Human Activity & Rainforests (AQA A Level Geography)
Revision Note
Written by: Jacque Cartwright
Reviewed by: Bridgette Barrett
Human Impacts on a Tropical Rainforest
Human activity within tropical rainforests (TRF) is widespread, with both global and local impacts
Deforestation is the main threat to TRFs, and involves conversion of forest land to farms, ranches, or urban use
Deforestation also results from mining and HEP projects
Impacts of deforestation can be group as economic, social and environmental
Causes and Impacts of TRF Deforestation
Cause | Details & Impact | Example |
|---|---|---|
Mining of minerals - gold, copper etc. | Large-scale deforestation which strips the soil and exposed to erosion Opencast mining is the cheapest but most environmentally damaging Water is clogged with silt, leading to downstream flooding | Carajas in northern Brazil |
Agricultural uses | Slash and burn to create pasture for cattle ranching, soil is exposed to erosion and increased leaching Commercial farming Single cash crops such as soy | Brazils cattle ranching is extensive Clearing forestry for soy farms in Borneo, have destroyed so much of the orangutans habitat that they are now on the REDD extremely endangered list |
Selective logging | Valuable hardwoods are chopped down, but as they fall, they damage surrounding trees and habitats Destructive clear-felling exposes the ground to erosion and decimates habitats and species | HDE demands for furniture and building materials, encourages felling in TRFs as a reliable source of income Japan accounts for 11million m³ of TRF hardwood a year |
Road construction | Highways connect areas within the forest which supports further TRF development Allows for ease of access for people and raw materials Large strips of land is cleared across the rainforest which destroys habitats | Trans Amazonian Highway extends over 6000 km into the Amazon forest |
Electricity | Construction of large dams for hydroelectric power to provide cheap energy Reservoirs for dams flood large areas of cleared forest Displacement of people, animals and destruction of habitats Poor construction of dams leads to failures and devastating flooding | HEP Tucurui Dam supplies power to the Carajas mine |
Settlement growth | Population pressures comes from natural growth and inward migration Brazil has an issue with landless people that need homes and relocation | Internal migration from the poorest parts of Brazil is encouraged and land allows individuals to grow food and wood is used for fuel, which reduces overcrowding in other parts of the country |
Global impacts
Burning releases CO2 into the atmosphere
Forests in the Congo and the Amazon are some of the world's largest carbon stores
Forest store up to 100 times more carbon than fields
75% of Brazil's carbon emissions come from deforestation
More than 1.5 billion tones of CO2 are released due to deforestation
Economic, environmental and social impacts
Economic | Environmental | Social |
|---|---|---|
Brazilian government gains much needed income | Loss of habitat and biodiversity. Without tree canopy to intercept rainfall or roots to bind soil, more nutrients are washed away and increases the risk of flooding and mass movement | Dilution of culture due to increased contact with TNCs |
TNCs are the main winners on export of goods from the forest | Increases CO2 levels globally leading to increased global warming | Loss of home and increased spread of diseases |
Local people can get some employment and have benefitted from education | HEP dams destroy large hectares of forest and displace local tribes and destroy habitats due to flooding. | Improved education and access to major towns and cities. Improved general health care |
Reduction in available resources over time | Evapotranspiration is reduced, this reduces water vapour and eventually rainfall is reduced - edges of Amazon rainforest are becoming savanna like | Conflict between stakeholders over use of land |
Development Issues in a Tropical Rainforest
Changes in population size, agricultural practices and economic activity cause further negative impacts on rainforests
Table Showing How Development Increases Threats to TRFs
Economic Development | Population Change | Agricultural Practices |
|---|---|---|
Economic development of the rainforest poses a threat to biodiversity and long-term sustainability of the TRF biome as a whole Commercial activities that cause deforestation (e.g. mining, agriculture, forestry) have brought significant economic development to countries with tropical rainforests This has allowed investment in infrastructure, e.g. construction of new roads, opening up previously inaccessible areas of forest which leads to further deforestation Economic development increases the populations wealth and access to resources. This drives an increase in consumption (e.g. food, energy) which further increases deforestation | Although the number of indigenous populations are decreasing, the overall populations in tropical rainforests are growing. In Manaus, Brazil, the population in the rainforest grew from a hundred thousand in 1950 to over 2 million by 2015 The greater the population the more resources are needed and the more space for settlements. This increases the pressure on forest clearance to accommodate the rise in demand There are has been an increase in small-scale subsistence farming, and land that has become unproductive or people with no land, are opening up more areas of forest | Consumption of meat is increasing, necessitating more land for cattle grazing. 80% of deforested land in Brazil is used for cattle ranching ‘Slash and burn’ farming can be sustainable, if the forest is given enough time to recover before being reused However, deforestation and population pressure has limited the amount of land available to indigenous farmers. Land is therefore, farmed again before soil fertility is restored, risking large areas of degraded land Cash crops, such as palm oil and soy, tend to be grown as monocultures (single crops) and these take up large areas of land which cause habitat fragmentation which essentially cuts off habitat populations and restricts movement |
Rainforest governance
Management takes place at a range of scales:
Local schemes within countries:
Ecotourism gives economic value to the forests and wildlife
Education - people receive environmental and biodiversity education. Subsistence farmers receive training and certification in sustainable agriculture
International schemes:
E.g. the Tropical Forest Alliance 2020 that aims to reduce deforestation around the world
Debt-for-nature swapping to reduce overall money owed to other countries. Countries agree to sell only timber that has come from sustainably managed legal forests. Consumers buy from certified sources
However, some schemes do have drawbacks:
Sustainable forestry supports fewer local jobs than conventional forestry
Conservation can bring conflict to areas where people are used to harvesting from the forest
Ecotourism can be too expensive for some people
Some agreements are hard to put into practice
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