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the living world Flashcards

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1
Q

what is an ecosystem

A

the interaction between the biotic and abiotic components of an enviroment

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2
Q

what are abiotic and biotic components

A

abiotic: non-living
biotic: living

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3
Q

example of a small-scale ecosystem

A

freshwater pond, hedgerow

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4
Q

abiotic components of hedgerow ecosystem

A
  • temperate climate, seasonal
  • rich fertile soils, brown earths
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5
Q

biotic components of hedgerow ecosystem

A
  • Producers : Hawthorn and blackberry bushes. Ash and oak
  • Consumers ladybirds, thrush, Blackbird, Sparrow hawk, Caterpillars badgers, mice
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6
Q

function of hedgerow ecosystem

A
  • shelter, corridor effect
  • food
  • home
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7
Q

what are global-scale ecosystems

A

large regions of the world with similar environmental conditions - biomes

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8
Q

what are producers

A

organisms that make their own food through photosynthesis

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9
Q

what are consumers

A

organisms that gain energy from eating other organisms

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10
Q

what are decomposers

A

decomposers break down dead organic material and release the nutrients back into the soil e.g. fungi and bacteria

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11
Q

what is a food chain

A

a diagram that shows what eats what

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12
Q

what is a food web

A

a series of overlapping food chains

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13
Q

explain nutrient cycling

A

nutrients are stored in three stores: litter layer, biomass, soil
- nutrients stored in plants/producers are eaten by consumers
- when these plants and animals die they become part of the litter layer
- they are then broken down by decomposers which releases the nutrients back into the soil
- plants/trees absorb these nutrients up from the soil and the cycle repeats

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14
Q

what is a biome

A

large-scale ecosystem

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15
Q

where are hot deserts found

A

On and around the tropic of cancer and Capricorn
Northern Africa - Sahara
Central Australia
SW USA
15-35 degrees N and S

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16
Q

what is the climate like in hot deserts

A

Very hot - close the equator
Little rain less than 200mm high pressure

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17
Q

what are the soils like in hot deserts

A

Aridisols by thin not very fertile as little organic content

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18
Q

what is the vegetation like in hot deserts

A

Shrubs and cactus adapt to lack of water can absorb water in stem

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19
Q

where are tropical rainforests located

A

On and around equator
South-East Asia
Central west Africa

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20
Q

what is the climate like in tropical rainforests

A

Hot - close the equator
Wet - low pressure more than 2000mm of rain

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21
Q

what are the soils like in tropical rainforests

A

Soil not very fertile as nutrient cycle very rapid due to ideal conditions for growth

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22
Q

what is the vegetation like in tropical rainforests

A

15 million species - high diversity
tall trees (up to 40 meters
buttressed bases for support
evergreen with large, dark green, leathery leaves

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23
Q

where are temperate rainforests located

A

40 - 60 degrees north
UK - western Europe

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24
Q

what is the climate like in temperate rainforests

A

Mild climates - average temp 20 in summer - plenty of rain - low pressure
Seasonal

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25
Q

what are the soils like in temperate rainforests

A

Brown earths - fertile

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26
Q

what is the vegetation like in temperate rainforests

A

Trees like ash and oak deciduous

Lose leaves in autumn to prevent water loss
Bluebells grow in spring when sunlight gets to forest floor

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27
Q

where is tundra found

A

Above 60 degrees north of equator

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28
Q

what is the climate like in tundra

A

Little rain - high pressure - often falls as snow

Cold temps average 10

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29
Q

what are the soils like in tundra

A

Soil frozen - permafrost - stops root growth - only top metre not - soil often wet - little evaporation

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30
Q

what is the vegetation like in tundra

A

Low species diversity - not many plants - climate not good for growth

Low lying to protect from wind
Short growing season
Leathery leaves to prevent water loss

