Forest mycorrhizal type mediates nutrient dynamics, which in turn can influence forest community
structure and processes. Using forest inventory data, we explored how dominant forest tree mycorrhizal
type affects understory plant invasions with consideration of forest structure and soil
properties. We found that arbuscular mycorrhizal (AM) dominant forests, which are characterised
by thin forest floors and low soil C : N ratio, were invaded to a greater extent by non-native invasive
species than ectomycorrhizal (ECM) dominant forests. Understory native species cover and
richness had no strong associations with AM tree dominance. We also found no difference in the
mycorrhizal type composition of understory invaders between AM and ECM dominant forests.
Our results indicate that dominant forest tree mycorrhizal type is closely linked with understory
invasions. The increased invader abundance in AM dominant forests can further facilitate nutrient
cycling, leading to the alteration of ecosystem structure and functions.