Plant cover is related to vegetation and soil features in limestone screes colonization : A case study in the Italian Alps

Background and aims Studies that consider the effects of screes plant communities on the soil properties are lacking and whether the plant cover could be used as an indicator of biotic and/or abiotic parameters of the scree colonization has never been assessed. Here we aimed to identify plant communities-soil relationships in the process of colonization of alpine limestone screes. Methods Plant communities and chemical-physical soil properties were studied on 50 plots from an area of the Italian Alps, and related to plant cover (colonization). Correlation and regression analysis were performed to determine the relationships and define the best trend models. Results At the varying of plant cover, plant communities and the soil properties changed greatly. Floristic analysis especially showed how the pioneer/early stages of colonization revealed a limited number of species (< 20) typical of unstable screes (Thlaspietea rotundifolii) while the late/final stage has a greater number of species (> 25), mainly of basophilic grasslands (Elyno-Seslerietea). Statistical analysis showed high correlation between plant cover and number of species, shear vane strength (τ), soil depth, pH, organic matter (OM), total nitrogen (TN), sand and medium gravel content. The number of species and the values of τ, soil depth, OM, TN and sand content increased over the colonization/succession, albeit with different trends. Conclusion This research allowed a better comprehension of the phenomenon of colonization of alpine limestone screes and showed how plant cover is a parameter useful to estimate some soil and vegetation features, therefore to facilitate the study/management of these environments.