The Importance of Biodiversity (Cambridge (CIE) IGCSE Biology)

Human Pressures on Other Species

Biodiversity

• Is defined as the number of different species that live in a particular area

• Human activities have tended to force biodiversity downwards, whereas, high biodiversity is needed for stable ecosystems

• Habitat destruction by humans is a major downward pressure on biodiversity

Reasons for Habitat Destruction

• The increasing human population of the planet is causing destruction of many habitats from rainforest to woodland to marine

• Many habitats are destroyed by humans to make space for other economic activities, or by pollution from these activities, and this reduces the biodiversity of these areas

• This interrupts food chains and webs, meaning that more species may die because their prey is gone

• The main reasons for habitat destruction include:

Deforestation

• Deforestation is the clearing of trees (usually on a large scale)

• If trees are replaced by replanting it can be a sustainable practise

• Generally the trees are being cleared for the land to be used in a different way (for building, grazing for cattle, planting of monocultures such as palm oil plantations etc) and therefore it is not sustainable

• As the amount of the Earth’s surface covered by trees decreases, it causes increasingly negative effects on the environment and is a particularly severe example of habitat destruction

• Undesirable effects of deforestation include:

  • Extinction of species

  • Loss of soil

  • Flooding

  • Increase of carbon dioxide in the atmosphere