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Title: Fragile Environments


1
Fragile Environments
2
What does it involve?
Management of soil erosion e.g. farming practices
Consequences
The fragile nature of environments/ concept of
sustainability
Causes of soil erosion desertification
Case study Sahel
Case study Amazon
Causes
Management
Deforestation
STOP HERE
Consequences
Case study Bangladesh Named egs of
causes/ consequences
Greenhouse effect and global warming
Causes
Examples of solutions eg Kyoto
Consequences
3
Introduction
  • There is a natural but delicate balance between
    the non-living soils, rocks and climate and the
    living plants animals.
  • There are natural disasters such as volcanoes and
    cyclones but the world has always recovered from
    these in the past.
  • Until recently, man has trod lightly on earth,
    living in harmony with it. Some native tribes
    still do this, e.g. the Awa in the NE Amazon. But
    this is a rare example. 90 of the Earth has been
    disturbed by man.
  • We focus on 3 processes that have increased
    fragility soil erosion, desertification,
    deforestation. These link to climate change as
    they are both a cause and a consequence of it.
  • These are not the only ones river and coastal
    management, pollution in general, and
    exploitation of natural resources also figure in
    this as well.

http//ih-igcse-geography.wikispaces.com/7.1Fragil
eenvirnmentsandsustainability
4
In fragile environment studies
This is NOT the Carbon footprint how is it
different?
  • Ecological foot print
  • The amount of land, resources etc we need to
    support our lifestyle. To find what we use, add
    the land to give us enough water, food, energy,
    raw materials and waste disposal. It has been
    worked out that 1.8 hectare per person is
    sustainable the 4.9 hectares per person in the
    UK is not
  • And
  • Sustainability
  • Activities and forms of progress that meet the
    needs of the present without reducing the ability
    of future generations to meet their needs.
  • keep coming up

5
Dark Green have an OK footprint does not look
good for the rest of us! Red is seriously bad,
orange and yellow still above the world average
both greens are below average (2.7 hectares per
person), but only dark green is less than the
planet can stand (1.8 hectares)
6
So..
  • The link between ecological foot print and
    sustainability is that the footprint informs as
    about just how sustainable (or not) we are being.
  • We know the footprint is influenced in turn by
    how fast the population grows (could mean we will
    all need to have a smaller footprint if it goes
    up too much?), what we consume and the type of
    technology we use.

7
What are fragile environments?
What is a biome?
  • Fragile environments are those biomes that under
    threat from change, damage or unsustainable use.
  • Although natural hazards, such as earthquakes,
    volcanoes, hurricanes can cause a lot of damage,
    it is mainly human intervention that causes the
    most even seemingly natural events like floods
    and droughts are often made worse by man.

Why do I say that?
8
What are the issues?
  • Issues include
  • Undeveloped land is becoming scarcer as there is
    less undeveloped land available, the pressure
    increases on that that remains.
  • Protecting biodiversity (plants and animals) is
    more difficult we want to conserve that which
    we have but our desire to visit and see these
    areas is destroying them
  • Desert edges are becoming deserts through
    overgrazing and the removal of trees/shrubs which
    give rise to soil erosion, and the decreasing
    rainfall all combine to turn productive farmland
    into useless scrub.

9
What are the issues?
  • At the other end of the scale, deforestation of
    rain forests flows as the natural resources are
    exploited.
  • Illegal logging - 20 of the timber supply comes
    from illegal sources.
  • "Europe remains one of the main markets for
    illegal timber despite a 2003 EU action plan to
    combat illegal logging and related trade. Strong
    legislation to halt illegal timber trade and to
    decrease Europe's devastating impact on the
    world's forests should be adopted as a bare
    minimum - there is no time to lose," said
    Friedrich Wulf from ProNatura / Friends of the
    Earth Switzerland.

10
What else are we doing wrong?
  • Human and industrial waste pollute rivers and
    seas.
  • At sea, oil spills and deliberate toxic dumping
    causes widespread pollution.
  • Many local problems cause more widespread
    difficulties.
  • Traffic in towns causes congestion and pollution.
  • Building new roads can solve these problems but
    causes others such as the destruction of rural
    environments.
  • This can also lead to more traffic and acid rain,
    production of greenhouse gases and global climate
    change.

