Microbial functional groups govern soil multifunctionality during alpine grassland restoration via turf transplantation

Abstract

Turf transplantation is a critical strategy for minimizing biodiversity loss in degraded alpine grasslands, yet its impacts on soil multifunctionality—a key indicator of ecosystem recovery—remain poorly understood. Based on high-throughput sequencing, ecological network, PICRUSt2, and FUNGuild analyses, this study investigated microbial traits, plant traits, and soil multifunctionality across stacked (Top, Middle, and Bottom layers) and relaid turfs (stacked turfs return to initial positions) on the eastern Tibetan Plateau. Results indicated that stacked turfs significantly reduced soil multifunctionality relative to natural soil, while relaid turfs partially restored functionality in the Top layer relative to stacked turfs, though still below natural grassland soil. Contrary to expectations, microbial taxonomic diversity and network complexity showed limited correlations with multifunctionality. Indeed, microbial life-history strategies (e.g., resource acquisition strategy (A-strategy)) and fungal functional guilds (pathotrophs, saprotrophs) emerged as primary drivers. Notably, fungal functional redundancy exacerbated soil function decline, whereas bacterial functional shifts mediated recovery. Plant diversity and taproot biomass exhibited strong positive feedback with soil multifunctionality, emphasizing the role of vegetation-microbe interactions. Our findings challenge the conventional focus on microbial diversity in restoration ecology, advocating for a paradigm shift toward functional trait-based frameworks. These insights refine turf transplantation protocols, highlighting the necessity to limit stacking height and prioritize microbial functional resilience in alpine grassland restoration.