management, waste-pollution creation and its management, maintaining ecosystems,
Doc Brown's Biology Revision Notes
Suitable for GCSE/IGCSE/O level Biology/Science courses or equivalent
This page will help you answer questions
such as ...
What is biodiversity and why is it so
Describe some sources of air, water and
How does pollution affect biodiversity?
Why is there a need for conservation
Sub-index for my BIODIVERSITY page
Introduction to biodiversity and why it is so
Biodiversity and the consequences of a rising world population
Biodiversity, the world's population and the creation and management of
waste and pollution
Biodiversity and what indicator species can
tell us (and measuring abiotic factors)
Biodiversity, global warming
and climate change
Biodiversity and managing resources, habitat destruction,
use/misuse land & water, deforestation, overfishing, land management -
problems of indigenous versus non-indigenous species
Biodiversity and conservation - issues and project
Introduction to biodiversity
and why it is so important
Biodiversity is a term (i) used to describe the variety of
living organisms in a particular area.
But, biodiversity also includes:
(ii) the diversity of different
ecosystems within the same area - lots of different food
chains in food webs in different habitats, even in the same
(iii) and the concept of genetic
diversity - the diversity of different genes-alleles in the
populations of organisms in a particular habitat - all
contribute to biodiversity in a given area.
A high level of biodiversity in a small
(e.g. field) or huge (a forest, country) is very good, especially if
environmental conditions change.
If an environmental change happens, the
variety of species (and their genes) and ecosystems in the area,
means that at least some of them will be able to survive,
reproduce and adapt to the new conditions.
This is also to our advantage as
human beings to learn how to manage and make the most of the
world's resources and maintain a high level of biodiversity.
The populations and distribution of organisms in
controlled by biotic and abiotic factors.
Human interactions with ecosystems
frequently affect biodiversity - humans have had quite an impact
on the environment, hence a big effect, and usually negative, on
Populations of organisms can adapt over time
by evolving through natural selection - remember mutations are
occurring all the time and advantageous traits are those most likely
to be passed on to successive generations.
BUT, the pace of human impact on the
environment is so fast, most organisms cannot cope with the rapid
rate of change around them and cannot adapt in time - populations
decline, species become extinct or migrate to another area.
The loss of any species affects food chains
and webs, causing further decline in biodiversity.
Much of the impact of human activity on the
environment, however justifiable, has had a negative effect
on biodiversity e.g. deforestation, building houses, factories, dumping
waste, mining and quarrying for coal and minerals, extracting gas and
oil and laying out transport systems.
All of these activities reduce the amount of land
for wildlife, impact on ecosystems and reduce biodiversity.
However there are sign we are realising more must
be done to protect and enhance biodiversity e.g.
wildlife conservation schemes including
'rewilding' - reintroducing species to a suitable habitat,
preserving and managing rare heathlands or
reforestation with the right kind of tree -
rain forests store the most carbon,
strict planning regulations that take into
account local wildlife and minimise impact.
More on these point later, but ....
What are the benefits of biodiversity and
(i) Ensuring a good food supply (see 'food
security') using sustainable methods of agriculture
without endangering the biodiversity of the surrounding landscape.
Overfishing not only reduces biodiversity
it jeopardises fish supplies for future generations.
We need to feed the world's rising
population in a sustainable way without further damaging the
(ii) Conserving one species also protects
other species in the same food chain.
Disruption of a food chain by the decline
of one species may cause the decline in others, so lowering
(iii) Conservation programmes provide
new jobs for local people and opportunities for ecotourism
too. Ecotourism can be defined as 'environmentally-friendly
We like to visit beautiful unspoilt
'wild' places and appreciate the variety (biodiversity) of
the wild animals and plants that live in their natural habitats
and this brings in much needed revenue to some of the poorer
regions of the world.
This is in some respects a healthy
cultural outlook on our planet and what lives in our
'biosphere'. Quite often an iconic national symbol of a country
is associated with a animal or plant e.g. the flightless bird
Kiwi's feather of New Zealand, the protected bald eagle of the
USA, the red rose of England (and the white rose of Yorkshire!)
and the shamrock of Ireland.
(iv) The pharmaceutical industry, and
eventually us, benefits from biodiversity, particularly the rich
biodiversity of rain forests.
Many plant species, discovered or
undiscovered, provide chemicals that can lead to the
development of new medicines - loss of rain forest through
their deliberate destruction, not only reduces biodiversity, but
we lose a valuable resource for our own medical needs - selfish,
BUT, it doesn't reduce biodiversity, unlike many other human
(v) Many industrial substances are
derived from various plant and animal species including paper,
vegetable oils (for food and fuels), wood products.
The more diverse the species, the more
biodiverse, the more choice we have to exploit them responsibly
in our environment.
Biodiversity and the consequences of a rising world population
The graphs shows the acceleration of the world's population and their
corresponding energy use.
Two important reasons why there is such an
increase in the world population are:
(i) improvements in farming efficiency
providing more food,
(ii) improvements in healthcare systems
and the provision of drugs, particularly antibiotics,
both of these reduce death rates from
disease or hunger, but the rise in population means an
increased demand on the Earth's resources.
This is NOT good for biodiversity - the
'variety of life' - an old fashioned saying goes "variety is the spice
The greater the biodiversity of ecosystems,
the more stable they are because species rely on each other -
interdependence of food, water and shelter etc.
Particular species are important for the physical and chemical
integrity of the environment e.g. the pH and the organic material in
soil - so important for growing food.
BUT, we need more and more land for
more food as the world population rises and there is far more
industry now as the demand for more consumer goods and services
rises too, and better technology has helped, but it doesn't
have all the answers!
All of this increases the demand for raw
materials like metal mineral ores, oil/gas, wood, limestone for
concrete, stone for roads, and all of these activities need extra
sources of energy.
I'm afraid this has increased pollution
and decreased the biodiversity of our environment.
