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- Author or Editor: B. Tóthmérész x
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Ground beetles were studied among grassland — forest edge — beech forest habitats in Hungary, using pitfall traps. We hypothesised that the activity density and species richness of carabids were the highest in the forest edge, the activity density and the number of forest species were decreasing, while the activity density and the number of generalist species increasing from the forest towards the grassland. Carabid assemblage of the grassland was the most diverse and the forest was the least diverse if measured by Rényi diversity. The average species richness per trap was significantly higher in the grassland and in the edge than in the forest. The number of forest species was significantly higher in the edge than elsewhere. The number of generalist species was highest in the grassland and decreased towards the forest. The activity density of carabids was significantly higher in the forest and in the forest edge than in the grassland. The activity density of forest species was higher in the forest and in the edge than in the grassland. The activity density of the generalist species was higher in the grassland than in the forest edge and in the forest. There were seven species characteristic to the grassland as identified by IndVal; two species were characteristic to the edge, and two species were characteristic both to the forest and the edge. We found that humidity was the highest in the forest; Pterostichus oblongopunctatus and Molops piceus were associated with the forest habitat, while Abax ater and Pterostichus melanarius were associated with the forest edge according to the RDA. The the shrub cover was the most relevant factor in the edge; Abax ater and Pterostichus melanarius were associated with this habitat.
We tested the relationship between water chemical variables and macrophyte vegetation in an oxbow-lake of the Upper-Tisza, Hungary. There were 42 relevés in random plots of 2 m by 2 m and 20 chemical variables (Ca, Fe, Hydrogencarbonate, K, carbonate, Kjeldahl-nitrogen, chloride, COD(Cr), Mg, m-alkalinity, Mn, Na, NH4, NO2, NO3, dissolved orthophosphate-P, total phosphorus, pH, sulphate and conductivity) and a biological one (chlorophyll a) were measured. Detrended canonical correspondence analysis was used to explore the species-vegetation-water chemical variables relationship. Our results revealed that there were pronounced differences both in the vegetation and the chemical variables among the different kinds of vegetation patches. According to the DCCA, Trapetum natantis, Glycerietum maximae, Ceratophyllo-Nymphaeetum albae and Typhetum angustifoliae associations could be separated based on the relevés and environmental variables. Kjeldahl nitrogen and carbonate were found to be the most important variables. Our results suggest that water chemical variables had strong influence on vegetation development. The groups of relevés identified by the DCCA were coherent with classical phytosociological categories.
Several managed native forest stands have been reforested with conifer trees in Europe during recent centuries. These habitat alterations have influenced ground-dwelling invertebrates. We studied carabid beetle assemblages from a native beech forest (70-y-old), and a recently established (5-y-old), a young (15-y-old), a middle-aged (30-y-old) and a mature (50-y-old) Norway spruce plantation by pitfall trapping to explore the effect of reforestation on carabid beetles. The total number of carabid species, and the forest species were highest in the beech forest. The number of open-habitat species was highest in the youngest, relatively open monoculture. Ordination also confirmed changes in carabid composition with change in the studied habitats. Newly proposed forest affinity indices, based on species specificity, fidelity, and on a combination of specificity and fidelity were significantly higher in beech forest than in spruce plantations. We found these affinity indices especially useful in revealing the ecological character of the studied carabid assemblages. Regression analyses showed that leaf litter cover, herbs, shrubs, canopy closure and prey abundance were related to the structure of carabid-beetle assemblages.
The abundance of terrestrial isopods (Isopoda: Oniscidea) was evaluated along an urban-suburban-rural gradient. We tested two hypotheses regarding the response of species: (i) habitat specialist hypothesis, according to which the abundance of the forest specialists would increase, while the abundance of the urban environment specialist isopods would decrease along the urban-rural gradient, and (ii) opportunistic species hypothesis (abundance of the generalist species would increase by increasing level of urbanization). The abundance of the forest specialist isopod Trachelipus ratzeburgii increased significantly along the studied gradient. An opposite tendency was observed for the abundance of the urban environment specialist isopod Porcellio scaber , as it was significantly higher in the urban area than in the suburban and rural sites. One generalist species ( Trachelipus rathkii) gained dominance in the urban area, while other two generalists ( Armadillidium vulgare and Porcellium collicola ) showed no significant changes in abundance along the gradient.
Intensification of land use in the last few decades resulted in an increased rate of fragmentation of natural forest habitats. With decreased patch size but increased total borderline length the influence of the surroundings also increased. The extent of influence is especially crucial where the forest stands are adjacent to agricultural lands. We studied the vegetation (cover) and seed bank (soil samples, seedling emergence) along adjacent stands of an abandoned vineyard and edge and interior of an oak forest community (Quercetum petraeae-cerris) widespread in Central-Europe, using five transects (16 m2 plots along each transect). We asked the following questions: (i) How do vegetation and seed bank composition differ between the vineyard and forest interior and (ii) which weeds are able to penetrate into the forest herbaceous understorey vegetation and seed banks from the vineyard? In total, 15 phanaerophytes and 147 herbs were detected. Negatively associated with canopy shading, herb cover proved the lowest in the forest inferior. Few weeds and other ruderals recorded in vineyard penetrated into the forest interior. Mean seed density decreased one order of magnitude from the vineyard to the forest interior (from 20,831 to 2,159 seed/m2). The seed banks of the abandoned vineyard and edge and forest interior were dominated by ruderals, but decreasing proportion of weeds was detected from the vineyard to the forest interior. Characteristic forest herbs possessed at most sparse seed banks. Our results suggest that high canopy cover mitigates the negative impact of surrounding weedy vegetation on the forest herb layer. Therefore, the effect of surroundings is detectable mostly in the seed banks. We can assume that the formation of an increased ruderal herb cover can be foreseen if canopy opens, because the local propagule sources of forest species are missing from vegetation and soil seed banks.
