Shared mycorrhizal networks of forest herbs: Does the presence of conspecific and heterospecific adult plants affect seedling growth and nutrient acquisition?

Abstract

Arbuscular mycorrhizal fungi can colonize the roots of a large number of plant species and individuals, simultaneously creating a network of hyphae connecting the roots of many plants. In this study, I examined the effect of the mycorrhizal network produced by conspecific and heterospecific adult plants on growth and nutrient content of seedlings of Arisaema triphyllum (L.) Schott. and Maianthemum racemosum (L.) Link ssp. racemosum. Seedlings of both plant species were planted so that they could become colonized by the mycorrhizal network or remain uncolonized, and were planted in the presence of a conspecific or heterospecific adult plant. After 2 years of growth, seedlings were harvested and biomass and nutrient content were determined. Biomass of A. triphyllum seedlings was not affected by the identity of the adult plant or colonization by mycorrhizal fungi. Biomass of M. racemosum seedlings was significantly affected by adult plant identity and mycorrhizal colonization. Maianthemum racemosum seedlings grown near a conspecific adult were significantly larger than when grown near a heterospecific adult, and mycorrhizal M. racemosum seedlings grown near a heterospecific adult had significantly less biomass than nonmycorrhizal seedlings. This suggests that the mycorrhizal network of some plants may confer positive or negative effects on mycorrhizal seedlings as compared to nonmycorrhizal seedlings.