As communication technology and transport
improved lots of countries are now better connected, often through
huge multi-national companies which can simultaneously operate in
many countries - we live in a time of globalisation.
Products and services are bought from, and
sold to, most countries in the world - development can be rapid
and often little thought given to biodiversity.
Unfortunately, human activities like:
(i) waste production and lack of its management is harming the
environment - land and water pollution and the production of methane
(a greenhouse gas),
(ii) deforestation, replacing trees and their complex ecosystems
with cattle or cash crops, is causing a significant drop in
(iii) global warming, causing climate change is having its effect
on habitats too - changes in weather patterns - changes or
disruption of animal migrations,
(iv) overuse of fertilisers and anti-pest agents,
are all contributing to a decline in biodiversity.
These negative aspects of our activity and in danger, and to some
extent already, have reduced our planet's biodiversity - it is
not good for our survival or the rest of the world's organisms we should
be living in harmony with - already many species have become extinct.
We are beginning to take the situation seriously, but there is
much damage to correct, as the problems become larger and more
widespread - following the spreading development of societies that
do not live in balance with the environment they are moving into and
BUT, with the world's population rising, there is an even
great pressure on societies to produce more food, including planting
crops for cash in poorer developing societies - and often the
revenue goes to multi-national companies and the local workers paid
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Biodiversity, the world's population and the creation and
waste and pollution
People in poorer underdeveloped countries, unsurprisingly, want
the same material standard of living as people living in richer more
So consumer demand and rising population are presenting us, and the
rest of nature, with rather a lot of issues to try and sort out as we
put increasing pressure on the environment by our methods of land
use and extracting minerals (coal, oil, gas , metals) that we want to
survive and increase our standard of living..
When the world's population was smaller, the problems were not as
great and the effects of human activity were much more localised.
The graphs shows the acceleration of the world's population and their
corresponding energy use.
Surely you would expect a similar acceleration
of waste from domestic and industrial human activity?
AND, much of this is having a negative effect
on the environment of our planet.
There is an increasing demand for a higher
standard of living ranging from greater quality of food, consumer goods
to transport and recreation facilities.
So we need more raw materials from the
natural resources of the land and sea to sustain our way of life -
food and consumer goods etc.
But, we also need more energy (see 2nd
graph above) to sustain our desired higher standard of living - so
we are continuing to exploit coal, oil and gas reserves - despite an
increasing use of renewable energy resources like wind turbines,
solar power and hydroelectric power.
So, overall, we are taking increasingly
larger quantities of many things from the Earth's resources at an
ever increasing rate!
If we continue to extract and consume these
natural resources at an even faster rate, we might just run out
of some important resources and be unable to meet the demands of
an ever increasing world population.
All of this human activity is creating a lot of
waste and spreading pollution locally and around the world.
e.g. pollution of 'local' land, lakes,
streams and river systems from
overuse of fertilisers, sewage-human effluent, factory effluent,
and now plastic waste is found all over our
oceans! Pollution has gone global!
Any pollution affects one or more food
chains with negative 'knock on' effects on other organisms
in the complex food webs of any ecosystem - so biodiversity
of waste and
pollution and their management
As our ever increasing world-wide consumer
society demands more and more and use more and more of the Earth's
resources, so we create more and more waste from producing
and consuming food, plastics, metals and burning fossil fuels for
We need to minimise the formation of polluting
gases and chemical waste to minimise the harmful polluting impact on
the environment and its fragile ecosystems-biodiversity - its
unlikely we will reduce this impact to zero, but we can try a lot
Ideally we should try to reduce waste and
pollution by recycling
materials, but this isn't always possible, but we can
try to minimise pollution of the atmosphere, water and land, all
of which has a negative effect on biodiversity!
(i) Burning fossil fuels emits acidic
gases like sulfur dioxide and nitrogen oxides - all of which are harmful to us and
other organisms the environment.
Trees and fish are especially
sensitive to acidic water after the acidic gases dissolve in
rain which falls into lakes and rivers.
You can operate desulfurisation
processes in power stations and use catalytic converters in
For more details on certain aspects of air pollution see
Fossil fuel air pollution
incomplete combustion, carbon monoxide & soot particulates
Fossil fuel air pollution - effects of sulfur oxides
and nitrogen oxides gcse chemistry revision notes
(ii) Road vehicles are also emitting carbon (soot) and
hydrocarbon (CxHy) particulates which are being taken in
and absorbed by our bodies.
We are just learning how so many
particulates are getting into our bloodstream and organs,
potentially having harmful effects - its an important
current area of scientific research.
(i) Overuse of fertilisers
(agrichemicals), some of the material runs off with rain
into streams, rivers and lakes so the water contains too much
nitrates and other nutrients in excess of what aquatic organisms
need. This causes an overgrowth
of choking algae and weeds that block light reaching life below
the water surface - the effect is called eutrophication.
The plants can't synthesise and die and begin to decompose.
The decomposer microorganisms respire and multiply using up any
remaining oxygen in the water. This deoxygenation of the
most other aquatic life requiring oxygen for respiration e.g.
fish and crustaceans, so food chains/webs badly affected - far
biodiversity in the aqueous habitat.
Synthetic fertilisers should be used
to the minimum required and in a pellet form that slowly
releases the nutrients, hopefully absorbed by plants with no
excess run-ff into water systems.
Toxic pesticides can be washed
of farmland into water courses.
Use of NPK fertilisers
and environmental problems
(ii) Oil spills from broken
pipelines on land or tanker accidents at sea lead to destruction of
wildlife, particularly of aquatic organisms like seabirds and
other animals in the sea.
A large and costly clean-up operation
must then be put in place.
and Economic Aspects of the Petrochemical Industry
(iii) Domestic sewage contains
pathogens that can kill aquatic life.
Sewage also contains all sorts of
chemicals we have used in household products.
No domestic effluent should be allowed
to flow into water systems untreated.
