Various stages in the succession of vegetation of peat bogs following disturbance were studied in the Třeboň Basin, Czech Republic. The disturbance was of two types: (a) natural, represented by windthrow, with subsequent bark beetle attack, and fire, and (b) human-made peat digging and industrial peat milling. The species composition at different stages in succession following disturbance were compared with that in undisturbed plots. Regeneration of peat bog vegetation was faster after a natural than after human-made disturbance. The lowest impact was caused by windthrow, followed by fire. Regeneration after peat digging took much longer. Regeneration after industrial peat harvesting only occurred if the groundwater table level remained high.
Článek představuje klíčové okamžiky evoluce suchozemských rostlin. Chce ukázat výsledky, které přinesl systematický výzkum nedávných let a které změnily naši představu o příbuznosti jednotlivých skupin cévnatých rostlin. Snaží se také vysvětlit a obhájit změny v zažitých skupinách a jménech., This article shows the evolution of land plants and presents the results of systematic research and changes in our understanding of phylogenetic relations. Changes in the group delimitation and in nomenclature are defended., and Milan Štech.
Nineteen isolated rocky outcrops of different sizes, tops of which were covered with natural grassland vegetation, were studied in the forested submontane belt (630–1020 m a.s.l.) of the Šumava Mts in the southern part of the Czech Republic, Central Europe. The species of vascular plants present in the treeless sites at each locality were identified. Those species with an Ellenberg indicator value for light equal 6 or higher were considered to be heliophilous. The distance to the nearest secondary treeless area was measured. There were 43 heliophilous species (23%) recorded among the 184 species identified. The number of species and the number of heliophilous species varied independently of the altitude and extent of the treeless area on the rocky outcrops, but were significantly correlated only with the distance to man-made treeless areas. The highest number of heliophilous species was recorded within approximately 400 m from the nearest man-made treeless area. Although the relict occurrence of some of the heliophilous species on the rocky outcrops cannot be completely excluded, obviously most of the species colonized these localities from nearby secondary treeless areas since their creation in the Middle Ages.
This study was conducted at 17 peatlands in the Czech Republic mined either by the traditional block-cut method or industrially. Phytosociological reléves of 5 × 5 m were carried out in representative parts of successional stages in disturbed peatlands. Age and environmental characteristics were assessed for each relevé (position of water table, water pH, substratum chemistry, geographical area) or each locality (altitude, average annual temperature and precipitation). Phytosociological reléves recorded in natural vegetation, representing the respective target stages, were included into some analyses. Altogether, 210 relevés were analysed by the DCA ordination. Separately, relevés from milled and block-cut sites were elaborated by CCA with marginal and partial effects calculated. Despite the great variability in vegetation, especially among industrially harvested sites, there is a general tendency for peatland vegetation to recover spontaneously, especially at traditionally harvested sites, which all were, however, older than 50 years. The vegetation at the younger industrially harvested sites exhibited only a tendency to recover. All environmental variables investigated had at least some significant effect on the vegetation pattern, among them, soil pH, water table, nitrates, successional age and geographical location were most important. Abiotic site factors together and geographical location appeared to be more important in determining species composition than successional age.
Urbanization is one of the most extreme forms of land transformation. It is supposed to change the frequencies of species trait states in species assemblages. We hypothesize that the flora of urban and rural areas differs in the frequency of trait states and ask which traits enable a plant to cope with the urban environment. We tested our hypothesis in Germany, which was divided into grid-cells of ca 130 km2. We distinguished urbanized (with more than 33% urban land use; n = 59), agricultural (with more than 50% agricultural land use; n = 1365) and semi-natural (with more than 50% forest and semi-natural land use; n = 312) grid-cells and calculated the proportions of plant species per trait state in each grid-cell. Multiple linear regressions explained the log-transformed ratio of one proportion to another with land use (urban, agricultural, semi-natural) and the environmental parameters (climate, topography, soils and geology). Additionally, linear mixed effect models accounted for the effects of land use and biogeography and differences in sample size of the three grid-cell types. Urbanized and rural areas showed clear differences in the proportion of trait states. Urbanized grid-cells had e.g., higher proportions of wind-pollinated plants, plants with scleromorphic leaves or plants dispersed by animals, and lower proportions of insect-pollinated plants, plants with hygromorphic leaves or plants dispersed by wind than other grid-cells. Our study shows that shifts in land use can change the trait state composition of plant assemblages. Far-reaching urbanization might consequently homogenize our flora with respect to trait state frequency.
Semi-dry grasslands in the White Carpathian (Bílé Karpaty) Mountains on the Czech-Slovak border are famous for their extremely high species richness. In places they contain more than 130 species of vascular plants per 100m2 and for some plot sizes they hold world records in the number of vascular plant species, but the reasons for this are poorly understood. Here we ask whether the high number of species in these grasslands can be explained by local ecological factors. We compared the White Carpathian grasslands with similar grasslands in adjacent areas in the west (southern Moravia) and the east (Inner Western Carpathians), which are on average notably poorer in species than those in the White Carpathians. In both of these areas, we sampled grasslands that were among the species richest in the regional context and had a similar physiognomy, species composition and ecology as those in the White Carpathians. We found 75 sites with >70 and >25 species of vascular plants per 100 m2 and 1 m2, respectively, in which we recorded species composition and local environmental conditions, including precipitation, soil depth, soil pH and nutrient concentrations, above-ground biomass production and nutrients in plant biomass. Although the White Carpathian grasslands were considerably richer in species than the richest grasslands in the adjacent regions, there were no differences in the values of the factors studied that could provide an unequivocal explanation of their high species richness. However, the values of the factors studied were within the ranges reported in the literature as conducive to high species richness in temperate grasslands. We conclude that the high species richness recorded in the White Carpathian grasslands cannot be explained by a single factor. It results from a unique combination of regional factors (long history of these grasslands, large size of individual grassland areas and their existence in a landscape mosaic with forests, scrub and small wetlands), local abiotic factors (soil pH, soil nutrient status, moisture regime and resulting grassland productivity that are suitable for many species from the regional species pool) and management (low fertilizer input and mowing once a year in late spring or summer).