The human impact on ecosystems: the causes and effects of deforestation in the tropical rainforest, the wider human pressures on ecosystems, and the strategies for the sustainable management of a biome.

What this dot point is asking

This is part of Eduqas GCSE Geography A (C111) Theme 5, Weather, Climate and Ecosystems, a core theme in Component 2. Eduqas expects you to explain the causes and effects of deforestation in the tropical rainforest, the wider human pressures on ecosystems, and the strategies for the sustainable management of a biome.

The causes of deforestation

Tropical rainforests are being cleared rapidly, for several reasons.

• Commercial farming: the biggest cause, clearing huge areas for cattle ranching and plantations (soya, palm oil).
• Logging: felling trees for valuable hardwoods and for paper, often with damaging access roads.
• Mining and oil: clearing forest to reach minerals (iron ore, gold) and oil.
• Road building: roads cut into the forest open it up for further clearance.
• Hydroelectric dams: reservoirs flood large areas of forest.
• Subsistence farming: local farmers clear small plots by slash-and-burn.

The effects of deforestation

Clearing the forest has serious effects.

• Lost biodiversity: the rainforest holds more species than any other biome, and clearance destroys habitats, driving extinctions.
• Soil erosion: without trees to protect and bind it, the thin soil is washed away by heavy rain, and the cleared land soon loses fertility.
• Disrupted cycles: removing trees breaks the water cycle (less evapotranspiration and rainfall) and the nutrient cycle.
• Climate change: trees store carbon; burning and clearing them releases carbon dioxide and removes a vital carbon sink, worsening global warming.
• Impacts on people: indigenous peoples lose their homeland, though clearance brings short-term jobs, money and resources to others.

Wider human pressures on ecosystems

Beyond rainforests, humans pressure all ecosystems.

• Pollution of air, water and land harms wildlife.
• Overfishing and overhunting deplete species.
• Climate change shifts habitats faster than species can adapt.
• Urbanisation and farming destroy and fragment habitats.

Sustainable management of a biome

Sustainable management means using a biome so it survives for the future. For the rainforest, the main strategies are:

• Selective logging and replanting: take only some mature trees and let the forest recover, or replant what is felled.
• Agroforestry: grow crops among the trees, keeping the forest cover.
• Ecotourism: earn money from tourists who come to see the standing forest, giving local people a reason to protect it.
• Protected areas: national parks and reserves where clearance is banned.
• International agreements: schemes such as REDD (Reducing Emissions from Deforestation) pay countries to keep forests standing, and debt-for-nature swaps cancel debt in return for conservation.

The key idea, which Eduqas rewards, is that management works only if the forest is worth more standing than cleared to the people who live there.

Try this

Q1. Explain one effect of deforestation on the soil. [4 marks]

• Cue. Without trees to protect and bind it, the thin soil is washed away by heavy rain and quickly loses its fertility.

Q2. Explain how ecotourism can help manage a rainforest sustainably. [4 marks]

• Cue. Tourists pay to see the standing forest, earning money and jobs for local people, so the forest is worth more protected than cleared.