Biodiversity

Habitat destruction - Deforestation 

• Some sources suggest we are losing an area of rainforest the size of a soccer pitch per minute.
• Forests supply much of the world with oxygen and rain and also remove carbon dioxide.
• Humans have been cutting down trees for 10,000 years.
• Wood was used as a fuel source and for building.
• It was also removed to clear land for agriculture.
• Deforestation has significantly reduced the world’s forests
   

Reasons for loss of forests:

In the last 100 years there has been extensive loss of rainforest due to:

• Logging – clear-cut logging generates short-term revenues quickly but results in almost total destruction of the forest with little chance of regeneration back to rainforest (succession). Logging also exports valuable nutrients away from the forest (in the wood)
• Roads – these are used to access areas for logging. Heavy machinery compacts and exposes soils leading to serious erosion. New roads, such as the Pan American highway, allow access to untouched forest and the development of towns and cities (urbanisation).
• Mining – some forests have rich underlying mineral resources. These are normally mined by clearing and open-cast mining methods, causing permanent loss of habitat. e.g. mining for aluminium ore in West African rainforest.
• Agriculture – In the Amazon, forest is ‘slashed and burnt’ to provide an area for farm settlements and for beef farms. ‘Slash and burn’ tends to produce good crops for a few years followed by crop failure, washing away of topsoil and serious erosion. Cleared land can also be used for crops such as rubber and coffee.
   

Consequences:

• Loss of species (biodiversity)
• Soil erosion
• Climate change due to change in transpiration
• Global warming due to effects on the Carbon cycle.
• Desertification via soil erosion
• Flooding (rainforests hold water like a sponge, letting it out slowly)
   

Solutions:

 See BEEP topic: Enhancing Biodiversity