Anti-pest agents used in agriculture - agrichemicals
The overuse of toxic pesticides,
and herbicides has had a dreadful effect on non-harmful
organisms such as wild flowers and insects like bees -
important pollinators. They pollute both land
(contaminated) and water (washed into by rain).
Food chains are affected - animals
rely on plants or other animals for their survival, and
ecosystems imbalanced and biodiversity is considerably
reduced. Pollutants enter the food chain and passed on
from one trophic level to the next, with increasing
concentration - animals like top predators suffer the
Chemicals from industry
Waste from chemical processes must be
carefully dealt with and not allowed to leak out and pollute
water courses - streams, rivers and lakes.
Certain metal compounds and
chemicals used in manufacturing plastics all have very
detrimental effects on organisms.
(i) Domestic waste is becoming an
increasingly worrying problem as the world's population
increases along with rising standard of living - both
contribute to the waste problem.
Much of our household waste is dumped
in landfill sites ('rubbish dumps') from which pollutants can leach
Organic material in dumps is
anaerobically decomposing giving off methane gas - a
powerful greenhouse gas - much more so than carbon
dioxide, which is also given off from aerobic respiration.
Decomposer organisms can respire both
aerobically and anaerobically, but landfill sites tend to
have low oxygen levels below the surface, which encourages
decomposers to respire anaerobically, hence the emission of
methane gas rather than carbon dioxide. This means landfill
site decomposition contributes more to global warming than
the natural decomposition in the
Recycling things like plastic,
metals and garden waste can help reduce the burden of
Landfill sites use up space once
occupied by wildlife, the less space we need the better and
existing landfill sites need to monitored for pollution
effects and eventually, after their useful life, the land
restored to a good ecological state and the local
biodiversity greatly improves!
Many supermarket chains and other
retail businesses are moving away from plastic packaging to
returning to use recyclable paper.
(ii) Overuse of anti-pest chemical
agents on farm land - see water pollution above.
(iii) Oil spillages contaminate
both land and water - see above in water pollution.
and Economic Aspects of the Petrochemical Industry
(iv) Nuclear waste is buried
underground or stored in tanks of water.
Highly radioactive waste from
nuclear power reactors is highly toxic (cancer
forming) and must be processed (at great cost) to separate
what can be re-used in nuclear reactors and what must be
Unfortunately the half-life of some
radioisotopes is in the region of thousands of years - so
that's a long term storage and management problem - no
leaks into the environment is acceptable, but thy happen!
See also in gcse chemistry and
physics revision notes
radioactive emissions - health and safety issues
Half-life of a
radioisotope - how long is it radioactive? implications!
See also Metal extraction -
economics, environmental Issues and recycling gcse
chemistry revision notes
POLYMERS, plastics, poly(ethene),
poly(propene), uses - problems and recycling
gcse chemistry revision notes
TOP OF PAGE
Biodiversity and what
indicator species can tell us (and measuring abiotic factors too)
The fact that certain organisms
are very sensitive to changes in their environment means they can be
used as indicators of pollution or other effects resulting from
Organisms used in this way are
called indicator species and studying them can reveal much about
local ecosystems and the habitats and populations of specific plants
are plant-like organisms that consist of a symbiotic
association of, usually green, algae or cyanobacteria and fungi.
Lichen are found worldwide in a variety of environmental conditions.
Species of crusty orange lichen and crusty grey lichen are shown in
the picture. They take on various physical forms e.g. bushy beards,
crusty spots, leafy pads and even small standing branches.
Specific types of lichen are
very sensitive to the concentration of sulfur dioxide in
the atmosphere, SO2 is formed on burning fossil fuels
- particularly coal burning power stations.
The relative population
numbers of different types of lichen can indicate how clean
(unpolluted) the air is in that location.
If the air is not polluted
with acidic gases like sulfur dioxide, you will see lots of
lichen, particularly bushy lichen on e.g. stone walls,
rocks, roof tiles, tree bark. Bushy lichen is much more
sensitive to pollution than crusty lichen.
Fungi can also be used as
indicator species e.g.
Black spot is a fungal
disease that affects roses. It develops as black spots on
rose leaves, which eventually causes the leaves to turn yellow
and drop off. Apart from looking unsightly, it can seriously
weaken the rose plant.
The blackspot fungus on rose
leaves is very sensitive to sulfur dioxide. If sulfur dioxide is
present in the air, the blackspot fungus will not thrive. It
seems ironic that the presence of an unwanted and
unsightly blackspot fungus on rose leaves actually
indicates the presence of 'clean air'!
You might see how much lichen you
see on stone walls in a busy urban area with lots of pollution from
traffic, compared to a rural location well away from busy roads.
You should find more lichen,
the further you are away from busy roads, that is the further
away from sources of polluting acidic gases like nitrogen
dioxide and sulfur dioxide from road vehicle exhausts!
The most common sources of water
pollution are rain run-off washing nitrates from fertilisers
into streams and rivers (excess nutrients), and the discharge of
raw sewage (which contains pathogens).
Both sources of pollution
facilitate the 'overgrowth' of particular microorganisms that
use up oxygen affecting many species in food chains - this
reduces the concentration of oxygen in water.
Invertebrate animals like
freshwater shrimps and stonefly larvae are very sensitive to the
concentration of oxygen in their aquatic habitat.
If these two species are
found in a stream or river it indicates a relatively high
level of oxygen and a low level of pollutants, like
those mentioned above - in other words the water is 'clean'.
However, conversely, other
invertebrates have adapted to live in polluted water e.g. blood
worms (bloodworms) and sludge worms (sludgeworms) - what lovely
names! - would Linnaeus approve!
