Symbiotic control of canopy dominance in subtropical and tropical forests

Subtropical and tropical forests in Asia often comprise canopy dominant trees that form symbioses with ectomycorrhizal fungi, and species-rich understorey trees that form symbioses with arbuscular mycorrhizal fungi. We propose a virtuous phospho-rus acquisition hypothesis to explain this distinct structure. The hypothesis is based on (i) seedlings being rapidly colonised by ectomycorrhizal fungi from established mycelial networks that generates positive feedback and resistance to pathogens, (ii) ectomycorrhizal fungi having evolved a suite of morphological, physiological, and molecular traits to enable them to capture phosphorus from a diversity of chemical forms, including organic forms, and (iii) allocation of photosynthate carbon from adult host plants to provide the energy needed to undertake these processes.

Automated summary

Subtropical and tropical forests in Asia have a unique structure where canopy dominant trees form symbioses with ectomycorrhizal fungi and understorey trees form symbioses with arbuscular mycorrhizal fungi. This structure is explained by the virtuous phosphorus acquisition hypothesis, which suggests that rapid colonization of seedlings by ectomycorrhizal fungi, their ability to capture phosphorus from different chemical forms, and allocation of carbon from host plants contribute to this distinct structure.