11
What else are we doing wrong?
  • If the diversity and the environment are to
    survive then careful management is necessary.
  • Local decisions have international effects.
  • International co-operation and legislation will
    be the only way to resolve the issues which will
    help us work together and sustain the world for
    future generations.

12
What else are we doing wrong?
  • This diagram shows some of the ways the world is
    being used in an unsustainable way.

13
Soil erosion
  • One of the major problems in fragile environments
  • Where removal by removal of portions of the soil
    by various means so that fertility of the soil is
    reduced

14
Where you find evidence of soil erosion and
degraded soil.
15
What are the causes of soil erosion
  • There are 3 main physical causes of erosion
  • Sheet erosion
  • Gulley erosion
  • Wind erosion
  • And then accelerated or human induced erosion

16
Sheet Erosion
  • Where there is sufficient rainfall, exposed soil
    will be moved downhill as a mass movement sheet
    erosion
  • Raindrop impact is the major cause of soil
    particle detachment which can result in the
    particles moving down slope as sheet erosion
    during a rainfall event.
  • Sheet erosion is the removal of fairly uniform
    layer of surface material from the land surface
    by continuous sheets of runoff water rather than
    concentrated into channels.

17
Sheet Erosion
  • Heavy rain that leads to a sheet of water
    removing a more or less uniform layer of fine
    particles from the entire surface of an area is
    sheet erosion. It often includes the best soil
    particles along with much of the organic matter.
  • While it causes severe erosion, it is very
    difficult to see, as the amount removed is often
    slight from any particular spot. Notice how these
    ploughed areas in Romania have been covered by
    the sheet erosion.

18
Gulley Erosion
  • More frequently, the water gathers together and
    quickly erodes a channel. This is called gulley
    erosion.
  • The example below can be seen in it all its glory
    in the blog (http//lindym.wordpress.com/2009/07/2
    2/the-power-of-water/ ). It was named locally as
    the Durham Great Canyon and appeared literally
    over night in a cornfield.

19
Gulley Erosion
  • You may also see mention of rill erosion which is
    a diminutive example of something similar.
  • This is an example of a rill forming during one
    particularly heavy rainstorm in Autumn 2008 in
    the field behind our house notice the murky
    colour of the water that is soil erosion

20
Wind erosion
  • Soil erosion by wind may occur wherever dry,
    sandy or dusty surfaces, inadequately protected
    by vegetation, are exposed to strong winds.
  • Erosion involves the picking up and blowing away
    of loose fine grained material within the soil.

21
Short-term effects of wind erosion
  • Dust storms are very disagreeable and also the
    land is robbed of its long-term productivity
    (humus (vegetable matter) is lighter and likely
    to be removed first).
  • Crop damage, especially of young crops, can be
    serious.
  • Either the roots are exposed as the wind blows
    away the top soil or else wind blown soil from
    elsewhere cover the seeding up either way the
    crop will be lost.

22
Long term effects of wind erosion
  • Long term damage is even greater.
  • Finer soil fractions (silt, clay, and organic
    matter) are removed and carried away by the wind,
    leaving the coarser fractions behind.
  • This sorting action not only removes the most
    important material from the standpoint of
    productivity and water retention, but leaves a
    more sandy, and thus an even more erodible, soil
    than the original.

23
The Impacts of humans on soil erosion
  • The most common human impact is due to population
    growth.
  • This leads to increased pressure on the land and
    its resources.
  • Overgrazing is a major problem.
  • This causes vegetation loss and makes the soil
    much more vulnerable to erosion without the
    protective net of roots to withstand the
    pressures of water and wind.
  • Intensive cultivation can cause loss of nutrients
    and soil exhaustion.
  • Another major cause is deforestation which is
    the cutting down of trees for fuel wood or
    clearing it for agriculture.
  • In practice the causes of soil erosion are
    usually a combination of physical and human
    causes, as you see below.

