JAEPRE23 -36: The potential of mycorrhizal fungi to mediate the direction of density dependence in tropical forests (JAEPRE23-36)

Mycorrhizal fungi directly affect tree community diversity and dynamics by altering plant establishment, recruitment, growth and survival via plant-soil feedbacks. Ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) associations typically promote contrasting plant-soil feedbacks. ECM associations often facilitate positive plant-soil feedbacks leading to a monodominance of ECM species, genera or families in forest stands. By contrast, AM associations often produce negative feedbacks encouraging tree species turnover and diversity. In addition, the dominance of a mycorrhizal type in a tree community may inhibit the establishment of seedlings from other mycorrhizal types due to reduced soil inoculum quantity or quality (e.g., reduced common mycorrhizal networks). Therefore, mycorrhizal fungi likely contribute to the variation in the magnitude and direction of the density dependence reported across tropical forests. However, direct empirical evidence testing the spectrum of density dependence across a range of forest stands varying in mycorrhizal types remains limited. This project intends to test the level of variation in the density-dependent effects on seedling establishment, growth and survival in tropical forests.