Tuesday, August 4, 2009
Exhibit Hall NE & SE, Albuquerque Convention Center
Andrea N. Nord, IGDP Ecology, Department of Crop and Soil Science, The Pennsylvania State University, University Park, PA, David A. Mortensen, IGDP Ecology, Department of Plant Science, The Pennsylvania State University, University Park, PA and Emily S.J. Rauschert, Department of Crop and Soil Sciences, The Pennsylvania State University, University Park, PA
Background/Question/Methods Microstegium vimineum (Japanese stiltgrass) is highly invasive in a variety of habitats throughout the eastern US. Because it is annual, an understanding of the role of the seedbank in population persistence is critical in designing control strategies. Published evidence suggests that the seed bank persists 3-5 years, but in the ridge-and-valley province of central PA we have observed very little re-emergence in the year following suppression of seed production. In order to investigate the fate of
M. vimineum seeds in the soil, we initiated a buried seed bank study beside unpaved forest roads, in seep wetlands, and in recently harvested deciduous forest.
In fall 2007 and 2008 we enclosed freshly-harvested seeds of M. vimineum in nylon mesh bags and buried them just below the surface of the soil in existing M. vimineum populations. Seed bags were recovered in April, June, August, and October 2008. Results/Conclusions
We found no significant differences in seed fate between the habitats. There was a wide range of germination in the first year, from 13% to 98%. Fewer than 0.01% of the seeds were lost to decomposition. Thus, the percentage of seeds remaining viable entering the second winter of the study ranged from 2 to 87. We used this data, along with results from other experiments and published literature, to parameterize a subperiodic matrix population model of M. vimineum. Preliminary analysis shows that variations in seed bank parameters do not play a very large role in population persistence under normal conditions. The model was most sensitive to fecundity and to the probability of new seeds germinating and surviving to reproductive age. These were also the most important population parameters in a simulation of population growth including varying frequency of control events with almost complete suppression of seed production. However, the model with control was much more sensitive to frequency and timing of control events than to any population parameter. These results suggest that reducing fecundity is the most effective management strategy.