24
Desertification and its consequences
25
What is desertification?
  • Desertification, as defined in Chapter 12 of
    "Agenda 21" and in the International Convention
    on Desertification, is the degradation of the
    land in arid, semi-arid and sub-humid dry areas
    caused by climatic changes and human activities.
  • When there was widespread famine in Africa in the
    1980s, the major cause was laid at the door of
    human activity, but as we shall see when we look
    at the Sahel, this is not the whole story

26
The lighter orange and yellow are all in danger
  • Note that while many areas are adjacent to
    current deserts, this is not always the case

27
As with soil erosion, there are both physical and
human causes
  • Physical causes
  • Soil erosion exposed soil is easily removed by
    wind or water
  • Changing rainfall patterns rainfall has become
    less predictable and prolonged droughts more
    common (although whether this is a human and
    physical cause is a moot point)
  • Intense rainfall when it does happen hard to
    store and causes more soil erosion

28
As with soil erosion, there are both physical and
human causes
  • Main human causes
  • Population growth more people need more food
    which puts pressure on the and
  • Overgrazing too many goats, sheep, cattle can
    destroy the vegetation
  • Over cultivation- grow too much without
    replenishing the soil and it becomes exhausted
  • Deforestation tress are cut down for fuel and
    building. The loss of roots to hold the soil down
    gives rise to erosion
  • War many sub-Saharan countries have suffered
    for years from civil war, where crops and animals
    have been destroyed leading to famine

29
  • Desertification is a world-wide phenomenon which
    causes the earth's ecosystems to deteriorate.
  • It affects about two-thirds of the countries of
    the world, and one-third of the earth's surface,
    on which one billion people live, namely,
    one-fifth of the world population.

30
What are the consequences of desertification?
  • Desertification reduces the lands resilience to
    natural climate variability.
  • Soil, vegetation, freshwater supplies, and other
    dryland resources tend to be resilient. They can
    eventually recover from climatic disturbances,
    such as drought, and even from human-induced
    impacts, such as overgrazing. When land is
    degraded, however, this resilience is greatly
    weakened. This has both physical and
    socio-economic consequences.
  • Soil becomes less productive.
  • Exposed and eroded topsoil can be blown away by
    the wind or washed away by rainstorms. The soils
    physical structure and composition can change for
    the worse. Gullies and cracks may appear and
    vital nutrients can be removed by wind or water.
    If the water table rises due to inadequate
    drainage and poor irrigation practices, the soil
    can become waterlogged, and salts may build up.
    When soil is trampled and compacted by cattle, it
    can lose its ability to support plant growth and
    to hold moisture, resulting in increased
    evaporation and surface run-off.

31
What are the consequences of desertification?
  • Vegetation becomes damaged.
  • The loss of vegetation cover is both a
    consequence and a cause of land degradation.
    Loose soil can sandblast plants, bury them, or
    leave their roots dangerously exposed. When
    pastures are overgrazed by too many animals, or
    by inappropriate types, edible plant species may
    be lost, allowing inedible species to invade.
  • Some of the consequences are borne by people
    living outside the immediately affected area.
  • Degraded land may cause downstream flooding,
    reduced water quality, sedimentation in rivers
    and lakes, and siltation of reservoirs and
    navigation channels. It can also cause dust
    storms and air pollution, resulting in damaged
    machinery, reduced visibility, unwanted sediment
    deposits, and mental stress. Wind-blown dust can
    also worsen health problems, including eye
    infections, respiratory illnesses, and allergies.
    Dramatic increases in the frequency of dust
    storms were recorded during the Dust Bowl years
    in the US, in the Virgin Lands scheme area in the
    former USSR in the 1950s, and in the African
    Sahel during the 1970s and 1980s.

32
What are the consequences of desertification?
  • Food production is undermined.
  • Desertification is considered a major global
    environmental issue largely because of the link
    between dryland degradation and food production.
    A nutritionally adequate diet for the worlds
    growing population implies tripling food
    production over the next 50 years. This will be
    difficult to achieve even under favourable
    circumstances. If desertification is not stopped
    and reversed, food yields in many affected areas
    will decline. Malnutrition, starvation, and
    ultimately famine may result. The relationship
    between soil degradation and crop yields,
    however, is seldom straightforward. Productivity
    is affected by many different factors, such as
    the weather, disease and pests, farming methods,
    and external markets and other economic forces.
  • Desertification contributes to famine.
  • Famine typically occurs in areas that also suffer
    from poverty, civil unrest, or war. Drought and
    land degradation often help to trigger a crisis,
    which is then made worse by poor food
    distribution and the inability to buy what is
    available.

