Invasion legacy weakens the positive effect of plant genotype diversity on soil multifunctionality

Background and aimsPlant diversity at both the species and genotype level can enhance multiple ecosystem functions (multifunctionality). How this diversity-multifunctionality relationship can be modulated by global changes such as plant invasions that alter soil biotic and abiotic processes, however, is not well understood.MethodsWe conducted a two-phase experiment to test the effect of soil legacy of a widespread invasive plant, Spartina alterniflora, on the relationship between soil multifunctionality and genotype diversity of a native foundational species, Scirpus mariqueter. We further sequenced soil bacterial and fungal communities to examine their roles in the genotype diversity-soil multifunctionality relationship.ResultsWe found that higher genotype diversity of the native plant led to higher soil multifunctionality, but this positive effect disappeared in soils conditioned by the invader. This was primarily because the invasion legacy disrupted the relationships between plant genotype diversity, fungal network complexity and soil multifunctionality.ConclusionOverall, our study suggests that plant invasion can influence the relationship between plant genotype diversity and soil multifunctionality through soil-legacy effects. These findings highlight the importance of considering the context-dependence of plant diversity-multifunctionality relationships under global change.