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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #341024
Title: Mycorrhizal colonization and its relationship with plant performance differs between exotic and native grassland plant species

Author
item SIELAFF, ALEKSANDRA - IOWA STATE UNIVERSITY
item POLLEY, HERBERT
item FUENTES-RAMIREZ, ANDRES - IOWA STATE UNIVERSITY
item HOFMOCKEL, KIRSTEN - PACIFIC NORTHWEST NATIONAL LABORATORY
item WILSEY, BRIAN - IOWA STATE UNIVERSITY

Submitted to: Biological Invasions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/2019
Publication Date: 2/21/2019
Publication URL: http://handle.nal.usda.gov/10113/6436803
Citation: Sielaff, A.S., Polley, H.W., Fuentes-Ramirez, A., Hofmockel, K., Wilsey, B.J. 2019. Mycorrhizal colonization and its relationship with plant performance differs between exotic and native grassland plant species. Biological Invasions. 21(6):1981-1991. https://doi.org/10.1007/s10530-019-01950-w.
DOI: https://doi.org/10.1007/s10530-019-01950-w

Interpretive Summary: Invasions by non-native or exotic plants are transforming grasslands worldwide. Yet, we have incomplete understanding why exotics are favored. Native species form potentially symbiotic relationships with soil arbuscular mycorrhizal (AM) fungi. Fungi acquire carbon required for growth from plant roots whereas plants benefit from the additional uptake of soil elements, such as phosphorus, through the hyphae of attached AM fungi. We examined the relationship between plant growth and root colonization rates by AM fungi for native and exotic grassland species in order to test the prediction that AM colonization provided a disproportionate benefit to growth of exotic plants. Eleven native and 11 exotic species were grown in monocultures in a common garden environment in Central Texas, USA. Each native species considered was matched with a closely related exotic species. Exotic species had significantly higher colonization rates than native species for all groups of plants examined, including forbs and warm- and cool-season grasses. Contrary to our prediction, greater AM colonization benefited growth of native species only. AM fungi apparently have neutral or even negative (pathogenic) effects on exotics. Our results indicate that factors other than AM colonization are contributing to the success of exotic grassland species.

Technical Abstract: Grassland plants commonly enter associations with arbuscular mycorrhizal (AM) fungi. These associations can be positively correlated with aboveground biomass production. However, it is poorly understood how exotic and native plant species differ in their mycorrhizal colonization rate in human altered landscapes, and how colonization rate is related to establishment success. We determined the colonization rates by AM fungi and plant growth in monocultures of 11 native and 11 exotic species that were paired based on their functional and phylogenetic group. The plots were established in a common garden environment in Central Texas, USA. Roots were collected from plants, stained with ink, and the percentage colonized was assessed with a microscope. Exotic species had significantly higher colonization rates than native species, and this result was consistent across functional groups. In contrast to our predictions, colonization was correlated with aboveground biomass only in native species. Although exotics had higher colonization rates than natives, the colonization was not a good predictor of successful invasion (i.e., average aboveground biomass over time). Our results indicate that higher colonization rates in exotic species in their novel ranges may be of neutral or even pathogenic character rather than mutualistic in comparison to native species.