PARENT SESSION
Contributed Oral Session 113: Forest Regeneration
Thursday, August 11, 8:00 AM - 11:30 AM, Meeting Room 515 A, Level 5, Palais des congrès de Montréal
Tree growth response to gap creation: Neighbourhood competition through space and time in hardwood forests of Central Ontario, Canada.
Jones, Trevor*,1, Caspersen, John1, Domke, Grant 1, Thomas, Sean1, 1 University of Toronto, Toronto, Ontario, Canada
ABSTRACT- Selection-system management practised in the tolerant hardwood forests of Eastern Canada relies on the creation of single tree or small multiple tree gaps to maintain indefinite stand level growth. Methods currently used to project growth in this system are non-spatial, relying, for example, on stand basal area as a predictor of future basal area increment. How the size and shape of gaps and the size and location of residual trees affects tree growth through time under selection management has not been well studied. We conducted a study examining both the temporal and spatial relationships of tree growth, to gap creation. A chronosequence of harvest blocks was chosen to evaluate growth response of canopy trees to gap creation. A total of 4700 trees from four species (Acer saccharum, Fagus grandifolia, Betula alleghaniensis and Tsuga canadensis) were cored, their growth increments measured, and their neighbourhood conditions quantified by tree mapping. All species showed increased growth after gap creation; however, as seen in previous studies, a multi-year lag in growth was observed. The magnitude of both the growth increase and the length of the lag in growth response varied with tree species and tree size. To further understand the growth response of trees to gap creation, tree competition was studied using neighbourhood analysis based on both pre-harvest and post-harvest growth increments and neighbourhoods. We examined both the distance and size dependence of competition, and species-specific interactions and temporal changes in growth rate. Results indicate that tree growth increased with decreasing competition, that species-specific competitive effects are substantial, and that the magnitude of the growth change was directly related to the magnitude of the change in competition post harvest.
Key words: Tree Growth, Likelihood Modeling, Competition, Management