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UNIT 4:
HUMAN
INFLUENCES
ON THE
ENVIRONMENT
ONLY USE LEARNING
GUIDE AND SLIDES TO
STUDY
READ PAGES IN
TEXTBOOK WHERE
INDICATED
INTRODUCTION
Human impact on the environment or
anthropogenic impact on the
environment includes:
Impacts on biophysical environments,
biodiversity &
other resources.
The term anthropogenic describes an
effect or object resulting from human
activity.
ENVIRONMENTAL ISSUES IN SA
 Many environmental issues affect SA 
urbanization & acts (LAWS) needed to survive.
 Keeping up with developing world + meet high
demands of growing population, SA 
exhausted its many resources  severe
environmental damage.
 Continuous depleting & improper treatment of
natural resources  SA  only harming their
environment.
HUMAN ACTIVITIES THAT
HAVE AN ENVIRONMETAL
IMPACT:
 Agriculture (FARMING)
 Fishing
 Irrigation
 Meat production
 Palm oil farming
 Energy harvesting and consumption
 Coal mining and burning
 Manufacturing of products
 Electricity generation
 The use of fertilisers may cause
eutrophication
THE EFFECTS OF HUMAN
INFLUENCES ON THE
ENVIRONMENT
 Human impact on biodiversity  significant.
 Human impact on coral reefs  significant. Coral
reefs are dying around the world. Coral reefs also
face high dangers from pollution, diseases,
destructive fishing practices and warming
oceans
 Human impact on nitrogen cycle  diverse.
 Humans  destroying habitats & reducing amount
of land available for other organisms by building,
quarrying, farming and dumping waste.
 Human activities  polluting water, air and land.
UNIT 4 HUMAN INFLUENCE ON THE ENVIRONMENT 2015
UNIT 4 HUMAN INFLUENCE ON THE ENVIRONMENT 2015
IMPACT OF
POLLUTION ON
THE
ENVIRONMENT
WATER POLLUTION
Water pollution  contamination of water
bodies.
Water pollution  pollutants are
discharged directly/indirectly into water
bodies without adequate treatment to
remove harmful compounds.
Water pollution affects plants & organisms
living in these bodies of water.
WATER POLLUTION
One of SA biggest issues is the lack of clean
water.
Water around Africa  unevenly distributed
 meaning that 60% of water  situated in only 20% of
land.
<10% of SA surface water is accessible
 majority of ground water lay under large rock
formations  becomes difficult to access.
Climate change & its related effects on
temperature & precipitation may have an
additional impact.
WATER POLLUTION – Coal
Mining
Coal mining  one of SA main energy source:
 huge negative impact on land’s water, air & soil quality.
Acid mine drainage  result of excess coal
mining.
Process to neutralize Sulphuric Acid released
from coal mining  extremely slow.
Clean, excess water  released from rock
masses that are broken through mining  mixed
with sulphuric acid  water becomes toxic.
WATER POLLUTION – Coal
Mining
Toxic, contaminated water
kills plants & animals,
dissolving aluminium & heavy minerals
found in clean water (increasing toxicity
level).
Rocks which contain calcium carbonate 
able to neutralize acidic water,
SA does not have the rocks which contain
these minerals.
2 CATEGORIES OF SOURCES OF
SURFACE WATER POLLUTION
Point source water pollution:
 Contaminants that enter waterway from single,
identifiable source, such as a pipe or drain.
 Examples of sources:
discharges from sewage treatment
plant,
factory, or
city storm drain.
POINT SOURCE WATER POLLUTION
Non–point source pollution (NPS):
 Diffused contamination  does not
originate from a single discrete source.
 Cumulative effect of small amounts of
contaminants gathered from a large area.
Common example: leaching out of nitrogen
compounds from fertilized agricultural
lands.
 Nutrient runoff in stormwater from "sheet
flow" over an agricultural field / forest
examples of NPS pollution.
