Grant: Discovery Grants Program - Individual

Landscape structure and its interactions with disturbance regimes are key elements to consider in understanding boreal forest mosaics. Several studies have demonstrated that frequent, large and severe fires may contribute to the creation of stands lacking late successional species as these species have to reinvade by seeds from unburnt areas. Fire severity, via its control of seed-bed availability and productivity, could also influence post-fire composition and successional development. My long term objective is to understand how fire regimes control forest composition and ecological processes in the boreal forest. In the next 5 years I propose to address this objective through 3 complementary projects. The first project aims to complete the reconstruction of long-term fire regimes in the Canadian mixedwood boreal forest. Previous works included territories in Quebec and in some parts of Ontario. This proposal will cover the gap to BC. Fire cycles will be reconstructed using time since fires maps and archives, and aerial photographs (since the 1930s) will be used to delineate fires that occurred during the twentieth century. The proportion of forests originating from older fires will be estimated using year of stand initiation as measured by dendrochronology. In a second project, I will use comparable aspen stands across a transect from eastern to western Canada to assess how fire regimes, acting at the regional and landscape level, control diversity and succession at the stand level. The third project will be undertaken in the eastern boreal where aspen, spruce and fir are abundant. I will assess how fire severity controls post fire forest composition and successionnal pathways. Low severity fires would be dominated by spruce and would favour mosses and exclude aspen and fir. The proposed research introduces a new spatio-temporal approach to interpreting vegetation mosaics in the boreal forest. Anticipated results will contribute towards understanding the effects of climate change on vegetation changes by determining ecosystem resistance to changes due to climate and disturbance regimes.