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31
Q

where are boreal/taiga/coniferous forests located

A

45-57 degrees north

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32
Q

what is the climate like in boreal/taiga/coniferous forests

A

Cool to cold in winter - warmer in summer
Rain in summer

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33
Q

what are the soils like in boreal/taiga/coniferous forests

A

Deep litter layer as little decomposition - too cold

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34
Q

what is the vegetation like in boreal/taiga/coniferous forests

A

Evergreen trees
Needles to prevent water loss

Black and white spruce

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35
Q

where are tropical grasslands found

A

Edges of the deserts often found between the equator and the tropics

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36
Q

what is the climate like in tropical grasslands

A

Hot all year round - not much rain and it tends to fall in one season
Often has periods of drought and fires

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37
Q

what is the soil like in tropical grasslands

A

Porous thin layer of humus

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38
Q

what is the vegetation like in tropical grasslands

A

Grasses and shrubs

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39
Q

where are polar desert (ice) located

A

Very high latitudes north /south pole

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40
Q

what is the climate like in polar desert (ice)

A

Very cold - little rain - mostly falls as snow

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41
Q

what are the soils like in polar desert (ice)

A

Very little soil mainly bare rock

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42
Q

what is the vegetation like in polar desert (ice)

A

ccasionally plants grow in cracks in rock. Eg Arctic poppy

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43
Q

climate of tropical rainforests (ID)

A

In general, tropical rainforests have hot and humid climates where it rains virtually everyday. The level of rainfall depends on the time of year. Temperatures vary a little through the year - but much less than the rainfall.

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44
Q

soils in tropical rainforests (ID)

A

They are red as they contain lots of iron.
They are deep but not fertile as the heavy rain washes away the nutrients.
They have a deep litter layer because they have an all round growing season so plants are constantly dropping their leaves.
The have a thin Humus layer because the leaves decompose quickly and the plants take up the nutrients quickly.

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45
Q

structure of rainforests

A
  • emergents
  • canopy
  • undercanopy
  • shrub layer
  • ground layer
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46
Q

why is there high biodiversity in tropical rainforests

A

Within the forest there is growth all year round because of the constant and favourable climatic conditions. The hot and wet climate enables high primary productivity. Many of the plants are evergreen with some deciduous trees which drop their leaves in the dry season. This means that there are lots of plants all year round and therefore it can sustain many animals - creating high biodiversity.
Vegetation also grows in distinct layers, in each layer the plants have adapted to the conditions so there are lots of different species, some going as high as 40m.

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47
Q

nutrient cycle in tropical rain forests

A
  • Most of the nutrients are in the biomass, includes plants like a banyan tree or a sloth
  • Nutrients fall to the ground all year round
  • The litter layer is very deep because leaves and plants are constantly falling
  • Because of the high humidity and temperature means leaf litter decomposes rapidly
  • Soils are deep but the fertile layer with the nutrients is only at the top. Nutrients are leached by the
    heavy rainfall
  • Plants take up the nutrients very quickly
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48
Q

what are plant adaptations in the rainforest

A

drip-tip leaves, buttressed roots, tall trees, epiphytes, lianas

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49
Q

describe the leaf adaptations in the rainforest

A
  • drip-tip leaves
    > leaves arranged at angles
  • thick waxy leaves
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50
Q

explain leaf adaptations in the rainforest

A

thick waxy, drip-tip leaves:
* absorb less water and encourages water run-off.
* avoids growth of fungus and bacteria resulting in rotting leaves
angled leaves:
* avoids shading own leaves and access as much sunlight

