Linkages between microbial communities and multiple ecosystem functions are context-dependent. However, the impacts of different restoration measures on microbial communities and ecosystem functioning remain unclear. Here, a 14-year long-term experiment was conducted using three restoration modes: planting mixed grasses (MG), planting shrub with Salix cupularis alone (SA), and planting shrub with Salix cupularis plus planting mixed grasses (SG), with an extremely degraded grassland serving as the control (CK). Our objective was to investigate how ecosystem multifunctionality and microbial communities (diversity, composition, and co-occurrence networks) respond to different restoration modes. Our results indicated that most of individual functions (i.e., soil nutrient contents, enzyme activities, and microbial biomass) in the SG treatment were significantly higher than in the CK treatment, and even higher than MG and SA treatments. Compared with the CK treatment, treatments MG, SA, and SG significantly increased the multifunctionality index on average by 0.57, 0.23 and 0.76, respectively. Random forest modeling showed that the alpha-diversity and composition of bacterial communities, rather than fungal communities, drove the ecosystem multifunctionality. Moreover, we found that both the MG and SG treatments significantly improved bacterial network stability, which exhabited stronger correlations with ecosystem multifunctionality compared to fungal network stability. In summary, this study demonstrates that planting shrub and grasses altogether is a promising restoration mode that can enhance ecosystem multifunctionality and improve microbial diversity and stability in the alpine degraded grassland.

Few systemic assessments have evaluated the success of these afforestation programs in alpine semiarid desert ecosystems in the Qinghai‐Tibet Plateau. In this study, we investigated the influences of three Salix cupularis plantation age classes (6, 18, and 34 years) on the carbon (C), nitrogen (N), and phosphorus (P) storages and stoichiometry of the soil–plant ecosystem. The consequences of S. cupularis plantation induced soil spatial heterogeneity. The soil–plant ecosystem C storage increased after the plantation. The N storage showed an increasing trend from 6 to 18 years and then slightly decreased. The P storage presented a continuously declining trend. The result indicated that the imbalance in soil N, P, C occurred with plantation age because of the imbalance of their inputs. The N and P uptakes from subsoil and redistribution to topsoil by S. cupularis may contribute to meet N and P demands for the understory plants. Leaf N:P ratios varied from 8.3 to 17.5. These results imply that N and P status are the main factors limiting plant growth in the alpine‐cold desert ecosystem. Thus, we recommend adding N and P fertilizers during plant growth.

Soil organic carbon (SOC) mineralization is affected by ecological restoration and plays an important role in the soil C cycle. However, the mechanism of ecological restoration on SOC mineralization remains unclear. Here, we collected soils from the degraded grassland that have undergone 14 years of ecological restoration by planting shrubs with Salix cupularis alone (SA) and, planting shrubs with Salix cupularis plus planting mixed grasses (SG), with the extremely degraded grassland underwent natural restoration as control (CK). We aimed to investigate the effect of ecological restoration on SOC mineralization at different soil depths, and to address the relative importance of biotic and abiotic drivers of SOC mineralization. Our results documented the statistically significant impacts of restoration mode and its interaction with soil depth on SOC mineralization. Compared with CK, the SA and SG increased the cumulative SOC mineralization but decreased C mineralization efficiency at the 0–20 and 20–40 cm soil depths. Random Forest analyses showed that soil depth, microbial biomass C (MBC), hot-water extractable organic C (HWEOC), and bacterial community composition were important indicators that predicted SOC mineralization. Structural equal modeling indicated that MBC, SOC, and C-cycling enzymes had positive effects on SOC mineralization. Bacterial community composition regulated SOC mineralization via controlling microbial biomass production and C-cycling enzyme activities. Overall, our study provides insights into soil biotic and abiotic factors in association with SOC mineralization, and contributes to understanding the effect and mechanism of ecological restoration on SOC mineralization in a degraded grassland in an alpine region.

The rhizosphere serves as a critical interface for plant–soil–microorganism interactions. Rhizosphere soil refers to the soil directly adhering to root surfaces, while non-rhizosphere soil denotes the surrounding soil not in direct contact with roots. This study investigated the characteristics of soil microbial community structure, diversity, and enzyme activity dynamics in both rhizosphere and non-rhizosphere soils of Salix cupularis (shrub) across different restoration periods (4, 8, 16, and 24 years) in alpine sandy lands on the eastern Qinghai–Tibet Plateau, with unrestored sandy land as control (CK), while analyzing relationships between soil properties and microbial characteristics. Results demonstrated that with increasing restoration duration, activities of sucrase, urease, alkaline phosphatase, and catalase in Salix cupularis rhizosphere showed increasing trends across periods, with rhizosphere enzyme activities consistently exceeding non-rhizosphere levels. Bacterial Chao1 and Shannon indices followed similar patterns to enzyme activities, revealing statistically significant differences between rhizosphere and non-rhizosphere soils after 8 and 24 years of restoration, respectively. Dominant bacterial phyla ranked by relative abundance were Actinobacteria > Proteobacteria > Acidobacteria > Chloroflexi > Gemmatimonadetes. The relative abundance of Actinobacteria exhibited highly significant positive correlations with carbon, nitrogen, phosphorus, and enzyme activity indicators, indicating that Salix cupularis restoration promoted improvements in soil physicochemical properties and nutrient accumulation, thereby enhancing bacterial community diversity and increasing Actinobacteria abundance. These findings provide fundamental data for restoration ecology and microbial ecology in alpine ecosystems, offering a scientific basis for optimizing ecological restoration processes and improving recovery efficiency in alpine sandy ecosystems.