SHEET FLOW 
 An overland flow / downslope movement of
water taking (thin, continuous film over
relatively smooth soil / rock surfaces)
NON-POINT SOURCES
Some of the main contributors
to water pollution are:
 Factories / Refineries
 Waste treatment facilities
 Mining
 Pesticides, herbicides & fertilizers
 Human sewage
 Oil spills
 Failing septic systems
 Soap (washing car)
 Oil & antifreeze leaking from cars
 Household chemicals
 Animal waste
IMPACT OF WATER POLLUTION ON
HUMAN HEALTH
 Increased incidence (tumours, ulcers)  nitrate
pollution.
 Increased incidence (skin disorders)  contact with
pollutants.
 Increased incidence (constipation, diarrhoea,
infections to intestine.
 Dangerous effects on growing foetus  pregnant
women.
 Concentration of pollutants  bio- accumulative
pesticides through secondary / tertiary food chain in
case of non-vegetarians.
 Still births, abortions and birth of deformed children.
HOW YOU CAN HELP TO PREVENT
WATER POLLUTION
Wash car far away from storm water drains
Don’t throw trash, chemicals, solvents into
sewer drains
Inspect your septic system every 3-5 years
Avoid using pesticides & fertilizers that can
run off into water systems
Sweep your driveway instead of hosing it
down
Use non-toxic cleaning materials
Clean up oil / liquid spills with kitty litter &
sweet them up
Don’t wash paint brushes in the sink
AIR POLLUTION
What are the sources of air pollution?
 Automobile emissions
 Tobacco smoke
 Combustion of coal
 Acid rain
 Noise pollution from cars and construction
 Power plants
 Manufacturing buildings
 Large ships
 Paint fumes
 Aerosol sprays
 Wildfires
 Nuclear weapons
AIR POLLUTION IN SA
SA  developing region (low-grade
fuels are used to meet high demands)
for food, energy.
SO2 & CO2 released in air  due to
deforestation & growing amount of air
pollution,
air pollutants in the atmosphere are
slowly building up.
THE IMPACT OF AIR POLLUTION ON
HUMAN HEALTH
 Principally affect the
body's respiratory
system and the
cardiovascular system.
 The health effects:
 biochemical and
physiological changes
 breathing, wheezing,
coughing
 aggravation of existing
respiratory and cardiac
conditions
HOW YOU CAN HELP TO
PREVENT AIR POLLUTION
 Carpool or join a ride share with friends and co-workers
 Don’t smoke
 Keep your car maintenance up-to-date
 If you have to drive, do your errands at one time
 Don’t buy products that come in aerosol spray cans
 Avoid using lighter fluid when barbecuing outside
 When you drive accelerate slowly and use cruise control
 Always replace your car’s air filter
 Use a push or electric lawnmower rather than a gas-
powered one
 Don’t use harsh chemical cleaners that can emit fumes
 Inspect your gas appliances and heaters regularly
UNIT 4 HUMAN INFLUENCE ON THE ENVIRONMENT 2015
LAND POLLUTION
 SELF STUDY
 KNOW THE SOURCE OF LAND POLLUTION
 KNOW THE IMPACT LAND POLLUTION HAS ON
HUMAN HEALTH
 KNOW HOW YOU CAN PREVENT LAND POLLUTION
LAND POLLUTION
 Land pollution is the deterioration (destruction) of
the earth’s land surfaces, often directly or
indirectly as a result of man’s activities and their
misuse of land resources.
 It occurs when waste is not disposed off properly,
or can occur when humans throw chemicals unto
the soil in the form of pesticides, insecticides and
fertilizers during agricultural practices. Exploitation
of minerals (mining activities) has also contributed
to the destruction of the earth’s surface.
GLOBAL
ENVIRONMENTA
L ISSUES
• OZONE
DEPLETION
• GREENHOUS
E EFFECT
• GLOBAL
WARMING
OZONE DEPLETION
Life on Earth is protected from damaging
effects of UV radiation by a protective
layer of ozone molecules in the
atmosphere.
Satellite studies suggest that the ozone
layer has been gradually thinning since
1975.
