Multifunctional Group Species Reseeding Reduce Community-Level Root Exudate Rate at Severely Degraded Alpine Meadows

Abstract Root exudates play a crucial role in the communication and interaction between plants and soil. However, the responses of carbon (C), nitrogen (N), and phosphorus (P) exudation rates, and their stoichiometric ratios to multifunctional group species reseeding in severely degraded alpine meadows remain poorly understood. This study was conducted in a severely degraded alpine meadow and four species composition treatments were established: grass mixtures, grass + legume mixtures, grass + legume + sedge mixtures, and grass + legume + forb mixtures. The results showed that among the four reseeding treatments, the grass + legume + sedge mixture exhibited the lowest root C exudate rate and total exudate capacity, while N and P exudation rates, as well as their total exudate capacities, did not differ significantly between treatments. The carbon-to-phosphorus (C:P) ratio of root exudate was lowest in the grass + legume + sedge mixture, while the carbon-to-nitrogen (C:N) and nitrogen-to-phosphorus (N:P) ratios showed no significant differences among the four reseeding treatments. Root C and P exudation rates, as well as the C:N and N:P ratios, were significantly correlated with plant diversity, aboveground biomass, total biomass, soil organic matter and electrical conductivity. Variation partitioning analysis showed that root C exudate rate was most strongly influenced by biomass, whereas N and P exudate rates were more strongly affected by plant diversity. These findings suggest that species reseeding patterns significantly influence root exudates and their stoichiometric characteristics and contribute to understand the trajectories of soil microbes and soil health under reseeding.