The microbial network exhibits higher complexity in the rhizosphere than in bulk soils along elevational gradients in the alpine forests

The soil microbial network complexity plays an integral role in ecosystem multifunctionality such as nutrient cycling, soil organic carbon pool and plant productivity. Nevertheless, the manner in which microbial network complexity, particularly within the rhizosphere region, responds to variable environments in the alpine forests with high symbiosis of ectomycorrhizal (ECM) fungi remains largely uncharted territory. In this study, we investigated the soil microbial network complexity in bulk and rhizosphere soils in two alpine coniferous forests along two elevation gradients on the eastern Tibetan Plateau. Meanwhile, the soil microbial diversity, functional group abundance and soil parameters were measured to assess the effects of elevation-dependent changes in soil microbial attributes and soil characteristics on soil network complexity in bulk and rhizosphere soils. The results showed that the soil microbial network complexity was significantly higher in the rhizosphere than in bulk soils across all elevations and were positively correlated with soil physicochemical characteristics. Moreover, the complexity of microbial network was positively correlated with the relative abundance of ECM fungi. The random forest model, which predicted 57.72 % of the variations in soil microbial network complexity, further confirmed the significant contribution of ECM fungi in maintaining network complexity. This empirical evidence highlights the importance of fungal functional groups in regulating microbial network complexity. Overall, our study offers insights into a more comprehensive understanding of the underlying mechanisms by which microbial traits modulate co-occurrence networks and interactions from the rhizosphere perspective.