PARENT SESSION
Contributed Oral Session 122: Invasive Species: Pollination - Dispersal
Thursday, August 11, 8:00 AM - 11:30 AM, Meeting Room 521 A, Level 5, Palais des congrès de Montréal
Competition and coexistence of two congeneric invasive thistles.
Rauschert, Emily *,1, Shea, Katriona1, 1 The Pennsylvania State University, University Park, PA
ABSTRACT- Carduus nutans and C. acanthoides are invasive thistles that cause considerable economic damage worldwide. These species are found in similar habitats in Pennsylvania, although they do not usually co-occur at smaller scales. Seed dispersal is extensive and both species occur across the US, so this pattern suggests that they do not readily coexist at local scales. To explore the potential mechanisms underlying their distributions, a series of resource-response experiments, manipulating both percent composition and density, were conducted in a pasture setting, and a simulation model was developed. Two experiments focused on interactions at the seed and seedling stages, and one focused on seedling through adult stage interactions. Contrary to expectation, the first experiment did not detect significant intraspecific density dependence; however, a weak interspecific effect was found. Results from the seedling through adult experiment show that, once they are established as rosettes, they do not seem to be greatly affected by competition from nearby conspecific or congeneric individuals.
Key words: Carduus, coexistence, competition