(1) Introduction to biodiversity - why is it so important? - what are its benefits

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

(a) Reminders of some important definitions

(in alphabetical order, explained in more detail where appropriate)

Carnivore - an animal that only eats other animals, not plants.

Consumer - not plants or algae, all animals that eat plants or other animals.

Decomposer - an organism that breaks down dead plant and animal material,

so nutrients can be recycled back to the soil or water.

Ecosystem - all the living things in a given area and their non-living environmental conditions.

Egestion - the act or process of discharging undigested or waste material from a cell or organism;

e.g. the discharging undigested food as faeces, contributes to wasted mass and energy in a food chain.

Environment - The surrounding air, water, rocks and soil where an organism lives.

Food chain - a linear part of a food web, starting with a producer, ending with a top predator.

Food web - shows how food chains in an ecosystem are linked - shows interdependence.

Herbivore - an animal that only eats plants - e.g. aphids, caterpillars, rabbits, tadpoles.

Interdependence - organisms in food chains and food webs are dependent on each other,

change in one organism population results in changes in other organism populations.

Omnivore - an animal that eats both plants or animals.

Population -  The number of a group of the same species living in an area.

Primary consumer - an animal that eats producers e.g. eats plants or algae.

Producer - plants and algae - initial producers of food from sunlight energy using photosynthesis

Secondary consumer - an animal that eats primary consumers i.e. another animal

Tertiary consumer -  an animal that eats secondary consumers i.e. another animal

Top carnivore - an animal not eaten by any other animal.

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(b) What exactly is 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.

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(c) Why 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.

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(d) The impact of human activity of 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.

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(e) SUMMARY of ideas about biodiversity

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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Key revision points - Summary of ideas

Based on the syllabus-specifications for students taking the AQA, Edexcel and OCR GCSE level biology examinations (~US grades 9-10).

Biodiversity refers to the variety of life on Earth - plants, animals, fungi, and microorganisms - as well as the ecosystems they form.

It includes genetic diversity within species, species diversity in different regions, and the broader ecological diversity across landscapes.

Why is biodiversity important?

Biodiversity is the backbone of a healthy planet. Here’s why it matters:

• Ecosystem Stability – Diverse ecosystems are more resilient to changes, such as climate shifts or natural disasters.

• Food Security – A wide range of crops and livestock ensures sustainable agriculture, helping to prevent food shortages.

• Medicine & Innovation – Many medicines are derived from plants, fungi, and bacteria found in nature.

• Air & Water Quality – Forests and wetlands filter pollutants and provide clean air and water.

• Climate Regulation – Forests absorb carbon dioxide and help mitigate climate change.

• Economic & Cultural Value – Tourism, agriculture, and traditional knowledge all benefit from a rich natural environment.

However, biodiversity is under threat from habitat destruction, pollution, and climate change.

Conserving it is key to sustaining life on Earth.

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Summary of learning objectives and key words or phrases about biodiversity

Be able to describe what is biodiversity and why biodiversity is so important to the health of our plant, in particular the band of rich life we call the biosphere of earth water and air and the benefits of a rich and varied biodiversity.

Know what the following terms mean: Carnivore, Decomposer, Ecosystem, Egestion, Environment, Food chain , Food web, Herbivore, Interdependence , Omnivore, Population, Primary consumer, Producer, Secondary consumer, Tertiary consumer, Top carnivore

• 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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