33
What are the consequences of desertification?
  • Desertification has enormous social costs.
  • There is now increased awareness of the
    relationship between desertification, movements
    of people, and conflicts. In Africa, many people
    have become internally displaced or forced to
    migrate to other countries due to war, drought,
    and dryland degradation. The environmental
    resources in and around the cities and camps
    where these people settle come under severe
    pressure. Difficult living conditions and the
    loss of cultural identity further undermine
    social stability.
  • Desertification is a huge drain on economic
    resources.
  • There is little detailed data on the economic
    losses resulting from desertification, although
    an unpublished World Bank study suggested that
    the depletion of natural resources in one
    Sahelian country was equivalent to 20 of its
    annual Gross Domestic Product (GDP). At the
    global level, it is estimated that the annual
    income foregone in the areas immediately affected
    by desertification amounts to approximately US
    42 billion each year. The indirect economic and
    social costs suffered outside the affected areas,
    including the influx of environmental refugees
    and losses to national food production, may be
    much greater.

34
The Sahel
  • Why is it like that?
  • What are the impacts of desertification on the
    people?
  • How can it be managed for the future?

35
The Sahel
  • Where is it?
  • What is it like?
  • How has it changed?
  • What are the main causes?
  • What are the consequences?
  • What are they doing about it?

36
The Sahel where is it?
  • The Sahel is a semi-arid tropical savannah and
    steppe ecoregion in Africa, which forms the
    transition between the Sahara to the north and
    wetter grasslands in the south. It extends from
    the Atlantic on the west to the Indian Ocean in
    the east.

37
The Sahel what is it like?
  • The picture on the left was taken in the wet
    season while that on the right was taken in the
    dry season.
  • Some places have a few more trees and some have
    less, but this should give you a flavour

38
The Sahel what is it like?
  • What do you notice about the temperatures in all
    these places?
  • The rainfall?
  • When does it occur?

39
The Sahel how has it changed?
  • In recent years, the rainfall has become
    irregular - from the graph what do you notice?
  • Anomalies are differences from what is expected

40
The Sahel how has it changed?
  • When was there the longest period of heavier than
    expected rain?
  • In 1951 there was about 3cm per month more than
    expected how many millimetres was that in a
    year?
  • When did the rain change to being in general to
    less than was expected? How many mm a year was
    that at worst?

41
When there was a severe famine in the Eastern
Sahel in the early 1980s
  • It was put down almost entirely to human landuse
    issues, and all the projects were geared to
    tackling this problem. However as you can see, in
    this particular case, rainfall had a greater
    influence.
  • Having said that, if the precipitation does
    reduce, then man needs to take more care than
    before of the scarce resources and of water and
    good soil.
  • Looking back over thousands of years of history,
    these episodes of low rainfall are a feature and
    have had consequences for man in the past.

42
Lets look at the last episode of wet weather in
this area
  • It was wetter than average between 1915 and about
    1964. What do you think was the affect of this
    unusually damp period?
  • What effect would you expect that to have on the
    population?
  • What do you think would happen to the number of
    animals and the amount ground under production?
  • The extra people would need housing and to cook
    their food? What effect would you expect that to
    have on the Savannah-like existence of the Sahel?

43
Then came the 1960s
  • What would the people try to do?
  • This lead to over cultivation, over grazing and
    bare soil.
  • With fewer trees to add humus to the soil, what
    would the soil be like?
  • Not only would the nutrients not be replaced, but
    soil without humus cannot hold water so well and
    it dried out.
  • This kind of soil is eroded easily by flash
    floods, which still occurred occasionally and
    wind erosion the dry season.. As a result there
    have been widespread crop failure and millions of
    animals have died.
  • Many people have had to leave the area but even
    then more than 100,000 have died across the Sahal
    from Ethiopia in the east right across to Burkino
    Faso and Mali in the West.

