Ectomycorrhizas and tropical soils: the importance of sampling scale and the recognition of ecosystem feedback

Post-publication 'Matters Arising' article. In a recent paper, Medina-Vega et al. (2024)1 claim that there are no general effects of soil nutrients on abundance of ectomycorrhizal (ECM) tree species across tropical rain forests. Results from an African site, Korup, where the hypothesis was tested in detail before—and provided strong supporting evidence for soil effects, are miscited and misused in their study. Medina-Vega et al. (2024)1 fail to apply the appropriate scale of field sampling, and they do not adequately recognize feedback effects of ECM trees on the soils. There are important confounding factors which also invalidate their conclusion. It is argued here that only where site-specific detailed studies use soil gradients and local ± ECM vegetation patches, can the effects of soils-on-trees versus those of trees-on-soils be estimated independently. Broad generalizations provide little insight into tree-soil processes which will differ between sites in various ways because each ecosystem operates under its own contingent conditions.