Effects of long-term mowing on coenological composition and recovery routes of a Brachypodium rupestre-invaded community: insight into the restoration of sub-Mediterranean productive grasslands

In low-mountain secondary grasslands of central Apennines, grazing cessation and undergrazing foster Brachypodium rupestre invasion, threatening the 6210* habitat (92/43/EEC Directive). The research aim was to understand the effect of multi-annual mowing and litter removal on recovery of coenological composition of a B. rupestre-invaded grassland. One hectare of grassland was mown, in late June and October, for 6 years, removing litter and hay. Before the first yearly mowing, we collected species and litter cover in 30 randomly selected plots (0.5 x 0.5 m). Festuco-Brometea/Festuco-Ononidetea species promptly increased, in number and abundance, in response to B. rupestre and litter removal, but decreased in the second half of the treatment, being partly replaced by Molinio-Arrhenatheretea species, progressively fostered by litter reduction. Litter removal also explained the increase in abundance of Sedo-Scleranthetea/Helianthemetea guttati species, whose richness peaked at treatment end, indicating the potential for higher species richness and the formation of patches of 6110* and 6220* habitats. Fringe and successional species decreased in richness and abundance, without a linear trend. The number of diagnostic taxa of the 6210* habitat increased significantly with the reduction of B. rupestre and litter, although the frequency/abundance of most of them did not change significantly, indicating that the studied community could be still considered habitat of community interest, although in a low conservation status. The treatment was effective in restoring grassland composition, although the achievement and maintenance of a favourable conservation status for the 6210* habitat require a long-term management planning, including sheep grazing during late spring/summer.