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51
Q

describe the buttressed roots adaptation

A

large roots that anchor the base of the tree

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52
Q

explain the buttress roots adaptation

A
  • roots which help stabilise tall trees whilst still enabling shallow roots to absorb nutrients
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53
Q

describe tree adaptation

A

thin smooth bark, tall trees, leaves arranged at angles

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54
Q

explain the tree adaptations

A
  • tall trees: to reach sunlight
  • leaves arranged at diff. angles: doesn’t shade itself
  • thin + smooth bark: enables more water loss and makes it difficult for other species to grow on it
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55
Q

describe what epiphytes are

A

plants that live on other plants, take nutrients + moisture from the earth

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56
Q

explain the adaptation of being an epiphyte

A

grow on other trees to reach sunlight in canopy layer

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57
Q

describe what lianas are

A

climbing woody vines

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58
Q

explain what the adaptation of a liana is

A
  • grow up other trees to reach sunlight
  • have roots in the ground + climbing high into the tree canopy to reach available sunlight
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59
Q

what are the diff. types of animal adaptations in a rainforest

A
  • camouflage
  • creating niches
  • living in trees
  • being nocturnal
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60
Q

describe the camouflage adaptation

A

blend in w/ background and avoid predators

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61
Q

explain the camouflage adaptation

A

e.g. sloths have blue/green algae that grows on their fur giving the cloth the colour of bark

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62
Q

explain the adaptation of creating niches

A
  • adapted to eating a particular food eaten by no other animals
  • dealing w/ high levels of competition
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63
Q

explain the adaptation of living in trees

A
  • can hide from large predators hunting on the ground, a source of shelter.
  • dealing w/ high levels of animal species
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64
Q

example of a nocturnal animal

A

the amazon tree boa has infrared receptors around its mouth

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65
Q

explain the adaptation of being nocturnal

A
  • adapted so it can hide from predators and eat more food
  • dealing w/ high levels of competition
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66
Q

what happened to global deforestation rates

A

deforestation peaked in the 1980s and 1990s since then the rate of deforestation has gone down, In the 1990s, 158 million hectares were deforested. where as in 2010 110 million hectares were deforested

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67
Q

are deforestation rates falling everywhere

A

some countries in south-east asia , africa and latin america have seen an increase in annual deforestation from 2005-2010.
- indonesia’s deforestation rate has risen by 107%
However, other countries in Latin america, west africa and east asia have seen a decrease in deforestation from 2005-2010
- rates of deforestation in Brazil have decreased by 21%

68
Q

where is the amazon rainforest located?

A

the amazon is found in south america. most of it is in brazil but it spreads into 8 countries: Bolivia, Peru, Ecuador, Colombia, Venezuela, Guyana, Suriname and French Guiana

69
Q

what are deforestation rates like in the Amazon

A

deforestation rates in brazil decreased from 26,000km2 in 2004 to 4,500km2 in 2012, however since then the deforestation rates have been increasing.

70
Q

what are the overall main causes of deforestation

A
  • resources: wood, rubber etc.
  • activities: palm oil, agriculture, cattle ranching
71
Q

what are the 7 causes of deforestation in the amazon

A
  1. cattle ranching
  2. commercial agriculture - soy beans
  3. road building
  4. wood or logging
  5. energy development
  6. settlement + pop. growth
  7. mineral extraction
72
Q

what is cattle ranching

A
  • land cleared to rear cattle
  • 70% of all the deforestation is linked to cattle ranching
  • leading cause of deforestation
73
Q

what is commercial agriculture

A
  • land cleared to grow crops - mainly soy beans
  • important in lagos - 2000s
  • since 2000, rates have decreased > pressure - linked to environmental movement - green peace
74
Q

what is road building

A
  • enables development further into forest
  • trans-amazonian highway built in 1970s > 2000 miles
  • not a major cause in itself but led to all other types of deforestation
75
Q

what is logging

A
  • trees cut down and sold to make paper, furniture
  • in particular, mahogany teak: 2-3% of cause
  • decreasing in brazil but increasing in peru
76
Q

what is energy development

A
  • flooded lands to create dams and reservoirs
  • balbina dam flooded 2400 sq km
  • dam building is increasing over time
77
Q

what is settlement and pop. growth

A
  • land cleared for houses
  • settlements cover 5.3% of amazon
  • short term increase but may decrease if if becomes a highly developed country
78
Q

