Mediterranean co-living: succession of soil mycorrhizal communities associated with Halimium lasianthum shrubs

Halimium lasianthum, a widespread shrub in the western Mediterranean, uniquely co-hosts ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) fungi. Despite its ecological significance, H. lasianthum is understudied, and its mycorrhizal communities remain largely unknown. To understand the mycological ecology associated with H. lasianthum, we analyzed soil samples from intermediate and senescent understories in Ourense, northwest Iberian Peninsula. We assessed the richness, diversity, relative abundance and community composition of ECM and AM fungi. Environmental and soil variables were also examined to determine their influence on fungal distribution. Total fungal richness and abundance were higher in intermediate plots compared to senescent plots, with ECM fungi following the same trend. In comparison, AM fungal richness was higher in senescent plots (p < 0.05). ECM fungal community composition shifted with H. lasianthum age, whereas the Shannon diversity index and abundance of AM fungi remained stable. Soil pH was significantly correlated with the ECM community in intermediate plots, while the stability of the AM community was due to lower nutrient requirements and the production of resistant propagules. These findings could help to improve the management of H. lasianthum ecosystems to preserve the diversity of the mycorrhizal communities associated with this host species.