XEROPHILOUS SCRUB: CHARACTERISTICS, DISTRIBUTION, FLORA AND FAUNA - BIOLOGY - 2025

The dry scrub is an ecosystem located in regions of low rainfall and high temperature where the desert vegetation prevails. The predominant vegetation, of the shrub type, has developed particular characteristics that allow them to live in unfavorable environments.

The term xerophilous derives from the Greek "xero" -seco- and "filo" -friend-. They are shrubby plants adapted to live in dry environments with low humidity and high temperatures.

Xerophilic scrub. Source: Harasmode, from Wikimedia Commons

Climatic conditions associated with xerophilous scrub range from relatively cool environments at night to very hot during the day. Rainfall is sporadic, lack of rain is common for 7-12 months, sometimes it does not rain for years.

The thorny vegetation is frequent, such as cacti and bromeliads, as well as low-growing shrubs, deciduous shrubs and semi-desert meadows. Most xerophytic species are endemic, as they have adapted to the special conditions of desert ecosystems.

characteristics

- Xerophilous bushes constitute a particular ecosystem where annual precipitation levels are very low, reaching just 250 mm.

- The low productivity of these areas is determined by sudden changes in temperature between day and night, reporting occasional variations of up to 20-25º C.

- This type of ecosystem is located in arid and semi-arid regions, which limits to some extent the prevalence of animal and plant life.

- The vegetation of the xerophilous scrub is made up of shrubs, creeping plants and columnar cacti.

- This type of vegetation has adapted to the lack of water, replacing the wide and succulent leaves with thorns, as in cacti.

- In cacti, photosynthesis is carried out through the epidermis of the stem, and the roots are of the deep pivoting type to reach the aquifers.

Columnar catus. Source: pixabay.com

- Around 60% of the vegetation is endemic, due to the high degree of adaptation it has experienced to survive in these conditions.

- The physical conditions of these regions are rocky and sandy, limiting the presence of vegetation to small specific areas generally exposed to solar radiation.

- Most of the soils are sedimentary or volcanic in nature, in some cases they come from alluvial soils.

- They are characterized by flat topographies, of low inclination with frequent undulations that come to establish low hills.

- The fauna is made up of small insects, reptiles, birds and mammals.

Geographical distribution

The presence of xerophilous shrubs or deserts is located around the planet. Specifically those areas where the climatic conditions are favorable to this type of vegetation.

South America

In South America it is located in the region called Caatinga in the northeast of Brazil. In the Peruvian Andes, at 3000 meters above sea level, the steppe mountain range is located and in the Argentine plains there are regions with a predominance of xerophilous scrub.

The Venezuelan and Colombian coasts are characterized by xerophilous areas, such as the Paraguaná peninsula and the Goajira region. In the Galapagos Islands there are xerophilous areas of ecological importance, in the north of Chile the xerophilous shrubs occupy large areas.

North America

Between the United States and Mexico is located one of the most important xerophilous regions in the world. This region is made up of the deserts of Mojave, Arizona, Colorado, Baja California, Sonora and Chihuahua.

In Mexico, xerophilous scrub covers most of the Baja California peninsula, the Sonora region, and the coastal plain. It is natural in wide regions of the high plateau from Coahuila and Chihuahua to Hidalgo, Guanajuato, Jalisco, Oaxaca, Puebla and the capital region.

Caribbean

Throughout the Caribbean, several islands have xerophilous ecosystems in coastal areas, such as the Lesser Antilles, Aruba, Bonaire, and Curaçao. Likewise, in Anguilla, Antigua, Barbados, Dominica, Grenada, Guadeloupe, Martinique, Margarita, San Martin, Santa Cruz, Santa Lucia, Trinidad and Tobago.

Europe

Much of the region around the Mediterranean has xerophilic zones typical of the dry Mediterranean climate. In the Iberian Peninsula, the Tabernas desert, the Talavera de la Reina region and the low mountains of the Tajo Valley stand out.

Africa

The areas around the Sahara desert, Mount Uweinat and Tibesti, are characterized by the presence of xerophilous scrub. In Ethiopia, Somalia and Namibia, savanna ecosystems are mixed with xerophilous scrub, such as the Kalahari, Namib and Kaokoveld deserts.

Asia and Oceania

Several semi-desert regions are located where xerophilous scrub predominates, such as the Sinai desert and the coasts of Arabia. In the Mesopotamian region between Iran and Iraq, the Persian Gulf and Oman there are particular regions of xerophytic vegetation.

In Central Asia, as in the Azerbaijan region, the deserts of Mongolia and China are located xerophilous regions. A high percentage of the territory of Australia and part of New Zealand have ecosystems typical of xerophilous scrub.

