PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Response of understorey vegetation to gaps in Populus tremuloides dominated forests in northeastern Ontario, Canada.
Hill, Steven*,1, Mallik, Azim2, Chen, Han2, 1 University of Toronto, Toronto, ON, Canada2 Lakehead University, Thunder Bay, ON, Canada
ABSTRACT- Despite many studies on stand-replacing disturbance in the boreal forest, there are few that examine the role small-scale disturbances during early stages of forest development. This is surprising since tree senescence during the break-up of the initial post-disturbance cohort defines an important ecological stage of boreal forest development. In this study we provide evidence that gap formation during the development of Populus tremuloides dominated forests is similar across different regions in Canada by comparing data from three independent studies. In a study conducted in northeastern Ontario, Canada, we also show that fungal pathogens are a frequent cause of direct or indirect tree mortality resulting in gap formation. However, abundance and growth of potential gap fillers was not affected by gaps of different size and age. Also, community structure of vascular plants in the understorey was not significantly affected by gaps. Despite the frequent occurrence of gaps during the break-up of the initial post-disturbance cohort dominated by P. tremuloides, understorey vegetation has a negligible response. This has two important implications for silvicultural systems that ascribe to the emulation of natural disturbance as a management method: first, gap creation alone is unlikely to be a strong predictor of canopy turnover; second, vascular plant communities are generally resistant to changes in overhead canopy closure.
Key words: Populus tremuloides, stand development, gap dynamics, boreal forest