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.

The future of the human species on Earth relies on us maintaining a good level of biodiversity. Many human activities are reducing biodiversity and only recently have measures been taken to try to stop this reduction.

Waste management

Rapid growth in the human population and an increase in the standard of living mean that increasingly more resources are used and more waste is produced. Unless waste and chemical materials are properly handled, more pollution will be caused.

Pollution can occur:
- in water, from sewage, fertiliser or toxic chemicals
- in air, from smoke and acidic gases
- on land, from landfill and from toxic chemicals.

Pollution kills plants and animals which can reduce biodiversity.

Land use

Humans reduce the amount of land available for other animals and plants by building, quarrying, farming and dumping waste.

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The destruction of peat bogs, and other areas of peat to produce garden compost, reduces the area of this habitat and thus the variety of different plant, animal and microorganism species that live there (biodiversity).

The decay or burning of the peat releases carbon dioxide into the atmosphere.

Deforestation

Large-scale deforestation in tropical areas has occurred to:
- provide land for cattle and rice fields
- grow crops for biofuels.

Global warming

Students should be able to describe some of the biological consequences of global warming.

Levels of carbon dioxide and methane in the atmosphere are increasing, and contribute to ‘global warming’.

Maintaining biodiversity

Students should be able to describe both positive and negative human interactions in an ecosystem and explain their impact on biodiversity.

Scientists and concerned citizens have put in place programmes to reduce the negative effects of humans on ecosystems and biodiversity.

These include:
- breeding programmes for endangered species
- protection and regeneration of rare habitats
- reintroduction of field margins and hedgerows in agricultural areas where farmers grow only one type of crop
- reduction of deforestation and carbon dioxide emissions by some governments
- recycling resources rather than dumping waste in landfill.