Maintaining biodiversity (AQA GCSE Biology Combined Science): Revision Notes
Maintaining biodiversity
Many human activities are reducing biodiversity around the world. However, scientists and other people are now taking steps to stop this loss and protect our natural world.
Why we need to take positive action
There are four main reasons why we should work to maintain biodiversity:
1. Moral and ethical reasons
Humans have a responsibility to respect and protect other living things. We should not cause other species to become extinct.
2. Aesthetic reasons
People enjoy seeing the variety of different species in their natural habitats. This makes our world more beautiful and interesting.
3. Ecosystem structure
All organisms in an ecosystem depend on each other (they are interdependent). For example:
- Decay microorganisms break down dead material in the carbon cycle
- If we lose important species, the whole ecosystem can be damaged
The concept of interdependence means that removing even one species from an ecosystem can have unexpected consequences throughout the entire food web. This is why protecting biodiversity is so crucial for ecosystem stability.
4. Value to humans
Some species are particularly useful to humans:
- Plants may provide new medicines
- Wildlife tourism brings money to local communities
- Many species have economic value
Conservation programmes
Scientists have created programmes to reduce or reverse the decline in biodiversity. These include:
- Protecting and regenerating rare habitats - like wetlands where endangered species live
- Replanting hedgerows in farms - to provide wildlife corridors
- Recycling resources - instead of dumping waste in landfill sites, which reduces activities like quarrying
- Reducing deforestation - to protect forest ecosystems
These conservation methods work best when used together as part of a comprehensive approach. For example, protecting habitats while also reducing deforestation creates larger, connected areas where wildlife can thrive.
Replanting forests
Reforestation means planting new trees to replace forests that have been cut down. This has several advantages:
- Restores habitat for endangered species
- Reduces soil erosion because tree roots bind the soil together
- Helps reduce carbon dioxide in the atmosphere as trees use it for photosynthesis
Worked Example: Reforestation Project
The Atlantic Forest restoration project in Brazil demonstrates successful reforestation:
Step 1: Scientists identified degraded areas near existing forest fragments Step 2: Native tree species were planted in these areas Step 3: Wildlife corridors were created to connect forest patches
Results: Over 700 species of birds and mammals have returned to restored areas, and soil erosion has decreased by 60%.
Protecting endangered species
Extinction happens when no living individuals of a species remain. An endangered species faces a high risk of extinction in the near future.
To help endangered species survive, scientists use breeding programmes. Animals or plants are bred over several generations. Reproduction is carefully planned to:
- Increase population numbers
- Avoid inbreeding (breeding between closely related individuals)
Inbreeding can lead to genetic problems and reduced survival rates in offspring. This is why breeding programmes carefully track family relationships and genetic diversity to ensure healthy populations.
Large carnivores (meat-eating animals) are often used to monitor biodiversity. If there are many large carnivores in an area, it suggests there are many other species there too, because carnivores need lots of prey animals to survive.
Large carnivores are called "indicator species" because their presence indicates a healthy, biodiverse ecosystem. Examples include tigers, wolves, and large eagles - their survival depends on a complete food web beneath them.
Key Points to Remember:
- Human activities reduce biodiversity, but conservation programmes can help protect it
- We need to maintain biodiversity for moral, aesthetic, ecosystem and economic reasons
- Key conservation methods include protecting habitats, replanting forests, recycling and reducing deforestation
- Breeding programmes help endangered species recover their population numbers
- Large carnivores can indicate how biodiverse an area is