La Souche is a commune in the Ardèche department in southern France. The commune is located in the Parc naturel régional des Monts d'Ard…La Souche is a commune in the Ardèche department in southern France. The commune is located in the Parc naturel régional des Monts d'Ardèche 15 km east of Aubenas; its main hamlets are located on the right bank of the river Lignon, which rises in the commune's western part, then flows east through the commune.