The glacial cirques of Lac Noir (Black Lake) and Lac Blanc (White Lake) are part of the Two Lakes Biological Reserve. They are home to rich and diverse biological life with numerous remarkable and sometimes rare species from the Vosges mountains. Black Lake's banks are surrounded by trees such as the mughos pine, introduced during the German occupation of World War II. Some beech groves mingle there, punier as the altitude increases. The area is also home to Nordic lakes species such as the lake quillwort (Isoetes lacustris) and the small water lily (Nuphar pumila).