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We report an exceptionally fast grassland recovery process from a karst plateau in SW Slovenia. Vegetation of old fields with different ages was sampled using a chronosequence of fields abandoned 1, 3, 6, 9, 13, 15 and 100 years ago. We prepared dendrogram dividing the data set into 9 clusters that were further analyzed: diagnostic species, ecological conditions and life forms were evaluated. The initial stage of succession was characterized by segetal weeds and indicated high levels of soil nutrients. The second stage was dominated by dense patches of perennial forbs (most of them ruderal species) preferring also high levels of soil nutrients. The third stage was dominated by caespitose hemicryptophyte grasses, many of them of sub-Mediterranean origin. The first two stages took 13 years and both could be considered as early successional stages developing on nutrient rich soils. These stages were switched to late successional stage characterized by seminatural grassland species. The quick succession can probably be attributed to the rich species pool of natural grassland flora, the small size and annual mowing of abandoned agricultural fields and the close proximity of seed sources.

The aim of our study was to reveal the differences in the species composition and soil properties of open sandy grasslands dominated by different Festuca species, Festuca vaginata and F. pseudovaginata. Due to the arid conditions, sandy grasslands are generally covered by xerothermic vegetation in which F. vaginata is a typical dominant species. Festuca pseudovaginata, a species newly described by the authors, can also gain dominance in sandy grasslands. However, species composition and soil properties of grasslands dominated by this recently discovered species are still undiscovered. Based on previous coenological studies, we hypothesised that the grasslands characterised by the endemic F. vaginata are more species-rich than those with F.pseudovaginata. Coenological sampling was carried out in May 2009 at two study sites using the Braun-Blanquet method in quadrats of 2 m × 2 m. Five relevés were sampled in stands dominated by F. vaginata and F. pseudovaginata respectively at two study sites in Central Hungary, resulting in a total of twenty relevés. Analyses were based on the cover scores of vascular plant species and cryptogam crust and values of seven soil properties (pH [KCl], pH [H2O], humus, total N, Ca, P2O5 and K2O) measured in the 0–15 and 15–30 cm soil layers. Soil properties of the grasslands dominated by F. pseudovaginata and F. vaginata (dependent variables) were compared by linear mixed models, where ‘grassland type’ was the fixed factor and ‘site nested in grassland type’ was considered as random factor. Data were analysed by cluster analysis, fusion algorithm was a combinatorial method (minimising increase of variance), and the correlation was used as comparative function. We compared the cover of subordinate species by Mann-Whitney U test. We found that F. pseudovaginata and F. vaginata samples were well separated, and grasslands dominated by F. pseudovaginata had nearly two times more species than those dominated by F. vaginata. Based on the cluster analyses using plant cover and upper 0–15 cm soil layer data, F. pseudovaginata and F. vaginata groups could be well separated. Linear mixed models revealed that F. vaginata grasslands were typical on soils with higher pH, nitrogen, phosphorous and potassium contents compared to F. pseudovaginata grasslands, which indicates a tight connection between the properties of the upper soil layer and the vegetation in sandy grasslands. In den semiariden Gebieten der pannonisch-biogeographischen Region bilden offene Sandtrockenrasen auf den entsprechenden Standorten die typische Vegetation (MOLNÁR 2003). Im Stromland zwischen Donau und Theiß in Zentral-Ungarn herrschen Sandmagerrasen mit Festuca vaginata und F. pseudovaginata vor; dabei wurde F. pseudovaginata erst kürzlich von F. vaginata abgespalten (PENKSZA 2003). Inwieweit die beiden Arten auch unterschiedliche ökologische Ansprüche besitzen und unterschiedlich vergesellschaftet sind, war dementsprechend bislang nicht bekannt. Unser Ziel war daher die Untersuchung möglicher Unterschiede in (1) der Artenzusammensetzung und (2) den Bodenbedingungen zwischen Sandtrockenrasen mit dominantem Auftreten von F. vaginata oder F. pseudovaginata. Die beiden Untersuchungsgebiete, Tatárszentgyörgy und Imrehegy, liegen in der pannonisch-biogeographischen Region in Zentral-Ungarn. In beiden Gebieten wurden im Mai 2009 Bestände mit dominanten Vorkommen von Festuca vaginata und F. pseudovaginata untersucht. Pro Gebiet und Vegetationstyp wurden fünf 2 × 2 m-Vegetationsaufnahmen (insgesamt 20 Aufnahmen) nach der Methode von BRAUN-BLANQUET (1951) erstellt. In jeder Aufnahmefläche wurden aus dem Oberboden (Bodentiefe 0–15 cm) und Unterboden (15–30 cm) Proben entnommen und die folgenden Parameter wurden darin gemessen: pH-Wert in KCl und H2O sowie die Gehalte an Humus, Gesamtstickstoff, Phosphat, Kalzium und Kalium. In den statistischen Analysen wurden die beiden Vegetationstypen als Faktor ‘Graslandtyp’ (F. pseudovaginata- vs. F. vaginata-Rasen) und die beiden Gebiete als Faktor ‘Gebiet’ (Tatárszentgyörgy vs. Imrehegy) definiert. Insgesamt (in allen 20 Aufnahmen) konnten wir 76 Gefäßpflanzenarten nachweisen, davon 23 Arten in beiden Rasentypen, vier Arten nur in Festuca vaginata-Rasen und 49 Arten nur im F. pseudovaginata-Rasen. Die beiden Rasentypen unterschieden sich in ihrem Artenreichtum deutlich. Mit 19,6 ± 1,1 Arten pro Aufnahmefläche (Mittelwert und Standardabweichung) in Tatárszentgyörgy bzw. 25,2 ± 4,0 Arten in Imrehegy waren die F. pseudovaginata-Rasen artenreicher als die F. vaginata-Rasen welche in Tatárszentgyörgy 10,0 ± 3,4 Arten und in Imrehegy 11,4 ± 1,3 Arten aufwiesen. Die Clusteranalyse mit allen Arten trennte die F. vaginata- und F. pseudovaginata-Rasen in beiden Gebieten voneinander.