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Effect of vegetation and management on occurrence of larvae and adults of generalist Maniola jurtina L. (Lepidoptera) in meadow habitats

Kulfan J., Strbova E., Zach P.

Polish Journal of Ecology

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2012

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Vol. 60, nr 3

601-609

EN

Larvae and adults of some generalist insect species co-occur in identical habitats whereas adults and larvae of other generalist species do not co-occur and occupy different habitats. The Meadow brown, Maniola jurtina (L.) (Lepidoptera: Nymphalidae), is common and widely distributed in Europe where it is considered a habitat generalist. As knowledge about the occurrence of the larvae of the Meadow brown is scarce (different and more difficult methods are needed to collect larvae compared to adults) a complex assessment of the life strategy of this generalist is limited. We addressed here the question as to whether the adults and larvae of the Meadow brown co-occurred in the same habitats and how they depended on the type of grassland vegetation and habitat management. We expected co-occurrence of adults and larvae and similar effects of habitat management on them. We selected four habitat types belonging to the alliance Arrhenatherion elatioris W. Koch 1926, which form mosaic patterns in the rural landscape of central Slovakia: (1) extensive meadows mown once a year, (2) extensive meadows mown twice a year, (3) abandoned meadows, and (4) ecotones between deciduous forests and meadows mown once a year. Adults were counted in each habitat on seven transects 50 m long (in seven replicates) during the summer of 2003, 2004 and 2005. Larvae were collected in each habitat on 10 transects 50 m long (ten replicates) by sweeping vegetation (60 sweepings per transect) at night in May 2005 and 2006. Both adults and larvae occurred in all the mentioned types of habitats. A high abundance of adults and larvae was recorded in extensive meadows mown once a year and in ecotones. The lowest abundance of adults and larvae was found in abandoned meadows. The differences between abandoned meadows and ecotones (in the case of adults) and between abandoned meadows and extensive meadows mown once a year (in the case of larvae) were significant in all study years (P <0.05; multiple comparisons, K-W ANOVA). In the abandoned meadows the number of adults and larvae (median) was approximately 2 to 5 and 5 to 25 times lower than in the preferred habitats, respectively. Maximum numbers of both adults and larvae per single recording/sampling date were obtained in extensive meadows mown once a year; that is 185 adults in a transect 350 m long and 4 m wide and 267 larvae in the transect 500 m long (600 sweepings). Hence, similar to adults, larvae tend to be habitat generalists. Our results have confirmed the "advantageous" life strategy of M. jurtina which enables the species to adapt to a wide range of habitats, including those under strong pressure from humans. Comparing management practices in the study habitats, meadows which are mowed once a year were the most appropriate alternative for this species.

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Long-term changes in the phytoplankton of Lake Charzykowskie

Wiśniewska M., Luścińska M

Oceanological and Hydrobiological Studies

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2012

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Vol. 41, No. 3

90-98

EN

The research on phytoplankton communities in Lake Charzykowskie was carried out at intervals since the 1940s till the beginning of the 21 century. Long-term observations, initially of the species composition and in the following years also of the biomass and the concentration of chlorophyll-a in relation to habitat conditions, allowed to assess the impact of the catchment area on changes in the trophic status of the lake for over 50 years. And thus, based on the results of physicochemical analysis and studies on the phytoplankton structure in the 1940s, the lake was classified as ß-mesotrophic (Cabejszek 1950), between the 1960s and the1990s as eutrophic (Szulkowska-Wojaczek 1968, 1976; Wiśniewska 1994, 2000), in 2004 as hypertrophic (Wiśniewska 2005), and in 2008 and 2009 as meso-eutrophic.

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The life strategy and dynamics of selected species of phyto- and zooplankton in a dam reservoir during "wet" and "dry" years

Pociecha Agnieszka, Wilk-Woźniak Elżbieta

Polish Journal of Ecology

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2006

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Vol. 54, nr 1

29-38

EN

The investigation was carried out during "dry" and "wet" ( average: 478.6 mm and 624.7 mm respectively) years in the Dobczyce Reservoir, which is located in a foothills area of southern Poland. The Reservoir covers 985 ha, has a volume of 108 [x] 10^6 m^3, a mean depth of 11 m and an average flushing rate of 2.9 yr^-1. Statistical analysis (ANOVA) showed that "dry" and "wet" years differed markedly as regards hydrological variables (water flow and flushing ratio). Among the physico-chemical variables, it was the concentration of NH4-N that differed most in years of the different hydrological types. The main aim of the study was to check the life strategies and dynamics of selected species among the phyto- and zooplankton during the aforementioned "dry" and "wet" years. The assessment centered on changes in population densities for algal species of differing life strategies according to the Reynolds' classification, particularly S-species (Microcystis aeruginosa (Kutz.) Kutz., Woronichinia naegeliana (Unger) Elenkin., R-species (Asterionella formosa Hass, Cyclotella sp.) and C/S-species (Ceratium hirundinella O. F. Muller) Bergh, Cryptomonas sp.). C species like Chlorella, Rhodomonas and Stephanodiscus hantzschii Grun. (in Cl. & Grunow), which were present in only small numbers, were not taken into consideration. No algal species presented any statistical differences in average population density between the studied years. Factors correlated (Pearson correlation) with the density of algae were found to be: flow, flushing ratio, transparency, turbidity and NO3-N. Changes in the density of selected zooplankton species representing r-strategists (Bosmina longirostris (O. F. Muller, 1785), Brachionus angularis Gosse, 1851, Pompholyx sulcata Hudson, 1851) and K-strategists (Daphnia cucullata Sars,1862, Daphnia longispina O. F. Muller, 1785, Eudiaptomus gracilis (Sars,1863)) were also studied. The densities of Keratella cochlearis (Gosse, 1851) and Mesocyclops leuckart (Claus,1857) differed significantly between hydrological years. Physical environmental factors like flow, flushing ratio, transparency and turbidity were correlated with zooplankton density, as was shown by Pearson correlation coefficient. Our investigations did not confirm the hypothesis that R (phytoplankton) and r (zooplankton) species are favored by "wet" years, while species of types S (phytoplankton) and K (zooplankton) prefer the conditions present in .dry" years. Only the two zooplankton species characterized as different strategists (i.e. the r-selected Keratella cochlearis and K-selected Mesocyclops leuckarti) responded in significantly different ways to "wet" and "dry" years.

