Habitat affinities of the red-listed and EU Habitat Directive moss species Hamatocaulis vernicosus and the more widely distributed allied species Scorpidium cossonii and Warnstorfia exannulata were analysed. Ecological preferences of these fen mosses, with respect to water pH, water conductivity, Ellenberg’s moisture and nutrient indicator values, were compared in three different European locations (Bohemian Massif, the West Carpathians and Bulgaria) using logistic regressions fitted by means of Huisman-Olff-Fresco models. Inter-specific co-occurrences of the species were also investigated. Warnstorfia exannulata preferred slightly acid conditions, about pH 5.6 at all the locations studied. Ecological behaviour of S. cossonii was very similar at all the locations, where it occupied base-rich habitats (pH > 7). The pH optimum of H. vernicosus, occupying habitats in the middle part of the base richness gradient, varied between locations from 6.0 in Bulgaria to 6.7–7.0 in the West Carpathians and Bohemian Massif. Niche diversification followed the gradient in Ellenberg nutrient indicator values and was similar at all the locations. In the Bohemian Massif and Bulgaria, the occurrence of W. exannulata was further associated with a relatively high moisture indicated by the Ellenberg indicator value. The results obtained from the Huisman-Olff-Fresco models accord with the results of inter-specific co-occurrences. Moreover, the latter method revealed a link between H. vernicosus and the occurrence of disjunctly occurring boreal sedges, suggesting the relic nature of H. vernicosus habitats at these locations.
The composition of the vegetation of fishpond mires in the Třeboň Basin (Czech Republic) was studied in relation to temporal fluctuations in certain environmental factors. The water-table depth, water pH and electrical conductivity at 49 permanent plots were measured at approximately threeweek intervals from March to October 2003. Minimum, maximum, mean, median and variation in the above-mentioned environmental factors were correlated with vegetation composition. The most important environmental factors explaining the variation in vegetation were mean pH and maximum water-table level. Median conductivity increased with increase in waterlogging and eutrophication. Some seasonal trends in the dynamics of these parameters were observed. The lowest conductivity was in spring, increased continuously throughout summer and peaked in autumn. In contrast, water level decreased in summer, when evapotranspiration was greatest, and rose in autumn after heavy rainfall. The pH increased from March to June, then was stable and decreased at the end of summer. Seasonal trends were generally identical in all vegetation types. The fluctuations in the environmental factors were so considerable that they may influence the reliability of vegetation environmental analyses.