Deserts

Question 1

characteristics of a hot desert

Answer 1

hot and dry
low biodiversity
little rainfall

Question 2

define desert

Answer 2

an area receiving less than 250mm of precipitation a year

Question 3

describe the distribution of deserts

Answer 3

along the tropics of cancer and capricorn
between 15 and 35 degrees north/ south of the equator

Question 4

give 3 examples of deserts

Answer 4

sahara, arabian, sonoran

Question 5

define diurnal

Answer 5

24 hour period

Question 6

explain the location of deserts

Answer 6

at the tropics, air is sinking- this creates areas of high pressure so there is less clouds and rainfall
lack of cloud cover means hot days and cold nights

Question 7

describe the characteristics of desert soils

Answer 7

sandy, infertile, rocky soils
1m deep
little organic matter due to little vegetation
white powder on the surface (salts drawn to the surface by evaporation)

Question 8

interdependence between soil and plants

Answer 8

-roots of plants hold the soil in place and stop it from blowing away
-when the plant dies, decomposers break it down and return nutrients to the soil
-plants provide shade and stop the soil from drying out

-soil provides the plant with nutrients

Question 9

positive human impacts on interdependence

Answer 9

afforestation
wilding
moving animals from area to area to allow land to regenerate

Question 10

negative human impacts on interdependence

Answer 10

urbanisation- building cities
footpath erosion (E.g grand canyon) makes soil vulnerable to blowing away
overgrazing

Question 11

reasons for low biodiversity

Answer 11

dry conditions- not ideal for plants growth
high temperatures
short periods of rainfall- plants grow quickly to make use of the rain, complete their life cycle quickly

Question 12

define xerophytes

Answer 12

-plants that can survive in dry conditions
-some have waxy cuticles which reduces transpiration and minimises water loss

Question 13

adaptions of the desert yellow daisy

Answer 13

waxy cuticles and small leaves reduces transpiration- minimises water loss
needles- protects against predators

Question 14

adaptions of the prickly pear cactus

Answer 14

shallow roots which spread over a large area- absorbs as much rainfall as possible

Question 15

adaptions of the saguaro cactus

Answer 15

grows slowly to conserve energy
stores it’s own water

Question 16

adaptions of the fennec fox

Answer 16

large ears- rids of excess body heat
thick fur- insulation for cold nights
sandy fur- reflects heat, camouflage
hunts at night instead of day

Question 17

adaptions of the kangaroo rat

Answer 17

dont sweat
produce little urine- conserves water
lives in burrows during the day

Question 18

adaptions of the desert camel

Answer 18

store fat in their hump- used for energy
wide feet- walk on sand easily
thick lips- can eat prickly plants

Question 19

case study desert

Answer 19

the western desert, USA

Question 20

the western desert is made up of 3 smaller deserts- what are they

Answer 20

mojave, sonoran, chihauhau

Question 21

what 3 states does the western desert cover

Answer 21

arizona, nevada, new mexico

Question 22

tourism in western desert and challenges

Answer 22

lake mead- boating, sailing
need more water for hotels and tourists->lack of water for locals

Question 23

farming in western desert and challenges

Answer 23

coachella valley- grow vegetables
only possible with irrigation->less water for locals

Question 24

energy generation in western desert and challenges

Answer 24

sonoran solar farm- powers 100,000 homes
oil undergound- still dependant on fossil fuels

Question 25

mineral extraction in western desert and challenges

Answer 25

earth is rich in minerals, E.g copper
uranium mining in grand canyon was halted due to conflicts between tourists and farmers

risk to wildlife species- habitat destruction
contamination of groundwater

Question 26

define carrying capacity

Answer 26

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

Question 27

challenges in desert areas

Answer 27

inaccessability- lack of surfaced roads
water shortages- little rainfall
extreme temperatures- no cloud cover

Question 28

management of water shortages

Answer 28

xeriscaping- changing the landcape, E.g instead of grass, have a rock garden

Question 29

management of inaccessibility

Answer 29

highways- connect cities and deserts
E.g route 70 through Utah

travel by air

Question 30

why are deserts inaccessible

Answer 30

low population density so a lack of surfaced roads

Question 31

management of extreme temperatures

Answer 31

whitewashed walls- reflect heat
thick earth walls- keep homes cool

Question 32

how many visitors a year to Las Vegas

Answer 32

37 million

Question 33

define desertification

Answer 33

land becoming desert as the soil quality degrades over time.

Question 34

explain over grazing as a cause of desertification

Answer 34

as the population increases, animals are grazed at a higher stock to feed more people. the animals eat the vegetation so amount of vegetation decreases.
soil is exposed to erosion and leaching
this makes soil infertile and dry

Question 35

explain the cycle of desertification

Answer 35

amount of vegetation decreases
no plants to shade soil or intercept rainfall
soil is exposed to sun so it cracks
when it rains, water runs on the surface
nutrients are leached
soil becomes degraded and infertile
hard to grow crops

Question 36

3 ways increasing population leads to the desertification cycle

Answer 36

1. overgrazing animals to get more food for more people, animals eat vegetation -> lack of vegetation
2. more people require more firewood for cooking, cut down trees -> lack of vegetation
3. land is farmed more intensively to get more food for more people, takes nutrients from soil -> vegetation decreases

Question 37

describe location of the Sahel region

Answer 37

sahel is a desert fringe area
stretches along central Africa
south of sahara desert
across countries like sudan, niger, chad

Question 38

what is the sahel like

Answer 38

very low income
low life expectancy
population is 50 million

Question 39

causes of population pressure in fringe desert regions

Answer 39

1. conflict- refugees migrate to neighbouring countries. E.g civil war in south sudan.
2. natural increase/ high birth rates- lack of family planning and contraception leads to high birth rates

Question 40

causes of desertification

Answer 40

climate change- decrease in rainfall, vegetation decreases (less water for photosynthesis= less growth)

overgrazing- animals eat vegetation, soil becomes exposed to heavy rainfall, causes leaching and soil erosion

migration and refugees- leads to population increase, leads to overgrazing

Question 41

management strategies to reduce desertification

Answer 41

encourage contraception- reduces overpopulation- reduces overgrazing

grow drought-resistant crops such as maize
rotate crops

Question 42

management (water and soil) bunds

Answer 42

bunds are circles of stones placed on the ground
they hold water on the soil rather than letting it run quickly over the surface.
retains soil moisture for longer

not effective on uneven land
E.g Burkina Faso

Question 43

management (tree planting)

Answer 43

tree roots bind soil together, prevents soil from blowing away

trees intercept rainfall, prevents leaching

E.g great green wall project 2007
-trees planted across the sahel
-brought 350,000 jobs

Question 44

management (appropriate technology)

Answer 44

efficient stoves that burn small amounts of firewood- less trees cut down so there’s more vegetation

Question 45

great green wall project 2007

Answer 45

line of trees across the sahel
less successful in chad and south sudan as they are dealing with conflict

brought 350,000 jobs