If these two indicator
species are present in water, it indicates a high level of
Soil and woodland conditions
Moss, for example, can indicate
high levels of acidity in the soil, which in turn may indicate acid
rain. Fungi are useful for measuring health of old-growth
forests. The diversity of wood-decay eating fungi correlates to the
diversity of insects in a shared habitat.
of surveying-monitoring pollution - measuring abiotic factors
(This section is repeated in the
Abiotic conditions means
the 'non-living' factors like temperature, water/soil pH,
soil nutrients, moisture level, light intensity, climate conditions
- again, all of these affect the distribution of organisms.
Measurement of abiotic factors
may help to explain differences in the populations and distributions
As described above, you can
survey and compare one location with another, looking particularly
for indicator species of plants or animals.
You might survey the length
of a stream or a stretch of a river, sampling-surveying at
regular intervals, looking at what species are present or not
present - relatively quick to do.
This might help to trace the
source of pollution in a polluted stream or river.
However, surveys based on
'present/not-present' do not tell you how polluted the
specific environment is.
To get quantitative data
you would need to count the numbers of each indicator
species present in a measured area or volume of water - this set
of numerical data takes longer and more costly to do, but gives
a better estimate of pollution levels.
But, even doing species counts
does still not give you very accurate data on levels of pollution,
but using modern analytical instrumental methods. These
non-living indicators and allow rapid and regular checks to be
carried out to monitor pollution levels and see how they
change with time and location.
You can analyse air or water
samples for traces of polluting chemicals even if their
concentrations are only in ppm with electronic sampling devices.
You can monitor ozone,
carbon monoxide, nitrogen oxides and sulfur dioxide in the
polluted air of towns and cities with an air quality
You can analyse for
traces of toxic organic chemicals or heavy metal compounds
Electronic pH meters
tell how acidic or alkaline a water system is - choosing
different locations along a stretch of stream or river.
You can use a simple
visual indicator strip to measure the pH of soil.
It uses a sort of
universal indicator where match the colour strip turns in a
soli/water mixture and match the colour it turns to a pH
You can also dip the
electronic pH probe into a soil/water mixture - a more
Another electronic probe
instrument can directly measure the oxygen concentration
in water - just dip in and press the button! - again, choosing
different locations along a stretch of stream or river to
broaden the survey.
You can use an electronic
thermometer probe to measure the temperature of land or
water - again, choosing different locations along a transect to
broaden the survey.
You can employ a light
meter sensor to measure light intensity in different
locations e.g. comparing open and shaded areas of a habitat.
You can use a soil
moisture meter to measure the relative water content of
You can compare the
results of measuring abiotic factors with the distribution of
selected organisms to look for similarities or differences.
TOP OF PAGE
and climate change
Global warming is causing climate change.
The diagram above describes how the Earth is kept
warm by so-called 'greenhouse gases'
The 'greenhouse effect'
The Earth's temperature is the result of a
balance between radiated energy received from the Sun and the energy
radiated from the Earth back into space.
The Earth's atmospheric gases act as an
insulating layer and absorbs some of the infrared heat radiation
that otherwise would be re-radiated away from the Earth.
This increases the temperature of the Earth
compared to what it would be without the atmosphere - this is one
reason why organic based life exists on Earth - not to cold - Mars
(little atmosphere) and our moon (no atmosphere) are much colder.
Certain gases in the atmosphere are more
effective than others in absorbing the re-radiated energy - water
vapor, carbon dioxide, methane, nitrous oxide and ozone all occur
but we have added other greenhouse
gases like chlorofluorocarbons (CFCs) and
hydrofluorocarbons (includes HCFCs and HFCs).
(that can have an infrared
absorbing greenhouse effect)
Water vapour and
The % water vapour in the atmosphere varies
considerably depending on the humidity and temperature - this then
affects all the other percentage contributions from the other
Note that the biggest greenhouse gas
contributor is water vapour, but also note the very disproportionate
effect of the relatively small concentration of carbon dioxide -
which is rising!
Data adapted from Wikipedia page
Absorption and emission of radiation by
materials - including global warming gcse
Global warming, climate change,
carbon footprint from fossil fuel burning gcse
The effects of human activity and greenhouse
However, although the naturally occurring
greenhouse gases have been in balance for thousands of years,
keeping the average temperature of the planet fairly constant, all
the evidence suggests that are planet is warming up - 'global
Carbon dioxide and methane are particularly
effective absorbers of the re-radiated infrared radiation
The extra carbon dioxide and methane added
to the atmosphere from human activity is causing the average
global temperature to rise by a small, but not insignificant amount
- and the temperature rise might be accelerating - see the graph
The effects on the environment and biodiversity
Global warming is causing climate changes in
weather patterns around the globe and this is having an effect on many
plants and animals around the world - including us humans!
The higher global temperature is causing the seas
and oceans to expand and the ice to melt e.g. in arctic regions
and glaciers around the world.
This will lead to flooding of lower level
coastal land, disrupting human agriculture and the habitats of many
As the temperature continues to rise weather
patterns are changing with 'knock on' effects on wildlife and us!
Changes in rainfall patterns can change the
distribution of plants and animals.
We humans are experiencing more exceptional
weather events such as:
(i) extreme temperatures leading to drought in
(ii) in other places excessive rainfall and
flooding destroying crops and animals and destroying animal
All these climate change effects are
reducing biodiversity and disturbing season cycles of balanced
populations of plants and animals.
Temperatures in the northern hemisphere are
rising both on the land and in the seas.
Many species of plants and animals are
becoming more widely distributed as they can now cope with
living in more northern regions. Changes in migration
patterns are causing some animals e.g. migrating birds, to
move further north producing a wider distribution of breeding
BUT, for other plants and animals, who
prefer cooler conditions, means they will tend to move north to
higher temperature regions e.g. cod in the North Sea are
moving to more northern fishing grounds. In this case,
species are becoming less widely distributed.
Most of these events and changes have a
negative effect on the environment and biodiversity.
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Biodiversity and managing resources -
use/misuse land and water including deforestation, overfishing and land
'scenario' - habitat destruction
All around you can see how we have impacted on
the landscape e.g. agriculture, buildings, mining, motorways,
quarrying, etc. etc. !!!
