PARENT SESSION
Contributed Oral Session 11: Invasive Species: Arid Lands
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 520 A, Level 5, Palais des congrès de Montréal
Divergence in an invading perennial grass.
Hansen, Malin1, Wilson, Scott 1, 1 University of Regina, Regina, Saskatchewan, Canada
ABSTRACT- Rapid selection in introduced plant species, which is likely to occur when a plant population colonizes a new habitat, may promote further invasions. Agropyron cristatum, a tussock grass introduced from Russia, has been planted for pasture restoration in abandoned fields across the northern Great Plains, and is invading native grasslands. We used a factorial transplant experiment to examine morphological differences between two A. cristatum populations: fields seeded with A. cristatum c 50 yr earlier (field population); and A. cristatum growing in native grassland 50 to 100 m from seeded fields (colonizing population). Transplants were grown in two habitats (field seeded with A. cristatum, and native grassland) and under two levels of competition (with and without neighbors). Transplants from field populations were significantly larger (higher number of new tillers) than transplants from colonizing populations. Transplants grown in native grassland were significantly larger than those grown in seeded fields. Also, transplants grown without neighbors were significantly larger than those grown with neighbors. There were, however, no interactions among population, habitat and competition. The lack of interactions suggests that all populations grow better in native grassland than in fields seeded with A. cristatum, which is consistent with A. cristatum invasion from seeded fields. The significant morphological difference between the populations suggests that species invasion may have caused the invading (colonizing populations) and non-invading populations (field populations) to diverge. Consequently, divergence within introduced plant species may enhance invasion and increase the threat for native plant communities.
Key words: divergence within introduced plant species, Agropyron cristatum, the northern great plains, non-native species invasion