Severe plant invasions can increase the abundance and diversity of soil-dwelling fungi.

March 26th, 2013

By: Ylva LekbergPh.D. Ecologist

Last week, we published our findings in the journal ISME. We show that invasions by knapweed and spurge, but not cheatgrass, increased arbuscular mycorrhizal fungal (AMF) abundance and diversity relative to native remnant communities. AMF can help plants acquire nutrients and protect against some plant pathogens, and are often considered beneficial. Our findings are unexpected, because the assumption has been that invasive plants seldom associate with AMF and therefore reduce AMF abundance and richness upon invasion. This, in turn, lowers the competitiveness of more AMF-dependent native plants and promotes further invasions. We argue that AMF richness and abundance are low in remnant native communities due to the dominance of grasses, because native grasses supported a lower abundance and fewer AMF species than native forbs.

The abundance of native forbs have declined in many intermountain grasslands due to the application of forb-specific herbicides used to combat exotic forb invasions. From the AMF’s perspective, exotic forb invasion is a welcome increase in good host abundance, and it does not matter if the plants are native or non-native. We will research the effects of these findings for native plant restoration. Is it possible that native forbs will thrive after knapweed?

We show that plant invasions can benefit selected soil microbial groups. What are the consequences of this for plant restoration?

About the Author

Ylva Lekberg

Ylva graduated from the Swedish University of Agricultural Sciences with a M.Sc. in Biology and Horticulture in 1996 and a Ph.D. in Ecology from Penn State University in 2004. She received the Alumni Association Dissertation Award for her work in agroecology and subsistence farming in Sub-Saharan Africa. Post-doctoral positions at Montana State University and later at Copenhagen University as a Marie Curie Fellow allowed her to explore the role of arbuscular mycorrhiza, a root-fungus symbiosis, for geothermal plants in Yellowstone National Park and coastal grasslands in Denmark. Her research has been published in international journals such as Nature Communications, Ecology Letters, and New Phytologist.

Ylva joined MPG Ranch in 2010. Since then, she has explored how invasive plants common to western Montana, including spotted knapweed (Centaurea stoebe), leafy spurge (Euphorbia esula) and cheatgrass (Bromus tectorum), influence soil microbial community composition and function, and how this in turn may affect invasive success. A lot of her research also focuses on the AM symbiosis in terms of community ecology and physiology. A current project addresses how exchange ratios in this symbiosis may differ among co-occurring plants and depend on soil nutrient availabilities. She uses surveys, field and greenhouse experiments, and literature approaches such as meta-analyses to address questions. To learn more about research and publications from Ylva and her group, see CV below and the Soils, Plants and Invasion section.

In addition to her work at MPG Ranch, Ylva is an adjunct professor at University of Montana at the Department of Ecosystem and Conservation Sciences.