title: Common ectomycorrhizal networks may maintain monodominance in a tropical rain forest.
abstract: Most tropical rain forests contain diverse arrays of tree species that form arbuscular mycorrhizae. In contrast, the less common monodominant rain forests, in which one tree species comprises more than 50% of the canopy, frequently contain ectomycorrhizal (ECM) associates. In this study, I explored the potential for common ECM networks, created by aggregations of ECM trees, to enhance seedling survivorship near parent trees. I determined the benefit conferred by the common ECM network on seedling growth and survivorship of an ECM monodominant species in Guyana. Seedlings with access to an ECM network had greater growth (73% greater), leaf number (55% more), and survivorship (47% greater) than seedlings without such access, suggesting that the ECM network provides a survivorship advantage. A survey of wild seedlings showed positive distance-dependent distribution and survival with respect to conspecific adults. These experimental and survey results suggest that the negative distance-dependent mechanisms at the seedling stage thought to maintain tropical rain forest diversity are reversed for ECM seedlings, which experience positive feedbacks from the ECM network. These results may in part explain the local monodominance of an ECM tree species within the matrix of high-diversity, tropical rain forest.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, 830 North University Avenue, Ann Arbor, Michigan 48109, USA. mcguirek@umich.edu
authors.forename: Krista L
authors.initials: KL
authors.lastname: McGuire
mesh_terms: D000704:Analysis of Variance; D044822:Biodiversity; D006172:Guyana; D038821:Mycorrhizae / Q000502:physiology*; D036226:Seedlings / Q000254:growth & development* / Q000382:microbiology; D013045:Species Specificity; D013559:Symbiosis; D014197:Trees / Q000254:growth & development / Q000382:microbiology*; D014329:Tropical Climate