Ozonelayerthickness(Dobsons)
Fig. 55-23
Year
’052000’95’90’85’80’75’70’65’601955
0
100
250
200
300
350
Destruction of atmospheric ozone
probably results from chlorine-releasing
pollutants such as CFCs produced by
human activity.
The “ozone hole” has increased in size as
ozone depletion has increased.
 Ozone depletion causes DNA damage in plants &
poorer phytoplankton growth
 An international agreement signed in 1987 has resulted
in a decrease in ozone depletion:
 The Montreal Protocol on Substances that
Deplete the Ozone Layer (a protocol to the
Vienna Convention for the Protection of the Ozone
Layer) is an international treaty designed to
protect the ozone layer by phasing out the
production of numerous substances that are
responsible for ozone depletion.
 As a result  ozone hole in Antarctica is slowly
recovering.
 Climate projections indicate that the ozone layer
will return to 1980 levels between 2050 and
2070.
UNIT 4 HUMAN INFLUENCE ON THE ENVIRONMENT 2015
GREENHOUSE EFFECT AND
GLOBAL WARMING
CO2, water vapour & other greenhouse gases
reflect infrared radiation back toward Earth;
 greenhouse effect
 Important for keeping Earth’s surface at a
habitable temperature.
Due to burning of fossil fuels, other human
activities,
 concentration of atmospheric CO2 has been
steadily increasing.
RISE IN [CO2] AND TEMP
Increased levels of atmospheric CO2 are
magnifying the greenhouse effect, which
could cause global warming and climatic
change.
Increasing concentration of atmospheric
CO2 is linked to increasing global
temperature.
Northern coniferous forests and tundra
show the strongest effects of global
warming.
A warming trend would also affect the
geographic distribution of precipitation.
Global warming can be slowed by
reducing energy needs and converting
to renewable sources of energy
Stabilizing CO2 emissions will require
an international effort.
UNIT 4 HUMAN INFLUENCE ON THE ENVIRONMENT 2015
Why is Global Warming important?
Temperature increases will have
significant impacts on human activities,
including:
where we can live,
what food we can grow,
how and where we can grow food,
and where organisms we consider pests
can thrive.
To be prepared for the effects of these
potential impacts we need to know :
how much the Earth is warming,
how long the Earth has been warming,
and what has caused the warming.
Answers to these questions provide us with a
better basis for making decisions related to
issues such as water resources and
agricultural planning.
NATIONAL
ENVIRONMENTAL
ISSUES
NATIONAL ENVIRONMENTAL ISSSUES
 DEFORESTATION
 OVERGRAZING
 DESERTIFICATION
 CROPS
 COMMERCIAL FORESTS
 WATER TABLE PROBLEMS
 MONOCULTURE EFFECTS BIODIVERSITY
 DEPOSIT OF TOXIC SUBSTANCES
 INTRODUCTION OF INVASIVE ALIEN
SPECIES INTO SOUTH AFRICA
 IMPACT ON BIODIVERSITY
 CONTROL MECHANISMS
DEFORESTATION
Deforestation is the permanent
destruction of indigenous forests and
woodlands.
The term does not include the removal of
industrial forests such as plantations of
gums or pines.
Deforestation has resulted in the
reduction of indigenous forests.
HOW DOES DEFORESTATION
OCCUR?
conversion of forests and woodlands to
agricultural land to feed growing numbers
of people;
development of cash crops and cattle
ranching,
commercial logging destroys trees as well
as opening up forests for agriculture;
felling of trees for firewood and building
material;
CONSEQUENSES OF
DEFORESTATION
1. Alteration of local and global climates
through disruption of the carbon and
water cycle
2. Soil erosion
3. Silting of water courses, lakes and
dams
4. Extinction of species which depend on
the forest for survival.
5. Desertification
UNIT 4 HUMAN INFLUENCE ON THE ENVIRONMENT 2015
OVERGRAZING
Overgrazing occurs when plants are exposed to
intensive grazing for extended periods of time, or
without sufficient recovery periods.
