The site of Serre-Ponçon lake has a remarkable biodiversity linked to an important altitudinal gradation - from 2,624 feet (800 m) to 7,874 feet (2,400 m) - and to a pivotal location between the intermediate southern Dauphinoise Alps and the internal Alps subject to a marked Mediterranean influence. Its location at the transition between hills and mountains as well as its highly contrasted geological and climatic environment explain the presence of a rich and diverse vegetation.