Beyond plants: How soil alterations shape restoration success in alpine grasslands

Alpine ecosystems face increasing disturbances from construction activities, prompting restoration efforts to mitigate soil erosion and biodiversity loss. We investigated the short-term outcomes of alpine grassland restoration measures at Curtinella, Corvatsch (canton of Grisons, Switzerland), comparing vegetation composition, soil properties, and soil bacterial communities of two restored sites – one seeded (2017) and one restored by turf transplantation (2020) – against an undisturbed reference site. Vegetation analysis revealed significant floristic differences between restored and undisturbed sites. Seeded plots showed reduced species diversity, richness, and dominance by non-native and compete- tively strong species, whereas turf transplantation plots demonstrated improved establishment of native species but featured considerable vegetative gaps indicative of slow recovery. Restoration substantially modified soil properties: shallower soils with higher gravel cover, elevated pH, and lower microbial biomass, likely influencing long-term vegetation patterns. Microbial community analyses using 16S rRNA gene sequencing indicated distinct bacterial com- munity shifts due to restoration measures, with increased diversity linked to altered soil conditions. Eight bacterial genera were identified as putative bioindicators for undisturbed alpine soils. These find- ings underscore the critical importance of topsoil conservation during alpine restoration. We recommend prioritizing spontaneous vegetation establishment over extensive seeding, limiting seeding primarily to erosion control, and preserving topsoil to sustain alpine biodiversity. Future re- search should explore microbial-plant interactions further and include additional taxonomic groups to strengthen ecological assessments and restoration practices in alpine regions.