Deserts of Coastal Peru
and Northern Chile

What are Lomas Formations

Floristic Checklist

Locality Checklists

Lomas Images

Lomas Localities

Lomas Map

The Deserts of Coastal Peru and northern Chile form a continuous belt along the western escarpment of the Andean Cordillera for more than 3500 kms from the Peru/Ecuador border (5°00'S) to northern Chile (29°55'S) . Seasonal fog allows for the development of rich fog-zone vegetation termed, lomas formations. These unusual plant communities have been the focus of an ongoing research project by Field Museum botanist, Michael Dillon. The formations have been visited repeatedly since 1983 and collecting has led to the discovery of several species new to science, including Tillandsia tragophoba - family Bromeliaceae (Dillon, 1991), Griselinia carlomunozii - family Griseliniaceae (Dillon & Muñoz-Schick, 1993), and Astragalus neobarnebyanus - Leguminosae (Gómez-Sosa, 1986).

The project generated a specimen-oriented database [LOMAFLOR] initiated to manage specimen label information for the plants of western, coastal South America (see Database Activities). LOMAFLOR currently contains over 9000 records (Jun 2010) representing ferns, gymnosperms, and flowering plants recorded from coastal Peru and northern Chile. A new searchable database, including scaned herbarium sheets, is hosted by the Field Museum and can currently be accessed at the following link: Go to LOMAFLOR


For nearly 3500 km along the western coast of South America [5-30 deg.S], the Peruvian and Atacama deserts form a continuous, hyperarid belt, broken only by occasional rivers valleys from the Andean Cordillera. Native vegetation of the deserts consists of over 1200 species, many highly endemic and largely restricted to the fog-zone locations or lomas formations("small hills"). The floristic communities of the lomas formations essentially function as terrestrial islands separated by hyperarid habitat where virtually no plants exist. No fewer than 80 localities have been recognized as unique assemblages. A map of localities and a listing of individual lomas formations are provided. The plants within the lomas formations have diverse origins including amphitropic disjuncts, semi-arid Ecuadorian and central Chilean species, montane Andean disjuncts, and many lomas endemics.

The phytogeography and ecology of the deserts of western South America have been reviewed in detail (see Rundel et al. 1991) and a floristic checklist of the entire area is available here. While the desert is continuous from Peru to Chile, the topography, climate, and vegetation of each desert is distinct. Aridity is controlled by three climatic anomalies. The first, an abrupt climatic transition both to the north and south resulting in a poorly developed steppe climate along the margins; second, brief periods of heavy rainfall and relatively high temperatures associated with rare, but recurrent, El Niño events (see Dillon 1985, Dillon and Rundel 1989) occasionally affect parts of the desert, bringing wet tropical conditions; and the third, the remarkable temperature homogeneity along the entire latitudinal extent of the deserts. This pattern of temperature stability results from the influence of cool, sea-surface temperatures associated with the south to north flow of the Humboldt or Peruvian Current. Also important is the influence of strong atmospheric subsidence associated with a positionally stable, subtropical anticyclone. The result is a mild, uniform coastal climate with the regular formation of thick stratus cloud banks below 1000 m during the winter months.

Diagrammatic view of vegetation zonation in the coastal fog zone
of (A) southern Peru and (B) northern Chile. Click on the image for an enlargement.
Where coastal topography is low and flat, this stratus layer dissipates inward over broad areas with little biological impact, but where isolated mountains or steep coastal slopes intercept the clouds, a fog-zone develops with a stratus layer concentrated against the hillsides. These fogs, termed garúa in Peru and camanchaca in Chile, are the key to the extent and diversity of vegetation throughout the deserts of the western coast. This moisture allows the development of lomas formations which other authors have referred to as the "fertile belt", "fog oases", or "meadows on the desert". While the extent of the Chilean and Peruvian deserts actually covers nearly 200,000 sq. km., the area covered by vegetation, even during periods of maximum development, is probably less than 4000 sq. km.

Recent field studies in northern Chile have lead to the discovery of a disjunct population of Lobelia anceps (Campanulaceae). To visit the publication at Chloris Chilensis, an electronic botanical journal you my click here: NEW DISTRIBUTION RECORD

Further Reading and References

Dillon, M. O. 1985. The Botanical Response of the Andean Desert Lomas Formations to the 1982-83 El Niño Event. Abstract Amer. J.Bot. 72: 950.

Dillon, M. O. 1989. Origins and diversity of the lomas formations in the Atacama and Peruvian Deserts of western South America. Abstract Amer. J. Bot. 76 (6): 950. 212.

Dillon, M. O. 1991. A new species of Tillandsia (Bromeliaceae) from northern Chile. Brittonia, 43: 1-6. (illustration based upon Dillon & Dillon 5869)

Dillon, M. O. 1997. Lomas Formations-Peru, pp. 519-527. In: S. D Davis, V. H. Heywood, O. Herrera-McBryde, J. Villa-Lobos and A. C. Hamilton (eds.), Centres of Plant Diversity, A Guide and Strategy for their Conservation. WWF, Information Press, Oxford, U.K.

Dillon, M. O., & A. E. Hoffmann-J. 1997. Lomas Formations of the Atacama Desert, Northern Chile, pp. 528-535. In: S. D Davis, V. H. Heywood, O. Herrera-McBryde, J. Villa-Lobos and A. C. Hamilton (eds.), Centres of Plant Diversity, A Guide and Strategy for their Conservation. WWF, Information Press, Oxford, U.K.

Dillon, M. O. and P. W. Rundel. 1990. The botanical response of the Atacama and Peruvian Desert flora to the 1982-83 El Niño Event, pp. 487-504. In: P. W. Glynn (ed.), Global Ecological Consequences of the 1982-83 El Niño-Southern Oscillation.

Dillon, M.O. and M. Muñoz-Schick. 1993. A Revision of the Dioecious Genus Griselinia (Griseliniaceae), Including a New Species from the Coastal Atacama Desert of Northern Chile. Brittonia 45:261-274. (type and illustration based upon Dillon & Dillon 5864)

Gómez-Sosa, E. 1986. Astragalus neobarnebyanus (Leguminosae): A New Species from Peru. Brittonia 38(4): 427- 429. (type based upon Dillon & Dillon 3813 (F))

Rundel, P., M. O. Dillon, B. Palma, H. A. Mooney, S. L. Gulmon, and J.R. Ehleringer. 1990. The Phytogeography and Ecology of the Coastal Atacama and Peruvian Deserts. Aliso 13(1): 1-50.

Teillier A., S., H. Zepdea F, & P. García V. 1998. Flores del Desierto de Chile. pps. 111. Marisa Cuneo Ediciones [Casilla 276, Valdivia, Chile, Fono/Fax 56-63-212323].


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