18.7 Maintaining Biodiversity

A free GCSE Biology lesson for AQA (8461) from OBA School: programmes that protect species and habitats, and the conflicting pressures involved. Watch the video, read the explanation and worked examples, then try the revision questions. You can work through the full lesson, with every video, practice quizzes and printable worksheets with mark schemes, in our free online course.

What you will learn

• Describe programmes that reduce the negative effects of humans on biodiversity
• Explain how each programme helps to protect or increase biodiversity
• Analyse data on the effect of conservation measures
• Evaluate the conflicting pressures on maintaining biodiversity

Key words

• Endangered species: A species with so few individuals left that it is at risk of becoming extinct.
• Breeding programme: Breeding endangered animals in captivity (e.g. in zoos) so their numbers increase, often to release them back into the wild.
• Monoculture: Growing one type of crop over a large area.
• Hedgerow: A line of shrubs and trees planted along the edge of a field.
• Field margin: A strip of land around a field left uncultivated, often sown with wild grasses and flowers.
• Conservation: Protecting species and habitats so that biodiversity is maintained.

Ways to protect biodiversity

Scientists, conservation groups and concerned citizens have set up programmes to reduce the harm humans do to ecosystems and biodiversity.

• Breeding programmes for endangered species; How it helps biodiversity Numbers increase in captivity; animals can be released into protected habitats; keeps genetic variation in the species.
• Protection and regeneration of rare habitats; How it helps biodiversity Rare habitats (e.g. coral reefs, heathland, mangroves, peat bogs) are protected by law or restored, so the species that depend on them survive.
• Reintroducing field margins and hedgerows; How it helps biodiversity In areas with one crop (monoculture) these give food, shelter and nesting sites to many species, and act as corridors linking habitats.
• Reducing deforestation and CO₂ emissions; How it helps biodiversity Some governments limit forest clearing and burning of fossil fuels. This protects forest habitats and slows global warming.
• Recycling resources; How it helps biodiversity Less waste goes to landfill, so less land is used and fewer raw materials are dug up.

Hedgerows and field margins

Many hedgerows were removed so farmers could use large machines and grow more crop. Putting them back, with strips of wild flowers, gives insects pollen and nectar, birds food and nesting places, and small mammals shelter. Predators of crop pests, such as ladybirds, also live there.

Worked example: how much difference does a margin make?

No margin: 5 bumblebees. Wildflower margin: 32 bumblebees.
Increase = 32 − 5 = 27. Percentage increase = 27 ÷ 5 × 100 = 540%
Or: 32 ÷ 5 = 6.4 times as many bumblebees.

Answer: 540% increase (6.4 times as many)

Conflicting pressures

Protecting biodiversity often costs money or conflicts with other needs. Decisions involve balancing these pressures.

• Food; Example of conflict Farmers need high yields to make a living and feed people. Hedgerows and margins take land away from crops.
• Money; Example of conflict Breeding programmes, habitat protection and monitoring are expensive.
• Jobs and development; Example of conflict Logging, mining and building bring jobs and income, but destroy habitats.
• Housing and land use; Example of conflict A growing population needs homes and roads, which take land from wildlife.
• Changing habits; Example of conflict People must choose to recycle, buy peat-free compost or use less energy.

Exam tip: In an “evaluate” question give points for and against (biodiversity benefits and economic or social costs), then finish with a justified conclusion.

Common mistakes

• Saying breeding programmes “save the species” on their own. Animals released into the wild also need a protected habitat to survive.
• Describing hedgerows as just “nice to look at”. Explain that they provide food, shelter and nesting sites, and link habitats.
• Forgetting the costs. Exam questions often ask about conflicting pressures such as food production, money and jobs.
• Giving “stop pollution” as a method. Be specific: e.g. recycling to reduce landfill, or cutting CO₂ emissions.

Revision questions

Try these, then check your answers below each one.

Question 1. Which action helps biodiversity on farmland where only one crop is grown? (Choose from: Replanting hedgerows and wildflower field margins, Removing hedgerows to make fields bigger, Spraying more herbicide on field edges, Draining nearby ponds.)

Answer: Replanting hedgerows and wildflower field margins

Working: Hedgerows and margins give food, shelter and nesting sites and link habitats.

Question 2. True or false? Animals bred in captivity can be released into a protected habitat to increase the wild population.

Answer: True

Working: True. They need a protected habitat with the right food and conditions to survive.

Question 3. Plots with no field margin had 8 insect species. Plots with a wildflower margin had 30. Calculate the percentage increase.

Answer: 275 %

Working: 30 − 8 = 22. 22 ÷ 8 × 100 = 275%.

Related lessons

• Previous lesson: 18.6 The Impact of Change
• Next lesson: 18.8 Trophic Levels and Biomass
• In this chapter: 18.1 The Human Population Explosion
• In this chapter: 18.2 Land and Water Pollution
• In this chapter: 18.3 Air Pollution

Continue in the full course

This lesson is section 18.7 (AGCBH1807) of our free GCSE Biology course for AQA. In the full course you get every video for this section, a self-marking practice quiz, a printable worksheet with a mark scheme, chapter tests, and your progress saved. Go to the full GCSE Biology course.