Document: STE-3-35-17

Do annual brome grasses impact plant biomass in a mixed grass prairie ecosystem?

OGLE, S.M.* and W.A.REINERS

University of Wyoming, Laramie, WY 82071 USA ¹

Abstract:
Our objective was to determine if annual brome grasses, Bromus japonicus and Bromus tectorum, impact plant biomass in a mixed grass prairie. We estimated biomass for the 1996 and 1997 growing seasons at two sites, by monthly sampling a series of 40 by 50 cm plots, representing a gradient of brome abundance. In addition, we sampled five paired plots monthly in 1997; brome had been removed from a treatment plot to compare with an adjacent control plot. All shoots were clipped to estimate aboveground biomass, and two soil cores were taken to estimate belowground biomass. Roots were washed to remove sediment and sorted into live and senesced portions. All samples were oven-dried and weighed to obtain final estimates. For the C₃ site, the bromes had no relationship with aboveground biomass in May and June, but biomass decreased with increasing brome abundance in July, August, and October. The results were identical for the C₃/C₄ site, except in May when aboveground biomass increased with higher brome abundance. As for belowground, biomass declined with increasing brome abundance across all months for both sites. The paired plot experiment corroborated these findings. Overall, the evidence suggested that annual bromes create spatial variability in plant biomass.

Keywords: Plant Invasion, Biomass Production

This abstract is being presented at: 10:30 AM in session:
RESTORATION ECOLOGY AND INVASIONS