PARENT SESSION
Poster Session 20: Invasive Species
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Neighborhood effects of N-fixing Morella faya on understory plant nutrients and soil N cycling.
O'Brady, Caitlin*,1, Creveling, Jc*,1, Hall, Sharon1, 1 Colorado College, Colorado Springs, CO, USA
ABSTRACT- Nitrogen fixers significantly alter soil and foliar nutrient cycling in N limited ecosystems, but less is known about the spatial extent to which N fixers can change their environment. We measured soil N transformation rates and foliar carbon and nitrogen concentrations in 5 understory plant species along transects away from exotic, N-fixing Morella faya trees in a N-limited tropical forest in Hawaii Volcanoes National Park. Net N mineralization and net nitrification rates in soils directly below M. faya (0.359 ug g -1 day-1 and 0.596 ug g-1 day-1, respectively) did not differ from those up to 2.5 meters from the edge of the canopy (-0.088 ug g-1 day-1 and 0.448 ug g-1 day--1, respectively) but were significantly larger than those seven meters from the canopy edge (-0.170 ug g-1 day-1 and 0.000 ug g-1 day-1). Similarly, preliminary results show that C/N ratios of understory plants within 2.5 meters from the canopy edge are significantly lower (C/N 25.4) than those that are 7 meters from the canopy edge (C/N 29.9). M. faya appears to alter nutrient cycling withing several meters outside its canopy but has little effect at greater distances.
Key words: Morella faya, nitrogen fixation, neighborhood, foliar nutrients