Causes & Impacts of Deforestation (AQA GCSE Geography)

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

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

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 

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

Case Study: Malaysia

• Malaysia is located in Southeast Asia

• Almost 70% of the land is covered by tropical rainforest

Deforestation in Malaysia

• It is estimated that Malaysia has the fastest rate of deforestation in the world

• Since 2000 an average of over 140,000 hectares of forest has been felled and cleared each year

Causes

• Logging

  • Malaysia is the largest exporter of tropical hardwoods

  • Although Malaysia has environmental protection policies there is still evidence of illegal logging in areas of Borneo

  • Selective logging is the dominant type of logging but this requires road construction and settlements which result in deforestation

• Energy

  • The construction of dams to provide Hydroelectric power results in the flooding of large areas of forest

  • The Bakun Dam will result in 700 km² of land being underwater in Sarawak, Malaysia

• Mining 

  • Tin mines are widespread and require deforestation for the mine itself but also for road construction 

  • An iron ore mine planned for the Som Forest Reserve will result in the deforestation of over 60 hectares

  • There is also drilling for oil and gas

• Commercial plantations

  • Malaysia exports over 30% of the world's palm oil and is the second largest producer

  • Many palm oil processes now adopting a zero-deforestation policy so that they do not buy palm oil from deforested areas. However, Clear felling permits are sometimes used in Malaysia to clear land and then sometime later another company will plant palm oil

• Settlements 

  • Up to 1980 people were encouraged to move to rural areas from the cities to try and reduce the pressure on urban areas

    • This led to the deforestation of approximately 15,000 hectares of rainforest

• Subsistence farming

  • This can sometimes involve slash and burn where areas are cleared using fires - these can sometimes get out of control and destroy large areas of rainforest

Effects of deforestation

• Soil erosion 

  • Without the tree roots to bind the soil, the soil is more easily eroded by wind and rain

  • Exposed soil is more vulnerable to the leaching of nutrients and the soil becomes less fertile

• Loss of biodiversity

  • Habitats are destroyed and the ecosystem is affected by deforestation so the variety of plants and animals decreases

  • Oil Palm plantations lead to a 35% reduction in species

  • Orangutans, pygmy elephants, Sumatran Rhino and Malayan tigers are all endangered

• Local climate change

  • Reduced transpiration and evaporation lead to a decrease in precipitation and an increase in temperatures

  • Rainfall patterns become less reliable and more extreme

• Global climate change

  • Felling of the trees leads to a decrease in the absorption of carbon dioxide 

  • Increases carbon dioxide concentrations in the atmosphere and as this is a greenhouse gas this increases human induced climate change

  • Use of fire for clearance also increases carbon dioxide emissions

•  Indigenous communities

  • Indigenous communities such as the Orang Asli and Temiar have been forced off the land 

  • Pollination of fruits has reduced due to a decrease in pollinating insects and animals such as bats

    • This has reduced the available food sources

  • In Kuala Koh village in 2019 at least 15 indigenous Batek died after an outbreak of disease possibly transmitted by loggers working near the village