We studied the early vegetation dynamics in former croplands (sunflower and cereal fields) sown with a low-diversity seed mixture (composed of 2 native grass species) in Egyek-Pusztakócs, Hortobágy National Park, East-Hungary. The percentage cover of vascular plants was recorded in 4 permanent plots per field on 7 restored fields between 2006 and 2009. Ten aboveground biomass samples per field were also collected in June in each year. We addressed two questions: (i) How do seed sowing and annual mowing affect the species richness, biomass and cover of weeds? (ii) How fast does the cover of sown grasses develop after seed sowing? Weedy species were characteristic in the first year after sowing. In the second and third year their cover and species richness decreased. From the second year onwards the cover of perennial grasses increased. Spontaneously immigrating species characteristic to the reference grasslands were also detected with low cover scores. Short-lived weeds were suppressed as their cover and biomass significantly decreased during the study. The amount of litter and sown grass biomass increased progressively. However, perennial weed cover, especially the cover of Cirsium arvense increased substantially. Our results suggest that grassland vegetation can be recovered by sowing low diversity mixtures followed up by yearly mowing. Suppression of perennial weed cover needs more frequent mowing (multiple times a year) or grazing.
Urban areas have been growing radically worldwide, causing considerable changes in biodiversity of natural habitats. In floodplain forests, we studied the effects of urbanization on ground-dwelling spider assemblages along a rural–suburban–urban gradient in Hungary. We tested three traditional hypotheses (intermediate disturbance hypothesis, habitat specialist hypothesis and hygrophilous species hypothesis) and two novel expectations (shade-preferring species hypothesis, and disturbance sensitive species hypothesis) on spiders. We found that the total number of species was higher in the suburban habitat than in rural and urban ones, supporting the intermediate disturbance hypothesis. We found a decrease in the species richness of forest specialist and shade-preferring species along the urbanization gradient. We found that the number of hygrophilous and disturbance sensitive species was the lowest in the urban habitat. The spider assemblages of the rural and suburban habitats were clearly separated from the assemblages of urban habitats. Based on our findings we emphasize that low and moderate intensity of forest management contributes to the preservation of the local species richness in floodplain forests.
The contamination level of oxbows depends on both natural and anthropogenic effects. The aim of our study was to identify those abiotic and biotic factors that determine the contamination level of oxbows. The effect of anthropogenic activities, seasonality, and vegetation types was studied on the contamination level of surface water of oxbows. The following chemical variables were measured: suspended solid, ammonium, nitrate, chlorophyll-a, Al, Ba, Fe, Mn, Pb, Sr and Zn from eight oxbows from 2013 summer to 2014 autumn in the Upper Tisza region in Eastern Hungary. Three of the studied oxbows were protected, four oxbows were used for fishing and one oxbow was contaminated with wastewater. Our findings revealed that anthropogenic activities had remarkable effect on the contamination level of oxbows. Seasonality also influenced the contamination level, except the concentration of suspended solid, chlorophyll-a and manganese. Significant differences were found among vegetation types for the concentration of suspended solids, aluminium, iron, manganese and lead. The high level of iron concentration was not explained by the anthropogenic activities, suggesting that the quality of oxbows depends on both natural and anthropogenic effects.
We studied the potential role of seed bank in the dynamics of the understorey in a turkey oak-sessile oak forest (Querceteum petraeae-cerris) in Hungary. We used long-term records of the herb layer (1973–2006) and the seed bank composition of 2006 to assess the role of seed bank in the regeneration of herb layer. The total cover of herb layer decreased from 22% (1973) to 6% (1988), and remained low (<10%) till 2006; coinciding with the increasing cover of secondary canopy dominated by Acer campestre. We found a low density seed bank (ca. 1300 seeds/m2). Altogether 33 species were germinated from the soil samples. A few generalist weed species composed the majority of seed bank. It was possible to assign a seed bank type for 19 species; 14 species out of 19 was long-term persistent. We found that the characteristic perennial forest herbs and grasses had only sparse seed bank. The Jaccard similarity between vegetation and seed bank was low (<30%). Our results suggest that the continuous establishment of forest herbs are not based on local persistent seed bank; it should be based on vegetative spreading and/or seed rain.
Phosphatase enzymes are capable of releasing phosphate through cleavage of phosphoester bonds. The seasonal importance of this process was examined by using a model substrate paranitrophenylphosphate and the Michaelis-Menten equation to estimate the release rate of PO 4 -P from phosphomonoesters. The seasonal occurrence of phosphomonoesters and acid phosphatase activity was used to estimate the velocity of phosphate release from these compounds. Filter fractionation of phosphatase activity demonstrated that most activity (>60%) was in size fractions less than 0.45 μm. The release rates were highest in May and June (15 to 25 nmol L −1 min −1 ) during the Gonyostomum semen (Raphidophyta) bloom and decreased to less than 2 nmol L −1 min −1 in two weeks and remained low throughout the summer and the fall. Fractionation of 32 P-H 3 PO 4 labelled dissolved organic phosphorus showed this fraction to vary considerably through the year. Potential phosphate release declined through the summer and into the fall. Significance of the co-occurrence of phosphomonoesters and acid phosphatase activity maxima and Gonyostomum semen (Raphidophyta) bloom is discussed.