It can be caused by either livestock in poorly
managed agricultural applications, or by
overpopulations of native or non-native wild
animals.
Overgrazing reduces the usefulness,
productivity, and biodiversity of the land and is
one cause of desertification and erosion.
Overgrazing is also seen as a cause of the spread
of invasive species of non-native plants and of
weeds.
UNIT 4 HUMAN INFLUENCE ON THE ENVIRONMENT 2015
MONOCULTURE EFFECTS
BIODIVERSITY
Monoculture is the agricultural
practice of producing or growing a
single crop or plant species over a
wide area and for a large number
of consecutive years.
Monocultures can lead to the
quicker spread of diseases, where
a uniform crop is susceptible to a
pathogen.
Therefore decreasing biodiversity.
DEPOSIT OF TOXIC SUBSTANCES IN
THE ENVIRONMENT
Humans release many toxic chemicals, into the
environment e.g. Acid mine water
In some cases, harmful substances persist for
long periods in an ecosystem .
One reason toxins are harmful is that they become
more concentrated in successive trophic levels.
Biological magnification concentrates toxins at
higher trophic levels, where biomass is lower.
 Pesticides such as DDT are subject to biological
magnification in ecosystems.
In the 1960s Rachel Carson brought attention to
the biomagnification of DDT in birds in her book
Silent Spring
INTRODUCTION OF INVASIVE ALIEN
SPECIES INTO SOUTH AFRICA
Invasive species, typically introduced to a
new environment by humans, often lack
predators or disease.
In total there are 200 species of plants that
are declared weeds or invaders in South
Africa.
E.G. Eucalyptus species, Port Jackson
willow, Black wattle.
PORT JACKSON WILLOW
EUCALIPTU
S
BLACK WATTLE
LOCAL
ENVIRONMENTA
L ISSUES
OVEREXPLOITATION OF LOCAL
INDIGENOUS RESOURCES
Overexploitation is human harvesting of
wild plants or animals at rates exceeding
the ability of populations of those species
to rebound
Overexploitation by the fishing industry has
greatly reduced populations of some game
fish, such as bluefin tuna
DNA analysis can help conservation
biologists to identify the source of illegally
obtained animal products.
OVEREXPLOITATION OF
BLUEFIN TUNA
Population growth, urbanization and the
unrestricted collection of medicinal plants
from the wild is resulting in an over-
exploitation of natural resources in
southern Africa.
Therefore, the management of traditional
medicinal plant resources has become a
matter of urgency.
Problems arising from the exploitation
of natural resources
 Deforestation
 Desertification
 Extinction of species
 Forced migration
 Soil erosion
 Oil depletion
 Ozone depletion
 Greenhouse gas increase
 Extreme energy
 Water pollution
 Natural hazard/Natural disaster
SUSTAINABILITY OF LOCAL
INDIGENOUS RESOURCES IN SOUTH
AFRICA
The concept of sustainability helps ecologists
establish long-term conservation priorities.
Sustainable development is development that
meets the needs of people today without
limiting the ability of future generations to
meet their needs
Sustainable development requires connections
between life sciences, social sciences,
economics, and humanities
SOME OF S.A. INDIGENOUS
RESOURCES THAT SHOULD BE
CONSERVED AND SUSTAINED
Devil’s claw
Rooibos
Fynbos
African potato
Hoodia
Pepperbark tree
DEVIL’S CLAW
Devil’s claw is an herb.
The botanical name, Harpagophytum, means “hook
plant” in Greek.
The fruit is covered with hooks meant to attach
onto animals in order to spread the seeds.
The roots and tubers of the plant are used to make
medicine.
Devil’s claw is used for “hardening of the arteries"
(atherosclerosis), arthritis, gout, muscle pain
(myalgia), back pain, tendonitis, chest pain,
gastrointestinal (GI) upset or heart burn, fever, and
migraine headache.
DEVIL’S CLAW
ROOIBOS
Rooibos is a member of the legume family of plants
growing in South Africa's fynbos.
Traditional medicinal uses of rooibos in South Africa
include alleviating infantile colic, allergies, asthma
and dermatological problems.
