Conservation and BiodiversityAQA GCSE Biology: Revision notes
Section 1
What Is Biodiversity and Why Does It Matter?
Biodiversity is the variety of all the different species of organisms on Earth, or within an ecosystem.
A high level of biodiversity is important because it:
- Ensures the stability of ecosystems by reducing how dependent one species is on any other single species for food, shelter or other resources
- Provides genetic resources that may be useful in medicine, agriculture and industry
- Makes ecosystems more resilient to environmental change
Many human activities are reducing biodiversity across the planet, which is why conservation measures are needed to try to stop this reduction.
If asked to explain why biodiversity matters, always link it to ecosystem stability, not just 'more species is nice'.
Section 2
How Do Human Activities Reduce Biodiversity?
Human activities reduce biodiversity in several ways.
Pollution can occur in:
| Type | Source examples |
|---|---|
| Water | Sewage, fertiliser, toxic chemicals |
| Air | Smoke, acidic gases |
| Land | Landfill, toxic chemicals |
Land use — humans reduce the amount of land available for other animals and plants by:
- Building
- Quarrying
- Farming
- Dumping waste
The destruction of peat bogs (e.g. for compost or fuel) releases stored carbon dioxide into the atmosphere and reduces biodiversity, because peat bogs are unique wetland habitats.
Don't just say peat bog destruction 'destroys a habitat' — it also releases the carbon dioxide stored in the peat, contributing to global warming.
Section 3
What Are the Effects of Deforestation and Global Warming?
Large-scale deforestation in tropical areas has occurred to:
- Provide land for cattle and rice fields
- Grow crops for biofuels
Biological consequences of deforestation include:
- Loss of habitats, reducing biodiversity
- Less carbon dioxide absorbed by trees, and carbon dioxide released when vegetation is burned, contributing to global warming
Global warming is caused by rising levels of carbon dioxide and methane in the atmosphere (greenhouse gases). Biological consequences of global warming include:
- Changes to the distribution of species, as habitats become unsuitable
- Melting ice caps and rising sea levels, flooding low-lying habitats
- Changes to migration patterns and breeding seasons
Clearing rainforest for cattle grazing both destroys habitat directly and releases stored carbon when trees are burned.
Section 4
How Can We Reduce Human Impact on Ecosystems?
Several programmes exist to reduce the negative effects of human activity on biodiversity:
- Breeding programmes for endangered species
- Protection and regeneration of rare habitats
- Reintroduction of field margins and hedgerows in agricultural areas, giving wildlife space to live and move between habitats
- Reducing deforestation and carbon dioxide emissions
- Recycling resources rather than dumping them in landfill
These measures aim to maintain biodiversity and keep ecosystems stable.
When asked to 'describe programmes', name the specific measure (e.g. hedgerow reintroduction) rather than a vague statement like 'protect nature'.
Must Know
- Biodiversity is the variety of species on Earth or in an ecosystem; higher biodiversity means more stable ecosystems
- Pollution reduces biodiversity via water (sewage/fertiliser/chemicals), air (smoke/acidic gases) and land (landfill/toxic chemicals)
- Building, quarrying, farming and waste dumping all reduce land available for wildlife; peat bog destruction also releases CO2
- Deforestation for cattle, rice and biofuels destroys habitats and contributes to global warming
- Rising carbon dioxide and methane cause global warming, which changes species distribution and habitats
- Conservation methods include breeding programmes, habitat protection/regeneration, hedgerows/field margins, reduced deforestation/emissions and recycling
That's the notes covered.
Carry on to the next subtopic.