deserts

Question 1

where are deserts found

Answer 1

subtropical areas 20 -30 degrees north and south of equator

Question 2

what is the climate like

Answer 2

hot dry arid less than 250mm rain/year very cold nights due to lack of cloud

Question 3

name the largest desert

Answer 3

sahara

Question 4

what is sehel

Answer 4

long strip of semi arid dry land that borders south of the Sahara

Question 5

what are desert fringes or drylands

Answer 5

border hot deserts

Question 6

are deserts fertile

Answer 6

some are because of the nutrents needed for plant growh are present, once irrigated land can be productive

Question 7

why do sand dunes form

Answer 7

in hot climates soil formination is limited by shortage of water and vegetaion. Weathering creates deep deposits of sand and loose material in some places wind build up tall sand dunes

Question 8

what are the challenges to biodiversity in hot dessets

Answer 8

biodiversity is limited because of
dry conditions
high temperatures
short periods of rainfall

Question 9

what are plants called

Answer 9

xerophytes they have thick waxy cuticle and shed leaves to minimise water loss by transpirtation

Question 10

how are plants adapted for desert(4)

Answer 10

1 have the bulk of their biomass below ground where it is cool
2 cactus thick waxy cuticle has rolled leaves to reduce transpiration and water loss
3 trees have long roots to go deep into soil, short 4 fat trunks to store water and are fire resistent
4 flowering plants have seeds that only germinate after heavy rain and can lie dormant for years and 5 complete lifecycle quickly
6 lichens do not need soils to grow they get nutrients by using chemicals to break down rocks

Question 11

can water be found in the desert

Answer 11

yes from aquifers or rivers eg nile

Question 12

how have animals adapted to desert kangaroo rats (4)

Answer 12

1 kangaroo rats do not need to drink water they get it from food,
2 live in burrows during the day to avoid heat and do 3 not sweat,
4 they have kidneys which produce small amounts of urine

Question 13

how has desert fox adapted to the desert (2)

Answer 13

1have thick fur on feet to protect from hot ground,
2 light coloured fur on bosy reflects sunlight and keeps them cool

Question 14

what are abiotic components of the desert

Answer 14

soil rocks water

Question 15

what interdependence exists in hot desets

Answer 15

links between parts of food web -
1 animals eating plants that gained nutrients from water and soil
2 vegetation roots stabalise the soil and plants stop soil from being blown away

Question 16

What makes up USA’s western desert

Answer 16

3 hot deserts Mojave Desert Sonoran Desert and

Chihuahuan Desrt

Question 17

what are the Western Deserts developmental opportunities

Answer 17

1urban residents can find work in retailing and service industries . In less populated areas farming, mineral extraction and tourism

Question 18

what are aquifers

Answer 18

stores of water below desert brought to the surface from wells

Question 19

can western deserts be farmed

Answer 19

yes high temperatures and sunlight are good if water can be fond

Question 20

name 2 important sources of irrigation in western deserts

Answer 20

aquifers and canals

Question 21

which minerals are western deserts rich in (5)

Answer 21

copper uranium lead zinc coal

Question 22

why is it not all the minerals are extracted

Answer 22

there are possible conflicts with land use eg tourism and farming

Question 23

which type of power are western deserts ideal for

Answer 23

solar power, there are also oil sources

Question 24

which is the western deserts most become western desserts most important for of income

Answer 24

tourism

national parks heritage museums, las vegas entertainment water sports

Question 25

why is there uneven development of western deserts (3)

Answer 25

1some of the environments are more challenging - to hot so no population
2 indigenous farm near water sources
3 accessibility can be challenging - lack of roads or it is dangerous if you break down in extreme temperatures train stations built near water sources

Question 26

how have people adapted to the climate

Answer 26

1 traditional native homes were adapted to the climate earth houses made with wooden frames packed with clay and thatched with grass kept homes cool in day warm at night

before air conditioning flat roofs collected water
homes small to reduce sunlight getting in
whitewashed to reflect the sun
outdoors they wear wide brimmed hats to prevent sunburn

Question 27

why was the hoover dam built

Answer 27

to supply water to the western desert during the summer when the colorado had low flow

