The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council. |
Tuesday, January 29, 2008
1
Methods to Select Promising Native Grass Genotypes as Competitors with Introduced Invasive Weed Species
Franklin P. Bartlett1, Ann L. Hild1, Karin E. Bergum1, Brian A. Mealor2, and Thomas Smith3. (1) Department of Renewable Resources, University of Wyoming, Box 3354, Laramie, WY 82071-3354, (2) The Nature Conservancy in Wyoming, 258 Main St., Suite 200, Lander, WY 82520, (3) U.S. Army Corps of Engineers, ERDC-CERL, P.O. Box 9005, Champaign, IL 61826
Interactions between native and introduced plant species have been extensively studied but little research has examined germination of individual genotypes that co-exist with introduced invasive weed species. Recent research suggests that native species may undergo selection and co-evolve in the presence of exotics. We examine genotypes of Sporobolus airoides Torr. (alkali sacaton) and Hesperostipa comata (Trin. & Rupr.) Barkworth (needle and thread) obtained from within invaded patches (IN) of Acroptilon repens L. (Centaurea repens, Russian knapweed) and from outside of invaded patches (OUT). We unite results of several experiments with maternal plant seed weight, germination, above- and below-ground growth and competitive response of grasses against Cirsium arvense L. Scop. (Canada thistle) and A. repens, and performance of weeds against grasses to rank individual genotypes for their potential to compete with invasive weeds. We assign a performance ranking to each genotype within the two grass species based on how each performed in all experiments. We ranked performance on a 1-20 scale within each experiment. To assess promising genotypes, we assigned a performance index to each genotype by totaling the number of experiments where genotypes ranked in the top 10 and totaling the times they ranked below this level. Promising genotypes were determined by superior number of high performance rankings (top 10 finishes). Our performance index allows us to select promising genotypes of S. airoides and H. comata that may resist reinvasion of C. arvense or A. repens competition. The notion that individual genotypes of native grasses may persist under selective regimes to better compete with invasive species may allow for improved success in revegetation in areas subjected to exotic populations.