what is mineral extraction

A
  • land is cleared to extract and transport resources such as gold
  • small scale gold mines increased by 400% in 13yrs
79
Q

impact deforestation has on global climate

A
  1. trees are deforested = less CO2 is absorbed from the atmosphere.
  2. sometimes those trees are burnt adding more CO2 into the atmosphere
  3. this means that overall there is more CO2 in the atmosphere, enhancing the greeenhouse effect and thickening the greenhouse layer
  4. a thicker GHG layer = more solar energy is trapped in the atmosphere
  5. this warms the earth’s surface and global temps. rise. they have risen by 1.1C since pre-industrial times.
80
Q

impact deforestation has on local climate

A
  1. fewer trees= less evapotranspiration
  2. less WCCCP ( less condensation and cloud formation)
  3. less rain = increasing droughts in amazon = leads to wildfires
81
Q

impact deforestation has on soil

A
  1. trees are cut down = no roots to bind soil
  2. when it rains heavily, top fertile layer is easily washed away
  3. reduces fertility of soil so hard for future veg. to grow
  4. soil is washed into river channels
  5. decreases carrying capacity of the river = flooding more likely
82
Q

how deforestation causes river poisoning

A
  1. land cleared for mineral extraction
  2. mercury used to separate gold from its ores washed into rivers
  3. poisonous for both aquatic life and humans
    e.g. serra pelada goldmine, brazil
83
Q

how deforestation causes a loss of biodiversity

A
  1. trees deforested and land is cleared
  2. there is a loss of habitat and species - 50k lost each year, many are endemic to the Amazon
  3. humans - loss of food, medicine and resources
84
Q

positive econ. and social impact due to deforestation

A
  • improves econ. development
  • provides job and wealth and improved quality of life
  • creates a positive multiplier effect
  • large companies make profits
  • companies pay taxes to the gov.
  • minerals such as gold and cobalt are v. valuable and earn large amounts of foreign exchange
85
Q

negative econ. and social impact due to deforestation

A
  • livelihoods of indigenous communities particularly affected e.g. yanomari tribe
  • ecotourism also suffers w/ deforestation esp. if forests are removed and rivers polluted
  • loss of income for those working in sustainable activities e.g. rubber tapping
86
Q

what has happened to the no. of endangered species in brazil

A

increased from 218 in 1989 to 628 in 2008
(loss of biodiversity)

87
Q

how many tonnes of carbon does the amazon rainforest store

A

100 billion
(impact on climate)

88
Q

name a tribe that has been moved due to deforestation

A

gurani
(negative soc. impact)

89
Q

how much money did brazil make from trading cattle in 2009

A

$6.9bn dollars
(positive econ. impact)

90
Q

how many people does vale mining company employ in brazil

A

184,000
(positive econ. and soc. impact)

91
Q

how many tons of topsoil are lost to erosion due to soy production in brazil

A

55 million
(impact on soil)

92
Q

what % of CO2 emissions globally come from the deforestation of the amazon

A

20%
(impact on climate)

93
Q

what value does resources found in rainforest have to people

A
  • rich in reserves off wood, nuts and fruit as well as minerals
  • everyday items such as bananas, cocao and sugar comes from tropical rain forests along w spices such as vanilla and cinnamon
94
Q

what value does medicine found in rainforest have to people

A
  • about 25% of medicines come from rainforest plants
  • more than 2000 plants have anti-cancer properties
  • less than 1% of rainforest plants and trees have been tested for medicinal qualities
95
Q

what value do indigenous tribes in the rainforest have to people

A
  • thousands of ppl live in rainforests w/ their lives depending on maintaining a healthy ecosystem.
  • e.g. the achuar tribe in peru - over 11k ppl
  • live in small communities relying on rainforest fro materials and fuel
96
Q

