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United States Department of Agriculture

Agricultural Research Service

Research Project: Redesigning Forage Genetics, Management, and Harvesting for Efficiency, Profit, and Sustainability in Dairy and Bioenergy Production Systems Title: Introduction risk of cultivated switchgrass in a native prairie ecosystem

Authors
item Eckberg, James -
item Johnson, Gregg -
item Shaw, Ruth -
item Casler, Michael
item Sheaffer, Craig -
item Jordan, Nicholas -
item Anderson, Neil -
item Flint, Shelby -
item Shafer, Robert -
item Wyse, Donald -

Submitted to: Ecological Society of America Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2013
Publication Date: N/A

Technical Abstract: There is growing interest in using switchgrass for bioenergy and bioproduct applications in the United States. Breeding programs are developing and releasing switchgrass germplasm with improved agronomic traits such as a rapid growth rate and increased yield. The ideal agronomic traits of bioenergy grasses are shared with many highly invasive plants and this has led to mounting concern that bioenergy grasses pose a risk of invasion. However, we lack basic knowledge to evaluate such risks; specifically, how does selectively bred switchgrass interact with other plant species or higher trophic levels? We address the following questions: 1) How does establishment and percent composition of switchgrass vary in relation to seed source (cultivar versus remnant populations) and seed density in a recently restored and remnant prairie? 2) How does switchgrass seed source and seed density influence the plant community structure of a recently restored prairie? 3) Does herbivory with resident leaf-chewing insects differ in relation to switchgrass seed source and propagule pressure? Initial switchgrass seedling emergence and end-of-season cover were over 200-300% higher for cultivars as compared to remnant switchgrass populations. The difference in establishment between cultivar and remnant switchgrass was much larger at higher seed densities. Further, high seeding densities of some switchgrass cultivars led to increased leaf area index suggesting the rapid formation of a switchgrass canopy in restored prairie. Switchgrass seed addition into established prairie, however, showed extremely low end-of-season switchgrass density despite a disturbance treatment prior to seeding. Low establishment of cultivars may have been caused by poor soil quality and insect herbivory. Frequency of insect herbivory on planted seedlings was 180-300% greater for most cultivars as compared to remnant switchgrass. These data suggest that emergent properties of switchgrass cultivars contribute to striking differences in early establishment and interactions with resident insect herbivores as compared to remnant populations of switchgrass.

Last Modified: 8/22/2014
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