The plant is used to make a herbal tea called
rooibos tea.
Rooibos leaves are dried and used to make tea,
though parts of the plant are now used in skin care
formulas as well
AFRICAN POTATO
(Hypoxis)
Africa Potato is rich in vitamins.
Boosts energy, improves immune system and helps
to prevent virus infections.
Lowers high blood pressure and blood sugar levels.
Older generations drink it as a herbal tea, creams and
tablet are also made from this plant.
HOODIA
Used as an appetite suppressant and for
treating indigestion and small infections
 Hoodia is a leafless spiny succulent plant
with medicinal properties.
 It grows naturally in South Africa and Namibia.
The flowers smell like rotten meat and are
pollinated mainly by flies.
PEPPERBARK AND
FYNBOS
 SELF STUDY
 FIND OUT MORE ABOUT THE MEDICINAL
VALUE OF THESE TWO PLANTS.

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UNIT 4 HUMAN INFLUENCE ON THE ENVIRONMENT 2015

  • 1. UNIT 4: HUMAN INFLUENCES ON THE ENVIRONMENT ONLY USE LEARNING GUIDE AND SLIDES TO STUDY READ PAGES IN TEXTBOOK WHERE INDICATED
  • 2. INTRODUCTION Human impact on the environment or anthropogenic impact on the environment includes: Impacts on biophysical environments, biodiversity & other resources. The term anthropogenic describes an effect or object resulting from human activity.
  • 3. ENVIRONMENTAL ISSUES IN SA  Many environmental issues affect SA  urbanization & acts (LAWS) needed to survive.  Keeping up with developing world + meet high demands of growing population, SA  exhausted its many resources  severe environmental damage.  Continuous depleting & improper treatment of natural resources  SA  only harming their environment.
  • 4. HUMAN ACTIVITIES THAT HAVE AN ENVIRONMETAL IMPACT:  Agriculture (FARMING)  Fishing  Irrigation  Meat production  Palm oil farming  Energy harvesting and consumption  Coal mining and burning  Manufacturing of products  Electricity generation  The use of fertilisers may cause eutrophication
  • 5. THE EFFECTS OF HUMAN INFLUENCES ON THE ENVIRONMENT  Human impact on biodiversity  significant.  Human impact on coral reefs  significant. Coral reefs are dying around the world. Coral reefs also face high dangers from pollution, diseases, destructive fishing practices and warming oceans  Human impact on nitrogen cycle  diverse.  Humans  destroying habitats & reducing amount of land available for other organisms by building, quarrying, farming and dumping waste.  Human activities  polluting water, air and land.
  • 9. WATER POLLUTION Water pollution  contamination of water bodies. Water pollution  pollutants are discharged directly/indirectly into water bodies without adequate treatment to remove harmful compounds. Water pollution affects plants & organisms living in these bodies of water.
  • 10. WATER POLLUTION One of SA biggest issues is the lack of clean water. Water around Africa  unevenly distributed  meaning that 60% of water  situated in only 20% of land. <10% of SA surface water is accessible  majority of ground water lay under large rock formations  becomes difficult to access. Climate change & its related effects on temperature & precipitation may have an additional impact.
  • 11. WATER POLLUTION – Coal Mining Coal mining  one of SA main energy source:  huge negative impact on land’s water, air & soil quality. Acid mine drainage  result of excess coal mining. Process to neutralize Sulphuric Acid released from coal mining  extremely slow. Clean, excess water  released from rock masses that are broken through mining  mixed with sulphuric acid  water becomes toxic.
  • 12. WATER POLLUTION – Coal Mining Toxic, contaminated water kills plants & animals, dissolving aluminium & heavy minerals found in clean water (increasing toxicity level). Rocks which contain calcium carbonate  able to neutralize acidic water, SA does not have the rocks which contain these minerals.
  • 13. 2 CATEGORIES OF SOURCES OF SURFACE WATER POLLUTION Point source water pollution:  Contaminants that enter waterway from single, identifiable source, such as a pipe or drain.  Examples of sources: discharges from sewage treatment plant, factory, or city storm drain.
