In this lesson we’ll learn about the desert ecosystem. Specifically, we’ll learn what biotic and abiotic factors are and then look at specific factors present in one example of a desert ecosystem, the Sahara Desert.
Driving down Route 66 in Nevada you enter Death Valley National Park. As you drive the area seems barren, devoid of life.
But when you enter the park service center though, they give you a brochure outlining the unique wildlife present in the desert. They suggest you look for creosote bush, mesquite, kangaroo rats, and rattlesnakes, or biotic factors. Biotic factors are any living things in a particular ecosystem, such as plants, animals, fungi, and bacteria. You’re also warned of the abiotic, or non-living factors, such as a lack of water and crippling heat.
Abiotic factors are all non-living factors in an organism’s environment. Precipitation, water availability, sunlight, and temperature are all abiotic factors. Deserts are characterized by their lack of rainfall. Although we usually think of deserts as being hot, some deserts can be cold too.Most deserts get around 10 inches of rain per year. Ground water exists far below the surface and plants have adaptations like incredibly long roots to reach it.
Occasional rains provide temporary pools of water in rocks. Deserts get a lot of sunlight due to low humidity and lack of tall plants. Since the desert is so dry there is little water to evaporate and form clouds.In a forest, towering trees provide shade on the forest floor, but with sparse vegetation, the desert remains exposed to sun during most hours of the day. Temperatures vary greatly in the desert depending on location and time of day. With no water to store heat from the day, the temperature fluctuates immensely.
For example, in the Chihuahuan Desert of Mexico, temperatures can reach 100 degrees Fahrenheit during the day, but dip to freezing 32 degrees Fahrenheit at night. Some deserts reach temperatures of up to 130 degrees Fahrenheit during the day.Deserts exist all over the world. Remember they’re not just hot areas. Torgersen Island in Antarctica is a desert biome. Temperatures remain cold all year round with temperatures dipping to below freezing in the winter and only a maximum of 70 degrees Fahrenheit in the short summer.
Biotic factors are all the living things in an ecosystem.
Although seemingly barren, deserts are home to a unique community of plants and animals with special adaptations to survive the harsh conditions. The saguaro cactus in the Sonoran Desert in Arizona can grow over 24 appendages and up to 2 feet in diameter. It towers above other plants growing up to 50 feet tall.
The long appendages and trunk are filled with water, like a water tower. This allows the plant to hold water when short torrential downpours happen saving it for the dry months to come.
Kangaroo rats, another biotic factor in the desert mainly live in the western and southwestern deserts of the United States. Like the saguaro, they have special adaptations to allow them to survive in scorching hot deserts. They don’t sweat or pant like other animals, eliminating evaporative water loss.
They also tend to stay in burrows during the day and come out at night to forage, keeping them cool. Urine is a big loss of water for many animals, so kangaroo rats hold on to most water in their urine excreting extremely concentrated waste. With such little lush vegetation, kangaroo rats have adapted to extract water efficiently from seeds, the main part of their diet.
The Sahara Desert, the largest desert in the world, is a harsh place. Abiotic factors like massive sand seas, sweeping sand dunes and windswept flat areas of sand, contain little to no vegetation. The soil underneath the sand also tends to be very salty or have high salinity.
Some sand dunes in the Sahara can rise up to 500 feet, as tall as a five-story apartment building in the city.Rivers in the surrounding areas contribute to the needed runoff and ground water that the few plants and animals depend on, such as streams branching from the Nile River. Precipitation is rare, only 3 inches of rain fall on average per year. With temperatures ranging between 55 degrees Fahrenheit in the winter and up to 120 degrees in the summer, biotic factors need some serious adaptations to live here.Halophytes, or plants that tolerate high salt can thrive in the salt flats of the Sahara, large stretches of desert covered in salt deposits. Near the occasional oasis, date palms grow long roots capable of penetrating valuable ground water sources.
The olive tree has similar adaptations, long roots and small leaves to prevent water loss due to transpiration.Camels are a common site in the Sahara and have been used for centuries to carry people and supplies through the desert. Their large, flat feet allow for traversing the sandy dunes with ease.
The characteristic humps store fat, which allows the camel to survive for long periods without food. And their fur is varied in thickness, thick fur allows for shade and thin fur allows for heat loss in the desert sun.The famous sidewinder snake has a tan color letting it camouflage with the sand, hiding it from both prey and predators.
It’s side-to-side motion, hence the name sidewinder, allows it to traverse the sand dunes. If you’ve ever tried to run at the beach, you know how hard sand can be to travel through.All animals in the desert need adaptations to survive, be it large ears for evaporative cooling, camouflage, nocturnal life, or extensive roots in plants to find water. These biotic factors are truly unique.
Abiotic factors are non-living factors in an organism’s environment. In the desert, extremely low rainfall, lots of sunlight, and limited water sources are abiotic factors.
Temperature varies greatly depending on the locations and time of day in the desert, with lows near freezing and highs up to 130 degrees Fahrenheit.Biotic factors are living things in the environment. Biotic factors in the desert like plants and animals have specific adaptations that allow them to move through the sand, keep cool, and conserve water.