We all want a good standard of living,
but the rising populations of the world are putting pressure on the
biodiversity of where we live and what we have created from the
All of this effects the original 'wild'
landscape, which we have been reshaping for thousands of years, but
never at a faster rate than the present time.
In perusing our developments we have left far
too little land for the animals and plants that once lived there.
Asking farmers to leave a 'wild' 3 m strip
around the perimeter of field is one small step!
The destruction of habitats and disruption of food
chains and food webs, that once made up a complex ecosystem is having
pretty negative effect on biodiversity.
The principal causes of habitat destruction
Human activity has considerably reduced
biodiversity by extensive building of houses, factories and
transport systems; quarrying/surface mining and large scale farming.
The land available for wildlife (animals and
plants) is much reduced and the decline in biodiversity follows e.g.
biodiverse woodland is cleared for houses or farming - but there is
no denying they are needed.
But plant/animal species population numbers
decline and animals have to move away to ever deceasing habitat
possibilities - migration is one way biodiversity declines in a
Deforestation - why? impacts?
One of the most worrying developments is the
deforestation of huge areas of the tropical rain forests
in South America and Southeast Asia.
This mainly due to the huge scale and
pace of deforestation e.g. in the tropical Amazon
forests of Brazil.
The deforestation is to clear the land
for farming e.g.
(i) growing crops for food (e.g.
wheat or rice)
(ii) growing crops from which to make
biofuels like bioethanol from sugar cane,
(ii) raising great herds of cattle for
milk and meat.
Its easy to be critical of countries
like Brazil, but many of us who live in well developed
countries and enjoy a good standard of living (I live in
England), should admit the people in other countries also
deserve to have a better standard of living too.
The pressure on the landscape from our
natural desires for lifestyle conflicts with what ideally we
would like to see in the very landscape we admire but so
strongly impact on!
There are no easy answers to
this conflict of interests!
Impacts of deforestation on global warming
Deforestation is reducing the rate of
photosynthesis taking place so less carbon dioxide is
being removed from the air which, theoretically, is going to
contribute to rising CO2 levels and global warming -
climate change, which is itself, having a negative effect on
Trees 'store' some of the 'carbon'
taken in during photosynthesis for many years and this biomass
of e.g. complex carbohydrates like cellulose, means there
would be less carbon dioxide in the atmosphere to
contribute to global warming - but not if you cut down huge
areas of forest.
To make matters worse:
(i) burning the trees to clear the
land, releases large amounts of carbon as carbon dioxide
back into the atmosphere,
(ii) and even if the trees are not
burned, microorganisms can aerobically decompose rotting
wood and also other organic material exposed on uprooting
trees, again releasing more carbon dioxide into the
Cutting down lots of trees has led to the
destruction of rich complex habitats of plants and
animals and an unprecedented decline in biodiversity -
many species are under threat and some have become extinct.
The variety of species of plants
and animals ('biodiversity') is being considerably reduced
by deforestation - destruction of habitats.
We should be
planting more trees than we are cutting down to absorb as
much carbon dioxide.
another example of an adverse landscape change
A bog or bogland is an acidic waterlogged
wetland that accumulates peat, a deposit of dead plant material,
Most peat bogs are in the northern hemisphere
- the largest are in Siberia, Russia.
Plants that live in bogs don't completely
decay when they die because of a lack of oxygen.
The partially rotted plants build up layer
after layer of peat over thousands of years.
This means a vast amount of carbon are stored
in the peat, that would otherwise be carbon dioxide in the
atmosphere and contribute to global warming.
Again, just like the 'Amazon rain forests',
but not involving trees, the pressure for food production has
meant that many areas of peat are being drained and converted to
The peat is sold to gardeners for compost
- its a rich source of nutrients.
It is also used as a fuel - even power
stations have been run off this semi-fossil fuel.
The result is that we are clearing away and
using peat at a much faster rate that it is being formed.
Unfortunately, when peat is drained, the
residual organic material comes into contact with air and
microorganisms can decompose it aerobically. In other
words they use the oxygen in are to respire and give out carbon
This means at the same time, the peat
carbon store is released and more carbon dioxide is released
into the atmosphere to contribute to global warming.
There is also another issue to do peat bog
With temperatures rising in the
northern hemisphere, bogs are naturally drying out as well as
This makes then susceptible to burning,
just as much as draining them.
This releases more CO2
into the atmosphere and any residual organic material exposed
can also be oxidised too.
As I write this (in August 2019) huge
fires are raging across the peatlands and forests of Siberia in
Russia releasing huge amounts of carbon dioxide into the
A positive note from Russia
The swamps and bogs surrounding Moscow
had been drained in the 1960s for agricultural use and
mining of peat as a fuel to generate energy. In 2002,
a series of hard-to-extinguish peat fires led the government
to recognize that the peat fields needed to be re-watered to
Both effects contribute to another example of
habitat destruction, disruption of food chains and food webs,
and a resulting decline in biodiversity as the 'local'
ecosystems are wrecked.
Overfishing and fish farms (aquafarming)
Overfishing is the removal of a
species of fish from a body of water at such a rate that the
species cannot grow to maturity and reproduce in time.
This results in those species either becoming depleted or very
underpopulated in that given area of sea. Overfishing has
spread all over the globe and has been going on for centuries
and in modern times become even worse as huge trawlers and
factory ships are hastening the depletion of fish stocks.
You need policies and regulations
that prohibit overfishing and check that fish catches don't
exceed a level that causes depletion of fish stocks.
One of the results of overfishing is
the rapid development of factory farming methods of
raising fish - an example of aquaculture, described next,
but this is not without problems of its own.
