Desert ecology is the study of how living things and non-living things in deserts interact. A desert ecosystem includes the relationships between plants and animals, the weather where they live, and other non-living factors that affect their habitat. Deserts are dry areas that are usually warm, but some deserts are cold. Deserts are found on every continent, with the largest ones in Antarctica, the Arctic, Northern Africa, and the Middle East.

Climate

Deserts have a wide range of temperatures and weather conditions and are divided into four types: hot, semiarid, coastal, and cold. Hot deserts have warm temperatures all year and very little rainfall each year. Low humidity in hot deserts causes high daytime temperatures and significant heat loss at night. The average yearly temperature in hot deserts is about 20 to 25 °C, but extreme weather can cause temperatures to range from -18 to 49 °C.

Rainfall in deserts usually happens in short bursts, followed by long dry periods. Semiarid deserts have conditions similar to hot deserts, but their temperatures are less extreme, generally ranging from 10 to 38 °C. Coastal deserts are cooler than hot and semiarid deserts, with summer temperatures averaging between 13 and 24 °C. They also receive more total rainfall than other desert types. Cold deserts have temperatures similar to coastal deserts but get more precipitation in the form of snow.

Deserts are most known for their dry climates, which are often caused by their geography. For example, mountain ranges that block rain and being far from oceans are two features that contribute to deserts being dry. When air rises over mountains, it cools, increasing humidity until rain falls on the windward side. The leeward side, called a rain shadow, receives little to no rain.

Deserts cover one-fifth of Earth’s land and are found in two areas: between 15° and 35° latitude in both the northern and southern hemispheres. These areas receive strong sunlight and dry air from atmospheric patterns called the Hadley and Ferell cells. Dry winds carry little moisture and often evaporate any water present.

Many desert ecosystems are limited by the amount of water available, not by heat or sunlight. Water movement in these ecosystems is similar to energy movement, and studying both together helps scientists understand desert life.

Water in deserts can also be limited by loose soil, which makes it hard for water to stay. Dust clouds often form in dry, windy areas. Scientists once thought these dust clouds might help increase rainfall, but recent studies show they actually reduce rainfall by absorbing moisture from the air. This process can create a cycle that worsens desert conditions.

Landscape

Desert landscapes contain many different geological features, such as oases, rock outcrops, dunes, and mountains. Dunes are formed when wind moves sand and dirt into mounds. Desert dunes are usually classified based on how they are shaped by the wind. Transverse dunes are the most easily recognized type, with crests that go across the direction of the wind. Many dunes are active, meaning they can move and change over time because of wind. However, some dunes are anchored in place by plants or land shapes, which stop them from moving. Some dunes may also be called sticky dunes. These dunes form when individual sand grains are stuck together. Sticky dunes are more stable and less likely to be changed by wind than loose dunes. Barchan and Seif dunes are two of the most common types in deserts. Barchan dunes are shaped like crescents and form when wind blows in the same direction over time. Seif dunes are long and narrow, with sharp crests, and are often found in the Sahara Desert.

Studying geological features in deserts can help scientists learn about the area’s history. By examining rock deposits, geologists can determine the order of events that happened during the desert’s formation. For example, research on the surface geology of the Namib Desert allowed scientists to understand ancient movements of the Kuiseb River by analyzing the ages and features of rocks in the area.

Organism adaptation

Deserts support many different types of plants and animals that have developed ways to survive in very hot and dry conditions. For example, desert grasslands are more humid and slightly cooler than nearby areas. Many animals eat plants for energy, but desert plants are harder to eat. To avoid the heat, most small desert mammals are active at night and live in burrows during the day. These burrows help them stay cool and prevent losing water. Desert ecosystems have dry, salty soil, low plant growth, and animals that eat plants or other animals when food is available. Other organisms survive by changing their life cycles to match dry seasons or storing water in special body parts.

Desert climates are very hard for animals that generate their own body heat, like mammals and birds. These animals have ways to keep water in their bodies in places like deserts, where droughts are common. When the outside temperature is lower than their body temperature, these animals can balance heat production and loss to stay comfortable. However, in deserts where the air and ground are hotter than their bodies, they must find ways to release heat. To survive, desert animals avoid heat, adjust their body temperature, or develop special traits. For example, kangaroo rats stay in cool underground burrows during the day and come out at night to find food. Birds can fly between water sources to avoid losing water. Some desert mammals, like camels, have body temperatures that match desert air temperatures, which helps them save water. Other animals, like the antelope ground squirrel and oryx, also have higher body temperatures. Some animals, like male sandgrouse, have special feathers that hold water, allowing them to bring water to their young.

Even though deserts are harsh, some plants still grow there. These plants are called xerophytes and can survive long dry periods. Some close their leaf openings during the day and open them at night when it is cooler, reducing water loss and taking in more carbon dioxide for photosynthesis. Xerophytes have traits like heat resistance, water storage, and small leaves to reduce water loss. Cacti, for example, have sharp spines to protect against animals and some spines reflect sunlight. Plants like oleander have leaf openings that are protected to keep water in. Ocotillo plants lose their leaves most of the year to avoid losing water.

Some plants, called phreatophytes, have very long roots that can reach underground water sources, ensuring they have enough water to survive.

Exploration and research

The extreme conditions in many desert areas make it difficult to study these environments. In places where survival requires special adaptations, it is often hard or impossible for scientists to stay for long periods to research the ecosystem. To address these challenges, some researchers have used technology like remote sensing and robots. In one study from 1997, a robot called Nomad traveled through part of the Atacama Desert. During this mission, Nomad covered more than 200 kilometers and took many pictures of the areas it visited. In another study in 2004, called the United Arab Emirates Unified Aerosol Experiment, scientists used satellites and computer models to examine emissions and how they affect the climate in the Arabian Desert.