what value does energy in the rainforest have to people

A
  • high rainfall totals in rainforests create the potential for hydro electric power
  • electricity can provide much needed light and power for locals
  • local micro hydro schemes can serve isolated communities
97
Q

what value does employment in the rainforest have on people

A
  • rainforests can provide employment opp. in tourism for guides or stewards.
    other opps. exist in construction, farming and mining
98
Q

what value does the rain forest have on the environment
- water

A
  • rain forests are important sources of freshwater
  • about 20% of the world’s freshwater come from the amazon
99
Q

what value does the rain forest have on the environment
- biodiversity

A
  • tropical rain forests contain 50% of the world’s plants and animals
100
Q

what value does the rain forest have on the environment
- climate

A
  • known as “lungs of the world”
  • contribute 28% of world’s O2 moisture emitted through transpiration , feeds into water cycle and prevents climate becoming too dry + hot.
  • evap. of water from rain forest helps cool air
101
Q

what value does the rain forest have on the environment
- climate change

A
  • rain forests absorb CO2 from atmospher acting as a carbon sink.
  • helps offset global warming
102
Q

what value does the rain forest have on the environment
- soil erosion

A
  • shelter and bind soil together
  • prevents harmful soil erosion which can silt up rivers and reservoirs
103
Q

what is sustainability

A

development that meets the needs of the present without compromising the ability of future generations to meet their own needs. it must be economically, socially and environmentally sustainable and be long-lasting.

104
Q

what are NGOs

A

non-governmental organisation (NGOs): not-for-profit organisation that is independent from the government . they are usually funded by donations and are run primarily by volunteers e.g. oxfam

105
Q

what is selective logging

A
  • cut down specific trees in order to retain the structure of the forest
  • tree audit, only cut down very mature trees and take tees from each species, not just tone
106
Q

what are the econ. soc. and env. benefits of selective logging and replanting

A

econ: can still make money from selling the timber
soc: retains the homes of indigenous tribes -> improves QOL for loggers
env: forest remains + absorbs as much carbon as before, keeps biodiversity

107
Q

is selective logging and replanting a long term solution

A

yes - forest regrows so people can keep logging

108
Q

what are international agreements (ITAs)

A

in 2006, international tropical timber agreements was signed by 71 countries and it bans the sale of non-selectively logged timber .
- covers 90% of global trade

109
Q

what are the econ. soc. and env. benefits of international agreements (ITAs)

A

econ: farmers who log sustainably earn more money per tree and don’t compete with non-sustainably logged timber.
soc: higher income improves QOL.
env: reduces deforestation and forces better protection of the structure of the forest

110
Q

is international agreements (ITAs) a long term solution

A

yes.

111
Q

what is agroforestry

A

agriculture within the forest e.g. planting cacao and coffee while caring for the forest

112
Q

what are the econ. soc. and env. benefits of agroforestry

A

econ: crops can be grown cheaper ( no pesticides or fertilisers)
soc: farmers increase income so increased QOL. retains indigenous communities way of life
env: retains structure of forest - biodiversity is protected, still absorbs CO2, no chemical pollution - forest provides natural nutrient cycling

113
Q

is agroforestry a long term solution

A

yes - soil doesn’t lose its fertility so can continue to sustain crops

114
Q

what is conservation and education by NGOs

A

education around buying sustainably produced tropical rainforest products
e.g. rainforest alliance sticker on bananas

115
Q

what are the econ. soc. and env. benefits of conservation and education by NGOs

A

econ: persuades consumers to purchase sustainably produced products so farmers earn a living
soc: decreases use of fertilisers + pesticides so reduces health problems
env: protecting the rainforests
conservation:
- creation of natural parks - activities limited and environment protected

116
Q

is conservation and education by NGOs a long term solution

A

yes

117
Q

what are conservation swaps/debt reduction

A
  • when a country’s debt is cancelled in exchange for investing in their rainforest
    e.g. usa + brazil: a debt of £13.5m cancelled in exchange for amazon conservation policies - enforcement officers to prevent illegal expansion
118
Q

what are the econ. soc. and env. benefits of conservation swaps/debt reduction

A

econ: country gains extra money for conservation (LIC)
soc: money can still be spent on social development programs
env: rainforest is protected