Aquaculture, also known as
aquafarming, is the farming of fish, crustaceans, molluscs,
aquatic plants, algae, and other organisms for commercial
purposes. Aquaculture involves cultivating
freshwater and saltwater populations of organisms under
controlled conditions e.g. fish farming in cages-nets, which is
quite different to commercial fishing of open waters, which is
the harvesting of wild fish from our lakes, seas and
Fish farms can be constructed in any
area of open water e.g. a large lake or sheltered bay of the
sea. Unfortunately fish farms can reduce
To make farms commercially viable and
increase productivity, food is added to the 'net-cages'
which produces a lot of waste after digestion. The food and
waste can leak into open water causing eutrophication and
the death of wild species of organisms. Fish farms
become breeding grounds for large numbers of parasites which
can escape and infect wild animals and can kill more healthy
wild fish. The fish farms attract predators like seals which
get caught in the nets and die. Farmed fish can escape
causing problems for the populations of wild species - they
might outcompete them for food, spread disease and
interbreed with wild fish of the same species - this dilutes
the gene pool of the fish best adapted to survive in 'wild
Some of these problems can be reduced
by raising the fish in large tanks rather than
enclosed nets in open water. BUT, this greatly reduces
biodiversity because the tanks must be kept free of plants,
predators and the parasites have to be killed along with
other microorganisms. In some countries, fish farmers add
antibiotics to the fish's 'artificial' food or water and
chemicals to kill parasites. Tank fish farms are
intensively crowded aquafarms, small fish are bullied and
killed by larger fish. Mortality rates are high and disease
and parasite infestations are common as is blindness.
Definitions - apply to plants or
An indigenous species is one
that occurs naturally in a given habitat area.
Many species can co-exist in an
ecosystem that functions with balanced populations of
plants and animals.
Indigenous species are also
referred to as native plants or animals e.g. the
red squirrel is native to parts of the UK.
A non-indigenous species is one
that doesn't occur naturally in a given habitat.
This is often due to 'accident' or
intentional human introduction for one reason or another
- for aesthetic reasons - deer look good in the park,
for food, for hunting.
The negative results on biodiversity of
introducing a non-indigenous species
Unfortunately introducing a
non-indigenous species can cause problems for indigenous
species e.g. they may compete with each other for the same
food, shelter or water resources.
e.g. the larger and stronger
non-indigenous (non-native, introduced to the UK in the
1890s) grey squirrel out-competes the red squirrel
for the same food resource. As a result, in the UK, with
declining populations, (down to zero in places - 'died
out') the native red squirrel is considered an endangered
Some non-indigenous species are
introduced to diversify our food supply e.g. the
signal crayfish, but it has spread into freshwater lakes,
streams and rivers where it out-competes many indigenous
aquatic species for food, reducing biodiversity.
Signal crayfish also causes
further problems by burrowing into river and canal banks
causing erosion, bank collapse and sediment pollution.
The 'out-competing' signal crayfish is a voracious
predator, feeding on a variety of fish, frogs and
invertebrates, as well as plants, and even eating
individuals of its own species!
Non-indigenous species can bring
new diseases to a habitat leading to less biodiversity,
because these can infect and kill indigenous species which
will not have time e.g. via mutations, to have any
protection against the 'invading pathogen'.
TOP OF PAGE
conservation - issues and project strategies
We need to maintain biodiversity at a high
level to ensure stable ecosystems.
Various conservation projects are being
pursued by organisations, often in partnership with scientists.
The idea is to minimise future damage and
reverse some of the damage done to biodiversity, particularly that
due to human activity.
It isn't going to be easy, but the aims and
objectives for biodiversity are VERY worthwhile!
With increasing 'globalisation' countries are
able to share resources, services and expertise. This aught
to help conservation and does throughout the world. But it can
actually decrease biodiversity too e.g. large multi-national
companies can dominate the 'market place' with the most profitable
seeds and crops. In doing so, the variety of seeds globally is
reduced, along with biodiversity. You could argue the same for using
just a few 'selected' breeds of cattle.
Examples of conservation projects - programmes
and legal regulation of the environment
(i) Conservation to protect and regenerate
rare natural habitats e.g. ancient oak woodland, coral reefs,
heathlands, mangrove swamps, rain forests. This allows a greater
biodiversity and allows plants and animals to continue to live in
their natural habitat.
Conservation areas must be protected
from building, dumping waste, farming, fishing (seas) and
quarrying - some of the main human activities that inevitably
destroy habitats of valuable biodiversity.
Conservation areas might be small local
projects or huge national parks both on land and sea
to protect all types of ecosystems in woodland, heathlands,
lakes, rivers and seas (important marine ecosystems).
The best way to conserve a species is to preserve
its habitat, in doing so you increase the health of
the ecosystems and raise the 'local' level of biodiversity.
In conservation areas species can be
monitored and protected in safe areas away from the impact
of human activity e.g. not allowing any development or
To help sustain and protect
ecosystems, the creation of national parks and specific
nature reserves on land (woodland, heathlands etc.), rivers,
lakes and the sea (restrict fishing access and catches) all
help in conservation.
You could be dealing with a local wood or
a huge safari park, look after them, manage them and restrict or
stop development in conservation areas.
Wetlands need their water levels
controlled to conserve them and re-flooding peat bogs that had
been drained - all helps to conserve natural habitats for native
plants and animals.
Reforestation of native woodlands
and forests i.e. replanting indigenous tree species back in an
area where the population has declined. It is also better to
plant a variety of native trees to give a greater
biodiversity e.g. different food resources for birds or insects.
Woodlands have a rich biodiversity,
exemplified by the ancient oak trees of England - an
amazing biodiversity of species rely on them for
food and shelter. Oaks have more associated
species of wildlife than any other native trees in England.
These organisms range from bacteria to fungi, lichens (fungi
in symbiosis with algae), free algae, mosses, vascular
plants, invertebrate animals, birds and mammals.
Ancient oaks are particularly important as habitats for many
of these organisms. They provide mutualistic 'services' for
a long time in the same place, and as they grow larger and
age, they provide additional niches for yet other organisms
Conservation of species and habitats is
expensive, so the costs of such programme must be weighed
against the potential benefit to biodiversity.
