Hot Deserts

Question 1

Define Mineral Extraction

Answer 1

the removal of solid mineral resources from the earth. These resources include ores, fuels, such as coil/precious stones

Question 2

define aridity

Answer 2

the state or quality of being extremely dry and lacking moisture

Question 3

define diurnal temperature range

Answer 3

the difference between maximum and minimum temperatures within a day

Question 4

define appropriate technology

Answer 4

technology suited to the needs of locals that combine cheap and environmentally friendly materials

Question 5

physical characteristics of a hot desert

Answer 5

dry, lack of biodiversity, barren (sparse vegetation), rocky, sandy, lack of cloud cover, high insolation levels

Question 6

definition of a desert

Answer 6

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

Question 7

Where are deserts found

Answer 7

15-35 degrees north/south of equator found near the tropics of cancer and capricorn
found on every continent EXCEPT EUROPE
high elevations

Question 8

what is the air pressure in deserts

Answer 8

high pressure systems and hot conditions - low vegetation cover + poor soils

Question 9

the worlds largest hot desert is…

Answer 9

the Sahara desert along the tropic of cancer

Question 10

why are deserts formed where they are

Answer 10

Subtropical High-Pressure Zones: Deserts form around 30° latitude (both north and south) because descending air from the Hadley Cells creates areas of high pressure, preventing cloud formation and rainfall.

Question 11

explain the location of the world’s deserts

Answer 11

The GAC system creates low pressure at the equator and high pressure around around the tropics. As the warm air rises at the equator it cools and condenses to form rain and sinks near the tropics. This leads of areas of high pressure with no clouds forming and no rain. This leads to a very dry/arid environment. Temperatures are therefore hot during the day and cold at night.

Question 12

how do temperature change between night and day in the desert

Answer 12

Can fluctuate dramatically from 50C in the day to below 0C at night due to the lack of cloud cover

Question 13

desert vs british soils

Answer 13

Desert soils are nutrient-poor, contain little organic matter, and have minimal leaf litter due to sparse vegetation and dry conditions. In contrast, British deciduous woodland soils are nutrient-rich, contain abundant organic matter from decomposed leaf litter, and support dense, diverse vegetation due to the temperate climate and regular nutrient cycling.

Question 14

describe desert soil

Answer 14

dry not very fertile
due to lack of rainfall = sparse vegetation to stabilise soil
little decomposing matter to enrich soil
nutrients are present but decay rapidly due to high temperatures
liited number of plants e.g drought resistance cacti

Question 15

describe the interdependence of canopy leaves + soil

Answer 15

The canopy of leaves intercepts (stops) rainfall, from here it falls gently to the ground by dripping from leaf tips. Without this interception, the raindrops would strike the soil and their force can erode small soil particles.

Question 16

describe the interdependence of leaves and soil

Answer 16

The leaves provide shade.
This can reduce air temperatures by up to 20°C
than in the open so the soil stays cooler

Question 16

describe the interdependence of plants and soil

Answer 16

The plants prevent the surface of the soil being baked in the heat.
Without vegetation cover more moisture in the soil is drawn upwards and evaporates from the surface. Plants contribute organic matter through leaf litter roots decaying plants = enhances soil fertility. The root system of plants stabilizes soil preventing erosion.

Question 17

describe the interdependence of roots and plants

Answer 17

Roots of plants help to bind the soil together and prevent gulley erosion.

Question 18

how humans negatively impact interdependence

Answer 18

Footpath = erosion
Soil vulnerable to blowing away
Mining/mineral extraction effects stability of soil
Agriculture reduces minerals in sand

Question 19

how much of the earth is deserts

Answer 19

1/3

Question 20

what are xerophytes

Answer 20

plants that can survive in very dry conditions using a range of adaptations including thick waxy cuticles and the shedding of leaves to reduce water loss (transpiration)

Question 21

why do some plants have the bulk of their biomass underground in deserts

Answer 21

temperatures are cooler

Question 22

adaptation of leaves and an example in the desert

Answer 22

Most plants will have small, linear leaves or needles in order to reduce loss of water through evapotranspiration
Leaves often also have a waxy resin, again to reduce evapotranspiration e.g The desert yellow daisy has small, linear, hairy leaves

Question 23

adaptation of roots and example in the desert

Answer 23

Some species have shallow roots that spread over a large area.
Others have tap roots which run deep in search of water (up to 25m) e.g prickly pear cactus

Question 23

adaptation of saguaro cactus

Answer 23

Grows only in the Sonoran desert An example of a xerophyte - a plant that has adapted to living in an environment with little water Grows very slowly in order to conserve energy * Can store up to 9 tonnes of water Body is made of vertical pleats that expand to allow greater water storage * Can lose 82% of its water before dying of dehydration

Question 24

how is vegetation adapted in tropical rainforests than deserts?