Distribution of deserts in the world. Source: Terpsichores, from Wikimedia Commons

Flora

Xerophilous scrub ecosystems have little vegetation, characterized by their great adaptation to low humidity conditions. Endemic species of the agavaceae, crassulaceae, cacti and species of the genus Fouquieria predominate.

Cactaceae

Endemic species of arid and dry regions characteristic of xerophilous scrub. Morphologically they are characterized by a thick and succulent stem, modified leaves in spines, which allows them to survive in low humidity conditions.

Agavacea

The maguey is a perennial plant widely distributed in warm areas typical of xerophilous, arid and semi-arid habitats. The thick and fleshy leaves arranged in the shape of a rosette on a short stem are used to obtain fiber and liquor.

Agave or maguey. Source: pixabay.com

Crassulaceae

Herbaceous plants adapted for the storage of water in succulent leaves, since they inhabit arid areas with high temperatures. To live in low humidity conditions they have developed specialized structures that allow them to prevent dehydration, such as hairs, thorns or pruines.

Fouquieria

With the name Fouquieria a group of 11 species of xerophytic plants belonging to the Fouquieriaceae family is known. They are particular plants with thin stems, but succulent with small leaves, which adapt to dry and arid conditions.

Fouquieria (desert coral). Source: pixabay.com

Fauna

The conditions of high temperature, low precipitation and scarce vegetation are not an impediment to the presence of numerous animal species. Among the most frequent in this type of ecosystem are arthropods, such as bees, bumblebees, wasps, spiders, scorpions and centipedes.

They inhabit diverse reptiles such as lizards, snakes and desert tortoises, and some birds such as woodpeckers, roadrunners, noisemakers and owls. As for mammals, there are small species such as some species of rats and bats.

Desert scorpion or scorpion

There are several species of scorpions adapted to dry and arid conditions, such as the Baja California bark scorpion (Centruroides exilicauda). It is a terrestrial species of arid regions, lives in the crevices of dry trunks and trees and is nocturnal.

Desert scorpion. Source: pixabay.com

Jingle Bell

The rattlesnake (Crotalus scutulatus) is a desert inhabitant that can reach 1.50 m in length. It inhabits desert areas frequently in gently sloping areas, under rocks and is highly poisonous, causing death.

Desert turtle

The desert tortoise (Gopherus agassizii) is endemic to the southwestern United States and northwestern Mexico. In xerophilous scrub areas it takes refuge in underground caves when desert temperatures are very high.

Desert tortoise (Gopherus agassizii). Source: Robb Hannawacker, via Wikimedia Commons

Owl

The owl is the common name of several species of birds of the Strigidae family that inhabit the desert areas of Mesoamerica. It is a nocturnal bird; inhabits dry plains where it locates holes conducive to sustenance, shelter, and reproduction.

Woodpecker

The desert woodpecker (Melanerpes uropygialis) is a species adapted to living in desert conditions, with high temperatures and low rainfall. Of singular beauty, it makes its nests in the large columnar cacti, managing to maintain a cool temperature by accumulating moisture under its plumage.

Desert Woodpecker (Melanerpes uropygialis). Source: Mike & Chris, via Wikimedia Commons

Nopalera rat

The nopalera rat or desert rat is a rodent belonging to the genus Neotoma of the Cricetidae family. It commonly inhabits around nopal plantations, being active twenty-four hours a day.

References

1. Alanís-Rodríguez, E., Jiménez-Pérez, J., Mora-Olivo, A., Martínez-Ávalos, JG, Mata-Balderas, JM, Collantes Chávez-Costa, A., & Rubio-Camacho, EA (2015). Structure and diversity of the submontane scrub contiguous to the metropolitan area of ​​Monterrey, Nuevo León, Mexico. Acta botánica mexicana, (113), 01-19.
2. Castillo-Argüero, S., Y. Martínez-Orea, M. Nava-López, and L. Almeida-Leñero. (2016) The xerophilous scrub of the Pedregal de San Ángel Ecological Reserve and its ecosystem services. In: Biodiversity in Mexico City, vol. III. Conabio / Sedema, Mexico, pp. 50-69
3. Challenger Antony and Soberón Jorge (2008) Terrestrial ecosystems, in Natural Capital of Mexico, vol. I: Current knowledge of biodiversity. Conabio, Mexico, pp. 87-108.
4. Terrestrial ecosystems (2007) Semarnat. Recovered at: semarnat.gob.mx
5. Xerophilous scrub (2010) Mexican biodiversity. Conabio. Recovered in: biodiversity.gob.mx
6. Xerophilous scrub (2019) Wikipedia, The Free Encyclopedia. Recovered at: wikipedia.org