Deforestation (AQA GCSE Biology): Revision Notes
Deforestation
What is deforestation?
Deforestation means cutting down forests permanently to use the land for something else. Once the trees are gone, they don't get replanted. This has been happening in the UK and Europe for many years. Today, it's mainly happening in tropical areas like rainforests.
The key difference between deforestation and normal tree cutting is that deforestation is permanent - the forest is completely removed and converted to other uses, rather than being replanted or allowed to regrow naturally.
Why does deforestation happen?
There are two main reasons why people cut down forests:
Land for farming
- Growing food crops - like rice to feed people
- Grazing land - grass areas where cattle can feed
- Growing crops for fuel - like plants used to make ethanol for cars
Getting timber
- Trees are cut down to get wood for building houses and making furniture
Problems caused by deforestation
Cutting down forests causes serious environmental problems that affect our entire planet:
Critical Environmental Impact
Deforestation contributes significantly to climate change through multiple pathways, making it one of the most pressing environmental issues of our time.
Carbon dioxide problems
- Burning trees releases carbon dioxide into the air - this adds to global warming
- Microorganisms become more active when they break down chopped wood - this also releases more carbon dioxide
- Fewer trees means less carbon dioxide removed from the air - trees normally absorb carbon dioxide as they grow
Loss of biodiversity
When forests are destroyed, many different species lose their homes. This reduces biodiversity in that area, disrupting entire ecosystems that took thousands of years to develop.
What is peat?
Peat is made from plant material that has only partly rotted away. You find peat in special wet areas called peat bogs.
Peat forms over thousands of years in waterlogged conditions where plant material decomposes very slowly due to lack of oxygen. These unique environments create important carbon storage systems.
Uses of peat
- Fuel - some places burn peat for energy
- Garden compost - gardeners use peat to improve soil
Problems with destroying peat bogs
Peat and Climate Change
Peat bogs store enormous amounts of carbon - when they're destroyed, this carbon is released as CO₂, contributing significantly to global warming. Protecting peat bogs is crucial for climate stability.
- Peat releases carbon dioxide when it's dug up or burned
- This adds to global warming
- Destroying peat bogs reduces biodiversity in those areas
Biodiversity and why it matters
Biodiversity means having lots of different species living in one place or on Earth.
Why biodiversity is important
The Interconnected Web of Life
Every species in an ecosystem plays a specific role, and these roles are interconnected. When we lose species, we weaken these connections and make the entire system less stable and resilient.
- Provides food and shelter for different species
- Keeps ecosystems stable - different species depend on each other
- Helps maintain the environment - each species has a role to play
High biodiversity means the ecosystem works better. If we lose too many species, the whole system can break down.
Human impact on biodiversity
Human activities are reducing biodiversity around the world. Our future depends on keeping biodiversity levels high.
Real example - Palm oil and rainforests
Research Study: Rainforest vs Palm Oil Plantations
Scientists studied what happened when tropical rainforest was cleared to plant palm oil trees:
Before (Original rainforest):
- Had 11 different groups of ground-living insects and small creatures
- Complex, diverse ecosystem with multiple food chains
After (Palm oil plantations):
- Only had 4-5 different groups
- Simplified ecosystem with reduced complexity
Impact: This shows how replacing diverse forests with single crop types dramatically reduces biodiversity by more than half. Fewer insect groups affects other animals like birds and mammals that depend on them for food, creating a cascade effect throughout the ecosystem.
Remember!
Key Points to Remember:
- Deforestation permanently destroys forests for farming and timber
- Two main problems: releases carbon dioxide and destroys biodiversity
- Burning and cutting trees increases carbon dioxide in the atmosphere
- Fewer trees means less carbon dioxide gets removed from the air
- Biodiversity loss makes ecosystems less stable and threatens our future
- Peat destruction also contributes to global warming and biodiversity loss