PARENT SESSION
Contributed Oral Session 158: Invasive Species: Management, Modeling, and Dynamics
Friday, August 12, 8:00 AM - 11:30 AM, Meeting Room 518 A, Level 5, Palais des congrès de Montréal
Plant invasion into an experimental riparian restoration project.
Quinn, Lauren*,1, Holt, Jodie1, 1 University of California, Riverside, CA
ABSTRACT- In California, a great deal of money and effort is being put into large-scale removal of the riparian invader Arundo donax. However, when upstream control has not been accomplished, flood disturbance allows new A. donax propagules to arrive into these removal areas. Based on the hypothesis that plant community composition can influence a site's susceptibility to invasion by exotic plant species, small-scale experimental restoration plots were established. Three riparian species (a tree, a shrub, and a reed) were planted into experimental plots in all possible combinations in 2002. Half of the plots received A. donax rhizomes in the spring of 2003, and the other half received rhizomes in spring 2004. Both groups were followed for one year to determine sprouting timing, shoot height, and senescence date. Survival time for the 2003 planting group differed between the resident plant community types, with A. donax plants surviving for significantly shorter periods of time in shrub-only plots, shrub + reed plots, and shrub + tree plots. Shoot emergence time showed a similar, but only marginally significant, pattern. The 2004 planting group, however, did not differ in terms of shoot emergence time, shoot height, or shoot survival. By 2004, colonization of some of the experimental plots by surrounding riparian plants had begun to occur. Data for percent colonization and number and identity of colonizing species were taken. Both percent colonization and number of colonizing species were significantly decreased in shrub-only plots, shrub + reed plots, shrub + tree plots, and plots with all three species. Plots initially planted with reeds-only, trees-only, or reeds + trees were significantly colonized, primarily by shrubs. These data suggest that resident community affects invasion by A. donax when other species are excluded through weeding, and that community type affects colonization by other native species in a similar pattern.
Key words: Arundo donax, community invasibility, riparian restoration