Answer 24

Drip tips: Help plants shed excess water, preventing the growth of mold and fungi, and allowing leaves to stay dry in the humid environment. Buttress roots: Provide stability for tall trees in shallow, nutrient-poor soil by spreading out and supporting the trunk. Epiphytes: Live on other plants to access sunlight in the dense canopy without competing for soil nutrients. They get nutrients from air, rain, and debris. Emergents: Tall trees that rise above the canopy to access more sunlight, giving them a competitive advantage in the dense forest. = Competing for sunlight

Question 24

adaptions of fennec fox in desert

Answer 24

- Their large ears, which are usually 6 inches long (15 centimeters), help dissipate excess body heat on hot days in the desert. Only carnivore living in the Sahara Desert able to survive without free water. - Their kidneys are adapted to restrict water loss, their extensive burrowing may cause the formation of dew, which can then be consumed, and they will receive moisture from the food that they eat. - Their thick fur helps insulate them from the cold desert nights. - Their sandy fur helps to reflect heat, and also provides excellent camouflage. - Also have thick fur on the soles of their feet, which insulate against the hot sand of the desert. This extra fur on the soles of their feet also affords them excellent traction in the loose sand FOUND IN SAHARA DESERT

Question 25

adaption of peringuey adder in desert

Answer 25

Move sideways - means less than 50% of body in contact with hot sand FOUND IN NAMIB DESERT

Question 26

adaption of kangeroor rat in desert

Answer 26

Don't sweat / have oily skin (reduce water loss) Produce little urine Live in burrows during day Don't need to drink - get water from food FOUND IN WESTERN DESERT USA

Question 27

adaption of camel in desert

Answer 27

- Can go 1 week or more without water, and they can last for several months without food. They can drink up to 32 gallons (46 litres) of water at one drinking session! - Camel store fat in the hump, not water. The fat can be metabolised for energy. - Unlike most mammals, a healthy camel body temperature fluctuates (changes) throughout the day from 34°C to 41.7°C (93°F- 107° F.) This allows the camel to conserve water by not sweating as the environmental temperature rises. - Feet are wide so they can walk on sand more easily. Their huge feet help them to walk on sand without sinking into it. FOUND IN GOBI AND SAHARA DESERT

Question 28

General opportunities of deserts

Answer 28

Large area can be used for recreational purposes e.g gold, quad-biking, dune buggies = tourism e.g camel rides + unique physical landscape Irrigation schemes = soils tend to become fertile if irrigated Low population density = no interference = less disruption = less risk

Question 29

Case study for desert

Answer 29

Western Desert USA made up of 3 smaller deserts; mojave, sohora, chihuahua

Question 30

What states does the western desert cover

Answer 30

New mexico, Arizona, California, Navarda

Question 31

Western Desert specific facts

Answer 31

Las Vegas region home to 2 million people Tourism has become western deserts most important source of income The entire economy og Las vegas attracts 37 million people per year

Question 32

Opportunities in Western Desert

Answer 32

- Urban residents can always find work in retailing and service industries. People can can earn living from farming, mineral extraction - High temperatures and sunlight are favourable conditions for agriculture + irrigated water schemes - Western desert rich in minerals e.g copper mining has taken place for centuries - Construction of solar power plants e.g Sonoran Solar project in Arizona will produce energy for 100,000 homes and requires 360 workers to help build it

Question 33

Challenges in Western desert

Answer 33

- Conflicts of land use - risk of wild-life/species due to tourism - contamination of water supplies - environmental concerns - less than one person per square kilometer so lack of surfaced roads = bad accesibility e.g 2015 elderly tousist died of dehydration - lack of water from hoover dam built in 1935 -low water supply - working outside is very hard for farmers

Question 34

land conflicts in desert

Answer 34

Agriculture vs. Livestock Grazing: Limited water and land resources often lead to competition between farming and grazing, resulting in overgrazing and desertification. Urbanization vs. Conservation: Expanding cities and infrastructure development threaten fragile ecosystems and biodiversity, especially in protected areas. Mining vs. Agriculture: Mining activities, particularly for minerals, disrupt local farming and water resources, impacting livelihoods. Water Use: Competition for scarce water resources between agriculture, industry, and domestic use often leads to over-extraction and environmental degradation.

