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 cactus enthusiasts include Copiapoa, Trichocereus, 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, many 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 the Coastal Range and form an inversion layer, which mitigates solar radiation and provides enough relief for perennial plants to survive multi-annual droughts.
The mountains shown in the in the photo are a geomorphological characteristic of northern Chile and form part of the Coastal Cordillera. This mountain range continues to slowly rise from the subduction of the Nazca plate underneath the South American Continental plate.
Cacti have adapted to many arid and semi arid habitats across the Americas and some species even appear in mesic habitats and the tropics when the terrain is edaphically arid. Historically, all cacti would have had large foliage leaves to facilitate photosynthesis, while all cacti still produce leaves, many of them are small or microscopic and the body or shoots are largely responsible for photosynthesis. Spines are actually modified bud scales. Cacti have made these modifications for two main reasons; firstly to minimize total plant surface area and therefore reduce the water lost during CAM photosynthesis, secondly to defend themselves from larger 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 faces north equatorially 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 to 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