119
Q

is conservation swaps/debt reduction a long term solution

A

yes

120
Q

what is ecotourism

A

small scale tourism that protects the environment and is beneficial to locals
e.g. santa rose community project

121
Q

what are the econ. soc. and env. benefits of ecotourism

A

econ: provides jobs and income for local pop. (NOT international TNCS)
soc: jobs which improves QOL not negatively impacted by presence of tourism
env: rainforest is protected

122
Q

is ecotourism a long term solution

A

yes

123
Q

where are hot deserts located

A
  • 15-35 degrees N and S of the equator
  • Generally found along the tropic of cancer and capricorn
  • the largest hot desert is the sahara` in northern africa
  • hot deserts are found across 5 continents
124
Q

what is the reason for where they are located

A

1) solar radiation causes warm air to rise, cool and condense into clouds
2) it rains and the air sink at 30 degrees N and S causing high pressure which brings dry conditions
- hot bc sun is relatively directly overhead

125
Q

describe the climate in the desert

A
  • rainfall is very low all year round
  • june>september are particularly dry. most months have no rainfall at all.
  • the temp. is more seasonal w/ the highest in july at 36 degrees, and the lowest in january dropping to 10 degrees
126
Q

why do temps drop below freezing at night in a hot desert

A

lack of cloud cover means heat is rapidly lost from the land, sometimes drops as low as 0

127
Q

describe desert soils

A
  • thin rocky grey
  • v. dry and quickly absorb any water that falls
  • crusty surface - hardpan
  • water evaporates from surface - leaves salt deposit
  • little veg. little humus layer
  • plants nourished by minerals
128
Q

plant adaptations in the desert

A
  • have horizontal root systems - can quickly absorb water that falls
  • long taproots (7-10m deep) - reach ground water
  • some plants store water in roots leaves, stems (succulents) - have water stores during times of drought
  • glossy or waxy leaves - reduce water loss
  • seeds can stay dormant for up to 20 years - can quickly germinate when there is rain
  • short growing cycle + rapidly produce flowers - attract pollinators
  • saguaro cactus (3-15m tall) - can hold/store up to 5 tons of water
129
Q

animal adaptations in the rain forest

A

camels:
- hump for storing fat - can go long lengths w/o food/water
- long muscular legs for walking - long time to find water
- long eyelashes and thin slit nostrils - protect from sand
- long large intestine - maximises water absorption

arabian death scorpion:
- absorbs moisture from small insects it eats
- avoids daylight sun and burrows in sand- conserve moisture
- exoskeleton is hard to crush - prevents water loss

130
Q

examples of desert ecosystem interdependence

A
  • lack of veg. > small litter layer> less decomp of dead plant material> less nutrients in soil
  • desert soils dry b/c of lack of water> causes hardpan> when it does rain its heavy> leaches away nutrients in soil
  • b/c of lack of veg. > many plants adapt to have spikes> deters animals eating it
131
Q

why do deserts have low biodiversity

A
  • hot deserts have extreme climates - v. hot and dry, v. cold at night (large diurnal range) except around oases
  • v. hard for species to survive - so only species that have adapted can live there
132
Q

describe the location of the western desert

A
  • it is located in south-west usa
  • found in cali nevada utah arizona and new mexico
  • 200,000km2
    made of 3 deserts - mojave. sonoran and chihuahuan
133
Q

what are the challenges of developing hot desert environments

A
  1. extreme temp.
  2. water supply
  3. inaccessibility
134
Q

what is carrying capacity

A

the number of people who can be supported by an environment

135
Q

kuj for tourism

A

j: tourism creates the most opp.
u. for people in the western desert. the good weather and spectacular scenery attracts a large number of tourists
k. e.g. 2 mil visit death valley each year
u. this creates jobs and increased wealth

