School biology notes: BIODIVERSITY - necessity, problems and solutions

Biodiversity, land management, waste-pollution creation and its management, maintaining ecosystems, conservation strategies

 Doc Brown's school biology revision notes: GCSE biology, IGCSE  biology, O level biology,  ~US grades 8, 9 and 10 school science courses or equivalent for ~14-16 year old students of biology

 This page will help you answer questions such as ...  What is biodiversity and why is it so important?   Describe some sources of air, water and land pollution?   How does pollution affect biodiversity?   Why is there a need for conservation projects?

Sub-index for my BIODIVERSITY page 

(a) Introduction to biodiversity, why it is so important, benefits

(b) Biodiversity and the consequences of a rising world population

(c) Biodiversity reduction, the world's population, creation & management of waste and pollution

(d) Biodiversity and what indicator species can tell us (and measuring abiotic factors)

(e) Biodiversity, global warming and climate change

(f) Biodiversity and managing resources, habitat destruction, use/misuse land & water, deforestation, overfishing, land management - including problems of indigenous versus non-indigenous species

(g) Biodiversity and conservation - issues and project strategies to increase biodiversity

See also Ecosystems - biotic & abiotic factors - interactions between organisms - interdependency

and Food chains, food webs, trophic levels, pyramids of biomass, transfer efficiency, pyramids of numbers

(a) Introduction to biodiversity - why is it so important? - benefits of biodiversity

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 area,

(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.

Some natural ecosystems like rainforests and tropical reefs have a high biodiversity, providing a variety of food and shelter for many species all year round.

Other natural ecosystems have a low biodiversity e.g. arctic tundra, deserts or deep-sea volcanic thermal vents, where a relatively few highly adapted species of plants or animals can survive.

All natural ecosystems are self-supporting, meaning all the resources an organism needs survive and reproduce are all present in their habitats.

However, such systems do need the input of energy, usually from sunlight and,

all animals need plants for oxygen and food,

and plants need carbon dioxide, pollination and seed dispersal from animals.

These connections are called interdependence.

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 habitat are controlled by biotic and abiotic factors.

Biodiversity is extremely important for the 'health' of any ecosystem and phrases like 'high biodiversity' or 'low biodiversity' sum up the good or bad state of an ecosystem.

Reminders: The living organisms in an ecosystem can be described as producers, consumers and decomposers.

Producers initiate a food chain e.g. plants producing food from photosynthesis.

Consumers are eating from a previous level in the food chain, up which the biomass is transferred.

Decomposers are live organisms that break down other dead organisms, recycling materials in the ecosystem.

An ecosystem with a high biodiversity has many advantages over a low biodiversity e.g.

a wider variety of food resources, reducing the dependency of a species on limited choices,

for our own needs, we are provided with food supplies, medicines derived from natural products, oxygen in the atmosphere and a water supply.

Biodiversity is reduced by removing too much of a species from an ecosystem e.g. overfishing, overhunting, deforestation, draining swamps or bogland.

Unless conservation-replacement measures are not taken, the population of affected species are not sustainable - possibly to the point of extinction.

Human interactions with ecosystems frequently affect biodiversity - humans have had quite an impact on the environment, hence a big effect, and usually negative, on biodiversity.

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 - all of the following are needed on a short-term or long-term basis, BUT we should manage them in a sustainable way with minimal harmful effect of biodiversity of the ecosystems of our environment.. Like it or not, all of the following are reducing biodiversity

deforestation for faming crops like maize or rice, palm oil, sugar cane for biofuels, grazing cattle - partly due to commercial pressures and a rising world population,

monoculture farming (including deforested land), overuse and reliance on fertilisers (eutrophication is one bad side-effect), food chains affected - pollinating insect populations are in decline, all contributing to lack of biodiversity,

building houses, shops, factories, transport systems - all removing habitats, reducing food, territory and other resources,

dumping waste, as more is created from increasing affluence and developing society - landfill and sewage are sources of pollution,

mining and quarrying for coal and minerals - slate, stone, iron ore, extracting gas and oil - shale oil is especially destructive to the environment,

All of these activities reduce the amount of land for wildlife, impact on ecosystems and reduce biodiversity and we do not have any real competitors or predators and so can dominate how the land is used.

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 ancient woodlands,

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 ....


SUMMARY: What are the overall benefits of biodiversity and conservation programmes?

(i) Ensuring a good food supply (see 'food security') using sustainable methods of agriculture without endangering the biodiversity of the surrounding landscape.

e.g. 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 environment.

