Friday, August 7, 2009: 11:10 AM
Brazos, Albuquerque Convention Center
Background/Question/Methods The high growth rate and reproductive potential of plant species proposed to be used as biofuels have raised concern about their invasive characteristics. A limitation to assess the invasion potential of a species is that current methods are qualitative and highly subjective. The development of quantitative weed risk assessment (WRA) protocols could help enhance our predictive potential to reduce the risk of introducing invasive species grown as biofuel crops. In this study, we used a population dynamics model to develop a WRA by using Camelina sativa as a model species. Specifically, we evaluated how disturbance regimes and propagule dispersal time impact the establishment of C. sativa, a species known to be tolerant of drought, frost, and poor soils. Two rangeland sites representing different environments (moist and dry) were selected for this study. The experimental design was a split plot with 18 replications between the two sites. Disturbances were applied in the fall of 2007 and 2008, and include two herbicides commonly used in rangelands, chlorsulfuron + metsulfuron and imazipic + glyphosate, and a mechanical disturbance. There was also a plot that received no disturbance. Approximately 6667 seeds m-2 were applied to half of the sub-plots after the disturbances. Seeds were applied to the other half of the sub-plots in March 2008 and 2009. C. sativa emergence and survival rates between the life stages were evaluated across the treatments.
Results/Conclusions The emergence rate averaged across all treatments at the dry site was 0.09 ± 0.078 and 0.045 ± 0.031 for spring and fall dispersal plots, respectively. The average emergence rate across all treatments was 0.149 ± 0.103 and 0.018 ± 0.029 for the spring and fall dispersed plots, respectively, at the moist site. Emergence at the dry site was greatest in the plots that received no disturbance (0.19 ± 0.13) for the spring dispersal plots. Emergence at the moist site was greatest in the mechanically disturbed plots (0.30 ± 0.11). The only plants to survive to maturity were found in the mechanically disturbed plots. Of the plants that emerged in the mechanically disturbed spring dispersal plots, 11.2 and 0.4 % survived to produce seeds at a rate of 85.63 ± 93.88 and 43.66 ± 9.07 seeds per plant at the moist and dry site, respectively. Results indicate that, contrary to previous claims, C. sativa can emerge, survive, and reproduce in rangeland conditions particularly in soil surface disturbed areas.
Results/Conclusions The emergence rate averaged across all treatments at the dry site was 0.09 ± 0.078 and 0.045 ± 0.031 for spring and fall dispersal plots, respectively. The average emergence rate across all treatments was 0.149 ± 0.103 and 0.018 ± 0.029 for the spring and fall dispersed plots, respectively, at the moist site. Emergence at the dry site was greatest in the plots that received no disturbance (0.19 ± 0.13) for the spring dispersal plots. Emergence at the moist site was greatest in the mechanically disturbed plots (0.30 ± 0.11). The only plants to survive to maturity were found in the mechanically disturbed plots. Of the plants that emerged in the mechanically disturbed spring dispersal plots, 11.2 and 0.4 % survived to produce seeds at a rate of 85.63 ± 93.88 and 43.66 ± 9.07 seeds per plant at the moist and dry site, respectively. Results indicate that, contrary to previous claims, C. sativa can emerge, survive, and reproduce in rangeland conditions particularly in soil surface disturbed areas.