136
Q

kuj for energy

A
  • it has a national importance because it is helping the us move away from fossil fuels
  • agua caliente solar project is the largest solar farm in the world
  • able to have solar plants as they have clear skies. this benefits locals as it improves their QOL
137
Q

kuj for mining

A
  • mining due to presence of extractable materials in the rock, creates jobs. extracted materials can be sold in the global market, increasing the economy. for e.g. uranium and copper are still mined in the sonoran region of cali. however these are finite resources so benefits are shot term. also it only employs 100 ppl in oil production so locals dont majorly benefit
138
Q

kuj for farming

A

2nd most important employment opp in the western desert. farming is productive here as there is year round sunshine and water from the colorado river and ground water supplies. this creates many opp.s for workers improving their QOL. coachella valley is one of the most productive farming areas in the world more than a bill crops produces. over extraction of water means farming will decrease over time.

139
Q

evidence of pop. growth in western desert

A

pop. of phoenix has double since 1980 to 4.5 mil.

140
Q

challenge created by inaccessibility

A
  • much of area is mountains - road building hard
  • few tarmacked road
  • extreme temp. - dangerous if car breaks down
141
Q

changes to combat the challenge of inaccessibility

A

railways - were built to key settlements like Las Vegas
better roads - have been laid like route 66 connects chicago to cali
new bus routes
major cities in the deserts have airports - 40mil to las vegas each year

142
Q

challenge created by climate

A
  • extreme temp. - working outside is hard - esp. farmers
  • high rates of evaporation - water shortages
143
Q

changes to combat the challenge of climate

A
  • traditional houses in the western desert have thick earth walls - keeps home cool in day and warm at night
  • whitewashed walls reflect sunlight
144
Q

challenges created by water

A
  • could be a major problem in the future as demand soars e.g. in phoenix arizona
  • temps are forecast to change/rise due to climate change
  • most rivers are erratic but settlements cluster along edge - climate change could make river flow less reliable
145
Q

changes to combat the challenge of water

A
  • indira gandhi canal constructed in 1958 has transformed the desert providing drinking water and irrigation
  • water is stored in natural ponds called tobas, used by farmers in remote areas
  • colorado river has provided water and irrigation and piped water, now supplies homes farms and gold courses
    • as demand increases the colorado river could dry up.
146
Q

what is desertification

A

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

147
Q

describe the global distribution of desertification

A
  • areas at risk of desertification are found on the fringes of existing deserts
  • africa, middle east and central asia are particularly at risk
  • 5 continents have area at risk of desertification
    > greatest risk to humans is Sahel, houses 50 mil
148
Q

what countries are in the sahel

A
  • senegal
  • mauritania
  • mali
  • burkina faso
  • nigeria
  • niger
  • chad
  • sudan
  • eritrea
149
Q

rainfall pattern in sahel

A
  • pre-1960s: there were more years w/ above average rain than below
  • post-1960s: mostly below average rainfall only broken by 4 years of rain
  • future: more extreme periods of flood and drought
  • temp. likely to rise
150
Q

what are the natural causes of desertification

A

changes to rainfall patterns due to the complex interactions between the land, ocean. atmosphere, biosphere and cryosphere. this is due to natural long term climate change.
- k: world’s major deserts created at end of last ice age and have gotten hotter and drier overtime.
- j: v. important cause b/c it created the major deserts

151
Q

what are the human causes of desertification

A
  • pop. growth
  • human induced climate change
  • armed conflict
  • removal of firewood
  • overgrazing
  • over-cultivation
152
Q

explain how pop. growth can cause desertification

A

k: in 1950 - 30 mil in sahel, today half bil., 2050, 1 bil.
u: high fertility rates + longer life expectancy - more people meaning more removal of firewood, farming and conflict.

