Melissa McCormick: Orchid Ecology

A second major theme in my research is orchid ecology. Orchids rely entirely on their mycorrhizal fungi for all nutrients as well as carbon early in life and this reliance continues to varying degrees later in life. I recently completed an NSF-funded project in collaboration with Dennis Whigham, D. Lee Taylor (University of Alaska), and Timothy Filley (Purdue University) that separated the effects of forest history, carbon source (wood or leaves), and availability of appropriate mycorrhizal fungi on orchid distribution. We found that the effects of carbon source and forest history primarily affected the germination of three orchid species through effects on the presence and abundance of appropriate mycorrhizal fungi. I am currently writing up two papers from this project.

In another orchid project with Dennis Whigham and Jay O’Neill I combined long-term population measurements and population mapping of the mycoheterotrophic orchid Corallorhiza odontorhiza with measurements of the abundance of appropriate mycorrhizal fungi in the soil and on tree root tips to separate the effects of climate and biotic factors on orchid distribution. This work will be published in an upcoming issue of Ecological Monographs. We are continuing research on this population in collaboration with Richard Shefferson (University of Georgia) to examine the effects of environmental variation on flowering and dormancy in this mycoheterotrophic plant.

I am also involved in applying studies of orchid mycorrhizal fungi to orchid conservation. I am working on a project funded by the U.S. National Park Service with Dennis Whigham and Jay O’Neill to identify the fungi associated with Isotria medeoloides in Prince William Forest Park. We will then develop specific PCR primers to examine the distribution of mycorrhizal fungi in the soil. We will be continuing this research in a new project that examines the distribution of appropriate mycorrhizal fungi in the soil around emergent and dormant plants as well as in locations where I. medeoloides occurred previously but in which it has not been seen recently. This information will be used to inform decisions about factors affecting extirpation and sites and methods for restoration.

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