Sugar maple (Acer saccharum) forests at their northern distribution limit are recurrently impacted by fire

Abstract

The sugar maple (Acer saccharum Marsh.) forest is a widespread temperate forest prevailing south of 48°N in Quebec. Windthrows are the principal disturbance maintaining the old-growth status of the forest supposedly since its postglacial establishment. Nonetheless, the presence of wood charcoal buried in several sugar maple forest soils attests to the occurrence of fire during the Holocene. In this study, we aimed to elucidate the long-term fire dynamics and species composition of three sites (Témiscamingue, Saguenay, and Gaspé peninsula) currently dominated by sugar maple situated at its northern range limit. The botanical identification and 14C dating of charcoal fragments extracted from the soil surface and the mineral soil indicate that the development of the sugar maple sites was influenced by recurrent fires at least over the last 1000 to 3500 years. Two of the studied sugar maple stands are of recent origin, with the Témiscamingue forest being established after the most recent fire in the late 18th to early 19th centuries. Our data highlight the resilience of sugar maple forests in a disturbance regime dominated by frequent fires and suggest that the northernmost sugar maple forests are young ecosystems at the Holocene timescale.