- There are relatively few large mammals in deserts because most are not capable of storing sufficient water and withstanding the heat.
- Deserts often provide little shelter from the sun for large animals.
- The dominant animals of warm deserts are nonmammalian vertebrates, such as reptiles.
- Mammals are usually small, like the kangaroo mice of North American deserts.
- Desert biomes can be classified according to several characteristics.
There are four major types of deserts:
- Hot and dry
- Semiarid
- Coastal
- Cold
Hot and dry desert
- The seasons here are generally warm throughout the year and very hot in the summer. The winters usually bring little rainfall.
- The seasons are generally warm throughout the year and very hot in the summer.
- The winters usually bring little rainfall.
- Temperatures exhibit daily extremes because the atmosphere contains little humidity to block the Sun’s rays.
- Canopy in most deserts is very rare.
- Plants are mainly ground-hugging shrubs and short woody trees.
- Leaves are “replete” (fully supported with nutrients) with water-conserving characteristics.
- They tend to be small, thick and covered with a thick cuticle (outer layer).
- In the cacti, the leaves are much-reduced (to spines) and photosynthetic activity is restricted to the stems.
- Some plants open their stomata (microscopic openings in the epidermis of leaves that allow for gas exchange) only at night when evaporation rates are lowest.
- These plants include: yuccas, ocotillo, turpentine bush, prickly pears, false mesquite, sotol, ephedras, agaves and brittlebush.
- Animals include small nocturnal (active at night) carnivores. The dominant animals are burrowers and kangaroo rats. There are also insects, arachnids, reptiles and birds. The animals stay inactive in protected hideaways during the hot day and come out to forage at dusk, dawn or at night, when the desert is cooler.
Semiarid Desert
- The summers are moderately long and dry, and like hot deserts, the winters normally bring low concentrations of rainfall.
- Summer temperatures usually average between 21-27° C.
- As in the hot desert, rainfall is often very low and/or concentrated with an average rainfall from 2-4 cm annually.
- The spiny nature of many plants in semiarid deserts provides protection in a hazardous environment.
- The large numbers of spines shade the surface enough to significantly reduce transpiration.
- Many plants have silvery or glossy leaves, allowing them to reflect more radiant energy.
- Semiarid plants include: Creosote bush, bur sage white thorn, cat claw, mesquite, brittle bushes, lyciums, and jujube.
- The animals in these areas include mammals such as the kangaroo rats, rabbits, and skunks; insects like grasshoppers and ants; reptiles are represented by lizards and snakes; and birds such as burrowing owls and the California thrasher.
Coastal Desert
- The cool winters of coastal deserts are followed by moderately long, warm summers. The average summer temperature ranges from 13-24° C; winter temperatures are 5° C or below.
- The average rainfall measures 8-13 cm in many areas.
- All of the plants with thick and fleshy leaves or stems can take in large quantities of water when it is available and store it for future use.
-The plants living in this type of desert include the salt bush, buckwheat bush, black bush, rice grass, little leaf horsebrush, black sage, and chrysothamnus.
- Some animals have specialized adaptations for dealing with the desert heat and lack of water.
- Some toads seal themselves in burrows with gelatinous secretions and remain inactive for eight or nine months until a heavy rain occurs. Amphibians that pass through larval stages have accelerated life cycles, which improves their chances of reaching maturity before the waters evaporate. Some insects lay eggs that remain dormant until the environmental conditions are suitable for hatching. The fairy shrimps also lay dormant eggs.
- Other animals include: insects, mammals (coyote and badger), amphibians (toads), birds (great horned owl, golden eagle and the bald eagle), and reptiles (lizards and snakes).
Cold Desert
- These deserts are characterized by cold winters with snowfall and high overall rainfall throughout the winter and occasionally over the summer.
- They have short, moist, and moderately warm summers with fairly long, cold winters.
- The mean winter temperature is between -2 to 4° C and the mean summer temperature is between 21-26° C.
- The winters receive quite a bit of snow. - The soil is heavy, silty, and salty. It contains alluvial fans where soil is relatively porous and drainage is good so that most of the salt has been leached out. - The plants are widely scattered.
- The main plants are deciduous, most having spiny leaves.
- Widely distributed animals are jack rabbits, kangaroo rats, kangaroo mice, pocket mice, grasshopper mice, and antelope ground squirrels.
Destruction that occurs in deserts
- Global warming is increasing the incidence of drought, which dries up water holes.
- Higher temperatures may produce an increasing number of wildfires that alter desert landscapes by eliminating slow-growing trees and shrubs and replacing them with fast-growing grasses.
- Irrigation used for agriculture, may in the long term, lead to salt levels in the soil that become too high to support plants.
- Grazing animals can destroy many desert plants and animals.
- Potassium cyanide used in gold mining may poison wildlife.
- Off-road vehicles, when used irresponsibly, can cause irreparable damage to desert habitats.
- Oil and gas production may disrupt sensitive habitat.
- Nuclear waste may be dumped in deserts, which have also been used as nuclear testing grounds.
Why is it important to teach this to students?
This is important to teach to our students because they will be familiar with the things that occur in our deserts. Especially because we all live in a desert it is important to know what damages occur so that we can better the quality of where we live. There really are not too many human impacts on the desert biomes, but we can limit the amount of some activity that takes place. Most deserts are not very populated, so they are the feeding ground of disposal of toxins and other harmful materials. But we really need to be aware of the damage that is occuring in order to keep the living organisms that are present from dying out.
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