  • 14. POINT SOURCE WATER POLLUTION
  • 15. Non–point source pollution (NPS):  Diffused contamination  does not originate from a single discrete source.  Cumulative effect of small amounts of contaminants gathered from a large area. Common example: leaching out of nitrogen compounds from fertilized agricultural lands.  Nutrient runoff in stormwater from "sheet flow" over an agricultural field / forest examples of NPS pollution.
  • 16. SHEET FLOW   An overland flow / downslope movement of water taking (thin, continuous film over relatively smooth soil / rock surfaces)
  • 18. Some of the main contributors to water pollution are:  Factories / Refineries  Waste treatment facilities  Mining  Pesticides, herbicides & fertilizers  Human sewage  Oil spills  Failing septic systems  Soap (washing car)  Oil & antifreeze leaking from cars  Household chemicals  Animal waste
  • 19. IMPACT OF WATER POLLUTION ON HUMAN HEALTH  Increased incidence (tumours, ulcers)  nitrate pollution.  Increased incidence (skin disorders)  contact with pollutants.  Increased incidence (constipation, diarrhoea, infections to intestine.  Dangerous effects on growing foetus  pregnant women.  Concentration of pollutants  bio- accumulative pesticides through secondary / tertiary food chain in case of non-vegetarians.  Still births, abortions and birth of deformed children.
  • 20. HOW YOU CAN HELP TO PREVENT WATER POLLUTION Wash car far away from storm water drains Don’t throw trash, chemicals, solvents into sewer drains Inspect your septic system every 3-5 years Avoid using pesticides & fertilizers that can run off into water systems Sweep your driveway instead of hosing it down Use non-toxic cleaning materials Clean up oil / liquid spills with kitty litter & sweet them up Don’t wash paint brushes in the sink
  • 21. AIR POLLUTION What are the sources of air pollution?  Automobile emissions  Tobacco smoke  Combustion of coal  Acid rain  Noise pollution from cars and construction  Power plants  Manufacturing buildings  Large ships  Paint fumes  Aerosol sprays  Wildfires  Nuclear weapons
  • 22. AIR POLLUTION IN SA SA  developing region (low-grade fuels are used to meet high demands) for food, energy. SO2 & CO2 released in air  due to deforestation & growing amount of air pollution, air pollutants in the atmosphere are slowly building up.
  • 23. THE IMPACT OF AIR POLLUTION ON HUMAN HEALTH  Principally affect the body's respiratory system and the cardiovascular system.  The health effects:  biochemical and physiological changes  breathing, wheezing, coughing  aggravation of existing respiratory and cardiac conditions
  • 24. HOW YOU CAN HELP TO PREVENT AIR POLLUTION  Carpool or join a ride share with friends and co-workers  Don’t smoke  Keep your car maintenance up-to-date  If you have to drive, do your errands at one time  Don’t buy products that come in aerosol spray cans  Avoid using lighter fluid when barbecuing outside  When you drive accelerate slowly and use cruise control  Always replace your car’s air filter  Use a push or electric lawnmower rather than a gas- powered one  Don’t use harsh chemical cleaners that can emit fumes  Inspect your gas appliances and heaters regularly
  • 26. LAND POLLUTION  SELF STUDY  KNOW THE SOURCE OF LAND POLLUTION  KNOW THE IMPACT LAND POLLUTION HAS ON HUMAN HEALTH  KNOW HOW YOU CAN PREVENT LAND POLLUTION
  • 27. LAND POLLUTION  Land pollution is the deterioration (destruction) of the earth’s land surfaces, often directly or indirectly as a result of man’s activities and their misuse of land resources.  It occurs when waste is not disposed off properly, or can occur when humans throw chemicals unto the soil in the form of pesticides, insecticides and fertilizers during agricultural practices. Exploitation of minerals (mining activities) has also contributed to the destruction of the earth’s surface.
