Human Effects on the Environment

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Human Effects on the Environment

As humans occupy every continent, we have changed the environment around us in countless ways. Many changes have been beneficial and many have been adverse, here we discuss deforestation as we can see directly many of the effects widespread deforestation has had on ecosystems.


Deforestation is the rapid destruction of woodland. Although it can occur due to natural catastrophe it is most commonly caused by human intervention.

Deforestation has been occurring since humans have been able to cut down trees, but it has increased greatly over the last century.

The major reasons for deforestation are:

  • Obtaining hardwood (e.g, teak) for furniture.
  • Obtaining softwood for paper and other wood products.
  • Clearing areas for cattle farming.
  • Clearing areas for agriculture.
  • Clearing areas for urbanisation, including road building.

Some effects of deforestation are:

  • Changes in nutrient cycles.
  • Less carbon dioxide is removed from the atmosphere by photosynthesis, leading to a rise in atmospheric carbon dioxide concentration.
  • Less oxygen is released into the atmosphere as less photosynthesis occurs.
  • Fewer trees means less transpiration, which may lead to a less humid atmosphere since less water evaporates from soil than from leaves.

Climatic changes

With a drier atmosphere there are knock on effects to the water cycle resulting in less rainfall.

With fewer trees to protect the soil there is a more rapid heating of the soil. This can lead to thermal gradients occurring resulting in an increase in wind intensity and frequency.

Reduced soil fertility

Removal of trees, particularly deciduous ones, removes the major source of nutrients for the soil. There may be as much as a 90% loss of nutrients through deforestation.

There is likely to be an increase in soil erosion as the bare soil is exposed directly to wind and rain and there are no trees roots to stabilise the soil structure.

Flooding and landslide

Under normal conditions most of the rain falling on woodland is absorbed either through the leaves or the roots. If the trees are removed the water accumulates in the soil, increasing instability and resulting in possible landslips.

As the rain water is not being absorbed, it can run off the area into adjacent rivers and lead to flooding.

Destruction of species

Many species are endemic to forested areas. If large areas of forest are lost they will be unable to move from one area to another, this will result in isolated populations, which may lead to a decrease in genetic diversity. There are many medically useful plants in forest habitats, these will be lost due to deforestation. There are many undiscovered species, particularly plants and insects that may have uses for humans.

Due to deforestation, these possible uses may never be discovered.