Chile – About Habitat
Cactus Habitats of Chile
Chile is home to over 140 species of cacti, most of which are located in Chiles north between 18° to 32°S. Popular genre among cacti enthusiasts include Copiapoa, Echinopsis, Eriosyce and Eulychnia.
Northern Chile comprises the driest non-polar desert in the world – the Atacama Desert – receiving an average of 1-70mm of precipitation annually depending on the exact location. Many species of cacti call the Atacama Desert home and have evolved to use water sparingly, but these are some extremely hyper-arid conditions. Why is The Atacama Desert so dry? And how can cacti survive here?
The aridity of the Atacama Desert results from a combination of three main factors: the cool Humboldt current, the presence of a strong Pacific anticyclone and a two-sided rain shadow caused by the Andes and the Chilean Coastal Cordillera. Curiously, most coastal Chilean cacti are streamlined directly along the Coastal Cordillera. They are growing here because stratocumulus could banks, that form from the cool Humboldt oceanic current, collect themselves against coastal cliffs and form an inversion layer, which provides all plants living in these oasis with the precipitation and protection from extreme solar radiation to survive.
The mountains shown in the in the photo are a geomorphological characteristic of northern Chile and are located in Pan de Azúcar National Park. The Coastal Cordillera continues to slowly rise from the subduction of the Nazca plate underneath the South American Continental plate.
To survive, cacti needed to adapt to the extreme, hyperarid conditions of the Atacama desert. Thousands of years ago, cacti would have had leaves to facilitate photosynthesis, but the body of a cactus is now responsible for photosynthesis and the leaves have evolved into spines for two main reasons. The first is to minimize total plant surface area and therefore reduce the water lost during photosynthesis, the second is for defence from herbivores.
The field of Copiapoa cinerea subs. columna-alba (pictured) is located in Pan de Azúcar National Park. It’s fascinating how this Copiapoa species all face north to the equator with such accuracy. This is because they are in the southern hemisphere, and also south of The Tropic of Capricorn – the suns southern most zenith, and are positioning their crown, or apices, to the north receive the most solar radiation possible for photosynthesis.
The same phenomenon occurs with Ferocactus living in the Sonoran Desert, USA. The barrel cactus in the northern hemisphere generally face south equatorially for the same reasons. Such species are colloquially known as ‘compass cacti’.
- Ehleringer, J., Mooney, H. A., Gulmon, S. L., & Rundel, P. (1980). Orientation and its consequences for Copiapoa (Cactaceae) in the Atacama Desert. Oecologia, 46(1), 63-67. doi: 10.1007/BF00346967
- Mauseth, J. D., Kiesling, R., & Ostolaza, C. (2002). A cactus odyssey: journeys in the wilds of Bolivia, Peru, and Argentina. Timber Press (OR).
- Miesen, F., Eugenia de Porras, M., & Maldonado, A. (2015). Pollen morphology of Cactaceae in Northern Chile. Gayana Botanica, 72(2), 258-271.
- Moreira-Muñoz, A. (2011). Plant Geography of Chile. Springer Science & Business Media, United Kingdom. 368 pp.
Schulz, R. (2006). Copiapoa. Schulz Publishing, Teesdale, Australia.
- Warren, S. D., Aguilera, L. E., & Baggett, L. S. (2016). Directional orientation of reproductive tissue of Eulychnia breviflora (Cactaceae) in the hyperarid Atacama Desert. Revista Chilena de Historia Natural, 89(1), 10. doi: 10.1186/s40693-016-0060-z