The arbuscular mycorrhizal fungal communities associated with Taxus brevifolia (western yew) are sensitive to soil pH and neighborhood forest composition

Temperate rainforest systems are being radically altered by commercial timber harvest and climate change, imposing unprecedented stress on the trees and their mycorrhizal fungal communities. We used marker gene sequencing to describe the arbuscular mycorrhizal fungal (AMF; phylum Mucoromycota) communities associated with in-situ, mature Taxus brevifolia Nutt. (western yew) and co-occurring Acer glabrum var. douglasii (Douglas maple) and Thuja plicata Donn ex. D. Don (western redcedar) in the inland temperate rainforests of southern interior British Columbia. We identified a total of 48 phylogroups (virtual taxa; VT) in the Mucoromycota, and observed a high degree of overlap in AMF composition within mixed-species groups at the same location. We additionally observed an unusually linear relationship between rhizosphere soil pH and the AMF richness of T. brevifolia. Rhizosphere soil pH was further related to the tree canopy composition (i.e., dominant and codominant tree species) immediately adjacent to the host trees. These results confirm that this community of late-seral temperate tree species shares a common guild of AMF and suggest that T. brevifolia and its associated AMF may be particularly sensitive to environmental changes, such as shifts in neighborhood forest composition.