Abstract

Knowledge of the changes in arbuscular mycorrhizal (AM) fungi is fundamental for understanding the success of exotic plant invasions in natural ecosystems. In this study, AM fungal colonization and spore community were examined along an invasive gradient of the exotic plant Eupatorium adenophorum in a secondary forest in southwestern China. With increasing E. adenophorum invasion, the density of arbuscules in the roots of E. adenophorum significantly increased, but the AM root colonization rate and the densities of vesicles and hyphal coils in roots of E. adenophorum were not significantly different. A total of 29 AM fungi belonging to nine genera were identified based on spore morphology. Claroideoglomus etunicatum, Funneliformis geosporus, and Glomus aggregatum were the most common AM fungal species. The E. adenophorum invasion significantly decreased the AM fungal spore density in the soil. Furthermore, with increasing of E. adenophorum invasion the spore densities of C. etunicatum, G. aggregatum, and G. arenarium significantly decreased, whereas F. geosporus significantly increased. Nonmetric multidimensional scaling demonstrated that the AM fungus community composition was significantly different (P=0.003) in the different invasive levels of E. adenophorum, and significantly correlated with plant species richness, soil total P, and soil NO3--N. The results suggest that the alteration in AM fungus community might be caused by E. adenophorum invasion via changing the local plant community and soil properties in a Chinese secondary forest ecosystem.

• Keywords: Arbuscular mycorrhiza; spore community composition; Crofton weed; invasion density