Species richness of tropical wood-inhabiting macrofungi provides support for species-energy theory

Abstract

A study was undertaken at the El Verde Field Station in Puerto Rico to determine the effect of energy available from newly dead trees on the species richness of macrofungal communities that inhabit them. It is hypothesized that there is a positive relationship between available energy and species richness. Energy was measured using the volume of the dead trees and the wood density of living trees of the same species. One hundred ninety-four logs of known tree species were surveyed 1 y for fruiting bodies of macrofungi at monthly intervals. For individual logs, log volume had a significant positive effect on macrofungal species richness. Younger logs had significantly higher species richness than older logs, and those with less apparent decay had more species than those with more decay. When logs were grouped by tree species, total wood volume and density of live wood had a significant positive effect and average log diameter had a negative effect on total species richness and abundance of the wood-inhabiting macrofungi. Macrofungal richness and abundance constantly increased with initial wood density; there was no evidence for a unimodal relationship. These results support the proposed relationship between species richness and energy.

• biodiversity
• competition
• host-specificity
• Puerto Rico

I thank Jon Bithorn, Sharon Cantrell, Zhigang Liu, D. Jean Lodge, Elvia Melendez, Jill Thompson and Jess Zimmerman for help and advice in Puerto Rico. Melinda Brady Schmit, Greg Mueller, Mathew Leibold, Mike Miller, Carol Shearer and Ellen Simms and two anonymous reviewers provided helpful comments on the manuscript. This study was financed by NSF Doctoral dissertation Improvement Grant DEB-9623523 and by grants BSR-8811902 and DEB9411973 from NSF to the Institute for Tropical Ecosystem Studies (ITES), University of Puerto Rico, and to the International Institute of Tropical Forestry, USDA Forest Service, as part of the Long-Term Ecological Research Program in the Luquillo Experimental Forest, and grant BSR-9015961 from NSF to ITES for establishment of the hurricane recovery plot.