44
What is all this about?
Michael Buerk A famine of biblical proportions
in the 20th century
45
As you see
  • .. While the precipitation shortage was the major
    cause of the problem, the situation that
    developed over previous decades, that led to more
    people moving there than the ecosystem could
    reasonable be expected to support in the long
    term, contributed in no small way to the disaster
    that followed.
  • During this period of drought, the problems of
    soil erosion were exacerbated both by natural and
    human causes.

46
Human influences on the Sahel
  • The drying of the Sahel in the late 20th century
    caused widespread famine that attracted
    world-wide attention, including the United
    Nations Conference on Desertification (UNCOD) in
    Nairobi, Kenya in 1977, the 1993 Convention to
    Combat Desertification, the 2006 International
    Year of the Desert and Desertification, and the
    Millennium Ecosystem Assessment.

47
  • The studies show that climate change strongly
    influences the Sahel in recent decades, but it is
    only part of the story
  • Rainfall variability is a major driver of
    vulnerability in the Sahel.
  • However, blaming the environmental crisis on
    low and irregular annual rainfall alone would
    amount to a sheer oversimplification and
    misunderstanding of the Sahelian dynamics.
  • Climate is nothing but one element in a complex
    combination of processes that has made
    agriculture and livestock farming highly
    unproductive.
  • Over the last half century, the combined effects
    of population growth, land degradation
    (deforestation, continuous cropping and
    overgrazing), reduced and erratic rainfall, lack
    of coherent environmental policies and misplaced
    development priorities, have contributed to
    transform a large proportion of the Sahel into
    barren land, resulting in the deterioration of
    the soil andwater resources.From UN
    Environmental Programme, World Agroforestry
    Centre

48
The human influences include
  • Population increase. Population is doubling every
    20 years. The growth rate of population (3 per
    year) exceeds the growth rate of food production
    (2 per year). The total population is around
    260,000,000 people.
  • Poverty. Per capita income varies from 500/year
    in Burkina Faso to 1,000/yera in Mali to
    2,000/year in Nigeria. In contrast, the per
    capita income in Western Europe is about
    35,000/year. All are estimates for 2007. The
    area includes three of the four poorest countries
    on earth.
  • Over grazing, poor farming methods, and use of
    trees and vegetation for firewood. Overgrazing
    and poor agricultural practices lead to soil
    erosion, further degrading the land.

49
Desertification in Bara, Sudan due to
restrictions on movement of herds of animals.
50
The human influences include
  • The traditional Parkland system (integrated
    crop-tree-livestock systems), which is the
    predominant land use system and the main provider
    of food, nutrition, income, and environmental
    services, is rapidly degradingwoody biodiversity
    and cover is being lost, and soil fertility is
    declining from already low levels through
    exhaustive cropping practices and soil erosion
  • Colonial Influence. The Sahel was divided into
    countries by European nations. The boarders were
    set by political processes that mostly ignored
    the local people and their use of the land. The
    new countries began to enforce boundaries
    limiting the ability of nomads to move their
    herds in response to changing rain, from dry to
    wet areas. As a result, nomads were forced into
    villages, and in dry years their herds overgrazed
    the area around villages and cities.
  • Major historical migration routes used by nomadic
    herders in the past. Now the borders with Chad
    and the Central African Republic are closed, and
    even borders between provinces in the Sudan are
    closed, and herders must stay within their own
    province. The closing of the borders causes
    environmental and political problems. Click on
    the map for a zoom.
  • Migration due to political instability and war.
    Conflicts in Niger, Nigeria, Mali, Darfur, and
    Eritrea have caused mas migration of people from
    rural areas to refugee camps to nearby countries.

51
  • Complete a case study of the Sahel, using what we
    talked about today and anything else you think
    may be relevant.
  • You need to fill in a table like this

52
Homework
  • You have seen that soil erosion and
    desertification are closely linked so to reduce
    or turn around desertification, practices that
    reduce soil erosion need to be implemented.
  • There are many examples of how soil erosion is
    being controlled many are taking place in
    Africa, although not exclusively there. We need
    to build up a body of examples of how it is being
    tackled, by whom and where
  • Your task is to find one or 2 examples of how
    this is being achieved good google searches
    would be soil erosion and either solutions or
    prevention or mitigation or management or
    conservation or control
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