Floristic and phytosociological features of the Brachypodium rupestre communities in Italy.

Abstract

The pale green dense Tor-grass (Brachypodium rupestre) tufts are a quite distinctive aspect of the Italian grassland pattern of the colline and submontane belts. B. rupestre is used to be found in secondary grasslands both in natural environments and in some aspects of the post-coltural environments such as forest clearances, abandoned terraced and extensive pastures. In northern Italy (Alps, Prealps and northern Apennines) B. rupestre has only sporadically been considered in the grasslands syntaxonomic frameworks. On the contrary it occurs in those regarding the central Italy where several semi-natural and post-coltural grassland associations (e.g. Polygalo flavescentis-Brachypodietum, Galio lucidi-B. Dorycnio-B. etc.) were described. As far as the southern Italy is concerned only the Polygalo mediterraneae-Brachypodietum is known whereas two new associations were recently proposed for Sicily (Gianguzzi et al. 2018 submitted). As regards the syntaxonomical ranks higher than association, the majority of the B. rupestre communities were classified in the Festuco-Brometea and a minor part to the Trifolio-Geranietea. In particular Di Pietro et al., (2015) proposed the classification of the Italian Brachypodium rupestre grasslands in the following three alliances: Coronillo-Astragalion Ubaldi 2003 (flyschoid eroded substrates); Cytiso-Bromion erecti Bonin 1978 (xerophilous mixed Brachypodium rupestre and Bromus erectus on limestone) and Polygalo mediterraneae-Bromion erecti (Biondi, Allegrezza et Zuccarello 2005) Di Pietro in Di Pietro et al. 2015 (post-coltural or natural environments on pelithic-arenaceous or marly-clayey colluvial soils). On the other hand Allegrezza et al. (2016) considered Brachypodium rupestre as a guide-species for the sub-Mediterranean heliophilous forest edges and proposed a new suborder Dorycnio herbacei-Brachypodienalia (Asphodeletalia macrocarpi, Trifolio-Geranietea) a new alliance, Dorycnio herbacei-Brachypodion, and three new associations (Galio erecti- Brachypodietum, Laserpitio siculi-B. and Bituminario-B.). In this presentation a synoptic table including all the B. rupestre communities described for the Italian Peninsula has been statistically analysed and discussed from a floristic and coenological point of view. From this analysis emerged that the B. rupestre communities described so far for the Italian peninsula are all characterized by the prevalence of the Festuco-Brometea species regardless of their original classification at the class rank.