Document: DOM-3-41-1

Fire frequency and tree species abundance in a stand of boreal forest during the last 5000 years.

ARSENEAULT, D.* and L.SIROIS

University of Quebec, Rimouski, Quebec, Canada ¹

Abstract:
In this study we examine how black spruce (Picea mariana) and jack pine (Pinus banksiana) have responded to past changes in fire frequency in a small well-drained stand of boreal forest (northern Quebec). More than 300 buried tree remains were extracted from the margin of a peatland where they have fallen from the adjacent study site. Time series of past species abundance were constructed from the age-depth relationship and identification of wood remains to species. Time elapsed between successive fires was estimated from number of tree rings in wood remains. Three periods of short fire intervals (5200-4700, 4000-3100 and 1600-200 calendar years BP) and two of lower fire frequency (4700-4000 and 3100-1600 calendar years BP) characterized the last 5300 years. Close correspondence between our stand-level data and previously reconstructed episodes of fire occurrence in a large area of northern Quebec suggests climatic control of fire frequency at the study site. Tree species abundance closely followed this long-term trend of disturbance frequency, as reflected by increase of the pine to spruce ratio during periods of high fire frequency. Taken together, our results suggest a fire-mediated response of tree species abundance to climate change.

Keywords: fire disturbance, black spruce, jack pine, boreal forest, northeastern Canada, late Holocene

This abstract is being presented at: 4:15 PM in session:
Oral Session #35: Fire Ecology.