We need to improve the quality of soil and rely less on agrichemicals e.g. less use of synthetic inorganic fertilisers, herbicides and pesticides.

(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 biodiversity.

(iii) Conservation programmes provide new jobs for local people and opportunities for ecotourism too.  Ecotourism can be defined as 'environmentally-friendly tourism'.

There is an important cultural aspect to biodiversity and conservation.

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.

People like to visit beautiful unspoilt countryside e.g. ecotourists visiting the great national parks of our planet to enjoy the presence of a wide variety of plants and animals in their natural habitats - and the income provides jobs and funding for further conservation projects.

Despite some people's objections to 'caged' animals in zoos, many operate successful breeding programmes for endangered species and releasing them back into the wild to repopulate their natural habitat.

(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 activities!

(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.

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(b) 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 of life"!

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 biodiversity,

(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 inhabiting.

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 minimum wages.

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(c) Biodiversity, the world's population, creation and management of waste & pollution

Effects on the environment - reduction of biodiversity

People in poorer underdeveloped countries, unsurprisingly, want the same material standard of living as people living in richer more developed countries.

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 decreases.


Reduction of biodiversity - sources 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 energy.

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 more effectively!

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!


Air pollution

(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 (I've measured rainwater pH as low as 3.5). See acid rain project

In this UK (NE England) based project we have monitored acid rain from UK fossil fuel power stations (thankfully much decreased now in 2020), but we have monitored acidic rain carried in air masses from continental Europe - even as far as from Eastern European countries like Poland and the Czech Republic,  which still rely very heavily on coal.

Acid rain has several damaging environmental impacts e.g.

The leaves and roots of plants are damaged by acid rain, inhibiting photosynthesis (making food) and uptake of nutrient ions (deficiency).

Acid rain washes out nutrient mineral ions from the soil, another cause of mineral deficiency in plants.

Acid rain also washes out from soil/rocks harmful ions like aluminium (Al3+), which end up in lakes and rivers. Aluminium affects the gills of fish, results can be fatal.

Most fish and other aquatic organisms are affected if the pH of water falls below 4 and many cannot survive the acidic conditions.

You can operate desulfurisation processes in power stations to reduce sulfur dioxide emissions and use catalytic converters in road vehicles to reduce nitrogen oxides.

For more details on certain aspects of air pollution see ...

Fossil fuel air pollution - incomplete combustion, carbon monoxide & soot particulates

and Fossil fuel air pollution - effects of sulfur oxides and nitrogen oxides gcse chemistry 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.

Many countries have strict anti-pollution laws to minimise polluting air emissions - also regulations to control toxic waste chemicals, use of landfill sites and treatment of sewage.


Water pollution

(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 water kills most other aquatic life requiring oxygen for respiration e.g. fish and crustaceans, so food chains/webs badly affected - far less 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. See also Use of NPK fertilisers and environmental problems

doc b oil notes(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.

Pollution, Accidents 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.

Untreated sewage entering waterways may carry polluting chemicals, parasites and microbial pathogens.

Microorganisms that decompose sewage use dissolved oxygen water in respiration, threatening the life of aquatic organisms.


(iv) Anti-pest agents used in agriculture - agrichemicals (water and land pollution)

The overuse of toxic pesticides, fungicides 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).

Toxic pesticides can be washed of farmland into water courses and these can increase in concentration up a food chain or they can accumulate in soil.

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 most e.g.

Cabbage ==> butterflies lays eggs - resulting caterpillars feed off cabbage ==> butterflies eaten by blue/great tit birds ==> bird of prey eg kestrel, catches smaller birds eg blue/great tits.

In this pyramid of biomass: 1 = cabbage, 2 = caterpillar, 3 = blue tit bird, 4 = bird of prey (raptor).

BUT, up the food chain, herbicides or pesticides can increase in concentration and often affect the top (apex) predator the most.

Before being banned in many countries, the insecticide DDT was being passed up the food chain - it is soluble in fat and reached dangerous levels in birds of prey. It affected the thickness of egg shells, so the eggs were easily broken prematurely and chicks unable to hatch out and survive in a healthy state.


(v) 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.

(vi) Fish farming

Fish can be in large enclosed nets in the open water of a lake or in sheltered bay of sea water. The adult fish can be regularly harvested and replaced with smaller younger fish.

Unfortunately there are environmental issues which reduce biodiversity.

