Soilborne fungi have host affinity and host-specific effects on seed germination and survival in a lowland tropical forest

Carolina Sarmiento, Paul Camilo Zalamea, James W. Dalling, Adam S. Davis, Stump M. Simon, Jana M. U'Ren, A. Elizabeth Arnold

Research output: Contribution to journalArticlepeer-review

89 Scopus citations


The Janzen-Connell (JC) hypothesis provides a conceptual framework for explaining the maintenance of tree diversity in tropical forests. Its central tenet - that recruits experience high mortality near conspecifics and at high densities - assumes a degree of host specialization in interactions between plants and natural enemies. Studies confirming JC effects have focused primarily on spatial distributions of seedlings and saplings, leaving major knowledge gaps regarding the fate of seeds in soil and the specificity of the soilborne fungi that are their most important antagonists. Here we use a common garden experiment in a lowland tropical forest in Panama to show that communities of seed-infecting fungi are structured predominantly by plant species, with only minor influences of factors such as local soil type, forest characteristics, or time in soil (1- 12 months). Inoculation experiments confirmed that fungi affected seed viability and germination in a host-specific manner and that effects on seed viability preceded seedling emergence. Seeds are critical components of reproduction for tropical trees, and the factors influencing their persistence, survival, and germination shape the populations of seedlings and saplings on which current perspectives regarding forest dynamics are based. Together these findings bring seed dynamics to light in the context of the JC hypothesis, implicating them directly in the processes that have emerged as critical for diversity maintenance in species-rich tropical forests.

Original languageEnglish (US)
Pages (from-to)11458-11463
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number43
StatePublished - Oct 24 2017


  • Diversity
  • Janzen-Connell
  • Pathogen
  • Pioneer species
  • Soil seed bank

ASJC Scopus subject areas

  • General


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