  • 28. GLOBAL ENVIRONMENTA L ISSUES • OZONE DEPLETION • GREENHOUS E EFFECT • GLOBAL WARMING
  • 29. OZONE DEPLETION Life on Earth is protected from damaging effects of UV radiation by a protective layer of ozone molecules in the atmosphere. Satellite studies suggest that the ozone layer has been gradually thinning since 1975.
  • 31. Destruction of atmospheric ozone probably results from chlorine-releasing pollutants such as CFCs produced by human activity.
  • 32. The “ozone hole” has increased in size as ozone depletion has increased.
  • 33.  Ozone depletion causes DNA damage in plants & poorer phytoplankton growth  An international agreement signed in 1987 has resulted in a decrease in ozone depletion:  The Montreal Protocol on Substances that Deplete the Ozone Layer (a protocol to the Vienna Convention for the Protection of the Ozone Layer) is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion.  As a result  ozone hole in Antarctica is slowly recovering.  Climate projections indicate that the ozone layer will return to 1980 levels between 2050 and 2070.
  • 35. GREENHOUSE EFFECT AND GLOBAL WARMING CO2, water vapour & other greenhouse gases reflect infrared radiation back toward Earth;  greenhouse effect  Important for keeping Earth’s surface at a habitable temperature. Due to burning of fossil fuels, other human activities,  concentration of atmospheric CO2 has been steadily increasing.
  • 36. RISE IN [CO2] AND TEMP
  • 37. Increased levels of atmospheric CO2 are magnifying the greenhouse effect, which could cause global warming and climatic change. Increasing concentration of atmospheric CO2 is linked to increasing global temperature. Northern coniferous forests and tundra show the strongest effects of global warming. A warming trend would also affect the geographic distribution of precipitation.
  • 38. Global warming can be slowed by reducing energy needs and converting to renewable sources of energy Stabilizing CO2 emissions will require an international effort.
  • 40. Why is Global Warming important? Temperature increases will have significant impacts on human activities, including: where we can live, what food we can grow, how and where we can grow food, and where organisms we consider pests can thrive.
  • 41. To be prepared for the effects of these potential impacts we need to know : how much the Earth is warming, how long the Earth has been warming, and what has caused the warming. Answers to these questions provide us with a better basis for making decisions related to issues such as water resources and agricultural planning.
  • 43. NATIONAL ENVIRONMENTAL ISSSUES  DEFORESTATION  OVERGRAZING  DESERTIFICATION  CROPS  COMMERCIAL FORESTS  WATER TABLE PROBLEMS  MONOCULTURE EFFECTS BIODIVERSITY  DEPOSIT OF TOXIC SUBSTANCES  INTRODUCTION OF INVASIVE ALIEN SPECIES INTO SOUTH AFRICA  IMPACT ON BIODIVERSITY  CONTROL MECHANISMS
  • 44. DEFORESTATION Deforestation is the permanent destruction of indigenous forests and woodlands. The term does not include the removal of industrial forests such as plantations of gums or pines. Deforestation has resulted in the reduction of indigenous forests.
  • 45. HOW DOES DEFORESTATION OCCUR? conversion of forests and woodlands to agricultural land to feed growing numbers of people; development of cash crops and cattle ranching, commercial logging destroys trees as well as opening up forests for agriculture; felling of trees for firewood and building material;
  • 46. CONSEQUENSES OF DEFORESTATION 1. Alteration of local and global climates through disruption of the carbon and water cycle 2. Soil erosion 3. Silting of water courses, lakes and dams 4. Extinction of species which depend on the forest for survival. 5. Desertification
  • 48. OVERGRAZING Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, or by overpopulations of native or non-native wild animals. Overgrazing reduces the usefulness, productivity, and biodiversity of the land and is one cause of desertification and erosion. Overgrazing is also seen as a cause of the spread of invasive species of non-native plants and of weeds.
  • 50. MONOCULTURE EFFECTS BIODIVERSITY Monoculture is the agricultural practice of producing or growing a single crop or plant species over a wide area and for a large number of consecutive years. Monocultures can lead to the quicker spread of diseases, where a uniform crop is susceptible to a pathogen. Therefore decreasing biodiversity.
