Biodiversity and the effect of human interaction on ecosystems — AQA GCSE Combined Science: Trilogy

Revision notes

6 short notes, in the order of the specification. Each one in short:

1. Biodiversity

   Biodiversity is the variety of all the different species of organisms on Earth, or within an ecosystem. A great biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for food, shelter and the maintenance of the physical environment. Many human activities are reducing biodiversity, and the future of humans relies on maintaining it.

2. Waste management

   Waste management is the proper handling of waste and chemical materials so that they cause less pollution. Rapid human population growth and a higher standard of living mean more resources are used and more waste is produced. Pollution in water, in air and on land kills plants and animals, so the number of species falls and biodiversity is reduced.

3. Land use

   Humans reduce the amount of land available for other animals and plants by building, quarrying, farming and dumping waste. Destroying peat bogs to produce garden compost reduces the area of this habitat, so it reduces biodiversity. The decay or burning of the peat also releases carbon dioxide into the atmosphere, which contributes to global warming.

4. Deforestation

   Deforestation is the large-scale clearing of forests, which in tropical areas has occurred to provide land for cattle and rice fields and to grow crops for biofuels. It reduces biodiversity because habitats are destroyed. It also increases carbon dioxide in the atmosphere, because fewer trees means less photosynthesis, and the decay and burning of the trees release carbon dioxide.

5. Global warming

   Global warming is caused in part by increasing levels of carbon dioxide and methane in the atmosphere. Its biological consequences include loss of habitats as ice melts and sea levels rise, changes in the distribution of species, and changes in the migration patterns of animals. Species that cannot adapt or move may die out, which reduces biodiversity.

6. Maintaining biodiversity

   Maintaining biodiversity means reducing the negative effects of humans on ecosystems. Programmes include breeding programmes for endangered species, protection and regeneration of rare habitats, reintroducing field margins and hedgerows where farmers grow only one crop, reducing deforestation and carbon dioxide emissions, and recycling instead of landfill. There are conflicting pressures, such as the need for land, food and jobs.