PARENT SESSION
Poster Session #4: Invasions.
Monday, August 6, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall

Dispersal, reproduction and physiological ecology of two invasive non-indigenous fern species; Lygodium microphyllum and L. japonicum.

Lott, Michael¹, Volin, John ¹, Owen, Dianne¹, ¹

ABSTRACT- One of the greatest threats to the integrity of native ecosystems is their invasion by non-indigenous species. Nowhere else in the continental United States is this threat more conspicuous than in Florida. Lygodium microphyllum and L. japonicum are two recent invaders that are spreading through Florida's native ecosystems. Once established in a community, these two species appear to displace native species and alter local fire ecology. L. microphyllum, in particular, can completely dominate a native habitat with time, causing the collapse of the natural community. We are studying both their reproductive strategies and their relative growth rate at different light levels. Preliminary analysis suggests that both species are capable of intragametophytic selfing, which supports the hypothesis that the spread of both species is partially explained by their reproductive strategies. Since spores are dispersed readily by wind, the ability of a single spore to form a sporophyte will aid in the ability of both species of Lygodium to rapidly infest new habitat. Early results also show that both Lygodium species have a growth advantage in low light irradiances compared to native species, the causes for this apparent advantage in low light are still being determined. With these studies, we expect to increase our understanding of the ecology and physiology of these highly invasive species. This, in turn, may assist land managers develop strategies to prevent and control the spread of Lygodium .

KEY WORDS: invasive, reproduction, relative growth rate