Long term changes of the inner-alpine steppe vegetation: the dry grassland communities of the Vinschgau (South Tyrol, Italy) 40–50 years after the first vegetation mapping

Abstract

Aims: The Vinschgau is the driest inner-alpine valley in the Eastern Alps and harbours a unique steppe vegetation. We studied these dry grassland communities and aimed to answer the following questions: Which plant communities can be found currently? Do the syntaxa described by Braun-Blanquet in the 1960s still prevail in the area? Has there been any change in species composition over the last 40–50 years? Study area: Along an approximately 40 km transect, the south-facing slopes of the Vinschgau valley (South Tyrol, Italy) from Mals to Plaus were investigated. Methods: For the classification, 92 relevés were sampled in 2019 and compared with 76 relevés from the 1960s and ´70s by means of vegetation tables and ordinations (Detrended Correspondence Analysis). Results: Based on our investigation, the majority of dry grassland communities can be classified as Festuco-Caricetum supinae. Three subassociations were defined by the dominant species Stipa capillata, Bothriochloa ischaemum and Stipa pennataagg. The comparison of new and old relevés shows an increase in species from the class Sedo-Scleranthetea (e.g. Trifolium arvense, Erodium cicutarium) and the association Artemisieto-Agropyretum. In addition, ruderal elements (e.g. Erigeron annuus, Convolvulus arvensis) have also migrated into dry grasslands. A shift in the dominance over time can be recognized as well. In particular, Festuca rupicola and to some extent also Stipa capillata, have increased in abundance and frequency. Conclusions: We suggest to include the investigated closed dry grasslands in the alliance Festucion valesiacae. The rank of the character species at association, alliance and order level should be re-analysed. In order to obtain a better syntaxonomic overview of western and eastern alpine dry grassland communities in relation to Eastern European dry grasslands, a comprehensive study is absolutely necessary. Furthermore, long-term vegetation dynamics and vegetation change need to be studied in more detailed future studies. Taxonomic reference: Fischer et al. (2008). Syntaxonomic references: Mucina et al. (2016) for syntaxa from alliance to class level; Braun-Blanquet (1961) for associations. Abbreviations: agg. = aggregate; cf. = confer (means ‘compare’); DCA = Detrended Correspondence Analysis; s. lat. = sensu lato; s. str. = sensu stricto