher.

4

Effect of macroarthropods on microbial and faunal numbers and organic matter content in soil

Kajak A., Kusińska A., Stanuszek S., Stefaniak O., Szanser M., Wasylik A., Wasilewska L.

Polish Journal of Ecology

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2000

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Vol. 48, nr 4

339-354

EN

A field exclusion experiment in Arrhenatherrethalia mown meadow was carried out in mesocosms to analyse the role of epigeic, mobile macroarthropods in decomposition processes. A mineral bag technique allowed assessment of annual organic matter accumulation in the sandy substrate of mesocosms. Higher total organic C content was recorded in the top substrate layer (0-3 cm) in mesocosms accessible for macroarthropods, than in closed, inaccessible ones (17 and 23% more, respectively, in the two years), as well as higher amount of C in humus acids (6 and 36% more in two years). Possible reasons for these differences were considered. The total plant biomass, the litter disappearenc3 rate and water content in litter did not differ significantly between the types of mesocosms. In the top layer of mesocosms accessible for macroarthropods higher content of comminuted plant material (38,9 g m^-2) and arthropods feces (12.3 g^-2) were found compared to the amount in closed mesocosms (17,1 and 2,1 g m^-2 respectively). But the particulate organic matter derived from comminuted plant remnants and from fecal pellets accounted, in the period of the highest content, for about a half of the total carbon accumulated in the top substrate layer. In the litter of the open mesocosms reduced number of fungivorous mites and aphids was found, coupled with higher density of bacterivorous nematodes and higher abundance of fungi. The density of fungivorous mites was negatively correlated with the intensity of area patrolling by Araneae (tau = -0.79, P=0,0028) and Staphylinidae (tau = -0.58, P = 0.03). The elimination of aphids was positively correlated with area patrolling by the last group (tau = 0.81, P = 0.005). These results suggest that predation by macroarthropods changed proportions between fungi- and bacteriovorous invertebrates and as a consequence proportions between fungi and bacteria.

5

Soil nematode response to root production in grasslands on fen peat soils

Wasilewska L.

Polish Journal of Ecology

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1999

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Vol. 47, no 3

231-246

EN

The density of soil nematodes was examined was relation to root production in peat grasslands that differed in the origin of peat and, consequently, in moisture and in physical and chemical soil properties. Root production was estimated by using the root ingrowth technique, and expressed in g dry wt m^-2, over the period April-October. Total nematodes, bacterivores, fungivores, and facultative plant feeders were not correlated with root production. Obligate plant feeders and the number of taxa forming this group were negatively correlated with root production. The ratio of numbers of bacterivorous + fungivorous to obligate plant feeding nematodes was highly positively correlated with root production. Based on earlier publications, the author argues that the specific character of drained peat soils, that is, intensifield N and C mineralization, obstructs full understanding of the relationship between root production and nematode abundance, especially in the case of nematodes from the detritus food web.