  • 51. DEPOSIT OF TOXIC SUBSTANCES IN THE ENVIRONMENT Humans release many toxic chemicals, into the environment e.g. Acid mine water In some cases, harmful substances persist for long periods in an ecosystem . One reason toxins are harmful is that they become more concentrated in successive trophic levels. Biological magnification concentrates toxins at higher trophic levels, where biomass is lower.
  • 52.  Pesticides such as DDT are subject to biological magnification in ecosystems. In the 1960s Rachel Carson brought attention to the biomagnification of DDT in birds in her book Silent Spring
  • 53. INTRODUCTION OF INVASIVE ALIEN SPECIES INTO SOUTH AFRICA Invasive species, typically introduced to a new environment by humans, often lack predators or disease. In total there are 200 species of plants that are declared weeds or invaders in South Africa. E.G. Eucalyptus species, Port Jackson willow, Black wattle.
  • 56. OVEREXPLOITATION OF LOCAL INDIGENOUS RESOURCES Overexploitation is human harvesting of wild plants or animals at rates exceeding the ability of populations of those species to rebound Overexploitation by the fishing industry has greatly reduced populations of some game fish, such as bluefin tuna DNA analysis can help conservation biologists to identify the source of illegally obtained animal products.
  • 58. Population growth, urbanization and the unrestricted collection of medicinal plants from the wild is resulting in an over- exploitation of natural resources in southern Africa. Therefore, the management of traditional medicinal plant resources has become a matter of urgency.
  • 59. Problems arising from the exploitation of natural resources  Deforestation  Desertification  Extinction of species  Forced migration  Soil erosion  Oil depletion  Ozone depletion  Greenhouse gas increase  Extreme energy  Water pollution  Natural hazard/Natural disaster
  • 60. SUSTAINABILITY OF LOCAL INDIGENOUS RESOURCES IN SOUTH AFRICA The concept of sustainability helps ecologists establish long-term conservation priorities. Sustainable development is development that meets the needs of people today without limiting the ability of future generations to meet their needs Sustainable development requires connections between life sciences, social sciences, economics, and humanities
  • 61. SOME OF S.A. INDIGENOUS RESOURCES THAT SHOULD BE CONSERVED AND SUSTAINED Devil’s claw Rooibos Fynbos African potato Hoodia Pepperbark tree
  • 62. DEVIL’S CLAW Devil’s claw is an herb. The botanical name, Harpagophytum, means “hook plant” in Greek. The fruit is covered with hooks meant to attach onto animals in order to spread the seeds. The roots and tubers of the plant are used to make medicine. Devil’s claw is used for “hardening of the arteries" (atherosclerosis), arthritis, gout, muscle pain (myalgia), back pain, tendonitis, chest pain, gastrointestinal (GI) upset or heart burn, fever, and migraine headache.
  • 64. ROOIBOS Rooibos is a member of the legume family of plants growing in South Africa's fynbos. Traditional medicinal uses of rooibos in South Africa include alleviating infantile colic, allergies, asthma and dermatological problems. The plant is used to make a herbal tea called rooibos tea. Rooibos leaves are dried and used to make tea, though parts of the plant are now used in skin care formulas as well
  • 65. AFRICAN POTATO (Hypoxis) Africa Potato is rich in vitamins. Boosts energy, improves immune system and helps to prevent virus infections. Lowers high blood pressure and blood sugar levels. Older generations drink it as a herbal tea, creams and tablet are also made from this plant.
  • 66. HOODIA Used as an appetite suppressant and for treating indigestion and small infections  Hoodia is a leafless spiny succulent plant with medicinal properties.  It grows naturally in South Africa and Namibia. The flowers smell like rotten meat and are pollinated mainly by flies.
  • 67. PEPPERBARK AND FYNBOS  SELF STUDY  FIND OUT MORE ABOUT THE MEDICINAL VALUE OF THESE TWO PLANTS.