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Vegetation variability, the participation of target and undesirable species, and the role of local species pool were studied in the course of spontaneous succession in disused gravel-sand pits. The study was conducted in various regions of the Czech Republic, Central Europe. The regions represented either agrarian lowlands with a relatively warm and dry climate or mostly woodland uplands with a relatively cold and wet climate. The gravel-sand pits (36) comprised stages of different age from 1 to 75 years since abandonment. Altogether, 224 vegetation samples were recorded with species cover (%) visually estimated. Species affinity to different vegetation types was assessed in each sample based on the species cover. Local site factors, such as water table and soil characteristics, and landscape characteristics, namely climatic parameters, presence of nearby (semi)natural plant communities and main land cover categories in the broader surroundings, were evaluated as well as the participation of target (grassland, woodland, and wetland) and undesirable (ruderal, alien) species. Ordination analyses showed that vegetation succession led to target grassland, wetland, or woodland vegetation depending on local site factors, especially moisture and the presence of (semi)natural vegetation in the surroundings (local species pool). Restoration of target vegetation in disused gravel-sand pits by processes of spontaneous succession can be possible and successful in about 25 years, especially if (semi)natural vegetation exists in the surroundings. The invasion of the alien tree Robinia pseudacacia must be taken into consideration within the dry sites in lowlands.

Questions (1) How do seres differ with respect to vegetation changes? (2) What are the directions of succession? (3) How do species numbers change? (4) How do target species, i.e. those typical of natural and semi‐natural vegetation, participate in succession? (5) Are spontaneously developed successional stages acceptable from the point of view of ecosystem restoration? Location Extracted peatlands, bulldozed sites in forests destroyed by air pollution, an emerged bottom of a water reservoir, corridors of former Iron Curtain, artificial fishpond islands and barriers, sedimentary basins, spoil heaps from mining, stone quarries, forest clearings, road verges, sand and gravel‐sand pits, ruderal urban sites, river gravel bars and abandoned arable fields, located in various parts of the Czech Republic in Central Europe. Methods Phytosociological relevés were recorded in 10–25 m2 plots located in the centre of representative successional stages defined by their age, ranging from 1 to 100 yrs. In total, we obtained 2392 vegetation samples containing 951 species. We performed DCA ordination to compare 19 seres. Desirable target species were considered as those representing (semi)‐natural vegetation and all Red List species. Results The seres studied are more similar in their species composition in the initial and early stages, in which synathropic species prevail, than in the later stages when the vegetation differentiates. This divergence is driven mainly by local moisture conditions. In most cases, succession led to woodland, which usually established after ca. 20 yrs. In very dry or wet places (with limited presence of woody species) open vegetation developed, often highly valuable from the restoration and conservation point of view. The total number of species and the number of target species increased in the majority of seres with successional age. Conclusions The vegetation in the sites studied formed a continuum along a moisture gradient and by successional age. The individual seres largely overlapped in their species composition; the sere identity was not significant. Spontaneous succession usually proceeded towards woodland, except at very dry or wet sites, and generally appeared to be an ecologically suitable way of ecosystem restoration of disturbed sites because target species became dominant over time.

Questions: What is the variability of succession over a large geographical area? What is the relative importance of (1) local site factors and (2) landscape factors in determining spontaneous vegetation succession? Location: Various regions of the Czech Republic, Central Europe. The regions represent two categories characterized by agrarian lowlands, with a relatively warm and dry climate, and predominant woodland uplands with a relatively cold and wet climate. Methods: Gravel‐sand pits ranged in age from 1–75 years since abandonment. Three types of sites were distinguished: dry, wet and hydric in shallow flooded sites. Vegetation relevés were recorded with species cover (%) visually estimated using the space‐for‐time substitution approach. Local site factors, such as water table and soil characteristics, and landscape characteristics, namely climatic parameters, presence of nearby (semi‐) natural plant communities and main land cover categories in the wider surroundings, were evaluated. Results: Ordination analyses showed that water table was the most important local site factor influencing the course of spontaneous vegetation succession. Succession was further significantly influenced by soil texture, pH, macroclimate, the presence of some nearby (semi‐) natural communities and some land cover categories in the wider surroundings. Spontaneous vegetation succession led to the formation of either shrubby grassland, deciduous woodland, alder and willow carrs, and tall sedge or reed and Typha beds in later stages depending predominantly on the site moisture conditions. Conclusions: Although the water table was the most influential on the course of vegetation succession, the landscape factors together explained more vegetation variability (44%) than local site factors (23%).

