Algeria Sahara Desert Photo From Drone 5

Desert ecology is the study of interactions between both biotic and

abiotic In biology and ecology, abiotic components or abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Abiotic factors and the phenomena associated with them und ...

components of

desert A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...

environments. A desert

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

is defined by interactions between

organism An organism is any life, living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have be ...

s, the

climate Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteoro ...

in which they live, and any other non-living influences on the

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

. Deserts are arid regions that are generally associated with warm temperatures; however, cold deserts also exist. Deserts can be found in every continent, with the largest deserts located in

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

, the

Arctic The Arctic (; . ) is the polar regions of Earth, polar region of Earth that surrounds the North Pole, lying within the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway ( ...

Northern Africa North Africa (sometimes Northern Africa) is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region. However, it is sometimes defined as stretching from the Atlantic shores of t ...

, and the

Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...

Climate

Deserts experience a wide range of temperatures and weather conditions, and can be classified into four types: hot, semiarid, coastal, and cold. Hot deserts experience warm temperatures year round, and low annual precipitation. Low levels of humidity in hot deserts contribute to high daytime temperatures, and extensive night time heat loss. The average annual temperature in hot deserts is approximately 20 to 25 °C, however, extreme weather conditions can lead to temperatures ranging from -18 to 49 °C. Rainfall generally occurs, followed by long periods of dryness. Semiarid deserts experience similar conditions to hot deserts, however, the maximum and minimum temperatures tend to be less extreme, and generally range from 10 to 38 °C. Coastal deserts are cooler than hot and semiarid deserts, with average summer temperatures ranging between 13 and 24 °C. They also feature higher total rainfall values. Cold deserts are similar in temperature to coastal deserts, however, they receive more annual precipitation in the form of snowfall. Deserts are most notable for their dry climates; usually a result from their surrounding geography. For example,

rain Rain is a form of precipitation where water drop (liquid), droplets that have condensation, condensed from Water vapor#In Earth's atmosphere, atmospheric water vapor fall under gravity. Rain is a major component of the water cycle and is res ...

-blocking

mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher t ...

ranges, and distance from

ocean The ocean is the body of salt water that covers approximately 70.8% of Earth. The ocean is conventionally divided into large bodies of water, which are also referred to as ''oceans'' (the Pacific, Atlantic, Indian Ocean, Indian, Southern Ocean ...

s are two geographic features that contribute to desert aridity. Rain-blocking mountain ranges create Rain Shadows. As air rises and cools, its relative humidity increases and some or most moisture rains out, leaving little to no water vapor to form precipitation on the other side of the mountain range. Deserts

Deserts occupy one-fifth of the Earth's land surface and occur in two belts: between 15° and 35° latitude in both the southern and northern hemispheres. These bands are associated with the high solar intensities that all areas in the tropics receive, and with the dry air brought down by the descending arms of both the Hadley and Ferell atmospheric circulation cells. Dry winds hold little moisture for these areas, and also tend to evaporate any water present. Many desert ecosystems are limited by available water levels, rather than rates of radiation or temperature. Water flow in these ecosystems can be thought of as similar to energy flow; in fact, it is often useful to look at water and energy flow together when studying desert ecosystems and ecology. Water availability in deserts may also be hindered by loose sediments. Dust clouds commonly form in windy, arid climates. Scientists have previously theorised that desert dust clouds would enhance rainfall, however, some more recent studies have shown that precipitation is actually inhibited by this phenomenon by absorbing moisture from the atmosphere. This absorption of atmospheric moisture can result in a positive

feedback loop Feedback occurs when outputs of a system are routed back as inputs as part of a chain of cause and effect that forms a circuit or loop. The system can then be said to ''feed back'' into itself. The notion of cause-and-effect has to be handle ...

, which leads to further

desertification Desertification is a type of gradual land degradation of Soil fertility, fertile land into arid desert due to a combination of natural processes and human activities. The immediate cause of desertification is the loss of most vegetation. This i ...

