Deserts ecosystem

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• TOPIC: DESERT
ECOSYSTEM
• Presented by: ADNAN KHAN
• C.No: 28
• Presented to: Dr. Farah zaidi

2. Definition of desert ecology, ecosystem
Desert ecology is the study of interactions between both biotic
and abiotic components of desert environments.
A desert ecosystem is defined by “interactions between
organism populations, the climate in which they live, and any
other non-living influences on the habitat”.
Deserts are arid regions which are generally associated with
warm temperatures, however cold deserts also exist.
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3. Contd…
 Deserts can be found on every continent, with the
largest being located in Antarctica (5.5 million square
miles), the Arctic, Northern Africa, and the Middle East.
 Among all the terrestrial ecosystems, deserts are
very typical landforms due to their unique ecological
conditions.
 Desert and near-desert areas cover nearly one-third
of the land surface of the globe .
 Deserts alone covers about seventh of the land
surface.
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4. 4
ANTARCTICA DESERT
North Africa desert

5. Contd…
 We normally call deserts as “sand seas or oceans of sands”.
 Most of the major desert areas like as
1. the Sahara,
2. the Arabian,
3. the Kalahari, and
4. the Deserts of Australia
 All lie between 10 and 30 degrees north or south of the
equator.
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6. 6
Sahara desert, Africa

7.  Several things which make up a desert ecosystem are:
 Structure
 Characteristics
 Animals
 The ecosystem is dependent upon the type of desert; temperate
deserts, also referred to as cold deserts, or hot or subtropical deserts.
 Hot deserts and cold deserts have different kinds of ecosystems.
However, despite being very different, the two kinds of deserts have a
few similarities.
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8. Similarities of temperate & subtropical deserts:
 Both get fewer than 10 inches of rain annually.
 Dry air is found in both kinds of biomes.
 Both have harsh living conditions that impact people or animals living
there.
 Plants have adapted to having less water and harsher temperatures.
 Animals have adapted to the conditions as far as energy, food
consumption and when to get out and be active.
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9. Biotic and Abiotic components:
 In general, deserts are made up of a number of abiotic components –
including sand, the lack of moisture, and hot temperatures – basically
anything that makes up an ecosystem that isn’t alive.
 However, there are also a number of biotic factors that affect deserts,
which include living things, such as plants and animals.
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10. Characteristics of Deserts
 Deserts are characterised by the following ecological factors:
 Sandy soils and a rocky substratum.
 Scanty rainfall and high evaporation.
 Hot and Cold weather.
 Prevailing Wind action.
 Poor Soil Moisture and water resources.
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11. Geomorphology** of Deserts
 Deserts are created by changes in climate and accumulation of sands
and other rocky wastes.
 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
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**the study of the physical features of the surface of the earth and their
relation to its geological structures

12. Sand dunes & Soils in Deserts
 Dunes are large piles of wind-borne sands reaching a maximum
height of 250 metres 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 regions are generally fertile but lacks soil moisture to
encourage plant growth
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14. 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.
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15. Rainfall over Deserts
Rainfall is a determining factor of deserts. Rainfall is very scanty in all desert regions. In 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.
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17. Water availability in Deserts
Another controlling
factor of desert is the
presence of water. Only
in some depressions
very little water may
exists. Soil moisture is
a rare feature in deserts.
Even if little soil
moisture is present, due
to hot climate and
prevailing winds, it will
be evaporated quickly.
The drainage system
is made up of dried
streams called
arroyos. After a
rainfall, water fills the
arroyos. They run
down the mountains
and cut away the land,
carrying deposits of
gravel, rock, and sand
to the bottom.
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18. Arroyos and oasis 18

19. Contd.. 19
 Oasis is a wet and fertile zone in a desert with vegetation.
Underground water comes nearer to the ground surface.
 Open wells and springs do exist in such spots. Water that occurs
within an oasis has been drawn through groundwater base flow from
distant catchments like mountains or hills.
 Some oases may be small and can support only a few people, but
others are large enough to support millions of people.

20. Oasis 20

21. Types of deserts
Major types:
Tropical
deserts
Topographic
deserts
Other types
based on
surface
forms and
soil
composition:
Rocky deserts Stony deserts Sandy deserts
Clayey
deserts
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22. Life forms of Plants
The following three life forms of plants that are
adapted to deserts:
The annuals, which avoid drought by growing only
when there is adequate moisture.
The succulents- such as the cacti, which store
water and survive.
The desert shrubs- which have numerous branches
with small but thick leaves to store water.
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23. Fauna of deserts
 Animals have developed special body structure and ways of life.
 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
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24.  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.
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25.  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.
 “Ship of the Deserts” ie. 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.
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26.  There are two chief kinds of camels:
1. the Arabian camel, also called dromedary, which has one hump, and
2. the Bactrian camel, which has two humps.
 The camels that graze in the Sahara can go all winter without water and may
refuse to drink if water is offered to them. But a large, thirsty camel can drink as
much as 200 litres a day. This water is not stored in the camel's body but replaces
water previously used up.
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28. Annual production of dry matter
 The primary production in deserts depend on;
 the little amount of available water and
 also the consumption strategy adopted by the plants.
 It is very low as 30-300 gm/ sq.m/year in arid zones, above the
ground.
 Lowest production 2.6gm/sq m/year in dune community in dry year
observed.
 Highest production 816gm/sq m/year observed in large arroyo in
Chihuahuan Desert.
 Average production 180gm/sq m/year.
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29. Annual production of dry matter
 The herbivores have a pronounced impact on primary
producers. The detrital food chain seems to be less important
in the desert than any other ecosystems.

 Because of the limited production and decomposition,
nutrients are limited in the deserts.
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30. Productivity
 Walter in 1954 has measured the net productivity of a series of deserts
and semi-arid communities.
 This has also shown that the overall limiting factor of deserts in
productivity is the moisture. It has been found that he annual net
productivity of true deserts is less than 2000 kg per hectare
 When this is overcome due to rain, then the soil becomes a limiting
factor.
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31. References
 DESERT ECOLOGY By Prof.A. Balasubramanian, Centre for Advanced Studies in
Earth Science, University of Mysore, Mysore.
 https://www.researchgate.net/publication/314933544_DESERT_ECOLOGY
 Conserve Energy Future
 https://www.conserve-energy-future.com/desert-ecosystem.php
 Wikipeda
 www.Wikipedia.org
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32. References
 JSTOR
 https://www.jstor.org/stable/1308782?seq=1#page_scan_tab_contents
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