Wednesday, August 6, 2008: 9:20 AM
103 DE, Midwest Airlines Center
Background/Question/Methods Proliferation of alien invaders can alter the disturbance regimes of native plant communities. Autumn olive (Eleaegnus umbellata Thunb.) is an invasive Asian shrub that is spreading rapidly in the understories of upland hardwood forests of southern Illinois . The long-held policy of fire suppression in this region has resulted in several fire free cycles and is coincident with establishment of this species, as well as many other non-natives. These forests have not historically contained a woody shrub layer, and it is unknown what effects this new mid-story is having on forest regeneration and the ability of managers to restore fire to the landscape. We established an experiment at Crab Orchard National Wildlife Refuge to determine if this shrub has an effect on fuel loads and flammability, and if prescribed fire can be used effectively as a management tool. Plots were established in six areas of the refuge, and each of the 48 plots was assigned to one of four autumn olive treatments/conditions: absent, abundant, removal, and litter. Like the abundant plots, removal and litter plots had abundant autumn olive present, but all of the stems were cut at the base and a cut stump herbicide treatment was applied; debris from the treatment was left in situ in the litter plots. Prior to the removal treatment, each autumn olive genet was tagged and the number of stems recorded. Duff depth, fuel depth, and amount of coarse woody debris were quantified for each plot using a planar intersect method. Plots in three of the areas were burned in 2007. The autumn olive census and fuel measurements were then repeated in the growing season after the prescribed fire.
Results/Conclusions The amount of fuel consumed by the prescribed fires did not differ among the treatments, but the surface area burned was significantly greater in plots where autumn olive had never invaded. Prescribed fire had no effect on autumn olive abundance or mortality. Our results suggest that heavy infestations of autumn olive can inhibit the spread of fire in oak-hickory forests and possibly render prescribed fire ineffective as a control measure and tool for managing native members of the community that rely upon those periodic disturbances.
Results/Conclusions The amount of fuel consumed by the prescribed fires did not differ among the treatments, but the surface area burned was significantly greater in plots where autumn olive had never invaded. Prescribed fire had no effect on autumn olive abundance or mortality. Our results suggest that heavy infestations of autumn olive can inhibit the spread of fire in oak-hickory forests and possibly render prescribed fire ineffective as a control measure and tool for managing native members of the community that rely upon those periodic disturbances.
