The living world - Hot deserts

Question 1

Appropriate technology (or Intermediate technology)

Answer 1

Technology that is suited to the needs, skills, resources, knowledge and wealth of local people in the environment in which they live.

Question 2

Biodiversity

Answer 2

The variety of life in the world or a particular habitat.

Question 3

Desertification

Answer 3

The process by which land becomes drier and degraded, as a result of climate change or
human activities, or both.

Question 4

Hot desert

Answer 4

An ecosystem that is characterised by high average temperatures and very low precipitation.

Question 5

Mineral extraction

Answer 5

The removal of solid mineral resources from the earth. These resources include ores, which contain commercially valuable amounts of metals (e.g. iron and aluminium), precious stones
(e.g. diamonds), building stones (e.g. granite), and solid fuels (e.g. coal and oil shale).

Question 6

Over-cultivation

Answer 6

Exhausting the soil by over-cropping the land.

Question 7

Overgrazing

Answer 7

Grazing too many livestock for too long on the land, so vegetation cover is depleted and is
unable to recover.

Question 8

Desert fringe areas

Answer 8

semi-deserts, semi-arid areas, drylands
borders of hot desert, they support greater biodiversity and larger plants
despite higher rainfall, still classified as fragile environment, at constant risk of desertification

Question 9

Case study opportunities: The Western Desert, USA - mineral extraction

Answer 9

• rich reserves of copper, uranium and coal
• copper mining in Sonoran Desert –> open cast mining on a large scale since underground water found in ancient lava flow

Question 10

Case study potential challenge of the opportunities: The Western Desert, USA - mineral extraction

Answer 10

• conflicts with other land uses i.e. tourism and farming
• contamination of water

Question 11

Case study opportunities: The Western Desert, USA - tourism

Answer 11

• Grand Canyon and California’s Joshua Tree National Park, Colorado
• Museum in Parker, Arizona celebrates culture and heritage of Native Americans
• Las Vegas attracts 37 million visitors a year
• Lake Mead and Lake Powell attracts 2 million visitors a year for fishing and water sports

Question 12

Case study potential challenge of the opportunities: The Western Desert, USA - tourism

Answer 12

• jobs encourage population increase in an already fragile environment
• tourists demand water –> showers, food requires huge amounts of water, swimming pools

Question 13

Case study opportunities: The Western Desert, USA - farming

Answer 13

• Aquifer based farming in California’s Coachella valley produces lush crops of vegetables, lemons, peppers and grapes (–> wine)
• farmers allocated 80% of Colorado water despite it making up just 10% of the economy

Question 14

Case study potential challenge of the opportunities: The Western Desert, USA - farming

Answer 14

• a lot of water is needed for irrigation of crops

Question 15

Case study opportunities: The Western Desert, USA - farming. Why does it happen?

Answer 15

High temperatures and sunlight are favourable for agriculture

Question 16

Case study opportunities: The Western Desert, USA - tourism. Why does it happen?

Answer 16

People have more money and leisure time
Chance to experience a wilderness area

Question 17

Case study opportunities: The Western Desert, USA - mineral extraction. Why does it happen?

Answer 17

The area is rich in minerals - copper, uranium, lead, zinc, gold

Question 18

Case study opportunities: The Western Desert, USA - energy

Answer 18

• Sonoran Solar Project (Arizona) energy for 100,000 homes and requires 360 workers to help build it
• Hoover Dam (Lake Mead) generates hydraulic power –> employed 5,000 people when in peak construction
• Navajo National oil and gas company for benefit of Navajo people –> 100 employees –> produce oil worth $50 million

Question 19

Case study potential challenge of the opportunities: The Western Desert, USA - energy

Answer 19

• Hoover Dam increases evaporation
• contamination of water downstream

Question 20

Case study opportunities: The Western Desert, USA - energy. Why does it happen?

Answer 20

Strong insolation, fantastic for solar power
HEP Hoover Dam
Fossil fuels (oil)

Question 21

Carrying capacity

Answer 21

is the maximum number of people an area of land can support before environmental damage occurs

Question 22

Case study: challenges of developing in a hot desert - extreme temperatures

Answer 22

• average temperature is 27 degrees C, summer temperatures can soar above 50 degree C
• work outside is very hard, especially for famers who have to work during the day
• leads to high rates of evaporation and water shortages

Question 23

Case study: challenges of developing in a hot desert - water supply

Answer 23

• Colorado river has a very low flow between September and April
• silts and sands get trapped behind both dams –> river ecosystems change and many species are lost
• high temperatures cause evaporation

Question 24

Case study: challenges of developing in a hot desert - inaccessibility

Answer 24

• low population density means that part of the Western Desert lacks surfaced roads
  –> tourist and explorers must find their own way
  –> extreme temperatures make this a dangerous place if your car breaks down - in 2015 elderly couple died of dehydration in the Los Coyotes Reservation near the edge of the Mojave desert

Question 25

What are the causes of desertification?