Food is added to the enclosed nets to feed the fish, who then produce large amounts of waste. The waste can leak out causing eutrophication and death of wild species - the waste contains pathogens. Fish farms are breeding grounds for parasites, again these can escape and threaten wild species.

Predators like seals and sea lions are attracted this food resource, but can get trapped in the nets and die.

The farmed fish can escape and compete with indigenous species of fish.

Fish tank farms only contain one species and are therefore low on biodiversity - they are also kept free of any plants or predators, the parasites and microorganisms are usually killed.

Many countries have strict anti-pollution laws to regulate the control of chemical toxic waste, use of landfill sites and treatment of sewage.


Introduction of non-indigenous species

A non-indigenous species is one that does naturally live in a particular habitat.

Non-indigenous species will compete with naturally occurring indigenous species.

If they can out-compete, a non-indigenous species can reduce the population of an indigenous species e.g. in the UK grey squirrels can out-compete the native red squirrels for food and territory.

They be introduced deliberately for food or hunting.

They can also enter a habitat accidently e.g. a plant or animal on the cargo of a ship.

Non-indigenous species can 'accidently' introduce new pathogens, causing disease to spread through indigenous populations.


Change in use of land - how the landscape is changing

There are significant changes going on in the way that we manage land.

Deforestation of many of the world's greatest forests in South America and Asia is happening now and at an alarming rate.  Large areas of forest are being destroyed in favour of removing trees to clear the land to raise cattle and grow crops - often amounting to monoculture - just one principal animal or plant product.

In agriculture intensive farming for one particular crop is replacing more traditional crop rotation methods.

The land of natural habitats is being used for factories, houses, mining and quarrying and motorways etc.

However needed these are, they all considerably decrease biodiversity.


Land pollution

(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 out.

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 carbon cycle.

Recycling things like plastic, metals and garden waste can help reduce the burden of landfill sites.

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.

Pollution, Accidents 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 safely stored.

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

Dangers of radioactive emissions - health and safety issues

Half-life of a radioisotope - how long is it radioactive? implications!

Reminder: Many countries have strict anti-pollution laws to regulate the control of chemical toxic waste, use of landfill sites and treatment of sewage, and of course the processing and storing of nuclear waste.


See also Metal extraction - economics, environmental Issues and recycling gcse chemistry revision notes

and POLYMERS, plastics, poly(ethene), poly(propene), uses - problems and recycling gcse chemistry revision notes


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(d) Biodiversity and what indicator species can tell us (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 human activity.

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 and animals.


Air pollution

Lichen 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!


Water pollution

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 pollution.

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.


Methods of surveying-monitoring pollution - measuring abiotic factors

(This section is repeated in the ecosystems notes)

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 of organisms.

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 meter.

You can analyse for traces of toxic organic chemicals or heavy metal compounds in water.

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 chart.

You can also dip the electronic pH probe into a soil/water mixture - a more accurate measurement.

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 soil.

You can compare the results of measuring abiotic factors with the distribution of selected organisms to look for similarities or differences.

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(e) Biodiversity, global warming and climate change

See also environmental changes and effects on ecosystems

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 incoming infrared radiation is absorbed by the land or water surface of the Earth, BUT, some of this is re-radiated at a longer wavelength of infrared radiation.

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.

When the two are balanced, on average, the Earth maintains a steady average temperature over many years.

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 naturally,

but we have added other greenhouse gases like chlorofluorocarbons (CFCs) and hydrofluorocarbons (includes HCFCs and HFCs), albeit in very tiny concentrations as well as significant extra carbon dioxide in the atmosphere from fossil fuel burning - both quantities are still n the increase!

The steady rise in carbon dioxide concentration means more re-radiated infrared radiation is being absorbed by the Earth's atmosphere.

The result is that the Earth is warming up a bit more than might have been expected and the average temperature is rising.

Gas (that can have an infrared absorbing greenhouse effect) Formula Concentration in 
atmosphere (ppm)
Water vapour and clouds H2O 10–50,000 36–72%  
Carbon dioxide CO2 ~400 9–26%
Methane CH4 ~1.8 4–9%  
Ozone O3 2–8 3–7%  

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 'greenhouse gases'.

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 https://en.wikipedia.org/wiki/Greenhouse_gas

For more on the theory and graphs on global warming see

Absorption and emission of radiation by materials - including global warming gcse physics

and Global warming, climate change, carbon footprint from fossil fuel burning gcse chemistry


The effects of human activity and greenhouse gases

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 warming'.