How ever worthy the aims of conservation,
there are often conflicting issues to deal with, and not
just humans versus environment e.g.
To protect and conserve one species in
a habitat from another less valued species, killing
the other competitive species might be necessary e.g.
'protected' red squirrels versus outcompeting 'vermin' grey
squirrels which are not native to the UK.
Killing rats and other animals that
raid sea bird nests on an island help conserve bird colonies
- important breeding grounds.
Are these actions morally justified?
and by what criteria?
(ii) Government regulation and strategies
Voluntary agreements with e.g. landowners,
is important for wildlife protection but legal regulation of the
environment works better in the end.
You can control pollution from factories
e.g. how toxic chemicals are dealt with, ensuring no pollutants
get into water courses, limiting potentially harmful emissions
into the atmosphere.
You can control the amount of carbon
dioxide that is allowed to be released into the atmosphere by
businesses - you can offer financial incentives to reduce CO2
emissions and move to 'greener' sources of energy - all to help
minimise the effects of global warming, and every little scheme
helps biodiversity directly or indirectly!
Banning the hunting of endangered
species helps biodiversity.
Co-operation between countries can
help too e.g. a band of European countries can ban the trapping
and killing of migrating birds from Africa to Europe - a work in
Banning whale hunting is
another issue that brings many peoples views in conflict
with those of Japan, Norway and Iceland and other countries
approach to the whaling industry, where despite protest
commercial killing of whales continues.
The International Whaling
Commission restricts the quantities killed to around
2000 whales per year.
In Africa, endangered animals such as
rhinos and elephants are hunted for their prized ivory horns
- many African governments have banned such hunting and the
sale of ivory - trafficking ivory is being tackled on a
world-wide basis by governments co-operating with each
Fishing ground used by several
countries need to be co-managed to avoid overfishing - this
can only be done by intergovernmental cooperation.
BUT, one of the problems is
keeping track of fishing quotas to check against
(iii) A lot of attention has turned to
modern methods of agriculture.
We need more sustainable methods of
agriculture but 'wildlife' must be taken into account too.
Monoculture, that is where fields
are just used to grow a single crop.
This is an efficient way for farmers
to use land for specific crops, but it does lead to a
decrease in biodiversity, often because habitats are cleared
away to make space for larger more efficient fields.
The excessive use of anti-pest chemicals
(herbicides and insecticides) means lots of potentially harmful
chemicals have got into the food chains.
Insect populations in many places
around the world are in decline, particularly important
pollinators like bees.
Overuse of artificial fertilisers,
resulting in rich nutrients washed by rain into lakes and rivers
and causing overgrowth of algae, deoxygenating the water and
killing most of the aquatic life beneath the algae.
Carefully controlling the amounts
of agrichemicals helps, BUT, their use will always
cause some harm to the local ecosystems - they basically
cause a decline in biodiversity - but we do want cheap
food, but at what price?
Some quite simple strategies can be
employed to improve the biodiversity of our landscape in farming
Reintroducing hedgerows that
give shelter and food for birds and a habitat lots of other
Leaving a 'wild' field margin
around the perimeter of a field allowing wild plants
(flowers and grasses) and insects to flourish.
These strategies work best for
single crop fields.
If trees are removed for timber,
replace them with other saplings to grow into mature
trees - temporarily stores up carbon - replacement is a
sustainable strategy and in the long-run does not
increase carbon dioxide in the atmosphere - this part of the
carbon cycle is kept in balance.
Many 'experts' say we should employ
more horticulture and less animal rearing in our
agricultural systems because they argue:
(a) The 'carbon footprint is less
growing grain and vegetables.
(c) You can produce more food for a
similar cost by growing crops.
(c) A vegetarian based diet is
BUT, at the moment, in the
'supermarket', its your choice of lifestyle!
(iv) We should all try to reduce our 'waste
I've already discussed examples of "sources
of waste and pollution and their management"
(v) You can instigate breeding
programmes for endangered species of animals.
Many people support the preservation of
endangered species, even though they are not necessarily of any
benefit to human beings.
Here the objective is to prevent the
extinction of rare animals, which is most likely to happen
because of human activity like large scale building development
Unless small populations of endangered
species are not boosted in some, extinction is always a
To increase their numbers,
endangered animals can be successfully bred in
captivity (often a zoo) which keeps the species going, and hopefully be
reintroduced into their natural 'wild' habitat from out of these
captive breeding programmes.
Zoos are controversial, but they are
safe areas and have proved successful with many endangered
This may help boost the remaining numbers
of an animal population or reintroduce it where it had become
completely absent from its original habitat - which itself might
need extra management.
Note on plant conservation - seed banks
and botanical gardens:
For plants, one method is to
build up stores of seeds - essentially a bank of plant genes. A
seedbank is a
store of genetic material for the future - an important
strategy for conservation. If any plant becomes
extinct in the wild, it can still be grown using the store
seeds and the new plants introduced back into the wild.
Botanical gardens have
proved successful at breeding rare tropical plants and
harvesting the seeds from a huge range of species.
Conflict of interests
Always a problem - usually preserving
wild natural habitats and biodiversity versus the pressure from
commercial companies and agricultural food production for us in
developed countries and feeding indigenous people or export crops
for much needed revenue.
Its our ideal of biodiversity versus our
quite natural demands for a high standard of living e.g. good
food and consumer goods.
Examples of competing pressures and
(i) Food security is top priority
and issue for many people in poorer countries.
Some animals are rightly seen as pests
and are killed by farmers - e.g. locusts who rapidly destroy
fields of crops - how can we argue against killing locusts.
We use pest control to protect crops
and livestock in order to produce more food.
But this harms food chains and food
webs and therefore reduces biodiversity.
