Fragile Environments

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Fragile Environments
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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
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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
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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

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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)
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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.

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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?
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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.

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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.

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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.

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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.

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What else are we doing wrong?

• This diagram shows some of the ways the world is
  being used in an unsustainable way.

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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

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Where you find evidence of soil erosion and
degraded soil.
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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

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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.

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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.

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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.

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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

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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.

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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.

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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.

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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.

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Desertification and its consequences
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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

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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

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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

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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

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• 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.

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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.

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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.

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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.

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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.

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The Sahel

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

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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?

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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.

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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

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The Sahel what is it like?

• What do you notice about the temperatures in all
  these places?
• The rainfall?
• When does it occur?

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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

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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?

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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.

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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?

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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.

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What is all this about?
Michael Buerk A famine of biblical proportions
in the 20th century
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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.

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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.

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• 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

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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.

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Desertification in Bara, Sudan due to
restrictions on movement of herds of animals.
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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.

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• 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