This mini-lesson covers Eduqas Theme 3 — Environmental Challenges: how humans use, modify and damage ecosystems, using the tropical rainforest and hot semi-arid grasslands as examples, the causes and consequences of desertification, and how ecosystems and drylands can be sustainably managed.
Work through each screen, answer the questions as you go (multiple-choice, short-answer and games) and collect ⭐ stars. Press Start when you're ready.
3.2.1 Using ecosystems
How humans use & modify ecosystems
An ecosystem is a community of plants and animals interacting with each other and their physical environment. People change ecosystems to obtain the resources they need:
Food — clearing land for farming crops and grazing livestock, and fishing.
Energy — collecting fuelwood, growing biofuels, and building dams for hydroelectric power.
Water — extracting groundwater and river water for irrigation, industry and homes.
Key idea: using an ecosystem is not automatically harmful — the problem comes when use becomes unsustainable, taking resources faster than the ecosystem can recover, so it becomes damaged.
3.2.2 Ecosystems under threat
Two ecosystems damaged by people
Eduqas expects you to know two real examples where human activity degrades an ecosystem:
Tropical rainforest — cleared (deforested) for logging, cattle ranching, soya and palm-oil plantations, mining and new roads.
Hot semi-arid grassland / savanna — degraded by over-grazing, over-cultivation and cutting trees for fuelwood, which strips the soil.
Quick check
Why is the rainforest cleared?
?Which of these is a genuine, well-documented reason the tropical rainforest is being deforested?
Rainforest under threat
Why rainforest loss matters
The tropical rainforest is the most biodiverse ecosystem on Earth, so deforestation has effects at both a local and a global scale:
Locally, clearing destroys habitats so species are lost, and heavy rain quickly washes away the thin forest soil. Globally, burning and removing trees releases stored carbon dioxide, adding to climate change.
Key idea: rainforests are described as the "lungs of the planet" because they store carbon and release oxygen — so their loss is both a local biodiversity problem and a global climate problem.
Drylands under threat
How grasslands are degraded
In hot semi-arid grasslands the vegetation is sparse and the soil is fragile. Several human activities strip it away:
Over-grazing — too many cattle, goats or sheep eat the grass faster than it can regrow, leaving bare soil.
Over-cultivation — growing crops on the same land year after year exhausts the soil's nutrients.
Deforestation for fuelwood — cutting trees and shrubs for firewood removes the roots that bind the soil together.
The result — soil degradation: with no plant cover, the topsoil is blown away by wind or washed off by rare heavy rain (erosion). The land loses its fertility, and biodiversity falls both locally and, as productive land is lost worldwide, globally.
3.2.3 Sustainable management
Managing the rainforest sustainably
We conserve ecosystems because of their biodiversity, the resources and medicines they provide, and their role in regulating climate. Several strategies let people use the rainforest without destroying it:
Selective logging — only certain mature trees are felled, so the forest can recover.
Agro-forestry — growing crops among the trees, keeping tree cover in place.
Ecotourism — small-scale, low-impact tourism that gives local people an income for protecting the forest.
Protected areas & national parks, plus debt-for-nature swaps (debt cancelled in return for conservation) and community forestry.
International agreements such as REDD+ (rewarding countries for keeping forests) and CITES (controlling trade in endangered species).
Sustainable means meeting today's needs without stopping future generations from meeting theirs — using the forest so it is still there for the future.
Match it
Match the strategy to what it does
Tap a sustainable-management strategy on the left, then tap what it does on the right.
Quick check
Which strategy?
?A forestry company fells only a small number of carefully chosen mature trees and leaves the rest of the forest standing so it can recover. What is this called?
3.4 Desertification
What is desertification?
Desertification is the process by which fertile, productive land turns into desert-like land. It happens on the fringes of hot deserts — for example the Sahel, the semi-arid belt south of the Sahara:
Desertification spreads outward from the desert edge, so the semi-arid Sahel is squeezed and productive land is lost along the desert fringe.
Key idea: desertification is caused by a combination of physical (climate) factors and human actions working together — not by one cause alone.
Explain it
Your turn — effects of deforestation
✎Explain how deforestation of the tropical rainforest damages the environment at both a local and a global scale. Use the words biodiversity, soil and carbon dioxide.
