Sechura Desert
The Sechura Desert is a coastal desert located in northwestern Peru, extending to northern Chile, and is characterized by its arid environment and unique geographical features. This desert is significantly wetter than its neighboring Atacama Desert, averaging about 3 inches (8 centimeters) of annual rainfall, largely influenced by fog from the Pacific Ocean. The climate exhibits minimal seasonal variation, with summer temperatures ranging from 77 to 100 degrees F (25 to 38 degrees C) and winter temperatures between 61 and 75 degrees F (16 to 24 degrees C).
The Sechura Desert supports a variety of life, including distinct plant communities that thrive in fog zones known as lomas, as well as unique animal species such as the Sechuran fox and several endangered birds, including the Chilean flamingo. Human settlements have developed along the rivers that traverse the desert, contributing to agricultural activities that have transformed the landscape over thousands of years. However, these human interventions pose threats to the ecosystem, with urban expansion and intensive agriculture leading to habitat disruption and increased competition from invasive species.
Despite its challenging conditions, the Sechura Desert remains a region of ecological significance, showcasing adaptations of flora and fauna that have evolved to survive in arid environments. The interplay between natural and human influences presents ongoing challenges for conservation efforts in this distinctive desert ecosystem.
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Subject Terms
Sechura Desert
Category: Desert Biomes.
Geographic Location: South America.
Summary: This coastal desert along the Pacific coast of Peru and Chile is prone to flooding from river surges and Pacific storms; the biota also depends on moisture delivered by coastal fogs.
The Sechura Desert is located north of the Atacama Desert in a narrow, longitudinal strip along the Pacific coast of South America, and extending inland to the foothills of the Andes Mountains. The entire stretch of the arid coastal desert from northwest Peru to northern Chile is commonly referred to as the Sechura Desert. Within Peru, the term is limited to the country’s northern coastal desert, ending with the city of Piura and its surrounding tropical-dry forest ecoregion. The climate of this desert biome varies little because of the moderating influence of the Pacific Ocean. The summer average range is 77–100 degrees F (25–38 degrees C); the range in winter is 61–75 degrees F (16–24 degrees C). Summer lows are comparable to winter highs, around 75 degrees F (24 degrees C). While arid by most standards—annual rainfall averages about 3 inches (8 centimeters)—the Sechura is nearly two orders of magnitude (100 times) wetter than the neighboring Atacama, generally accepted as one of the driest places on Earth. The Sechura also derives groundwater recharge from the many rivers along its edges and those that cut across its main body.
The Sechura Desert is filled with rocks degraded by weathering, erosion, and the formation of salt crystals that remain even after it rains. The soils are dry, low in organic matter, and more saline than the average soil of less arid regions. The desert district receives moisture via fog that forms over the nearby ocean. As in other coastal deserts, the biota has adapted to take advantage of these fog zones.
Fossils of mollusks and marine mammals from the Miocene are frequently found in the sedimentary deposits of sandstone in the center of the desert. Some rivers cross the desert, and human settlements have developed along them for thousands of years. The town of Sechura was relocated to its current location when a tsunami wiped out the original town in 1728. In 1998, the El Niño rain-fed floods temporarily turned part of the Sechura into Peru’s second-largest lake, more than 10 feet (3 meters) deep and 90 miles (145 kilometers) long, punctuated by small islands of sand and clay. During the wet season, many local families take advantage of opportunities to add protein to their diets by fishing for tilapia.
Vegetation
Before the river valleys of the Sechura were converted to agricultural land, they supported large plant populations of Acacia macracantha, Salix humboldtiana, Schinus molle, Sapindus saponaria, Muntingia calabura, and semiwoody shrubs. Today, these rivers are diverted for intensive irrigated agriculture, and the city of Piura—one of the five largest in Peru—depends on the Sechura agricultural region, which is prone to flooding due to the proximity to so many bodies of water. In addition to floods from river surges, especially after wet springs or when snow melts rapidly in the Andes, the Sechura regularly experiences storms from the Pacific Ocean and floods at least briefly in most El Niño years.
Most of the vegetation in the Sechura region grows near the rivers. Squash and peanuts are indigenous to the bottomlands and have been cultivated for thousands of years. The carob tree, palo verde, salta grama grass, mangrove tree, giant reed, ditch reed, wild tomato, Peruvian daffodil, Peruvian papaya, and divi-divi are all found in the area. In the Piura vicinity, a variety of the mesquite tree called the algarrobo is endemic, that is, a species found nowhere else.