Questions: Although the role of landscape context, often interpreted as the available species pool, is generally assumed to be important for the restoration of disturbed sites, not many studies evaluating this role quantitatively in restored dry grasslands have been carried out. There is especially a lack of large-scale, multi-site studies. We asked how many unsown target species established spontaneously in restored dry grasslands and how spontaneous establishment depended on their occurrence in the surrounding landscape.Location: White Carpathian Mts., eastern Czech Republic (48°50 0 -49°05 0 N,Methods: We studied spontaneous colonization by unsown target species in dry grasslands on ex-arable land at 82 sites, sown with a regional seed mixture, commercial clover-grass seed mixtures or left to spontaneous succession. In total, 246 phytosociological relev es in 5-m 9 5-m plots were recorded. Restoration started 1-31 yr ago. Nearby semi-natural grasslands were included as reference sites (94 phytosociological relev es). A total of 108 target species were defined and their presence evaluated in the surroundings of the restored grasslands, i.e., in grid cells (3.1 km 9 2.8 km) in which the restored sites were situated. Data were processed using multivariate analyses (DCA, CCA) and GLM.Results: The number of target species at the restored sites significantly increased with time elapsed since restoration started and the number of target species occurring in the surroundings. The sites, although restored in different ways, converged in their species composition towards ancient grasslands. The maximum relative colonization of a restored grassland by target species from the surroundings was 23.4%, and the restored grasslands contained max. Fifty-seven percent of the average number of dry grassland target species present in the ancient grasslands.Conclusions: Sowing seed mixtures should be seen as not more than a first phase in the restoration of species-rich grasslands. In a next phase of restoration, we can reasonably rely on gradual spontaneous colonization by target species if they occur in the surroundings, even at sites sown with commercial seed mixtures or restoring spontaneously. However, full restoration probably takes decades or more.

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We performed detrended correspondence analysis (DCA) ordination to compare seven successional seres running in stone quarries, coal mining spoil heaps, sand and gravel pits, and extracted peatlands in the Czech Republic in central Europe. In total, we obtained 1,187 vegetation samples containing 705 species. These represent various successional stages aged from 1 to 100 years. The successional seres studied were more similar in their species composition in the initial stages, in which synathropic species prevailed, than in later successional stages. This vegetation differentiation was determined especially by local moisture conditions. In most cases, succession led to a woodland, which usually established after approximately 20 years. In very dry or wet places, by contrast, where woody species were limited, often highly valuable, open vegetation developed. Except in the peatlands, the total number of species and the number of target species increased during succession. Participation of invasive aliens was mostly unimportant. Spontaneous vegetation succession generally appears to be an ecologically suitable and cheap way of ecosystem restoration of heavily disturbed sites. It should, therefore, be preferred over technical reclamation.

Questions: (1) Do 17 seres studied proceed towards corresponding potential natural vegetation;(2) what are the similarities between seral and potential natural vegetation, and is it possible to estimate how long it takes to reach potential natural vegetation; and (3) do primary and secondary seres differ?Location: Extracted peatlands, corridors of the former iron curtain, artificial fishpond islands and barriers, sedimentary basins, various spoil heaps after mining, various stone quarries, forest clearings, burned-down forests, road verges, sand and gravel-sand pits, river gravel bars and abandoned arable fields located in various parts of the Czech Republic.Methods: Seral stages were sampled by phytosociological relev es (2602). The following categories of successional age were considered: early (1-10 yrs), intermediate (11-25 yrs) and late (>25 yrs). Phytosociological relev es (386) representing corresponding potential natural vegetation were extracted from the National Phytosociological Database. DCA and CCA ordinations were performed to compare the pattern of seral stages with potential natural vegetation and between primary and secondary seres. Dissimilarity between seral stages of primary and secondary successions and the corresponding potential natural vegetation was further assessed using the Bray-Curtis dissimilarity measure. Extrapolation was performed to estimate when the seres will reach the stage corresponding to potential natural vegetation. Results:The ordination showed that successions proceeded towards the corresponding potential natural vegetation and reflected substrate pH, site moisture and successional age. The estimated average time needed to reach potential natural vegetation was about 180 yrs for primary successions and about 260 yrs for secondary successions, considering presence-absence species data, and 200 and 250 yrs, respectively, considering cover data. All species recorded in potential natural vegetation (421) were also recorded in seral vegetation. Conclusions:In the general view across the high number of seres spread over the whole country, successions advanced in the direction of the corresponding potential natural vegetation. The extrapolated recovery of potential natural vegetation is faster in primary seres than in secondary ones, and seres sooner resemble the corresponding potential natural vegetation in species composition than in vegetation structure.