desert ecosystem Deserts and semi arid lands are extremely specialised and sensitive ecosystems that are easily destroyed by human activities. The plants and animals that inhabit these dry areas can live only in this ecosystem. Desert ecosystem, is usually believed to be barren, but this fragile ecosystem supports numerous amazing living creatures, known for their adaptability. Deserts alone covers about seventh of the land surface. We normally call deserts as “sand seas or oceans of sands”. Most of the major desert areas like as the Sahara, the Arabian, the Kalahari, and the Deserts of Australia all lie between 10 and 30 degrees north or south of the equator. Deserts are dry ecosystems comprising a substantial part of the globe

1. DESERT
ECOSYSTEM
PREPARED BY MANSHI
SHARMA
CENTRAL UNIVERSITY OF
JAMMU
MSc Biotechnology

2. WHAT IS A DESERT ECOSYSTEM?
Deserts and semi arid lands are extremely specialised and sensitive
ecosystems that are easily destroyed by human activities. The plants
and animals that inhabit these dry areas can live only in this
ecosystem.
Desert ecosystem, is usually believed to be barren, but this fragile
ecosystem supports numerous amazing living creatures, known for
their adaptability.
Deserts alone covers about seventh of the land surface. We normally
call deserts as “sand seas or oceans of sands”. Most of the major
desert areas like as the Sahara, the Arabian, the Kalahari, and the
Deserts of Australia all lie between 10 and 30 degrees north or south
of the equator. Deserts are dry ecosystems comprising a substantial
part of the globe

3. DISTRIBUTION OF DESERTS

4. CHARACTERISTICS OF DESERTS
Deserts are characterized by the following ecological factors:
A. Sandy soils and a rocky substratum
B. Scanty rainfall and high evaporation
C. Hot and Cold weather
D. Prevailing Wind action
E. Poor Soil Moisture and water resources

5. GEOMORPHOLOGY OF DESERTS
Deserts are created by changes in climate and accumulation of sands and
other rocky wastes. A high proportion of the desert floor is an erosion
surface of a bedrock.
Sand covers about 10 to 20 per cent of the deserts. The rest of the land
consists mostly of gravels, boulders, mountains, and various types of soils.
A desert landscape includes various landforms created by wind erosion.
Wind erosion creates mounds of sand dunes and flat-topped hills known as
mesas and buttes. The sand bodies of deserts are always on rolling motion
due to the prevailing action of wind.
Sand drifts, Crescentic Dunes or Barchans, Loess and Longitudinal dunes
and sand sheets are the notable wind-borne geomorphic features. One of
the most remarkable features of desert dunes is their power of collecting all
the sand from their neighborhood.

6. SAND DUNES
Dunes are large piles of wind-borne sands reaching a maximum height of
250 meters above the surface. Dunes show many shapes and patterns that
change continually due to the highly active winds. Deserts are considered to
be highly dynamic geomorphic features. Dunes are characterized by two-
sided slopes one along the windward direction and the other along the
leeward side.
SOILS IN DESERT
Soils in desert regions are generally fertile but lacks soil moisture to
encourage plant growth
TEMPERATURE IN DESERTS
Climatologically, deserts are the hottest places in the world because they
absorb more heat from the Sun than any other land in humid climates.
Deserts are mostly under arid to semi-arid climates. The temperature varies
during day and nights. In summer, desert temperatures often reach upto 38
°C during the day. They drop upto 25 degrees Celsius or more at nights.
During the winter, temperatures in the desert range from 10 to 21 °C.
Clouds would reflect much of the sun's intense radiation during the day,
SAND DUNES

7. RAINFALL OVER DESERTS
Rainfall is a determining factor of deserts. Rainfall is very scanty in all desert regions. It
spite of these deserts are not barren wastelands. Characteristics that are common to all
deserts include
a) irregular rainfall of less than 250 mm per year,
b) very high evaporation rates often 20 times the annual precipitation, and
c) low relative humidity and cloud cover. Most of the deserts receive less than 200 mm
rainfall per year. However, the amount of rainfall may vary greatly from year to year. A
desert may not receive any rain for several years and in some cases about 250mm of rain
might fall within a few hours.
WIND MOVEMENTS IN DESERTS
Wind movements in deserts are capable of eroding, transporting and depositing the sand
masses. The following are the processes expected:
• DEFLATION
• ABRASION
• DUST STORMS IN DESERTS
• SAND STORMS
WATER AVAILABILITY IN DESERTS
Another controlling factor of desert is the presence of water. Due to very scanty rainfall and

8. DESERT TOPOGRAPHY
The typical desert topography includes:
• ALLUVIAL PLAINS
• PEDIMENTS
• INSELBERGS
• MESSAS
• BUTTES
• BADLANDS
MAJOR KIND OF DESERTS
The distribution of arid regions or deserts is determined by the climate and topography. Based
these two factors, arid terrains are subdivided into
a) tropical deserts
b) topographic deserts.
Alluvial plain Inselbergs
Mesas Buttes Badlands

9. TYPES OF DESERTS
Based on their surface forms and soil composition, deserts are
classified into the following four types:
Rocky Deserts
 Stony Deserts
 Sandy Deserts
 Clayey Deserts.