There are many species of pea-family algarrobo or bayahonda trees and shrubs, including Prosopis abbreviata, P. affinis, P. alba, P. chilensis, P. fiebrigii, P. flexuosa, P. juliflora, P. kuntzei, P. nigra, P. pallida, P. rojasiana, P. rusciflolia, P. strombulifera, and P. tamarugo. The Piura region also is home to the oldest limes in South America; a variety of endemic species of orchids; bananas; coconuts; rice; and mangos, both wild and commercially cultivated.
Advective fog (called garua in Peru and camanchaca in Chile) that forms over the Pacific, with its cold seawater upwelling zones along the coast, carries moisture to the southwestern hills and ridges of the Sechura, leading to the development of fog-zone plant communities called lomas, for small hills. Older botanical literature sometimes refers to the lomas as the fog belt, fertile belt, desert meadows, or fog oases, but in contemporary literature, the Spanish-language term is preferred. There are 40 discrete lomas in the Peruvian portion of the Sechura, and even more in the Chilean stretch, all of them fairly small. Lomas are extremely localized discrete communities of plant life, like islands surrounded by otherwise-arid desert.
Altitude affects the variety of plant life to some degree. Low shrubs are common below 328 feet (100 meters); cactuses thrive at higher elevations. Parkinsonia aculeata and Alternanthera peruviana are common, as are grasses that serve to stabilize the dunes: Distichlis spicata and Cryptocarpus pyriformis in the west, nearest the coast; and Capparis scabrida and C. avicenniifolia farther inland. Nearest to the Andes foothills, terrestrial bromeliads and columnar cactuses are common, as are dwarf trees such as Eriotheca discolor, Bursera graveolens, and Acacia huarango.
Fauna
Animal biodiversity is generally low in the Sechura, but it is an important corridor for migratory birds such as Baird’s sandpiper (Calidris bairdii) and the Arctic sanderling (Crocethia alba). Distinctive short-range species include the pizarrita slender-billed finch (Xenospingus concolor) and Raimond’s yellow-finch (Sicalis raimondii). Endangered birds here include the Chilean flamingo (Phoenicopterus chilensis), red-fronted coot (Fulica rufifrons), and white-winged guan (Penelope albipennis).
Among characteristic mammals here, the Sechuran fox (Lycalopex sechurae) is thought to be the smallest of the false fox canids, also called zorro. About the size of a cat, the Sechura fox is 20–30 inches (508–762 millimeters) long, with a 12-inch (305-millimeter) tail, and weighs 6–10 pounds (3–5 kilograms). Adapted for feeding on desert seed pods, capers, fruit, insects, and the occasional bird egg or small rodent, this nocturnal scavenger stays underground by day. Considered an at-risk species, the Sechuran fox has some protection in Ecuador and Peru.
The wild guinea pig known in Peru as the cuy has been part of the ecosystem since at least the time of the Moche civilization 2,000 years ago, which used it as a food source and may have introduced it from another region. Reptiles typical of the biome include Roedinger’s lance head snake (Bothrops roedingeri) and Sechura Desert coral snake (Micrurus ischudii).
Environmental Threats
Major threats to the ecosystem include urban expansion and more damaging forms of commercial agriculture. As city areas swell, the remaining agricultural lands on which they depend are forced to use increasingly intensive methods, which can sometimes disrupt or destroy existing habitat in order to plant and irrigate crops. Agriculture also can attract new pests, while pesticides and fertilizers can harm microflora and microfauna, as well as riverine life. Opening carob groves to livestock can lead to overgrazing and invite new nonnative plant species. Hunting of some animals, principally ducks, periodically puts their populations at risk.
Rising temperatures, increased rainfall, and the potential for more flooding in the Sechura Desert is projected to interrupt plant growth cycles for some species, and to limit normal activity for some fauna. These effects of climate change may also encourage more invasive species as habitat ranges shift.
Bibliography
Cooke, Ronald, Andrew Warren, and Andrew Goudie. Desert Geomorphology. New York: Taylor and Francis, 1992.
Gomez, Ivan, Evelyn Inguil, Maya Gomez-Coultas, and Gabriel Bonnamy. "The Sechura Desert and the Economic Activities of Its Inhabitants." Farming and Fishing in the Desert, 1 June 2021, elninophenomenon.wp.st-andrews.ac.uk/the-sechura-desert-and-the-economic-activities-of-its-inhabitants/. Accessed 31 Aug. 2022.
Huey, Raymond B. “Parapatry and Niche Complementarity of Peruvian Desert Geckos.” Oecologia 38, no. 3 (1979).
Huey, Raymond B. “Winter Diet of the Peruvian Desert Fox.” Ecology 50, no. 6 (1969).
Laity, Julie J. Deserts and Desert Environments. Hoboken, NJ: Wiley-Blackwell, 2008.