10.5 - Human Impact on Biodiversity

How does human population growth affect biodiversity? (5)

• The increase in human population size has led to biodiversity loss across the planet because:

• We need land for housing and agriculture; involving deforestation

• Urban sprawl; towns and cities keep expanding which isolates populations of wild species- so they can’t breed, which reduces genetic diversity

• Pollution; air, water/soil and light pollution can kill species by damaging their habitats

• Overusing natural resources; increases competition between species, causing some to go extinct.

How does needing land for housing and agriculture reduce biodiversity? (2)

• Involves habitat destruction such as deforestation

• Can destroy entire ecosystems.

How does the increase of urban cities reduce biodiversity? (3)

• Cities expand out into surrounding natural areas

• Isolating populations of wild species by creating barriers between them

• This reduces genetic diversity, which can make them vulnerable to diseases.

How does pollution reduce biodiversity? (1)

• Air, water/soil and light pollution can kill species, damage their natural habitats and disrupt their behaviour.

How does overusing natural resources reduce biodiversity? (2)

• Increased competition between species that rely on these resources

• If one species is more successful at competing than the other, the other may go extinct.

How does farming affect biodiversity? (5)

• Creating farmland; Existing habitats are destroyed and the species that depends on them.

• Farms that grow cops are often monocultures; replacing diverse natural ecosystems

• Herbicides and pesticides can affect wild plants nearby or pollinators

• Fertilisers; can lead to water pollution via runoff from fields into lakes and rivers; so algae at top of water grows excessively- which harms other organisms as it reduces dissolved oxygen levels in water.

• Overgrazing- reduces plant diversity and erodes soil, making it harder for plants to regrow.

How does creating farmland affect biodiversity? (1)

• Existing habitats are destroyed and the species that depends on them.

How do monocultures affect biodiversity? (1)

• By replacing diverse natural ecosystems

What are monocultures? (1)

Farms that only grow 1 type of crop.

How does herbicides and pesticides affect biodiversity? (2)

• They are designed to target specific species

• Can affect other organisms such as wild plants nearby and pollinators.

How do fertilisers affect biodiversity? (3)

• can lead to water pollution via runoff from fields into lakes and rivers

• so algae at top of water grows excessively

• which harms other organisms as it reduces dissolved oxygen levels in water.

How does overgrazing affect biodiversity? (2)

• reduces plant diversity

• erodes soil, making it harder for plants to regrow.

State ways to balance biodiversity and agriculture. (4)

• Maintaining hedgerows and woodland around farms

• Reducing pesticide and herbicide use

• Replacing chemicals with organic alternatives (e.g. chemical fertilisers with manure)

• Crop rotation- improves soil fertility and biodiversity.

Define climate change. (1)

Long-term changes in temperature and rainfall patterns around the world.

How does climate change affect biodiversity? (2)

• Animals must either adapt or migrate to more suitable areas

• If they dont, they face extinction

How does climate change in polar regions reduce biodiversity? (3)

• Melting ice caps lead to habitat loss

• Species depend on ice for hunting, breeding and survival

• So as ice melts, populations decline.

How does climate change in coastal regions reduce biodiversity? (2)

• It causes sea levels to rise

• Leading to flooding and habitat destruction

How does climate change in tropical regions reduce biodiversity? (2)

• Tropical diseases spread to new areas due to warmer weathers

• Species that haven’t evolved alongside diseases don’t have resistance to them