Answer 25

- climate change - population growth - removal of fuel wood - overgrazing - over-cultivation - soil erosion

Question 26

Causes of desertification - climate change

Answer 26

- since 1970s the Sahel region of West Africa has experienced significant reductions in annual rainfall - scientists believe climate change is disrupting the normal patterns of rainfall and causing more droughts

Question 27

Causes of desertification - population growth

Answer 27

- in the Sahel region, population has increased from 30 million people in 1950 to almost 500 million --> this is expected to double by 2050 - demand for food increases --> puts land under large amounts of pressure --> leads to vegetation destruction, soil erosion and ultimately desertification - made worse by people migrating away from drought stricken regions or areas affected by war or natural disaster

Question 28

Causes of desertification -removal of fuelwood

Answer 28

- millions of people living in semi-arid regions depend upon wood as their primary source of fuel - when land is stripped of its trees, it is vulnerable to erosion by wind and rain --> can quickly become degraded and turn into a desert

Question 29

Causes of desertification - overgrazing

Answer 29

- overgrazing by animals such as goats, sheep, cattle results in vegetation being stripped from an area and soil being left bare --> vulnerable to erosion - happens because the available pasture land is reduced by natural causes (such as droughts) or human factors (such as political conflicts) - population pressure can also lead to overgrazing

Question 30

Causes of desertification - over-cultivation

Answer 30

- similar to overgrazing but takes place when land is over-cultivated for growing crops --> exhausting the soil of its nutrients - soils in semi-desert regions are not very fertile and contain little organic matter - when soils are over-cultivated - often in response to population pressure or restrictions in available land - the soil becomes dry, dusty and infertile --> then prone to soil erosion

Question 31

Causes of desertification - soil erosion

Answer 31

- when vegetation is stripped or killed, the soil is left bare --> to be baked hard by the Sun - when rainfall occurs, it washed over the hard surface, eroding rills and gullies and washing away the top soil - this leaves behind very infertile sub-soil that cannot be used for anything - soil can take thousands of years to form but can be eroded away in just a matter of hours

Question 32

What are the causes of population pressure in fringe desert regions?

Answer 32

- natural increase - migration - armed conflict

Question 33

What are the strategies that can be used to reduce the risk of desertification?

Answer 33

water and soil management --> addresses rainfall washing away loose soil and causing soil erosion --> often involves water storage and attempts to control the surface flow of water tree planting --> protect soil --> roots bind soil together use of appropriate technology --> low walls to manage water --> alternative cooking devices that uses efficient stoves

Question 34

Definition of deserts

Answer 34

an area receiving less than 250mm of rainfall resulting in extreme aridity

Question 35

Describe the location of Deserts

Answer 35

- found between 15 degrees and 35 degrees North and South of the equator --> where the air is sinking --> leads to areas of high pressure --> few/no clouds --> temp high in the day, low in the night - the Tropic of Cancer and Tropic and the Tropic of Capricorn pass through most of the World's Hot Desert regions - there are no deserts located in Europe

Question 36

diurnal temperature range

Answer 36

the difference between the maximum and minimum temperatures withing 1 day

Question 37

Desert soils

Answer 37

- sandy, rocky soils - typically about 1m deep - often little organic material due to lack of vegetation - may have white powder on the surface because salts are drawn to the surface by evaporation

Question 38

irrigated

Answer 38

artificial process of applying controlled amounts of water to land

Question 39

How are soil and vegetation interdependent?

Answer 39

- the canopy of leaves intercepts rainfall --> falls gently to the ground by dripping from leaf tips --> without this interception, raindrops would strike the soil, eroding the small soil particles - the leaves provide shade --> can reduce air temperatures by up to 20 degrees C than in the open --> so soil stays cooler - plants prevent the surface soil being baked in the heat --> without vegetation cover more moisture in the soil is drawn upwards from the surface - roots of plants help to bind the soil together and prevent gulley erosion

Question 40

State some primary consumers found in hot desert

Answer 40

insects, lizards, rodents, kangaroo rats

Question 41

How do humans positively impact interdependence in hot deserts?

Answer 41

- sustainable land management practices - wilding - afforestation - using underground or surface water at a sustainable rate

Question 42

How do humans negatively impact interdependence in hot deserts?

Answer 42

- urbanisation putting pressure on scarce resources - deforestation/removal of vegetation - footpath erosion in busy places like the Grand Canyon, making soil vulnerable to blowing away

Question 43

Challenges related to biodiversity

Answer 43

dry conditions high temperature short periods of rainfall

Question 44

Plant adaptions - leaves

Answer 44

small, linear leaves or needles in order to reduce loss of water through evapotranspiration leaves often also have a waxy resin, again to reduce evaporation

Question 45

Plant adaptions - roots

Answer 45

adapted roots to make the most of sudden rainfall some species have shallow roots that spread over a large areas others have tap roots which run deep in search of water (up to 25m)

Question 46

xerophyte

Answer 46

a plant that is adapted to living in an environment with little water

Question 47

Examples of 4 animals that live in the desert

Answer 47

fennec fox peringuey adder kangaroo rat camel

Question 48

How are kangaroo rats adapted to hot deserts?

Answer 48

don't sweat/have oily skin to reduce water loss produce little urine live in burrows during the day don't need to drink - get water from food

Question 49

How are peringuey adders adapted to hot deserts?

Answer 49

move sideways - means less than 50% of body in contact with hot sand

Question 50

How are fennec foxes adapted to hot deserts?

Answer 50

large ears help dissipate excess body heat kidneys are adapted to restrict water loss their extensive burrowing may cause the formation of dew, which can be consumed they will receive moisture from their food thick fur helps insulate them from the cold desert nights sandy fur helps to reflect heat and provides camouflage thick fur on the soles of their feet, which insulate against against the hot sand of the desert --> also provides excellent traction in the loose sand

Question 51

How are camels adapted to hot deserts?

Answer 51

can go a week or more without drinking water and they can last several months without food they can drink up to 32 gallons (46 litres) of water at one drinking session store fat in the hump --> can be metabolised for energy healthy body temperature is from 34-41.7 degree C --> allows camel to conserve water by not sweating as the environmental temperature rises feet are wide so they can walk on sand more easily --> without sinking thick lips so they can eat the prickly desert plants without feeling pain ears covered with hair --> keeps out sand or dust that might blow into the camel's ears