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A comparative study of the life strategies of two bacterial-feeding nematodes under laboratory conditions. 3, Influence on the initial nematode density on the interactions of Arobeloides nanus (de Man 1880) Anderson and Dolichorhabditis dolichura (Schnei

Ilieva-Makulec K.

Polish Journal of Ecology

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2001

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Vol. 49, nr 2

137-144

EN

Population development and interactions between two bacterial-feeding nematodes Acrobeloides nanus and Dolichorhabditis dolichura were studied in mixed cultures at different initial density of nematodes. Population dynamics of the two studied species differed significantly in both competition experiments, with the initial numerical advantage of A. nanus as well as with the initial numerical advantage of D. dolichura. In all experimental variants population peak of D. dolichura occured always earlier than that of A. nanus. Population dynamics of A. nanus and D. dolichura depended significantly on the initial density of the second species in the mixed cultures. The higher initial density of D. dolichura the less abundant populations of A. nanus were noticed. However, no consistent trend in the influence of the A. nanus initial density on the abundance of D. dolichura was found. Numerical advantage of D. dolichura never led to the extinction of A. nanus and in the opposite, numerical prevalence of A. nanus in two cases resulted in a complete elimination of D. dolichura. Population dynamics of A. nanus and D. dolichura in mixed cultures showed a distinct difference in the way of food utilisation by these two species. As food resources become scarce with time, D. dolichura density decreased but A. nanus density started to increase. It appears therefore that, under the present laboratory conditions, A. nanus was the better competitor. That species maintained a positive growth rate even at low food concentrations at which its competitor could no longer sustained.

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A comparative study of the life strategies of two bacterial-feeding nematodes under laboratory conditions. 1, Influence of culture conditions on selected life-history parameters of Acrobeloides nanus (de Man 1880) Anderson 1968 and Dolichorhabditis dolic

Ilieva-Makulec K.

Polish Journal of Ecology

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2001

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Vol. 49, nr 1

29-43

EN

Selected life-history parameters like age of maturity, fecundity, egg development time, pattern of growth and reproduction, longevity and intrinsic rate of natural increase (r) were compared for two bacterial-feeding nematode species in xenic (with a several bacterial species as food) and monoxenic (with a bacteria Sporosarcina sp. as a food organism) agar cultures at 20 stopni C. There were pronounced differences in the life-history patterns of the two species in both types of culture conditions. D. dilichura showed a higher growth and development rate than A. nanus. D. dolichura had a shorter pre-reproductive period, a shorter reproductive period but more intensive pattern of reproduction, a shorter total life span and a considerably greater r than A. nanus. The differences in life-history traits of the two nematode species were discussed with reference to their adaptive significance for habitat properties. While D. dolichura represents short-lived habitats with temporarily high food supply, A. nanus can be found in habitats of various food abundance.

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A comparative study of the life strategies of two bacterial-feeding nematodes under laboratory conditions. 2, Influence of the initial food level on the population dynamics of Acrobeloides nanus (de Man 1880) Anderson 1968 and Dolichorhabditis dolichura

Ilieva-Makulec K.

Polish Journal of Ecology

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2001

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Vol. 49, nr 2

123-135

EN

Population dynamics of two bacterial-feeding nematodes Acrobeloides nanus and Dolichorhabditis dolichura in relation to the initial food level was studied under laboratory conditions. Population density, age structure and selected productivity parameters of the two nematodes were compared in single and mixed species cultures. Initial food (bacteria Sporosarcina sp.) level significantly affected population dynamics of A. nanus and D. dolichura in the laboratory cultures. While A. nanus grew well at the three food levels, D. dolichura developed only at the highest initial density of food. There were significant differences in population dynamics of both studied species at the highest initial density of the bacterial food. In single species cultures population peak of D. dolichura occured earlier than that of A. nanus and maximal density of D. dolichura was significantly higher than maximal density of A. nanus. In mixed cultures population maximum was observed at the same time in both species and their peak densities were similar. Population maximum of A. nanus in mixed cultures was observed earlier than in its single cultures but the peak density of that species in single cultures was significantly higher than in mixed ones. Population peak of D. dolichura at the highest food level occurred at the same time irrespective of the type of culture, while peak abundance of that species in mixed cultures was almost 50% lower than in single cultures. The differences observed in population dynamics of the two nematode species were discussed with respect to the differences in the food supply of their natural habitats and the role they play in the processes of decomposition and mineralisation in soil.