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 below.

Global warming graph

Rise of CO2 level

Graph 2: The rise in use of fossil fuel use in terms of CO2 emission 1850-2003 Burning fossil fuels


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 animals.

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 poorer countries,

(ii) in other places excessive rainfall and flooding destroying crops and animals and destroying animal habitats.

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 grounds.

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.

See also environmental changes and effects on ecosystems

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(f) Biodiversity and managing resources - habitat destruction

How we use/misuse land and water including deforestation, overfishing and land management

The '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 Earth's resources.

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 particular area.


Deforestation - why? impacts?

Why deforestation?

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 and biodiversity

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 biodiversity.

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 atmosphere.

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.


Peat - 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, usually mosses.

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 farmland.

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 dioxide.

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 drying up.

With temperatures rising in the northern hemisphere, bogs are naturally drying out as well as being drained.

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 atmosphere.

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 prevent wildfires.

From Wikipedia https://en.wikipedia.org/wiki/2010_Russian_wildfires

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 oceans.

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 biodiversity.

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 water'.

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.

Indigenous and non-indigenous species

Definitions - apply to plants or animals

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 species.

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'.

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(g) Biodiversity: conservation - issues and project strategies to increase biodiversity

The objectives

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.

Strategies may involve ...

research and scientific understanding of the issues,

long-term funding for research conservation projects,

international agreement to conserve areas of endangered plants and animals and their habitat,

national protection legislation and policing of protected areas and the plants and animals in their habitats.

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 hunting.

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, like forests, 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 to exploit!

The case of peat bogs is of increasing concern to environmentalists.

In marshy areas, it takes thousands of years to create peat bogs form and they store large amounts of carbon (another part of our planet's carbon sink). The low oxygen level and acidic marshy conditions prevent decomposer microorganisms from completely breaking down the plant material.

Peat is harvested as a fuel and a cheap compost for gardeners - it does improve soil quality making it more organic and increasing food production (at least on a small scale).

But peatlands have their own unique biodiversity, AND a second negative aspect of draining bog lands is the removal of peat from a carbon sink - carbon compounds get oxidised to carbon dioxide e.g. from burning or microorganism respiration.

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 is important.

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 progress!

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 other.

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 overfishing.


(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 areas e.g.

Reintroducing hedgerows that give shelter and food for birds and a habitat lots of other organisms too.

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:

(i) The 'carbon footprint is less growing grain and vegetables.

(ii) You can produce more food for a similar cost by growing crops.

(iii) A vegetarian based diet is considered healthier by many experts.

BUT, at the moment, and rightly so, in the 'supermarket', its your choice of lifestyle!


(iv) We should all try to reduce our 'waste footprint'.

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 and deforestation.

Unless small populations of endangered species are not boosted in some, extinction is always a possibility.

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 animals.

Many large 'game' animals have in some cases been hunted to extinction and others on an 'endangered species' list e.g. some species of lions (trophy kills) or rhinos (poached for valuable ivory of horns).

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:

Cloning plant species can be done quickly and economically using stem cells found in the meristems - this ensures a good stock and avoiding extinction!

See section on plants in Cloning - tissue culture of plants

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 interests:

(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.

See also Food security - population growth and sustainability issues


(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 animals.

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 environment.

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 important priorities.

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 results.

(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 got.

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!

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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.

      • Recycling reduces polluting waste, and uses less energy than if you were e.g. producing a metal from its naturally occurring ore.

  • 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 as wood.

  • 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 that:

    • 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 of land.

    • Enables an increase in cattle and in rice fields to provide more food.

    • 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 plants.

    • 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.

      • If the demand for peat compost is reduced, less bogs will be drained and less carbon released.

  • Know and understand that biofuels can be made from natural products by fermentation, but on a large scale, at the cost of biodiversity?

    • Know that biogas, mainly methane, can be produced by anaerobic fermentation of a wide range of plant products or waste material containing carbohydrates.

    • Ethanol (C2H5OH), sometimes called bioethanol, can be made by fermenting sugar solution with yeast (a microorganism with right enzyme to effect the change).

      • sugar eg glucose ===> ethanol + carbon dioxide

      • The sugar comes from sugar beet or sugar cane.

      • The alcohol is fractionally distilled from the fermented mixture.

      • In Brazil, ethanol from sugar cane, is blended with petrol and the fuel mixture for cars is called 'gasohol'.

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