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New Study on Microbes and Plant Competition

A new study published in Ecology Letters suggests there is more to plant competition than ecologists initially thought.

Plants interact with many biotic entities – from other plants and microorganisms to animals – but little is known about the relative influence each of these interactions has on determining plant growth and survival. Most plants compete with each other for resources, such as space and light. Plants also interact with microbial mutualists, which can be beneficial for the plants because these microorganisms acquire nutrients the plant needs to grow and thrive. The interplay of all these interactions determines the success and growth of an individual plant.

“The relative importance of competition versus plant soil feedback on plant performance is poorly understood,” says Stephanie Kivlin, co-author and assistant professor in the Department of Ecology and Evolutionary Biology.

Kivlin and her colleagues quantified the relative importance of plant-plant and plant-microbial interactions on plant growth across 150 difference plant species. They discovered that competitive plant-plant interactions were the main driver of plant growth, but negative plant-microbial interactions were also prevalent.

“What we discovered suggests microbes limit plant growth of the strongest competitor in a variety of natural ecosystems,” Kivlin says.

Microbes and fungi can have a significant impact on plant diversity. Without them, plants that compete best for light, water, and nutrients would dominate environments such as grasslands and forests. This study suggests microorganisms play a key role in maintaining biodiversity of plant species in natural environments.

Since this is the first work to document the relative importance of plant-plant and plant-microbial interactions, it will most likely shape the theory about when and where each of these interactions structures plant community diversity and composition.

“Our department is a hub of biodiversity and conservation research,” Kivlin says. “As we move forward as a center for biodiversity research in one of the most biodiverse areas on the planet, this work will be key in reminding us to consider the invisible microbial actors that silently structure many of the plant communities in this region and across the globe.”

The authors would like to acknowledge MPG Ranch for generously supporting the plant-soil feedback workshop that generated the ideas for this publication.

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