Poster Session # 11: Disturbance Ecology.

Tuesday, August 5 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Clonal demography and multiple disturbances in Louisiana cane stands.

Gagnon, Paul*,1, Platt, William1, 1 Louisiana State University, Baton Rouge, LA, USA

ABSTRACT- Species-rich and monodominant plant communities sometimes occur side by side with no obvious environmental differences at their boundary. These community differences may be the result of variation in the effects of natural disturbances. We are exploring how natural windthrow affects population and genet dynamics of cane (Fam. Poaceae, Arundinaria gigantea, W. Muhlenberg). Cane occurred historically in extensive monospecific stands called canebrakes alongside diverse bottomland forests throughout the southeastern U.S. Our fieldsite in northeastern Louisiana is on the Buckhorn Wildlife Management Area within the Lower Mississippi Alluvial Valley. Here a massive tornado blowdown provides an opportunity to examine cane response to large-scale disturbances. We are conducting life table response experiments (LTREs) in the blowdown and adjacent forest to quantify 1) effects of natural windthrow gaps on cane ramet demography, 2) ramet demography of flowering cane stands, and 3) ramet demography in small, discrete stands compared to dense, continuous (canebrake-like) stands. Initial results indicate that cane culms in blowdown plots are shorter in stature and have smaller diameter than those in forest-grown plots. Cane culms in blowdown plots are younger, more vigorous and less-often damaged than those growing under forest canopy. Cane genets in blowdown plots therefore have higher average (lambda) than those in forest-grown plots. These results may indicate mechanisms underlying potential environment-mediated changes between species-rich and species-poor communities, and will be useful for canebrake and bottomland hardwood forest restoration efforts.

Key words: multiple disturbances, clonal biology, cane, bottomland hardwood forests