10. ROCKY DESERTS
Rocky deserts have uneven
topography between mountain
ridges and groups of small hills.
Mountain ridges have rugged
summits and crests, steep slopes
with outcrops of rocks. Talus and
scree debris are numerous on hill
sides. They are not completely
devoid of vegetation. Isolated
small and large shrubs can be
located on the lower parts of the
slopes., in valleys and
depressions. Some water springs
appear on valley floors.

11. STONY DESERTS
Stony deserts are completely flat
or gently undulated areas with
stones of rocky wastes
comprising sharp edged rock
fragments or pebbles. There may
not be any vegetation and water.
Sahara and Arabian Deserts are
stony deserts.

12. SANDY DESERTS
Sandy deserts are areas of loose
sand which forms hillocks in the
shape of barchans and dunes.
These are characterized by
uneven surfaces of undulating
chains of dunes with isolated
short valleys or hollows with little
vegetation. They resemble like
sea-waves. Barchans reach a
height of 200m. It is difficult to
walk straight across on these
zones. One has to climb the crets
and descend into the hollows. It
is easier to walk aided by wind.
Sand storms are common
creating an atmospheric haze.

13. CLAYEY DESERTS
Clayey Deserts are not extensive.
The clayey floors are cracked into
polygonal sections. Soil is of fine
silt in composition with sparse
vegetation. Soils of Clayey
deserts are mostly saturated with
salts.

14. GEOGRAPHICAL CLASSIFICATION
OF DESERTS
Deserts are also classified based the geographic conditions.
The geographical classification of deserts also include:
CONTINENTAL DESERTS
e.g.- Gobi Desert

15.  RAIN SHADOW DESERTS
Due to tall mountain ranges
E.g.- Judean Desert in Israel
 COASTAL DESERTS
E.g.- Atacama Desert in S. America.
 TRADE WIND DESERTS
E.g.- Sahara desert- Temp goes
upto 57 degree Celsius.
 MONSOON DESERTS
E.g.- Thar desert in India

16.  POLAR DESERTS
E.g.- The Dry Valleys of
Antarctica – are ice free for
thousands of years.
 EXTRA TERRESTRIAL DESERTS
Deserts of other planets
E.g.- Mars have shown EOLIAN
(created by wind and dust)
features
 MONTANE DESERTS
Arid places with a very high altitude; the most prominent example is found north of the Himalayas, in
the Kunlun Mountains and the Tibetan Plateau.

17. ECOLOGICAL CLASSIFICATION OF
DESERTS
From an ecological point of view, deserts
are also classified into two major kinds
as
HOT DESERTS
Hot deserts are hot arid areas with little
rainfall, extreme temperature and sparse
vegetation. Generally, the deserts that
are found in the tropical and sub-
tropical regions (western coasts of
continents) between the 15 degrees and
30 degrees north and south of the
equator are hot deserts.
The annual rainfall in a hot desert is less
than 250 mm that makes them very dry.
Most of the hot deserts tend to lose
water continuously as they are located on
the path of trade winds. Their aridity is
mainly due to the off-shore trade winds,
so they are also known as Trade Wind
Deserts. They are also devoid of cover of
clouds due to the strong winds.
E.g.- SAHARA DESERT, THAR DESERT,
KALAHARI DESERT

18.  COLD DESERTS
The cold deserts are mostly found in
temperate regions at higher latitudes,
e.g. Arctic, the Antarctic and
Greenland including the areas above
the tree lines of mountain ranges.
They have mildly hot summers and
extremely cold winters. They generally
experience low temperature and long
winters. The average temperature
ranges from - 2 to 4 degree Celsius in
winter and 21 to 26 degree Celsius in
summer.
The precipitation is higher in cold
deserts and snowfall is common in
winter. Vegetation is scattered with
needle like leaves to reduce the water
loss. The animals commonly found in
cold deserts include foxes,
jackrabbits, kangaroo rats, pocket
mice, badger etc.
GREENLAND

19. FLORA OF DESERTS
Desert plants cannot use so much water at once, and the desert soil
cannot absorb all of it. Most of the water runs off, carrying away the
soil particles.
Most deserts plants are drought or salt tolerant, such as Xerophytes.
Some store water in their leaves, roots and stems.
Other desert plants have long tap roots that penetrate the water
table, anchor the soil, and control erosion. The stems and leaves of
some plants can lower the velocity of sand-carrying winds and
protect the ground from erosion.

