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In limestone quarries, after quarry abandonment, ecological restoration takes place subsequently over several years, often with the use of different procedures and backfilling materials. The success of the different restoration actions performed at a limestone quarry (Colle Pedrino, Lombardy Prealps, Italy) in terms of vegetation cover and biodiversity levels, compared to the surrounding natural areas, was evaluated in this work. Taking into account the soil’s chemical-physical characteristics, 24 vegetation plots of 3 × 3 m were set up on seven restored parcels of different ages inside the quarry, of which one was left to spontaneous succession, and one control area outside the quarry was also considered for comparisons. Linear mixed models were employed to assess the effect of the following environmental variables on restoration: age, and several soil factors (stoniness, sand content, CN, K, and organic matter). The restoration success at the different parcels, in terms of total plant cover, grass cover and α- and β-diversity (including Lepidoptera), were thus determined. The variations in plant traits associated with the main environmental factors and floristic composition at the restored parcels were also assessed. The linear models revealed that the grass cover strongly depends on the age of the parcel and some soil factors: sand and potassium contents in the topsoil and organic matter in the subsoil. Moreover, plant and butterfly richness depend on the soil’s stoniness and sand content. The species traits also significantly explained the variation in species distribution along the environmental gradients: stronger correlations with sand, potassium contents and stoniness were found. The restoration success in the quarry slopes depended on the backfilling materials used for slope reclamation over time. This factor concurs with the time passed since the restoration/abandonment and has a key background role in shaping the quarry’s grass cover and biodiversity gradients. Regarding species assemblages, the key leaf traits of plants linked to resource availability (leaf area, leaf nitrogen and leaf carbon contents) consistently responded to the soil variables within parcels. In conclusion, site-specific studies to evaluate the grain size and the chemical composition of the backfilling materials used in the slope remodelling are recommended to favour a resource-driven plant establishment, spontaneous recolonisation, higher biodiversity and slope stability.

Ambrosia artemisiifolia is able to dominate the early stages of vegetation succession in open/disturbed habitats, spreading out into available empty niches, after which it can be progressively replaced by perennial plants. In this study, we considered the time-span in which the species is suppressed during active (restoration actions) and passive (spontaneous) vegetation recovery. In particular, we envisaged that A. artemisiifolia growth and fitness may be strongly reduced and that the species may rapidly be suppressed within a short time during succession as a consequence of the increase of vegetation cover, both natural or artificially induced, in a disturbed area of northern Italy. Three different treatments were applied within an abandoned quarry area commonly invaded by A. artemisiifolia : (i) spontaneous succession i.e. (control), (ii) hayseed and (iii) a commercial seed mixture. We determined the effect of mixtures of grassland species, established from native hayseed or from a commercial seed mixture, on A. artemisiifolia growth and fitness traits over time in comparison to a non-seeded area left to spontaneous succession. The results demonstrated that, after the first growing season, compared with spontaneous succession, both commercial seed and hayseed resulted in a strong reduction of A. artemisiifolia abundance and growth rate, in terms of both vegetative and reproductive traits. After the second growing season, A. artemisiifolia was completely suppressed in the commercial seed treatment, and after the third growing season it was also suppressed in the spontaneous succession and hayseed treatments. This study indicated that both active and passive vegetation recovery (by niche filling and competitive exclusion) could be used as methods individually or in combination with other methods, such as mowing and biological control, to suppress A. artemisiifolia from anthropogenic habitats.