Model answer
Locally, clearing trees destroys habitats so biodiversity falls, as many plant and animal species lose their home.
With no tree roots to hold it, the thin forest soil is quickly washed away by heavy rain, so the land loses its fertility.
Globally, burning and removing the trees releases stored carbon dioxide into the atmosphere, which adds to climate change.
Physical causes
Desertification: physical causes
The climate of hot semi-arid regions makes them naturally vulnerable. These physical causes are outside human control:
Under a belt of high pressure the air sinks and dries, so rainfall is low and unreliable. The hot sun drives high evapotranspiration, and periodic droughts dry the land further.
Watch out: physical causes (unreliable rainfall, high evapotranspiration, drought, sinking air under high pressure) are natural. The human causes on the next screens then push the land over the edge.
Sort it
Physical or human cause?
Tap whether each cause of desertification is a physical (natural) cause or a human cause.
Human causes
Desertification: human causes
A rising population needs more food, fuel and water from fragile land. This pressure produces the human causes of desertification:
Over-grazing, over-cultivation, cutting trees for fuelwood and over-use of water — driven by population pressure — all remove the plant cover, leaving the soil bare and easily eroded.
Consequences: crops fail and animals die, so food and water become scarce, people can fall into poverty, and some are forced to migrate — while the bare, degraded land spreads.
Explain it
Your turn — causes of desertification
✎Explain how human activity can cause desertification in a hot semi-arid region like the Sahel. Use the words over-grazing, fuelwood and soil.
Model answer
A growing population keeps too many animals, so over-grazing eats the grass faster than it can regrow and leaves bare ground.
Cutting trees and shrubs for fuelwood removes the roots that hold the ground together.
With no plant cover, the exposed soil is blown or washed away, so the land loses its fertility and turns to desert.
Managing drylands (local)
Local dryland management
At a local level, NGOs and communities use simple, low-cost, appropriate technology to hold water and soil in place so land can recover:
Lines of stones ("magic stones" / bunds) laid along the contour trap rainwater and soil so seeds can grow. Drip irrigation delivers water straight to plant roots, wasting almost none.
Also used: planting drought-tolerant crops (like millet and sorghum) and agroforestry (growing trees among crops) so roots bind the soil and give shade.
Quick check
Local management
?In the Sahel, farmers lay lines of stones ("magic stones") along the contours of gently sloping fields. How does this reduce desertification?
Sort it
Sustainable or unsustainable?
Tap a practice, then tap the box it belongs in.
♻️ Sustainable
⚠️ Unsustainable
Managing drylands (international)
The Great Green Wall
Desertification crosses borders, so it is also tackled at an international scale. The best-known scheme in the Sahel is the Great Green Wall:
Countries across the Sahel are planting a belt of trees and shrubs along the desert's southern edge. Their roots hold the soil, give shade and shelter, and help hold back the advancing desert.
Why international? Because the desert and drought ignore national borders, countries and organisations must work together — sharing funding, science and drought-tolerant tree species.
Quick check
International management
?The Great Green Wall is an international project across the Sahel. What is it, and why does it help against desertification?
Quick check
Local & global effects
?Rainforest deforestation is said to have effects at a global scale, not just locally. Which statement best explains the global effect?
Recap
The key ideas to know
Using ecosystems: humans change ecosystems for food, energy and water; harm comes when use is unsustainable.
Rainforest damage: deforestation for logging, ranching, soya, palm oil, mining & roads → local loss of biodiversity & soil, and global CO₂ release.
Dryland damage: over-grazing, over-cultivation & fuelwood cutting strip the soil in hot semi-arid grasslands.
Desertification: productive land turning to desert on the fringes of hot deserts (e.g. the Sahel).
Physical causes: unreliable rainfall, high evapotranspiration, drought, sinking dry air under high pressure.
Human causes: over-grazing, over-cultivation, fuelwood collection, over-use of water, population pressure.
Dryland management: local NGO methods (drip irrigation, "magic stones"/bunds, drought-tolerant crops, agroforestry) & international schemes (the Great Green Wall).
You've covered Eduqas Theme 3 — Environmental Challenges. Press Finish to see your score.
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