Assembly processes of rare and abundant taxa are closely related to the bacterial and fungal functionality during desert vegetation reestablishment

Effective vegetation reconstruction plays a vital role in the restoration of desert ecosystems. However, in different types of vegetation reconstruction, the community characteristics, assembly process, and functions of different soil microbial taxa under environmental changes are still disputed, which limits the understanding of the sustainability of desert restoration. Hence, we investigated the soil microbial community characteristics and functional attributes of grassland desert (GD), desert steppe (DS), typical steppe (TS), and artificial forest (AF) in the Mu Us Desert, China. Our findings confirmed the geographical conservation of soil microbial composition, but highlighted decreased microbial diversity in TS. Meanwhile, the abundance of rare taxa and microbial community stability in TS have improved. Heterogeneous and homogeneous selection processes determined the assembly of rare and abundant bacterial taxa, respectively, with both significantly influenced by soil moisture. In contrast, fungal communities displayed stochastic processes and exhibited sensitivity to soil nutrient conditions. Furthermore, our investigation revealed a noteworthy augmentation in bacterial metabolic functionality within the TS, aligning with improved vegetation restoration and the assemblage of abundant bacteria taxa. However, within nutrient-limited soil (GD, DS, and AF), the assembly dynamics of rare fungal taxa assumed a prominent role in augmenting their metabolic capacity and adaptability to desert ecosystems. These results highlight the variations in the assembly process and metabolic function of soil microorganisms during vegetation reestablishment and provides a corresponding theoretical support for anthropogenic revegetation of desert ecosystems.