Vegetation in the river Danube was studied in 1972–2001 to document the changes associated with the construction of a water reservoir. Before 1993, only a single species of aquatic plant, Potamogeton pectinatus, was known to occur in the main channel of the river Danube, which forms the frontier between Slovakia and Hungary. In the 1980s the building of the Gabčíkovo hydroelectric power station started and was finished in 1993. At present, five different aquatic habitats occur in the study area. (i) In the upper part of the Čunovo reservoir, there are stands of reed; Zannichellia palustris and Elodea nuttallii were the first other macrophytes to colonize this area where there are now 11 species. (ii) The Old Danube consists of shallows and margins of the original riverbed, which since 1992 (1851–1811 river km) were occupied predominantly by Zannichellia palustris. The adjacent pools were colonized by Elodea nuttallii, Potamogeton species, Batrachium trichophyllum, Ceratophyllum demersum and Lemnaceae species, and Phalaris arundinacea dominates the littoral areas. (ii) The bypass canal harbours only the moss Cinclidotus riparius growing on the boulders. (iv) Two seepage canals were rapidly overgrown by macrophytes, many species of which were threatened species in Slovakia (Apium repens, Groenlandia densa, Hippuris vulgaris, Chara species). (v) Succession occurred in river arms on the left bank after the damming of the river which resulted in changes in spatial distribution and species composition of macrophytes; a North- American alien species Elodea nuttallii spread rapidly there.
Variability in vegetation, participation of target and non-target species and the role of the local species pool in the spontaneous succession on acidic bedrock were studied in quarries. The study was conducted in the Českomoravská vrchovina uplands (central Czech Republic). A total of 135 relevés, 5 × 5min size, were used to sample 41 quarries that were abandoned from 1 to 92 years ago. Three types of sites were distinguished: mesic, wet and periodically flooded. Species cover (seven point Braun-Blanquet scale) was visually estimated. The following characteristics were noted: steep rocky slopes, bottoms and levels, dumps and screes as habitat types; age; proportion of the main land-cover categories (arable land, ruderal and urban, grassland,woodland and wetland) in the surroundings up to 100 m and 1 km from each quarry; and the occurrence of target (grassland, woodland, wetland) and non-target (ruderal, alien) species up to 100 m from each quarry. Ordination indicates that the spontaneous succession of vegetation results in the formation of mixed woodland, Alnus and Salix carrs, or tall sedge and Typha beds with scattered Salix, depending on the wetness of a site, surrounding vegetation and land cover. Restoration of target vegetation in the quarries by spontaneous succession is possible and can occur within about 25 years, especially if the target species are present close by.
We reviewed 37 studies on vegetation succession in which the succession started on bare ground, was followed in at least six sites, and where these sites were spatially separated over at least 10 km2. The effect of environmental factors, which were explored in at least five studies, on the course of succession was assessed, based on the proportion of significant and non-significant results. Surrounding vegetation, macroclimate, soil moisture, amount of nitrogen and soil texture appeared to have the highest influence on the course of succession. Less influential were the size of a disturbed site, pH, organic matter and phosphorus content. Surrounding vegetation exhibited a significant effect in all cases where this was considered. These results imply that succession cannot be studied without the landscape context. The large-scale approach to succession has the potential to contribute substantially to both the theory of succession and practical applications, especially in restoration ecology.