PARENT SESSION
Monday, August 7, 5:00-6:30 pm
Poster Session 2 - Invasive species
Exhibit Hall, Ballroom Level, Cook Convention Center

Relative importance of propagule pressure, light availability, and nutrient concentration upon the establishment and physiology of a model invasive species, Imperata cylindrica.

Holly, D. Christopher^*,1, ¹ Mississippi State University, Starkville, MS

ABSTRACT- Imperata cylindrica (L.) Beauv. is a highly invasive perennial grass that threatens agriculture, forestry, and native plant assemblages in many regions of the world. Imperata cylindrica is a prolific seed producer, but the importance of this vector of invasion has not been adequately addressed. Further highlighting the need for studies on seed-mediated spread in this species is the growing support in the ecological literature that propagule pressure plays a key role in many successful invasions. The relative importance of propagule pressure across environmental gradients is an area of research that is quickly becoming important in understanding invasion success. The present study was conducted in order to test the effects of varying propagule pressure upon the ability of I. cylindrica to grow and establish across experimentally manipulated light and soil gradients. The results point out several biologically significant trends in the establishment and growth of I. cylindrica seedlings in the experimental environments. Seedlings growing in high nutrient soils performed the best regardless of the amount of available light, but overall biomass was always greatest in high light environments. Imperata cylindrica showed a very strong trend in biomass allocation, with seedlings in reduced light environments always partitioning more biomass to aboveground tissue. The data provided no evidence that initial propagule density affected the growth and establishment of I. cylindrica seedlings, but realized propagule pressure (number of surviving seedlings) had a positive effect on growth and biomass production.

Key words: Invasion Ecology, Propagule Pressure, Imperata cylindrica