20. LIFE FORMS OF PLANTS
The following three life forms of plants that are adapted to deserts:
a) The annuals, which avoid drought by growing only when there is adequate moisture
b) The succulents- such as the cacti, which store water and survive
c) The desert shrubs- which have numerous branches with small but thick leaves to
store water.
PRICKLY PEAR CACTUS (Opuntia) GHOST PLANT (Graptopetalum
paraguayense)

21. CENTURY PLANT (Agave
americana)
BRITTLEBUSH (Encelia farinosa)
DESERT LILY (Hesperocallis)

22. FAUNA OF DESERTS
Animals of the deserts have developed special body structure and ways of
life that enable them to survive under the extreme heat
Centipedes, gerbils, kangaroo rats, snakes, and scorpions spend the day in
burrows. They come out to search for food only when temperatures drop at
night.
Many insects, lizards, and tortoises can tolerate high desert temperatures
and are active in the daytime. Many of them retreat underground or find the
shade of a tree, during the hottest part of the day.
Some snails, insects, frogs, lizards, mice, and ground squirrels aestivate in
deserts, i.e they sleep through the summer.
Elf owls, roadrunners, snakes, spiders, bees and butterflies are the other
fauna of deserts.
Many desert dwellers have light-coloured skin, which helps keep them cool
by reflecting sunlight. Desert animals include many kinds of insects, spiders,
reptiles, birds, and mammals. Deer, foxes, wolves, and other animals may
visit a desert after a rainfall

23.  Desert foxes and hares have long ears. When overheated, these animals move to a
cool cave or burrow where they can get rid of excess body heat through their ears.
 Larger desert animals try to remain in shady areas during the day. The evaporation of
water from their bodies lowers their body temperature, but this water must be
replaced. Such animals obtain water from the food they eat and from the few water
holes that exist in a desert.
 Whenever deserts are discussed no one can forget about the “Ship of the Deserts” i.e.
The Camels. These are unique creatures which can not only survive, but also help the
human beings across hot, dry deserts with little food or water. They walk easily on
soft sand where even trucks would get stuck, and carry people and heavy loads to
places that have no roads. Camels also serve the people of the desert in many other
ways. A Camel carries its own built-in food supply on its back in the form of a hump.
The hump is a large lump of fat that provides energy if food is hard to find.
 Adaptation to the topography, landforms and climate is a unique feature of desert
animals. They live with very scanty food resources.

24. CHART OF FAUNA AND FLORA OF DESERTS

25. FOOD WEB OF DESERTS
Producer (Photosynthetic)
Cactus
Primary consumer(Herbivore)
Butterfly
Secondary consumer(Carnivore)
Lizard
Tertiary consumer(Carnivore)
Snake
Quaternary consumer(Carnivore)
Roadrunner

26. HUMAN POPULATION IN DESERTS
Human population in deserts are also equally
facing the same issues. Deserts do not
support a large number of people as in
humid regions. People living in desert regions
must adjust to the local and prevailing hot or
dry climate. Air-conditioning and irrigation
projects have made life more comfortable for
other desert dwellers.

27. NATURAL RESOURCES OF
DESERTS
Deserts have enormous sands and soil resources. The soil of deserts
are mineral soils often called as arid soils with low organic content.
Most desert soil is too dry to support widespread vegetation, but
much of it is rich in salt, uranium, and other minerals. Playas are
sources of mineral deposits formed by evaporation.
Gypsum, sodium nitrate, sodium chloride salts and Borates are the
major precipitates.
Minerals formed by evaporation are often referred to as evaporites.
Many of them are used in the manufacture of glass, ceramics,
enamel, agricultural chemicals, water softeners and pharmaceuticals.
Sodium nitrites are used for explosives and fertilizers. Many metallic
and nonmetallic mineral resources also are obtained from the desert
zones.

28. OTHER PRODUCES
Date palm tree produces date fruits. They thrive in hot, dry climates.
They grow along oases throughout northern Africa and the Middle
East. The date palm is one of the oldest crop plants known to have
been used for at least 5,000 years
In addition to these, large deposits of oil and natural gas lie under
many desert lands. Some of the more productive petroleum areas on
Earth are found in arid and semi-arid regions of Africa and the Middle
east although oil fields were originally formed in shallow marine
environments.

29. THREATS TO DESERT ECOSYSTEM
Several types of development strategies as well as human population
growth have begun to affect the natural ecosystem of the desert and
semi arid lands
Residential development
Off-road recreational activities destroy habitat for plants and
animals
Careless use of potassium cyanide which is left over, used in gold
mining. This is horrible to biodiversity as if plants or animals or even
the soil consume it, it can prove lethal or damage their body. (sahara
desert)
Oil, Gas, and Nuclear waste being dumped.
Conversion of these lands through extensive irrigation systems has

30.  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.

31. CONSERVATION OF DESERT
ECOSYSTEM
We can more efficiently use existing water resources and better
control salinization to improve arid lands, find new ways to rotate
crops to protect the fragile soil, and plant sand-fixing bushes and
trees.
Planting leguminous plants, which extract nitrogen from the air and
fix it in the ground, can help restore soil fertility.
People can also use off-road vehicles only on designated trails and
roadways and dig artificial grooves in the ground to retain rainfall and
trap windblown seeds.

32. THANK YOU!!!