DESERT ECOSYSTEM

Desert is a terrestrial ecosystem which receives very little, lesser than 25cm per year, rainfall or precipitation. Deserts cover as much as one fifth of the earth's land surface and forms one of the major ecosystems on earth. 

Examples : Namib desert, South Africa. 

                    Atacama desert, South America

                    Sahara desert, Africa

                    Thar desert, India - Pakistan

The word comes from a Latin word desertum which means 'to abandon'.

Desertification is an ongoing process, though we don't realize it on a real time basis. We can sense the rise in atmospheric temperature, lack of rain etc., which will gradually lead to the formation of new deserts. Ancient civilizations of Greece, Mesopotamian and Mayan were demolished by the process of desertification.

Life is difficult in desert habitats, challenged with dehydration, lack of drinking water, extreme heat and sweat, lack of biodiversity which leads to lack of food material etc. Many of the organisms which survive on the deserts have specific adaptations for its survival. The camel has a bump on its back for storage of fat (NOT WATER) and they can live many days without eating anything. Their nose is adapted to prevent sand entering while sand storms. webbed feet to prevent sinking in to the sand and long eye lashes for preventing sand entering eyes.

Deserts can be classified in to two types;

1) Hot Deserts

2) Cold Deserts

Hot Deserts

Hot deserts are places with very high temperature as high as 50 degree Celsius in the day and freezing cool in the night. The soils are nutrient poor. They are found around latitude 20-30 degrees north and south of the equator. They occupy nearly 20% of the earth's surface. 

Exaples include Sahara, Atacama of Chile, Kalahari of Africa and Simpson of Australia.

The plants of the hot desert include succulents such as cactus, annuals, desert shrubs such as Fonquieria splendens. The cactus can store water. Many plants have volatile chemicals to prevent herbivores.

Animals include ants, birds, rodents, lizards, snakes, small mammals etc. Examples - Horned viper, Addax antelope, Ostrich, Camel, Golden Jackal etc.

Cold Deserts

The day time temperature in cold deserts can be around 2-4 degree Celsius, though it can raise upto 26 degrees in summer. In winter, the temperature is as low as minus 26 degrees. Precipitation is less than 25 cm per year. They show the formation of ice coated regions during winter. 

Examples-  Gobi desert, Mongolia; Great basin desert, North America; Patagonian desert, Argentina.

Succulents are absent in cold deserts, as they are susceptible to freezing. Many species have spines and shed leaves. Examples- Artemesia, Sagebrush etc

Animals live in burrows to escape the cold weather. Examples- Jack rabbit, Pocket mice, Kit fox and Coyote.

Importance

1. Deserts account for one sixth of world's population.

2. They cover one fifth of land mass.

3. Formation of minerals via dehydration- example Gypsum, borates, nitrates.

4. Carbon sequestration- The cyanobacteria in deserts store CO2 from air.