The Endemic Plants of Chile

Rising towards the Andean mountains, are a range of altitudinal levels which vary in elevation depending on the geographical area. The foothills comprise low thickets of succulent shrubs and woody-based perennials, which give way to the Puna, generally above 3,300 m of altitude. The latter has a cold and dry climate, with summer rains, with characteristic shrubs that include species of Baccharis, Chuquiraga, Ephedra, Fabiana and Junellia; hummock forming cacti, such as Maihueniopsis species are also prevalent. The high Andean level has a lower limit of about 4,000 meters above sea level, although to the south this limit lies at lower elevations. The lower level vegetation formations include tolares, dominated by species of Parastrephia and Baccharis, followed by grasslands dominated by species of Festuca and Stipa. Finally, the queñoales (characterized by Polylepis tarapacana) and llaretales (with Azorella compacta) are characteristic of the high Andean formations. Bofedales, with low hard hummock grasses, are found at different altitudes where water is abundant due to the water table being close to the surface. The climate here extreme with temperatures below zero almost every night of the year and with daily extreme temperature between 25-30 °C. A promimanat feature of the high altitude Andes is a series of salt flats. The largest are the Atacama salt flats in the precordillera and Pedernales, Maricunga, and Pajonales. It is estimated that there are more than 60 important salt flats between the regions of Arica and Parinacota and Atacama. Salt flats are dried-up desert lakes that are formed in 'enclosed hydrographic basins' from which water can not drain away. In a desert enviroment the water is heated and evaporates faster than it is replenshed, hence the salt minerals are left behind as a solid crust.