Positive and negative plant-soil feedbacks are caused by mycorrhizal type, soil fertility, and phylogenetic relatedness in a mixed Dipterocarp rain forest

Abstract

While work in temperate forests suggests that there may be consistent differences in plant-soil feedback (PSF) between plants with arbuscular and ectomycorrhizal associations, it is unclear whether this is compatible with the high diversity of tropical rainforests. To examine this, we tested the effect of mycorrhizal type, phylogenetic distance, and soil fertility on variation in PSF strength in a mixed-tropical rainforest with a uniquely high diversity of ectomycorrhizal and arbuscular mycorrhizal trees. We found positive phylogenetic PSFs for ectomycorrhizal tree species that were insensitive to soil fertility. By contrast, PSFs for arbuscular mycorrhizal tree species were negative, and increasingly so with greater soil fertility. Our results demonstrate consistent effects of mycorrhizal types on plant population dynamics across biomes, and help explain biogeographic variation across tropical forests, such as familial dominance of the Dipterocarpaceae in SE Asia. However, they also raise questions about the role of PSFs in maintaining tropical diversity.\n\nStatement of authorshipRMS, SER, SJD and KGP designed the experiment. RMS conducted the experiment and collected data. RMS analyzed data with input from KGP and SER. RMS wrote the first draft of the manuscript, and all authors contributed to subsequent revision and preparation of the manuscript.