Abstract Detail

Symbioses: Plant, Animal, and Microbe Interactions

Ellenwood, Jalynn [1], Johnson, Shaylee [2], Garcia-Kerboul, Marjorie [3], Helzer, Christopher [4], Pec, Gregory [5].

Repeated defoliation mediates growth and alters the composition of root-associated fungi in big bluestem (Andropogon gerardii) seedlings.

Prairie ecosystems are extensively impacted by land use changes such as grazing and fire, which also vary in both their frequency and intensity on the landscape. Of these, grazing has shown to have a significant impact on the composition, diversity, and functioning of prairies due, in part, to its influence on aboveground plant productivity. Less understood is the response of roots and their associated microbial communities to sudden reductions in leaf and stem tissues due to varied levels of grazing intensity and frequency. Toward this goal, a glasshouse experiment was conducted to characterize the magnitude of growth for big bluestem (Andropogon gerardii) seedlings, a perennial grass commonplace within native prairie systems, under varying intensity (i.e., non-grazing, low, high) and frequency (i.e., one vs. multiple) of simulated defoliation. As root-associated microbes, particularly fungi, play vital roles in enhancing the nutrient uptake and overall seedling survival of their hosts, a secondary objective was to explore any relationships between root-associated fungal communities (i.e., soil inoculated vs. non-inoculated) and plant growth following defoliation. Overall, defoliated seedlings showed biomass accumulation under low simulated defoliation intensity and frequency. However, under high levels of simulated defoliation intensity and frequency, growth of seedlings was altered, leading to increased root-to-shoot ratios. In the absence of root-associated fungi, there were declines in the growth of defoliated seedlings. Moreover, changes in the composition of root-associated fungal communities driven by high levels of simulated defoliation intensity and frequency resulted in decreases of above-ground tissues of seedlings. Taken together, lower grazing intensity and frequency may produce the most beneficial effects on perennial grasses, such as A. gerardii, and are mediated through effects of belowground fungal mutualists.

1 - University Of Nebraska At Kearney, Department Of Biology,, 2401 11th Ave, Rm. 335, Kearney, NE, 68849, USA
2 - University Of Nebraska, Biology, 2401 11th Ave, Rm. 335, Kearney, NE, 68849, United States
3 - University Of Nebraska At Kearney, Department Of Biology, 2401 11th Ave, Rm. 335, Kearney, NE, 68849, USA
4 - The Nature Conservancy, Eastern Project Office, Aurora, NE, 68818, USA
5 -

Keywords:
Andropogon gerardii
defoliation
root-associated fungal communities.

Presentation Type: Oral Paper
Number: SYM2004
Abstract ID:777
Candidate for Awards:None