- Very little rainfall (less than 250mm per yr). - When it rains varies a lot (might only rain once every 2 or 3 years). - Extreme temperatures (very hot in day (e.g. 45C), very cold at night (e.g. 5C))
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Soil
- Usually shallow with a coarse, gravelly texture. - Hardly any leaf fall so soil isnt very fertile. - Lack of rainfall and plant material mean soil is often very dry.
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Plants
- Sparse plant growth due to lack of rainfall. - Plant that do grow include cacti and thornbushes. - Plants are usually quite short (e.g. low shrubs or short woody trees) though catci can grow fairly tall. - Short life cycle - appear when it rains.
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Animals
- Animals adapted to survive in harsh environment. - E.g. lizards, snakes, insects and scorpions. - Small and nocturnal mammals, e.g. kangaroo rats. - Most birds leave deseert during harshest conditions - some (e.g. road runner) live there all yr.
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People
- Many people living there grow a few crops where there are natural springs or wells to supply water, usually in desert fringes. - Indigenous people are often nomadic (travel all the time in search of food+water for their herds (mostly goats+sheep)).
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Interdependance
-Plants gain nutrients from soil+provide nutrients and water to animals.-Animals spread plant seeds through dung.-Plants struggle to grow due to evaporation causing soils to be salty,+soils low in nutrients.-People have to irrigate as lack of water.
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Plant adaptations - long/spread out roots
- Long roots to reach very deep water supplies, or roots spread out very wide nr surface to catch max. amount of water when it rains.
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Plant adaptations - succulents
- E.g. cacti. - Large, fleshy stems for storing water and thick waxy skin to reduce water loss(transpiration). - Some have sharp spines and toxins to stop animals stealing water from stems.
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Plant adaptations - seeds
- Seeds of some plants only germinate when it rains - the plants grow, flower and release seeds in just a few weeks - makes sure they only grow when there's enough water to survive.
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Animal adaptations - nocturnal
- Animals can stay cool in burrows during day or sit still in shade when its hottest, e.g. fennec foxes.
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Animal adaptations - long limbs or ears
- Provides large surface area to lose heat from.
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Animal adaptations - toleration of high body temp.s
- Lizards and snakes are able to tolerate high body temp.s. - E.g. desert iguanas can survive temp.s up to 42C.
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Animal adaptations - storing large amounts of fat
- Some bigger animals store large amounts of fat which they can break down into water when needed. - E.g. camels' humps.
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Animal adaptations - getting water from food
- Some animals get all the water they need from what they eat. - E.g. cactus mice get water from cactus fruits and insects.
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Animal adaptations - minimising water loss
- Most desert animals minimise water loss from sweat and urine.
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Animal adaptations - coping with sand
- E.g. camels keep sand out of their eyes and nose by having triple eyelids, long eyelashes and being able to close their nostrils - also have large, flat feet so that they dont sink into the sand.
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Biodiversity
-Relatively low biodiversity (compared with tropical rainforests).-Small areas around water or along desert margins=highest biodiversity.-Lots of water=highest density of people.
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How is biodiversity threatened?
-Increasing desertification.-Over-using or contaminating water supplies.-Habitats being divided up by roads.-Global warming.-Biodiversity hotspots: places with a higher proportion of endemic (unique) species that are threatened with extinction.
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Other cards in this set
Card 2
Front
Soil
Back
- Usually shallow with a coarse, gravelly texture. - Hardly any leaf fall so soil isnt very fertile. - Lack of rainfall and plant material mean soil is often very dry.
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