Fungal Community Assembly along the Root-Soil Continuum: Divergent Effects of Monoculture vs. Mixed Plantations in Sandy Ecosystems

Mixed-species plantations may enhance ecosystem functioning by modulating soil microbial communities, yet how different companion species influence fungal community assembly along the root-soil continuum in sandy ecosystems remains poorly understood. Here, we investigated poplar monoculture (P) and three mixed plantations with Salix psammophila (PS), Caragana korshinskii (PC), and Pinus sylvestris var. mongolica (PZ) in the Kubuqi Desert. Soil properties and fungal communities in root (R), rhizosphere (RS), and non-rhizosphere (NRS) compartments were analyzed using ITS1 sequencing, functional prediction, network analysis, and null modeling. Companion tree species exert specific filtering effects on fungal communities along the root-soil continuum, with consequences for community assembly and function. The predominance of EcM fungi and low pathogen abundance suggest a microbial balance favoring symbiosis, offering insights for sustainable afforestation in degraded sandy lands.