153
Q

explain how human induced climate change can cause desertification

A
  • more GHG in atmosphere- thicker GHG layer - more suns energy trapped - global temp. rise - veg dies.
    k: temps up 1.1C since pre-industrial times
  • longer drought and more extreme floods - veg. dies
154
Q

explain how armed conflict can cause desertification

A

u: conflict can arise between agricultural farmers and herders as pop. increases and more comp. for space.
k: 2.5 mil homeless in 2018 in darfur region
u: refugees cut down trees to make houses and for fuel (less evapotrans. less WCCCP - drier and degraded) over extraction of water - drier.
k: when families return home they need 30-40 trees each to rebuild

155
Q

explain how the removal of firewood can cause desertification

A

u: cut down for fuel + houses
- less trees - less evapo. - less WCCCP - ++DRIER
- no roots to bind soil - rain washes soil away - loses its fertility -
++DEGRADED
- smaller litter layer - soil fertility decreases - ++DEGRADED
j: problem may decrease as renewable energy gets cheaper.

156
Q

explain how overgrazing can cause desertification

A

u: more cattle reared (due to growing pop.)
> all veg. and saplings are eaten
- soil is exposed - no roots to bind soil - rain washes soil away - loses its fertility -
++DEGRADED
- less trees - less evapo. - less WCCCP - ++DRIER
- smaller litter layer - soil fertility decreases - ++DEGRADED

157
Q

explain how over-cultivation can cause desertification

A

u: longer life expectancy and high birth rate - families have to produce more food on the same amount of land
- removes nutrients form soil - becomes infertile - ++DEGRADED
- over-extraction of groundwater leads to the area becoming drier

158
Q

what are the effects of desertification on people

A
  • food insecurity
  • food prices rise
  • malnutrition and starvation - leads to famine
  • refugees go to cities
  • crops and livestock die
  • girls spend longer collecting water and not in school
  • rise in poverty
  • fall in GDP/GNI
159
Q

what is afforestation (the great green wall) and what does it prevent

A
  • planting trees along the edge of the sahel
  • going to be 8000km long
  • stops the drying out and degradation of the land
  • organised by the african union
160
Q

how does afforestation stop desertification

A

1) more trees results in more evapo. - more cloud cover and formation - more precipitation = wetter
2) more trees - protection from the sun - doesn’t bake - more infiltration when it rains - increases soil moisture and decreases soil erosion
3) more roots - binds soil - decreases soil erosion
4) more trees - bigger litter layer -soil fertility increases = land becomes more fertile and quality is improved

161
Q

assessment of afforestation

A
  • success of the scheme is threatened by further human induced climate change
162
Q

what are stone wall (bunds) and what does it prevent

A
  • low level stone walls built along the contours of farmland
  • slows and traps water leading to soil infiltration
  • eroded soils trapped behind
  • increasing soil fertility and water retention
163
Q

how do stone walls stop desertification

A

1) stone walls slow down and trap water leading to more infiltration which reduces water loss = wetter more fertile
2) more trees - protection from the sun - doesn’t bake - more infiltration when it rains - increases soil moisture and decreases soil erosion

164
Q

assessment of stone walls (bunds)

A
  • very effective - all the materials are readily available for free
  • easy to construct
165
Q

what are efficient stoves and what do they prevent

A
  • a stove made of local materials which use less fuel
  • toyola stove, ghana
  • trying to stop deforestation
  • energy-efficient stoves use 50% less fuel
166
Q

how do energy efficient stoves stop desertification

A

1) more trees results in more evapo. - more cloud cover and formation - more precipitation = wetter
2) more trees - protection from the sun - doesn’t bake - more infiltration when it rains - increases soil moisture and decreases soil erosion
3) more roots - binds soil - decreases soil erosion
4) more trees - bigger litter layer -soil fertility increases = land becomes more fertile and quality is improved

167
Q

assessment of energy efficient stoves

A

quite small-scale

geography (4 decks)

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