PARENT SESSION
Poster Session 3: Aquatic Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 210 D, Level 2, Palais des congrès de Montréal
Competitive ability of a species along a successional gradient: growth, turnover rates and plant size.
O'Hara, Jill*,1, Ryser, Peter1, 1 Laurentian University, Sudbury, Ontario, Canada
ABSTRACT- Plant species characteristic of different stages of secondary succession tend to differ in their leaf characteristics, such as specific leaf area (SLA), tissue dry matter content (DMC) and leaf lifespan: Fast-growing species with high SLA, low dry matter content and short-lived dominate initially, being then replaced by species with low SLA, high DMC and a long leaf life span. This is often thought to be a result of decreasing nutrient availability in course of a secondary succession. In the present work we tested to what extent the change in species characteristics along a successional gradient is influenced by nutrient availability, and to what extent the change is a result of the disturbance itself. We conducted an experiment with sixteen herbaceous species of northern Ontario wetlands, growing them in monocultures, and in four mixtures of four species, based on taxonomic grouping: the family Poaceae, the genus Carex, other monocots, and dicots. The plants were grown at high and low nutrient levels, and each species-group contained species with contrasting leaf lifespan. We monitored the species abundance (point-quadrat method) in the first growing season after the set-up of the experiment ("disturbance"), and will continue this monitoring in the second year. The first-year results show that species respond differently to competition, but this response is only weakly influenced by nutrient availability. Species response to competition in the first year was not related to its leaf-life span.
Key words: disturbance, succession, leaf life span, turnover