PARENT SESSION
Contributed Oral Session 135: Invasive Species: Plant - Soil Feedbacks; Invasion Success
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 518 A, Level 5, Palais des congrès de Montréal

Wax myrtle controls recruitment of Chinese tallow and native wetland species in a Louisiana floating marsh.

Battaglia, Loretta^*,1, Inczauskis, Jason¹, ¹ Southern Illinois University, Carbondale, IL

ABSTRACT- Chinese tallow is an invasive tree in the floating marshes of Louisiana. Prior studies have shown that tallow is most abundant where wax myrtle, a native nitrogen-fixing shrub, is present. It is unknown whether this is due to high seed dispersal into the thickets, reduced competition with herbaceous species, or if soil features of the thicket promote its germination. We collected soil from three dense wax myrtle thickets, three sparse thickets, and three open marsh sites. Tallow seeds were collected in the field, cold-stratified, and sown into flats containing the soils. Seed germination was highest in soils taken from dense thickets; few seedlings emerged from the open marsh soils. Aboveground biomass and diversity of seedbank recruits exhibited an inverse relationship with number of tallow germinants. Polygonum spp. and Galium tinctorium were the dominant recruits from the open marsh seedbank, while Polygonum spp. and Ptilimnium capillaceum dominated soils with sparse wax myrtle. Recruitment from dense wax myrtle seedbanks was lowest with few species present. Germination patterns did not change after harvest of standing vegetation. Collectively, our results suggest that soil chemistry of dense thickets, rather than high dispersal rates or herbaceous competitors, drive tallow germination in floating marsh communities.

Key words: invasive species, Chinese tallow, facilitation, wetlands