Vegetation cover and biodiversity levels are driven by backfilling material in quarry restoration

摘要

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 3x3 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 alpha- and beta-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.