Canadian Forest Service Publications
Ecological controls on post-fire vegetation assembly at multiple spatial scales in eastern North American boreal forests. 2015. Boiffin, J.; Aubin, I.; Munson, A.D. 2015. Journal of Vegetation Science 26:360-272.
Issued by: Great Lakes Forestry Centre
Catalog ID: 35915
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A taxonomic and a trait-based approach were combined to evaluate the relative influence of habitat characteristics, burn severity and biotic processes on understorey regeneration at multiple spatial scales. Sampling of understorey vegetation cover was carried out in 133 recently burned plots located in 14 different fires across a 600-km transect. The spatial hierarchy for sampling consisted of five fire regime zones (regional scale), two to four fires within each zone (landscape) and two to four toposequences within each fire (local). The environmental control of fire severity and habitat characteristics on understorey regeneration was assessed using a canonical redundancy analysis (RDA) and variation partitioning. We investigated environmental and biotic filters of species traits at different scales by modelling trait–spatial assemblages with Moran eigen vector maps (MEMs). Results
In spite of the large variability of environmental conditions covered by our sampling design, low depths of burn were measured in the large majority of the studied sites. Incomplete consumption of the forest floor is frequently observed in eastern boreal forests characterized by long fire cycles. In situ biological legacies persisted through the low-severity fires, which conserved the pre-fire relationships between plant communities and their environment. As a result, fire severity was neither the unique nor the dominant control on post-fire regeneration. Habitat characteristics explained a three times higher proportion of variation in species composition. Biotic controls on trait assemblage increased at the two finer scales.
Plain Language Summary
Many of the mechanisms that shape the recovery of plant communities after a forest fire remain little known. We investigate the impact of fire severity on the recovery process, and ask which habitat characteristics may be most important in shaping these biological communities afterwards. The functional trait approach has been developed to better understand plant communities by simplifying each species into a suite of characteristics that matter for ecosystem processes. Here we combine this and a more traditional species-based approach to examine the post-fire communities of black-spruce dominated forests of eastern Canada. We find that fire severity is not the best predictor for community recovery after fire in this region. This is largely because fires tended not to consume the organic soil layer entirely, allowing some species to form shoots from persistent buds or sprout from their seed bank. Instead, we find that habitat characteristics explained the most variation. This study shows that, in forests affected by low severity fires, habitat characteristics like pre-fire community composition are better predictors of community recovery than fire severity.