Landscape

Desert landscapes can contain a wide variety of geological features, such as

oases In ecology, an oasis (; : oases ) is a fertile area of a desert or semi-desert environmentrock outcrops,

dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat ...

s, and

s. Dunes are structures formed by wind moving sediments into mounds. Desert dunes are generally classified based on their orientation relative to wind directly. Possibly the most recognizable dune type are transverse dunes, characterized by crests transverse to the wind direction. Many dunes are considered to be ''active'', meaning that they can travel and change over time due to the influence of the wind. However, some dunes can be anchored in place by vegetation or topography, preventing their movement. Some dunes may also be referred to as ''sticky.'' These types of dunes occur when individual grains of sand become cemented together. Sticky dunes tend to be more stable, and resistant to wind reworking than loose dunes. Barchan, and Seif dunes are among the most common of desert dunes. Barchan dunes are formed as winds continuously blow in the same direction, and are characterized by a crescent-shape atop the dune. Seif dunes are long and narrow, featuring a sharp crest, and are more common in the Sahara Desert. Analysis of geological features in desert environments can reveal a lot about the geologic history of the area. Through observation and identification of rock deposits, geologists are able to interpret the order of events that occurred during desert formation. For example, research conducted on the surface geology of the

Namib Desert The Namib ( ; ) is a coastal desert in Southern Africa. According to the broadest definition, the Namib stretches for more than along the Atlantic coasts of Angola, Namibia, and northwest South Africa, extending southward from the Carunjamba Ri ...

allowed geologists to interpret ancient movements of the

Kuiseb River The Kuiseb River is an ephemeral river in western-central Namibia. Its source is in the Khomas Highland west of Windhoek. From there it flows westwards through the Namib-Naukluft National Park and the Namib desert to Walvis Bay. Several settlement ...

based on rock ages and features identified in the area.

Organism adaptation

Animals

Deserts support diverse communities of plant and animals that have evolved resistance, and circumventing methods of extreme

temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...

s and arid conditions. For example, desert grasslands are more humid and slightly cooler than its surrounding ecosystems. Many animals obtain energy by eating the surrounding vegetation, however, desert plants are much more difficult for organisms to consume. To avoid intense temperatures, the majority of small desert mammals are nocturnal, living in burrows to avoid the intense desert sun during the daytime. These burrows prevent overheating and dehydration as they maintain an optimal temperature for the mammal. Desert ecology is characterized by dry,

alkaline In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The ...

soils, low net production and opportunistic feeding patterns by

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

s and

carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they ar ...

s. Other organisms' survival tactics are physiologically based. Such tactics include the completion of life cycles ahead of anticipated drought seasons, and storing water with the help of specialized organs. Desert climates are particularly demanding on

endotherm An endotherm (from Greek ἔνδον ''endon'' "within" and θέρμη ''thermē'' "heat") is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions inst ...

ic organisms. However, endothermic organisms have adapted mechanisms to aid in water retention in habitats such as desert ecosystems which are commonly affected by drought. In environments where the external temperature is less than their body temperature, most endotherms are able to balance heat production and heat loss to maintain a comfortable temperature. However, in deserts where air and ground temperatures exceed body temperature, endotherms must be able to dissipate the large amounts of heat being absorbed in these environments. In order to cope with extreme conditions, desert endotherms have adapted through the means of avoidance, relaxation of

homeostasis In biology, homeostasis (British English, British also homoeostasis; ) is the state of steady internal physics, physical and chemistry, chemical conditions maintained by organism, living systems. This is the condition of optimal functioning fo ...

, and specializations. Nocturnal desert rodents, like the

kangaroo rat Kangaroo rats, small mostly nocturnal rodents of genus ''Dipodomys'', are native to arid areas of western North America. The common name derives from their bipedal form. They hop in a manner similar to the much larger kangaroo, but developed thi ...

, will spend the daytime in cool burrows deep underground, and emerge at night to seek food. Birds are much more mobile than ground-dwelling endotherms, and can therefore avoid heat-induced dehydration by flying between water sources. To prevent overheating, the body temperatures of many desert mammals have adapted to be much higher than non-desert mammals.

Camel A camel (from and () from Ancient Semitic: ''gāmāl'') is an even-toed ungulate in the genus ''Camelus'' that bears distinctive fatty deposits known as "humps" on its back. Camels have long been domesticated and, as livestock, they provid ...

s, for example, can maintain body temperatures that are about equal to typical desert air temperatures. This adaptations allows camels to retain large amounts of water for extended periods of time. Other examples of higher body temperature in desert mammals include the diurnal

antelope ground squirrel Antelope squirrels or antelope ground squirrels of the genus ''Ammospermophilus'' are sciurids found in the desert and dry scrub areas of the southwestern United States and northern Mexico. They are a type of ground squirrel and are able to resi ...

