Classification and syntaxonomical revision of mesic and semi-dry grasslands in Hungary.

Mesic and semi-dry grasslands are among the most valuable and species-rich anthropogenic habitats in Hungary. In contrast to the high respect with which they are regarded by conservationists, the diversity of this vegetation and its syntaxonomy were neglected for a long time. In this paper we present the first country-level synthesis and syntaxonomical review of this vegetation based on the numerical classification of the Arrhenatheretalia order, and an update of Brometalia erecti. After careful data selection and resampling, we classified 1204 relevés to 60 clusters. Clusters representing the same association were merged on the basis of a minimum spanning tree and expert assessment of their species composition. Species composition, geographical distribution and environmental background of each mesic and semi-dry grassland association are discussed. The relationships of associations were also examined by ordination. Evaluation of clusters and associations were based only on those relevés that were unambiguously classified. We recognized 11 associations in the Arrhenatheretalia order in two alliances. In the Arrhenatherion alliance, several new association names are adopted from the literature of other countries, and a new one is proposed. According to our concept, Arrhenatherion includes Ranunculo-Alopecuretum, a mesohygrophilous type; Filipendulo-Arrhenatheretum and Anthoxantho-Festucetum pratensis, which are typical for meadows of fluctuating soil water level but have a different geographic distribution; Pastinaco-Arrhenatheretum, that is a widespread mesic meadow with many generalist species; Ranunculo bulbosi-Arrhenatheretum containing drought-tolerant and less nutrient-demanding species; Tanaceto-Arrhenatheretum, a semi-ruderal type; and Diantho-Arrhenatheretum, that harbours many species of montane meadows. In the Cynosurion, four associations are distinguished. Cynosuro-Lolietum is an intensively grazed type on nutrient-rich, mesic or moist soil in humid climates; Alopecuro-Festucetum pseudovinae is also a heavily grazed type, but in areas with a more continental climate and on packed soil. Anthoxantho-Festucetum pseudovinae and Colchico-Festucetum rupicolae are lowland mesic pastures that contain some xerophilous species, however, they differ in grazing intensity and regional species pool. Two associations of Cirsio-Brachypodion transitional towards more mesic types are detected for the first time in Hungary: Filipendulo-Brometum with sub-Atlantic distribution and Brachypodio-Molinietum with a more montane and Carpathian distribution.We also recognized Sanguisorbo-Brometum, that is a common semi-dry grassland type on rocky soils in Transdanubia; Polygalo-Brachypodietum, a colline type with many Pontic species; Trifolio-Brachypodietum, an association of more forested and montane landscapes, and Euphorbio-Brachypodietum, the semi-dry grassland type of Pannonian loess regions. We concluded it is unlikely that Phyteumo-Trisetion and Bromion erecti occur in Hungary.