COS 83-7
Comparing the invasive characteristics of a US non-native forage grass with its Czech Republic wildtype
Concerns with invasive species have included exotic forage grasses that have undergone extensive breeding and development programs for higher success of establishment. These grasses have been widely distributed for soil erosion control and livestock forage production throughout the United States and as a result many of these species have escaped their intended boundaries and become invasive in native habitats. To determine whether plant breeding procedures developed the invasiveness of these exotic grasses relative to their native counterparts, we assessed the competitiveness of an old world bluestem (Bothriochloa ischaemum; OWB) a known invader of the Great Plains in the United States, relative to its "wildtype" from the Czech Republic, and two native tallgrass prairie grasses (big bluestem [Andropogon gerardii] and little bluestem [Schizachyrium scoparium]). To assess interspecific and intraspecific competition between species a substitutive design greenhouse competition experiment was conducted in Stillwater, Oklahoma with partners from the Czech University of Life Sciences. Sixty pots filled with native soil were planted with all pair-wise combinations of species (total of ten species combinations; six replications). Measurements of above and belowground biomass, percent arbuscular mycorrhizal fungi (AMF) root colonization, and soil nutrients were quantified after fourteen weeks to determine dominance of each species.
Results/Conclusions
Contrary to our hypothesis, there was no significant difference between above- or belowground biomass produced between the wildtype and the invasive OWB cultivar when paired together or with themselves. Previous research on OWB indicates that when OWB was grown in competition with a native species (S. scoparium or A. gerardii) OWB aboveground biomass production was significantly greater, due to reduced intraspecific competition. Consistent with previous research, our study found that the invasive US OWB cultivar produced significantly greater aboveground biomass than the native grasses (S. scoparium and A. gerardii) by 260% and 152% respectively. Additionally the wildtype OWB also produced significantly more aboveground biomass then the native grasses (223% and 213% respectively). Previous studies propose an additional aspect of OWB superior competiveness is altering native fungal communities. Preliminary results on percent of AMF root colonization suggest that both the wildtype and invasive OWB experienced lower colonization when grown with conspecifics. However, percent colonization of the OWB cultivars was noticeably higher when grown together with a native grass. In determining whether the US inadvertently bred invasive characteristics into OWB our study suggests that the invasive characteristics of the US OWB cultivar are also present it the wildtype.