Canada
Plant-plant interactions are considered an important driver of community dynamics. Historically, competition was emphasized, leading to the expectation that plants living together result in competitive exclusion and the dominance of a few species. However, plant-plant interactions are not always negative. In this talk, I examine the function of plant-plant interactions at multiple scales to better understand their consequences for community dynamics. First, I test whether trait similarity predicts competitive intensity and instead find stronger suppression when neighbours are dissimilar, challenging common assumptions about trait-based competition. Second, I assess whether competitive ability is a species-level trait and show that species commonly both compete and facilitate, with some specializing at either end of this interaction gradient. Finally, I explore how resource manipulations, diversity, and plant social context (identity of and interactions with neighbours) affect species turnover in a native grassland. Nutrient addition, but not light removal, drove species loss, and communities with more positive species co-occurrences were less invasible. I conclude by outlining how plant–plant interactions may be used to inform restoration planning.
Presenter: Emily Holden is a Vegetation Ecologist at the Alberta Biodiversity Monitoring Institute. Her work brings a trait-based lens to the drivers of plant diversity and community dynamics, with a special focus on grasslands