Biodiversity
what is biodiversity?
Biodiversity is a term used to describe the
number, variety and variability of living
organisms on our planet – the diversity of
all life on Earth. There are three levels of
biodiversity – ecosystems, species that live
in the ecosystems and the genes that each
of these species have.
Scientists still do not fully understand all of
the links that exist within and between all of
the different ecosystems in our world.
However, what is clear, is that everything is
linked, and that biodiversity preservation is
not only nice to have, but is necessary for
our very survival!
Ecosystems
An ecosystem is a physical area on Earth
where a lot of different species interact
with each other and the environment.
Ecosystems provide the requirements for
life such as clean air, food, shelter and
water. Human beings rely on healthy
ecosystems as places to live, grow food,
clean our air and water, and provide
medicines and many other resources.
Loss of biodiversity affects ecosystems,
making them more vulnerable to change.
For instance, if a certain species already
has an environmental stress due to
limited food, climate change can add
an additional stress. This in turn means
that these ecosystems are weaker.
A key part of an ecosystem is that all
parts are linked i.e. the plants depend
on the animals, and the animals in turn
depend on the plants for different things.
If a fragile or weak ecosystem is
disrupted and certain links are broken,
the results could be very severe and the
whole ecosystem could break down.
Quiver Trees
Aloe dichotoma
Why are they dying
away? Changing weather
and reductions of rainfall
in South Africa and
Namibia have resulted in
drastic reductions in the
populations of this
species. This iconic
plant’s survival is already
seriously threatened by
climate change – will our
children be able to see
any of these plants in
their natural habitat, or
will they be the first of
many losses to
biodiversity linked to
climate change in South
Africa?
A loss of biodiversity threatens all these
things. It is important to conserve the
world that we live in, and the animals
and plants that share our world with us.
Species
A species becomes extinct
when the last existing
member of that species
dies.
Extinction therefore becomes a certainty
when there are no surviving individuals
that are able to reproduce and create a
new generation. A species may become
functionally extinct when only a handful
of individuals survive, which are unable
to reproduce due to poor health, age,
sparse distribution over a large range,
or other reasons.
Species richness is the number of
different species in a given area.
Typically, species richness is used in
conservation studies to determine the
sensitivity of ecosystems and their
resident species.
Biodiversity 3
Endemic Species
Endemic species are species that live
in one specific area only. For example
South Africa has a very rare floral
kingdom called Fynbos that is home
to many endemic plants and animals.
Table Mountain Species
The Table Mountain Ghost Frog is an
endemic species that is not likely to
be able to adapt to climate change. It
has tadpoles that take two years to
grow into adults.
They need constant, fast-flowing,
clear, mountain streams in which to
develop and grow. Because water
reservoirs have changed the flow,
these frogs now occur in only 6
streams; changing weather patterns
could further reduce the areas in
which this frog can live.
On Table Mountain, the endemic
Table Mountain Beauty Butterfly is
the only insect that pollinates red
disa flowers and other red flowers.
If this butterfly dies out because of
rising temperatures, so too will
the disas.
Climate Change
and Biodiversity
Loss
The single biggest threat to
biodiversity is climate change. Global
climate change will have dramatic
consequences for our Earth and all
its ecosystems.
Group activity
Choose your favourite animal.
Draw a map that charts
everything that your animal
eats and anything that may eat
it. Now add where your animal
sleeps and lives- it’s habitat.
Then, think about what would
threaten this animal’s survival.
Think as well about what would
happen to the animal’s
prey/predator if it was no
longer around. See any
connections?
Discuss these with
your group.
Human activities like deforestation,
bad farming practices, clearing of
land for building and development,
pollution, invasive alien species, and
damage to habitats are also severe
threats to biodiversity.
Did you know that a big threat
to biodiversity is
consumerism?
All the material ‘stuff’ we buy and
accumulate in our daily lives has to
come from some limited natural
resource and will eventually end up in
a landfill somewhere for the Earth to
deal with. Do we really need bigger
TV’s, faster cars, fancier sunglasses
if the true cost is the loss of our
Biodiversity…?
