Palaeoecological study of Pyrenean lowland fir forests: Exploring mid-late Holocene history of Abies alba in Montbrun (Ariège, France)

Fir (Abies alba Mill.) occupies an important place in the Pyrenean context, where the species finds its optimal conditions in this mountain zone (800-1800 m a.s.l.). In the Pyrenees, the fir woods of Volvestre (Ariège, France) are of particular interest because of two peculiarities of its location: its northern latitude with respect to the usual location of fir in the Pyrenean axis, and its lower altitude (330-440 m a.s.l.). This has given rise to various theories, some considering the silver fir forests as a glacial relic and others pointing to anthropogenic interference and possible plantings during the Middle Ages. Pedoanthracological and palynological studies have been performed to establish the origin and history of this ancient forest, and both approaches show an ancient anthropized landscape with a continuous presence of Abies alba throughout the mid- and late-Holocene. The fir woodlands of Volvestre are testimonies to the ancient and significant presence of fir on the northeast slope of the Pyrenees and the current suitability of this species for lowland areas. Pedoanthracological sampling inside the forest has shown differences in vegetation dynamics at different valley points (north slope, south slope, and valley bottom).