Question 28

what were the benefits of the hoover dam (2)

Answer 28

water brought to the cities throughout the western desert

colorado aquaducts bring water to farms and irrigate land agricultural benefits =41.5 billion per year

Question 29

what are the disadvantages of the dam (3)

Answer 29

1 silt gets trapped behind the dam
2 and the water is colder changing the eccosystem and losing some species
3 sandbanks at the side of the river have been starved of sediment and this has caused some species to have decline.
4 the banks can no longer be used for fishing and rafting

Question 30

what problems will the western desert face in the future

Answer 30

1 as the population grows there is a limit to the amount of water that can be taken from the colorado
climate change will effect the rainfall in an already scarce in water

Question 31

what are the characteristics of desert fringe areas (3)

Answer 31

rainfall patterns are predictable

they support greater biodiversity and larger plants
more
drought resistent trees grow

Question 32

why are desert fringes classed as fragile environment

Answer 32

climate change and poor land management can have huge impact so they are at constant risk of desertification

Question 33

what is desertification

Answer 33

when habitable desert fringe areas are turning into hot desert areas

Question 34

what is main cause of dersertification

Answer 34

change in natural rainfall cycle declining rainfall

Question 35

will climate change result in less rain in deserts - why

Answer 35

we do not know if global temperatures rise there is a possibility of more rain in these areas due to the heating of the oceans and thus more water vapour in the atmosphere = more rain
but ckimate could become drier

Question 36

what role does population growth and human factors have on desertification

Answer 36

1 population growth is linked with poverty and lack of education, growth caused by increase in children and people living longer
2 migration is another factor - drought and desertification in one region displaces people to another fragile area. As desertification happens there the number of people increase and the problem spreads
3 other people have been forced to move into desert fringe areas because of armed conflict

Question 37

why has desertification become a problem in Darfur

Answer 37

1 one year in five brings drought - crops fail and cattle die
2 the ability to produce food has not kept up with growing population
3 conflict between nomadic farmers and settled farmers who fight over water supplies and land- it has led to overgrazing
4 some fled to refugee camps but this to has put stress on the land causing desertification

Question 38

3 human causes of desertification in populated areas

Answer 38

1 overcultivation - overcroppng land exhausts soils fertility. more crops planted to cope with growing population
2 overgrazing - to many cattle grazing for to long eating all the vegetation means it may not be able to regrow because of new political reasons nomadic tribes can no longer leave land to let it recover
3 soil erosion - over cultivation and over grazing result in soil erosion. if vegetaion is eaten by cattle of destroyed by drought the exposed topsoil is baked hard in the sun. When rain eventually comes it washes over the soil rather than soaking into the ground as it flows it carries the topsoil away . making it impossible for vegetation to grow back.

Question 39

what land management measures can help preserve soli quality and water (6)

Answer 39

1 tree planting schemes to bind and protect soil
2 planting grass on slopes to help stablise topsoil
3 collect rainwater on roofs
4 build small rock dams to trap water
5 build terraces on farmed slopes
6 construct low stone walls - bunds tjey help prevent flow over rainwater off baked ground and allows it to soak in

Question 40

how does planting trees help with desertification

Answer 40

roots help to stabalise soil

decomposing leaf litter add nutrients

Question 41

what is the green wall project

Answer 41

the plan to plant a wall of trees across the Sahel
it will secure physical environment and generate work and will help bring about political cooperation which might reduce conflict and number of refugee camps

Question 42

what threatens the green wall project

Answer 42

climate change may prevent the survial of the trees

Question 43

how can changing cooking methods help against desertification

Answer 43

removing trees for firewood for cooking and heating is most damaging human activity
it has increased with population growth
when trees are cut down soil errosion stops future regrowth

Question 44

what is an alternative way of cooking (2)

Answer 44

using efficient stoves which are made locally using more available materials eg clay and use smaller amounts of wood or charcoal. Some can generate electricity to power a mobile phone which allows farmers access to weather forcasts and so can prepare for drought
move to solar power as well as energy for cooking earning can be used to tackle desertification