Question 35

Desertification is

Answer 35

the process of land becoming drier and degrading in quality due to both human activities and natural processes.

Question 36

Define desert fringe areas

Answer 36

Semi desert/drylands with higher rainfall on the edge of a desert. These fragile environments are at constant risk of desertification

Question 37

List 6 causes of desertification

Answer 37

Climate change (low rainfall) Removal of fuelwood (land stripped of trees becomes degraded as it vulnerable to wind/rain = erosion) Population growth - (higher food demand = more land stripped of resources) Overgrazing (animals strip vegetation) Over cultivation (soil becomes dry/infertile) Soil erosion

Question 38

Change in population in sahel region since 1950

Answer 38

30 million to almost 400 million today

Question 39

Effects of high population on desert

Answer 39

Animals grazed at higher stick numbers to feed people = less vegetation in area Land farmed more intensely = takes nutrients out of soil + degraded People collect more wood to keep warm at night for cooking = loss of forest cover + deforestation

Question 40

Cycle of desertification

Answer 40

Amount of natural vegetation decreases -> No plants/leaves to intercept rain + soil exposed to hot sun Sun bakes soil so it cracks When it rains, water runs over soil instead of soaking in Soil is washed away Soil degrades loosing fertility and structure Soil warn out/poor quality = harder to grow crops on natural vegetation

Question 41

describe the the sahel

Answer 41

Spans atleast 7 nations east to west Strip 5000km long South of Sahara desert Runs through centre of Africa Close to Equator

Question 42

Causes of desertification in Sahel region

Answer 42

Over 300 million live in this region In recent years rainfall is well below average = rivers drying up, waterholes disappearing and ground water diminishing = vegetation dies + ground cover reduced Soil is subject to wind/water erosion Overgrazing Overcultivation Deforestation

Question 43

Management strategies of desertification in Sahel

Answer 43

Growing higher yielding drought resistant crops Improving grazing schemes + irrigation techniques Slowing rainfall run off so water soaks into soil Planting local fruit producing trees and bushes Agro forestry scheme = Great Green wall = 1980s = 15km deep band of trees/shrubs across southern border of sahel = would span nearly 9000km long through 11 countries Senegal = leader of this project having planted120 million trees/shrubs + restored 25,000 hectares to the productive state

Question 44

Annual rainfall in Sahel

Answer 44

Annual rainfall in sahel varies from 100mm on the edge of the sahara and 500mm in the south

Question 45

What are the causes of population pressure in desert fridge areas

Answer 45

poverty high number of births migration- drought of one region will displace people to another fragile environment or people forced to move there by armed conflicts

Question 46

explain the soil and water management strategy for desertification

Answer 46

Water and soil management addresses the problem of intense rainfall events washing away loose soil and causing soil erosion. It often involves water storage and attempts to control the surface flow of water. One common strategy used in parts of the Sahel le.g. Burkina Fasol and the Middle East (e.g. Jordan] involves constructing a series of low rock walls called bunds. These are deliberately constructed to follow the contours of the land, interrupting the downslope flow of surface water. Any soil carried by the water is deposited on the upslope side of the walls, creating a reasonable thickness of soil that can then be cultivated.

Question 47

explain the tree planting ( acai trees) for managing desertification

Answer 47

trees are very effective in preventing sail erosion and desertification. They act as an umbrella, protecting the soil from the direct impact of torrential rain and providing shade for seedlings. Their roots help to bind the soil together, preventing it being washed or blown away. * In the Thar Desert, India, the Prosopis cineraria tree will provide foliage and seed pods for animals to eat and wood for firewood and building. * In 2007, the African Union launched a project called the 'Great Green Wall', an ambitious plan to plant trees across the southern edge of the Sahara Desert. Some 21 African countries are involved, and already 15 million hectares of land have been restored in Ethiopia alone.

Question 48

explain the use of appropriate technology to manage desertification

Answer 48

* The use of low walls (bunds) to manage water is a good example as it makes use of local materials, basic tools and transport and is based on a simple idea. Community-led, it makes use of local people who work together for a common aim. * Alternative cooking devices that use efficient stoves (often supplied by charities such as Practical Action) burn small amounts of wood or charcoal, reducing the quantity of fuelwood required. - using stone lines prevents water being washed down sloped in heavy rainfall