Desert fog oasis

Located in the upper parts of the farellón (coastal cliffs) and in the coastal mountain range, extending along the coast of northern Chile, relict areas known as “fog oasis” are found. Here cool moisture-laden air is trapped beneath a layer of warm dry air above. As as a consequence, an adjacent stratocumulus cloud bank develops between 300 and 1200 m above sea level, developing into fog when the relief intercepts the droplets from the cloud. This quasi-constant supply of water supports unique islands of vegetation in an otherwise ocean of semi- or hyper-arid desert, leading to ultra-high levels of species endemism. Typically, the fog banks (known as camanchaca) engulf small mountains or steep coastal slopes that are south or southwest-facing; similar formations extend north into Peru where they are known as 'lomas'. These formations have two seasons, a dry season, and a humid season (mostly between July and November) with a characteristic daily cycle and when fog occurs, it provides much needed moisture. However, during El Niño events, occasional precipitation occurs during the austral winter, resulting in the development of vegetation, especially of ephemeral herbs and the replenishment of the soil seedbank. In Chile, fog oasis formations are scattered from Cerro Camaraca (close to Arica) to Llanos de Challe National Park (just north of Huasco).

Endemic Taxa in Desert fog oasis