Late Holocene deforestation of a tree line site: estimation of pre-fire vegetation composition and black spruce cover using soil charcoal

Anatomical identification of soil charcoal fragments was used to reconstruct the pre-fire vegetation composition of a tree line site that burned ca 930 cal. AD in northern Quebec, Canada. Soil charcoal was also used as a proxy to estimate black spruce Picea mariana palaeo-cover. The site (a low-elevated hilltop) is presently devoid of spruce trees and dominated by dwarf birch Betula glandulosa, lichens, ericaceous shrubs (Ledum decumbens, Vaccinium vitis-idaea) and sedges. In contrast, black spruce dominated before the fire with an understory of Empetrum nigrum and Vaccinium vitis-idaea. Pre-fire black spruce cover was estimated at 32%, giving an indication of the potential for warming-induced natural reforestation of the forest-tundra.