Polypore fungal diversity and host density in a moist tropical forest

In a moist tropical forest in Panama, the wood-decay polypore fungi comprise many rare species (more than half found only once) and exhibit diversity that exceeds that of the supporting tree community. The most abundant fungal species were non-specialists, each found on several host species from multiple plant families. In diverse fungal communities, each of many species should infect a given host species in a density-dependent manner, so that the infected proportion of a host population should increase with host density. Applied across host species, hosts with denser populations should support greater fungal diversity. For 10 tree species, fungal incidence and diversity increased with abundance of the host in the community, consistent with across-species density-dependent infection. Fungal diversity associated with individual trunks did not, however, vary with host-species density. Both host density and persistence of decaying logs may be important in determining fungal diversity associated with tree species.