Living World - [Optional] - Hot Deserts (Paper 1) Flashcards

This is one of the optional topics for the exam. You have a choice between cold environments or hot deserts. If you are unsure, ask your class teacher.

1
Q

Define ‘biodiversity

A

The variety of plants and animals living in a particular ecosystem.

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2
Q

What is a hot desert?

A

A hot desert is an area that is very dry (usually receiving less than 250mm of rainfall per year). They also experience very high temperatures of 45°c.

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3
Q

Where are hot deserts located?

A

Generally found 30°N and 30°S of the equator in areas of land away from large expanses of coast.

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4
Q

What is the climate (temperature and precipitation) like in a hot desert?

A
  • Temperature: highs of 45°c in the day, lows of 5°c at night.
  • Precipitation: less than 250mm per year
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5
Q

Why is it hot and dry in hot deserts?

A

Hot: Close to the equator where suns rays are more concentrated

Dry: in areas of high pressure where air is sinking.

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6
Q

What is the soil like in a hot desert?

A
  • Shallow and dry
  • Coarse texture
  • Infertile due to lack of leaf litter
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7
Q

What wildlife (plants and animals) would you find in a hot desert

A
  • Animals that are well adapted to the hot, dry climate, limited vegetation. e.g snakes, lizards
  • The animals are generally very small in size and tend to sleep through the day time when temeperatures are high.
  • Limited plants. Those that do grow are short in height and don’t live a long time.
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8
Q

How have animals adapted to hot deserts?

A
  • Nocturnal - hunt in the cool evenings
  • Big ears to allow temperature regulation
  • Can store fat that breaks down into water e.g. camels
  • Long eyelashes, flat wide feet to cope with sand
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9
Q

How have plants adapted to hot deserts?

A
  • Long plant roots to reach water deep in soil
  • Small leaves to reduce moisture lost
  • Succulent plants (fleshy skin to retain moisture)
  • Sharp needles on surface to deter predators
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10
Q

What is the biodiversity like of hot deserts?

A
  • Limited due to extreme climate
  • This means any changes can have drastic consequences
  • Global warming is the biggest threat to hot deserts biodiversity.
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11
Q

Why are hot deserts are interdependent ecosystem?

A
  • Plants gain nutrients from soil, animals require energy and nutrients from plants
  • The climate causes the soils to be infertile and unable to support large amounts of vegetation.
  • Changes to one part of the ecosystem can have huge knock-on impacts on another part e.g. removing vegetation can cause soil erosion.
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12
Q

What are the opportunities in the Thar Desert?

A
  • Tourism: tens of thousands of tourists visit each year. Lots of desert safaris at Jaisalmer and desert festival.
  • Mining: gypsum (for cement), feldspar (for ceramics), phosperite (fertiliser)
  • Energy exploitation: rich in coal and oil. Opportunities for wind (Jaisalmer Wind Park) and solar power (Bhaleri solar plant)
  • Farming: mostly subsistence farming. Irrigation has made commerical farming possible e.g. cotton, wheat.
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13
Q

What are the challenges facing the Thar desert?

A
  • Extreme temperatures: highs of 50°c makes it difficult to work outside and plants and animals need large amounts of shade to survive.
  • Inaccessibility: limited roads to the area due to low population density. Tarmac roads don’t cope well in high temperatures.
  • Water supply: farming and population increase has put pressure on water use. Low temperatures and high evaporation rates makes water scarce.
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14
Q

What is desertification?

A

When land becomes degraded to the point it turns to desert. This tends to happen on the edges of existing deserts.

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15
Q

Define ‘salinisation

A

The accumulation of salts in the soil that occur as a result of rapid evaporation of water.

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16
Q

What are the phyiscal causes of desertification?

A

_Climate change:_

  1. Less rainfall - less rainfall in areas that are already dry. This means less plants (plants hold soil together) which leads to soil erosion
  2. Higher temperatures - increasing tempratures which causes water to evaporate from ground, in turn, killing plants which hold they soil together.
17
Q

What are the human causes of desertification?

A
  1. Over grazing - cattle eat too much vegetation which holds the plants together. Soil becomes easily eroded if there is less vegetation.
  2. Over cultivation - repeated farming exhausts the soil
  3. Population pressures - more deforestation to make space leads to soil exhaustion
  4. Demand for fuel wood - removing branches for fuel exposes soil to erosion
18
Q

List the four strategies used to reduce desertification

A
  1. Water management
  2. Soil management
  3. Tree planting
  4. Use of appropriate technology
19
Q

How can water and soil management reduce desertification

A
  • Switching to growing crops that don’t require as much water to grow e.g. olives, millet.
  • Drip irrigation means drip feeding the soil with water rather than over-irrigating the soil at once. This prevents soil degradation.
  • Contour traps - building embankments along contours of a hill side so that soil doesn’t slow down hillsides during rainfall.
  • Rotating crop yields and giving a rest period between crop rotations allows soils to recuperate.
20
Q

How can tree planting reduce desertification

A

Trees are important in soil health. They can be planted to act as a wind break to prevent the top soil blowing away. They also provide shade for crops to be grown underneath, reducing moisture loss.

21
Q

How can appropriate technology reduce desertification?

A

Appropriate technology means using technology that is cheap and sustainable for the chosen location. Examples include:

  1. Sand fences that trap windblown sand
  2. Solar panel cookers reduces need for fuelwood
  3. Magic stones - lines of stones along contours to prevent water loss from soil. The stones catch the water and retain it.