Food security - population growth and
(ii) Similarly to example (i), it isn't
just food we want, all around the world people want a higher
standard of living - good houses to live in,
places to work in, transport systems to get to work or go on
holiday, and of course extra land for more farming needed to
feed our increasing populations.
All of these developments take up land
that was once 'wild' and full of many species of plants and
Any of these developments is worthy in
its own right, but they do remove habitats and reduce
biodiversity because of their high impact on the
Not easy to strike a balance!
(iii) Like many worthwhile things in life,
biodiversity costs money, and sometimes a lot, and
competing against other financial interests.
Generally speaking conservation
doesn't make a profit so protecting biodiversity in our
environment faces strong competition from public services
like roads, school and hospitals etc. all of which are
We have to pay farmers subsidies to
reintroduce things like hedgerows and field margins, fencing
off cattle to stop them polluting streams and rivers.
We have to pay inspectors from local
authorities or government environmental agencies to check
such programmes are being carried out and monitor the
(iv) many poorer developing countries have
abundant natural resources such as minerals, timber and oil/gas
hydrocarbons, but often in areas rich in biodiversity.
Exploiting these resources brings in
much needed revenue to the country's government and people.
You can't expect people not to want a
higher standard of living and compromises have to be sought,
hopefully as sustainable and as biodiverse as possible.
Is it morally justifiable to expect
people in developing countries to be prevented/discouraged
from exploiting their natural resources to improve their
standard of living in favour our 'developed' view of what
biodiversity should mean?
Its ok for people in well developed
countries to expect poorer countries with vast areas of unspoilt
land to protect the biodiversity, but they want what we have
e.g. restricting deforestation,
restricts the land available for agriculture to feed
indigenous peoples and raise their standard of living AND
they must have alternative source of employment-income other
than timber logging.
(v) Local communities may object to a
conservation schemes because they might potentially interfere
with their traditional way of life.
Coastal fishing communities may object
to limits on fish catches as this reduces their income.
Farmers may object to not being able
to exploit ever square metre of farmland, and not leave
field margins, conserve and manage woodland or replant
hedges. All these things add to biodiversity, but they do
come at a cost to the productivity of a farm, but its where
government grants can help a great deal - money talks!
There few easy decisions and solutions!
TOP OF PAGE
Some learning objectives for this page
Know and understand that rapid growth in the human
population and an increase in the standard of living means that increasingly
more waste is produced and has an increasing impact on our environment, and
on a global scale!
A world population graph shows a dramatic exponential growth of the global population of 'planet
Earth' over the past 2000 years.
In 2013 it is estimated that the
world population is now 7 billion! and rising fast!
Over the past few hundred years,
with increasingly more modern medicine reducing disease and more efficient agriculture (eg
artificial fertilisers increasing food production) have enabled more people
to survive and themselves reproduce!
Therefore there is a greater
demand for the Earth's resources from extracting oil for petrol and plastics
to mining/quarrying mineral/metal ores to extract metals such as iron or
copper and these resources are finite - they will run out eventually - not
sustainable for ever!
The bigger the world's
population, the bigger the environmental impact and the more waste we create
and have to deal with by 'safely dumping' in landfill sites (which may
include toxic materials), recycling selected waste materials or burning to
make useful heat etc.
Know and understand that unless waste is properly handled, more pollution
will be caused.
Know and understand that waste may pollute:
water in rivers, lakes and even
seas and oceans are polluted
with sewage, fertilisers from farms or toxic chemicals from industry,
air pollution from smoke and gases such
as sulfur dioxide from burning fossil fuels, which contributes to acid rain,
land pollution, with
agricultural chemicals (agrichemicals) like toxic
chemicals such as pesticides and herbicides, which may be washed from the
land into waterways.
Know and understand that humans reduce the amount of
land available for other animals and plants by building, quarrying, farming
and dumping waste.
Know and understand that large-scale deforestation in
tropical areas is caused by cutting down forests for timber and to provide land for agriculture,
and this has:
increased the release of carbon dioxide into the atmosphere (because of
burning and the activities of microorganisms on dead wood),
and reduced the rate at which
carbon dioxide is removed from the atmosphere and ‘locked up’ for many years
Deforestation leads to
reduction in biodiversity.
Rain forests are amongst the
most biodiverse habitats on the planet. As the forests recede, reducing
these rich areas of complex ecosystems, so does the number of individual
animals and plants and some species may become extinct if no suitable
habitat is available.
Rain forest plants and animals
are in their unique way a source of useful chemicals and molecules found in
various plants and animals have lead to useful drugs and plastics etc.
Deforestation also decreases
photosynthesising plant life that absorb carbon dioxide from the atmosphere
and photosynthesis is important in the carbon cycle.
Know and understand that deforestation has occurred so
Crops can be grown from which biofuels, based on ethanol, can be
produced from sugar cane or sugar beet, but these crops require large areas
Enables an increase in cattle and in rice fields to provide
Know that these organisms (crops
& cattle) produce methane and this has led to increases in
methane in the atmosphere - a greenhouse gas produced by anaerobic bacterial
decomposition of organic material eg in warm wet rice paddy fields or in the
gut of cattle (prior to expulsion!).
With rising populations and
material aspirations of people there is great pressure to make a quick
profit from timber and then increase food production by developing the
cleared land for agricultural use eg raising cattle for beef and milk,
growing cash crops like sugar cane and palm oil, grain and rice fields
Know and understand that the destruction of peat
bogs and other areas of peat releases carbon dioxide into the atmosphere.
Peat bogs are waterlogged areas
of land containing layers of vegetation growing on decaying organic plant
material, which after thousands of years forms peat.
Therefore peat is a huge store
of carbon in the form of organic material.
Peat is used as a fuel but also
for making garden compost because it is rich in mineral ions needed by
If peat bogs are drained the
peat breaks down releasing carbon dioxide into the atmosphere - increasing
the greenhouse effect.
You should understand why ‘peat free’ composts
are of increasing importance.
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