PARENT SESSION
Poster Session 20: Invasive Species
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Effects of mowing on seed dispersal and patch growth of cut leafed teasel (Dipsacus laciniatus.
Parrish, Judy*,1, 2, Oliver, Amanda1, Wiedenmann, Robert2, Post, Susan2, Helm, Charles2, Timpe, Megan1, 3, 1 Millikin University, Decatur, IL2 Center for Ecological Entomology, Illinois Natural History Survey, Urbana, IL3 Illinois State University, Normal, IL
ABSTRACT- We measured the impact of mowing on changes in patch sizes of the invasive weed, Dipsacus laciniatus, at the Mascoutin Recreation Area in DeWitt County,IL. Nine sets of discrete patches of teasel were paired according to habitat, location, and teasel density. One plot of each pair was mowed in 2001 and 2002. Distances from the center to the edge of plots were measured in each of eight compass directions in June 2001 - 2003. Mowed patches grew significantly more in area (33 m2) than did unmowed patches (4.2 m2). We found that the unmowed plots were significantly more dense to the east of the plot, consistent with wind dispersal. There was no difference in direction of plot growth for mowed patches. Density of all life stages of teasel was greater in unmowed plots north, south, and east of the original patch as compared to mowed plots, and higher to the west in mowed plots. A recovery study of ten marked teasel heads showed that mowing dispersed 95% of seeds within 6 meters of origin, but that over 1% were moved more than 10m from the origin by the mower. Mowing may be responsible for dispersing teasel seeds far beyond natural wind and water mechanisms, and results in faster enlargement of patches of cut-leafed teasel.
Key words: dipsacus laciniatus, natural area management, invasive species, mowing