Prairie grasses for biofuels and ecological restoration: Modifications to native species and their place in human-modified landscapes
Michigan State University
In the 19th century, North American prairie grasses were plowed under for agricultural expansion. Nearly two hundred years later, in the 21st century, these same grasses have become key species in ecological restoration and appear likely to become equally important as novel bioenergy crops that provide ecosystem services. In these new roles, these plants’ traits are being changed through selective pressures, both intentionally and inadvertently. At the same time, human activities have fundamentally altered the landscapes in which these species are now found. To understand how propagation and selection pressures alter native prairie grasses, I conducted a suite of field and greenhouse experiments to test plant interactions with abiotic and biotic factors. Since the use of marginal lands is a major focus of sustainable bioenergy development, I established common gardens of both wild-collected and propagated populations of Andropogon gerardii (big bluestem) and Schizachyrium scoparium (little bluestem) in fertile loamy soils and marginal sandy soils to measure growth traits. To assess biofuel-valuable traits in Panicum virgatum (switchgrass), I examined relationships between growth rates and biomass recalcitrance to digestion in five populations, ranging from near-wildtype to highly selected cultivars, grown in a common garden. I then evaluated relationships between these traits and P. virgatum susceptibility to a widely distributed group of aphid-transmitted Poaceae viruses (Luteoviridae: Barley and cereal yellow dwarf viruses, B/CYDVs), which cause major yield losses in cereal crops. Significant trait differences were evident among populations of all grasses studied. Propagated populations of A. gerardii exhibited a stronger plastic response to growth on fertile soils in both biomass production and reproductive investment than did wild-collected populations. In P. virgatum, fast growth in highly selected populations was further associated with increased susceptibility to virus infection. These findings highlight the need to evaluate potential selection trade-offs between fast growth and other plant traits, particularly as native grasses are further modified for biofuel-valuable traits.
Schrotenboer AC (2011) "Prairie grasses for biofuels and ecological restoration: Modifications to native species and their place in human-modified landscapes." Ph.D. (Michigan State University, East Lansing).
Submitted by aterrab on Wed, 2012-02-01 15:41