Biodiversity 5
Rooibos Tea
Rooibos tea is made from an
indigenous fynbos specie Aspalathus
lineari. There are a number of
different varieties of rooibos tea and
these occur only in the semi-arid
regions of the Western and Northern
Cape. Rooibos tea is an important
crop for many people who depend on
the money earned from growing and
exporting this product both in South
Africa and around the world. Both wild
and cultivated rooibos tea varieties are
very susceptible to rainfall and
changing rainfall patterns could
seriously affect this plant.
Climate change is already
having an impact on
biodiversity:
Coral bleaching, caused by
increased sea temperatures, is
destroying coral reef communities
from Australia to the Caribbean.
Climate change will affect global
sea levels, rainfall patterns and
temperatures. This is turn will affect
many habitats.
Polar bear populations are coming
under threat as food becomes
harder to hunt because their natural
habitat is melting.
Those species that are unable to
adapt are facing extinction. In fact,
scientists estimate that up to one
million species may become extinct
as a result of climate change.
Mountains
… cover 27% of the Earth’s land area.
Many plant and animal species are
endemic to particular mountains, and
found nowhere else on Earth. These
species are very vulnerable to
climate change.
In the Alps and the Himalayas,
species are already moving higher up
the mountains and many alpine (high
mountain) species will eventually
have nowhere to go and will die out.
Added to this, alpine glaciers are
melting much faster than in the past.
These glaciers are the source of
water for 50% of the world’s human
population. If the glaciers disappear,
it will have devastating consequences
for half the people on Earth.
Forests
…cover one third of the Earth’s
surface and contain two thirds of the
biodiversity of land species on Earth.
Already 45% of the Earth’s forests
have been lost.
Small changes in temperature and
rainfall can have dramatic
consequences for
forests.
Biodiversity 7
Dry and Sub-Humid Lands
… cover 47% of the Earth’s surface and
are home to two billion people.
Change in rainfall patterns and wildfires
are the biggest threat to biodiversity, food
security and livelihoods in these regions.
Inland Waters
… are all of the fresh water sources on
Earth including lakes, rivers and dams.
They are also an important food source.
Swamps and wetlands are the most
effective land based carbon sinks on Earth.
They cover 3% of the Earth’s surface, but
store twice as much carbon as all the
forests combined!
Tropical Reefs
… cover only 2% of the ocean’s surface
area, but are home to 25% of marine
biodiversity. Coral reefs and mangroves
also protect many coastal settlements from
wave damage and adverse weather.
Changes in ocean temperatures are
seriously affecting the growth of coral.
Changes in rainfall patterns will also affect
fresh water entering the oceans, and may
also add to the effects of erosion – this will
impact reef survival as silt and fresh water
can damage reef species.
Question:
Name 3 regions in
the world with large
reefs. Which is the
biggest in the
world?
Islands
… are typically areas of high endemicity. Of
all of the Earth’s species that have become
extinct in recent years, 75% of animals and
90% of birds are from islands.
Many mainland species can migrate,
allowing their populations to move in
response to climate change. This cannot
happen very easily on islands. Islands are
also much more vulnerable to damaging
weather events and a rise in sea level.
Marine and Coastal Areas
Oceans cover 70% of the Earth’s surface.
Oceans are the primary source of food for
many people around the world.
Plankton (microscopic plants and animals
that live in the sea) is the food source for
many of the fish that we eat. Plankton is very
susceptible to changes in sea temperature.
The loss of plankton will have a significant
impact on fish stocks.
Polar Regions
The Arctic (top of the world) and Antarctic
(bottom of the world) regions are seriously
threatened by a rise in global temperatures.
The melting of land ice and the expansion of
sea water when it warms up will cause sea
levels to rise.
Many species depend on ice to live,
including polar bears, seals, penguins and
many marine animals. Their survival is
already being
threatened by
Biodiversity 9
climate change.
Biodiversity 11
This booklet has been printed on Triple Green, an
environmentally friendly paper produced in South
Africa. The fibre composition of Triple Green
includes on average 60% sugar cane. This fibre
(Bagasse) is the remaining fibre after sugar has
been extracted from the harvest cane.