In plant communities, microbes crucially affect on growth and survival of plants, shaping community structure. However, little is known in the relative importance of symbiotic-microbes (e.g., arbuscular mycorrhizal fungi: AMF; ecto-mycorrhizal fungi: ECMF) and antagonistic-microbes (e.g., pathogenic fungi) on plant performance in field conditions. We estimated relative importance of mycorrhizal- and pathogenic fungi on plant performance for two hardwood species (Acer mono and Quercus serrata) in a reciprocal seed-sowing experiment in gap-understory continuum. In forest understories, seedlings mortality was higher beneath conspecific- compared to heterospecific-adults in A. mono, due to severe attack of pathogenic fungi, while most of the seeds were predated by wood mice beneath both conspecific- and heterospecific-adults in Q. serrata. In gaps, seedling growth and survival were greater in the place previously dominated by conspecific- compared to heterospecific-adults in both species, because of the higher percentage of root colonization by AMF and ECMF for A. mono and Q. serrata seedlings, respectively. The results suggest that the relative importance may change according to light conditions and the presence of conspecifics.