, and the

oryx ''Oryx'' ( ) is a genus consisting of four large antelope species called oryxes. Their pelage is pale with contrasting dark markings in the face and on the legs, and their long horns are almost straight and annulated. The exception is the sci ...

. Certain desert endotherms have evolved very specific and unique characteristics to combat dehydration. Male

sandgrouse Sandgrouse is the common name for Pteroclidae (), a family (biology), family of sixteen species of bird, members of the order Pterocliformes (). They are traditionally placed in two Genus, genera. The two central Asian species are classified as ...

have specialized belly feathers that are able to trap and carry water. This allows the sandgrouse to provide a source of hydration for their chicks, who do not yet have the ability to fly to water sources themselves.

Plants

Although deserts have severe climates, some plants still manage to grow. Plants that can survive in arid deserts are called

xerophyte A xerophyte () is a species of plant that has adaptations to survive in an environment with little liquid water. Examples of xerophytes include cacti, pineapple and some gymnosperm plants. The morphology and physiology of xerophytes are adapted to ...

s, meaning they are able to survive long dry periods. Such plants may close their

stoma In botany, a stoma (: stomata, from Greek language, Greek ''στόμα'', "mouth"), also called a stomate (: stomates), is a pore found in the Epidermis (botany), epidermis of leaves, stems, and other organs, that controls the rate of gas exc ...

ta during the daytime and open them again at night. During the night, temperatures are much cooler, and plants will experience less water loss, and intake larger amounts of carbon dioxide for photosynthesis. Adaptations in xerophytes include resistance to heat and water loss, increased water storage capabilities, and reduced surface area of leaves. One of the most common families of desert plants are the

cacti A cactus (: cacti, cactuses, or less commonly, cactus) is a member of the plant family Cactaceae (), a family of the order Caryophyllales comprising about 127 genera with some 1,750 known species. The word ''cactus'' derives, through Latin, ...

, which are covered in sharp spines or bristles for defence against herbivory. The bristles on certain cacti also have the ability to reflect sunlight, such as those of the old man cactus. Certain xerophytes, like

oleander ''Nerium oleander'' ( ), commonly known as oleander or rosebay, is a shrub or small tree cultivated worldwide in temperate and subtropical areas as an ornamental and landscaping plant. It is the only species currently classified in the genus ...

, feature stomata that are recessed as a form of protection against hot, dry desert winds, which allows the leaves to retain water more effectively. Another unique adaptation can be found in xerophytes like

ocotillo ''Fouquieria splendens'', commonly known as ocotillo, is a plant indigenous to the Mojave, Sonoran, Chihuahuan and Colorado deserts in the Southwestern United States (southern California, southern Nevada, Arizona, New Mexico, Texas), and nor ...

, which are "leafless during most of the year, thereby avoiding excessive water loss". There are also plants called phreatophytes which have adapted to the harsh desert conditions by developing extremely long root systems, some of which are 80 ft. long; to reach the water table which ensures a water supply to the plant.

Exploration and research

The harsh climate of most desert regions is a major obstacle in conducting research into these ecosystems. In the environments requiring special adaptations to survive, it is often difficult or even impossible for researchers to spend extended periods of time investigating the ecology of such regions. To overcome the limitations imposed by desert climates, some scientists have used technological advancements in the area of

remote sensing Remote sensing is the acquisition of information about an physical object, object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring inform ...

and

robotics Robotics is the interdisciplinary study and practice of the design, construction, operation, and use of robots. Within mechanical engineering, robotics is the design and construction of the physical structures of robots, while in computer s ...

. One such experiment, conducted in 1997, had a specialized robot named Nomad travel through a portion of the

Atacama Desert The Atacama Desert () is a desert plateau located on the Pacific Ocean, Pacific coast of South America, in the north of Chile. Stretching over a strip of land west of the Andes Mountains, it covers an area of , which increases to if the barre ...

. During this expedition, Nomad travelled over 200 kilometers and provided the researchers with many photographs of sites visited along its path. In another experiment in 2004, named the United Arab Emirates Unified Aerosol Experiment, researchers used satellites and computer models to study emissions and their effect on the climate in the Arabian Desert.

References

{{Authority control Deserts *Ecology Ecology by biome Habitats