Causes & Impacts of Deforestation
- There are six main human causes of deforestation
- Wildfires are a natural cause of deforestation:
- The frequency and severity of wildfires have increased this is linked to human induced climate change
Human causes of deforestation
Exam Tip
It is important to remember that deforestation is often the result of a combination of factors which are linked together rather than any one cause. For example, the growth of settlements also leads to more land being cleared for agriculture to support the people in the settlements.
Impacts of deforestation
- Many of the impacts of deforestation are environmental including:
- Areas that have been deforested are planted with monoculture which reduces biodiversity
- Interception and infiltration decrease which reduces evapotranspiration and as a result precipitation decreases
- This also increases overland flow which leads to soil erosion and sedimentation of the rivers
- Sediment builds up on riverbeds reducing their capacity and increasing the flood risk
- Lack of interception increases the leaching of nutrients
- Fewer trees increase the amount of CO2 in the atmosphere adding to the enhanced greenhouse effect
- Soils become less fertile and drier
- They may turn reddish brown due to increased iron oxide
Environmental impacts of deforestation
Impact on the nutrient cycle
- The majority of nutrients in the tropical rainforest are held in the biomass
- When trees and vegetation are cleared by deforestation the main store of nutrients is removed
Effect of deforestation on the nutrient cycle
Social impacts of deforestation
- Indigenous communities have less land to sustain their traditional way of life this means:
-
- Land does not get the opportunity to recover
- Less food available
- Improved quality of life for some people due to increased income and jobs
- Indigenous communities may give up their way of life leading to a loss of culture and traditions
- Increased risk of landslides which can destroy homes and block roads
- Loss of potential medicines
- Increased risk of flooding settlements
Economic impacts of deforestation
- More jobs available in mining, forestry, agriculture and HEP
- Increased income for the country through the export of goods from the forest - minerals, timber, crops
- Almost a quarter of Brazil's GDP comes from activities in the deforested areas of the Amazon
Worked example
Give one effect of deforestation on the soils of the rainforest.
[1 mark]
Answer:
- They become less fertile [1]
- They become drier as they more exposed to the wind [1]
- They are eroded/washed away (as tree roots no longer hold the soil in place) [1]
- They lose their nutrients/ heavy rain leads to leaching [1]
- They turn red/may have a reddish colour due to the presence of iron oxide [1]