Changing ecosystems
Compare Antarctic and tropical-rainforest ecosystems, explain adaptations and evaluate human pressures and sustainable management.
Section 3 · Changing ecosystems
Exam scope and assessment notes
Cambridge IGCSE Geography 0460, 2027–2029 syllabus, Topic 3. The syllabus does not prescribe one universal set of named detailed specific examples: centres select places suited to their learners. Sixteen optional StudyForA evidence packs now cover all sixteen example objectives, but the centre's choices are unconfirmed. Match each pack to your centre's chosen place and replace any mismatch before treating the course as complete. Original StudyForA explanations and self-check practice are not Cambridge papers, official grades or teacher-marked coursework. Map, graph and written answers are not automatically assessed. Paper 4 practice uses supplied or invented data and cannot certify safe fieldwork, equipment use or real data collection. Centre-set coursework and specialist teacher review remain pending.
Before you begin
- No previous Geography course is assumed. Use the supplied map, data or scenario; distinguish observation from explanation and support conclusions with evidence.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which is abiotic: a soil nutrient or a bird?
What you will learn
- Locate and describe Antarctica and tropical rainforests
- Explain climate, abiotic/biotic links and adaptations
- Assess threats, impacts and management strategies
- Use a named tropical-rainforest example selected for the exam course
Ecosystems link living and non-living factors
Abiotic factors include temperature, precipitation, soil, light and water; biotic factors include plants, animals and decomposers. Producers capture energy, consumers transfer it through food chains and decomposers recycle nutrients. Changes to one factor can affect others, although the size and direction depend on the ecosystem.
Antarctica lies around the South Pole and is shaped by high latitude, low solar angle, cold temperatures, high pressure and low precipitation. In the tropical rainforest, equatorial latitude and overhead sun support high temperatures and convectional rainfall through much of the year.
Adaptations match local conditions
In Antarctica, organisms cope with cold, seasonal light and limited liquid water; insulation, migration, seasonal breeding or life near the ocean can help particular species survive. Rainforest vegetation is layered, with competition for light; broad leaves, drip tips, climbing plants and shallow or buttress roots are adaptations to specific conditions. Name the pressure and explain how the feature helps; avoid treating every species as identical.
Threats and management involve competing needs
Antarctic pressures can include climate change, fishing, tourism and resource exploitation; damage may affect food webs and slow-recovering environments. Rainforest threats include logging, farming, mining, roads, settlement and hydroelectric development. Impacts can include habitat fragmentation, biodiversity loss, carbon release, soil changes and livelihood effects.
Management may use protected areas, international agreements, sustainable harvesting, restoration, environmental-impact assessment and community-led alternatives. Evaluate enforcement, funding, local rights, economic needs and long-term ecosystem effects. Use a named country or rainforest example selected for the learner's exam course.
Pause and explain
Why should a rainforest protection plan consider local livelihoods?
Worked example
A forest road is built to reach a mine. Explain two ways this may affect a tropical-rainforest ecosystem beyond the cleared road surface.
Show the worked solution
- The road can fragment habitat and make movement between patches harder.
- It may open access for logging, settlement or additional land conversion.
- Runoff and edge effects can alter nearby soil, streams and microclimate.
Answer The road may fragment habitat directly and enable further clearing or settlement nearby. Runoff and edge effects may also change neighbouring conditions; the scale depends on route and control measures.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
In a rainforest, annual rainfall remains high but a newly cleared slope has more surface runoff. Explain the likely link to soil erosion.
Give me a hint
Consider canopy interception, roots, infiltration and overland flow.
Compare my reasoning
- Clearing reduces canopy interception and can remove roots that bind soil.
- More rain may reach the surface quickly; compacted or exposed ground can reduce infiltration.
- Faster runoff can detach and carry more soil downslope.
With less canopy and root cover, runoff can increase and soil is less protected, so erosion may intensify. The effect depends on soil, slope and how the land is cleared.
Look for these in your work
- Vegetation role identified
- Water transfer explained
- Soil movement linked
An Antarctic management proposal limits tourism but supports monitored visits. Evaluate one ecological benefit and one social or economic trade-off.
Give me a hint
Identify a possible pressure from visits and consider local or international benefits.
Compare my reasoning
- Limits may reduce disturbance, waste or pressure on sensitive sites.
- Tourism can also support education and economic activity for operators and gateway communities.
- Assess visitor numbers, rules, monitoring and enforcement before judging the balance.
Carefully controlled visits may reduce disturbance while retaining educational and economic benefits. The outcome depends on monitoring, enforcement and site sensitivity; a blanket claim that all visits are harmless or harmful is too strong.
Look for these in your work
- Environmental impact explained
- Trade-off included
- Decision conditions stated
Build a short evidence plan for a named tropical-rainforest area: identify one threat, one impact, one management strategy and the evidence you would use to judge success.
Give me a hint
Use the syllabus-selected country or area and make the evidence measurable and place-specific.
Compare my reasoning
- Name the country or forest area and the threat, such as road expansion or logging.
- Connect it to a local impact, such as habitat fragmentation or livelihood change.
- Choose evidence such as forest-cover change, habitat indicators, enforcement records and community outcomes.
A defensible plan names a place, links a specific pressure to a local environmental and/or social effect, and judges management with evidence over time. Add the case facts selected by your centre; this page does not supply a complete named case pack.
Look for these in your work
- Place named
- Threat-impact link
- Measurable management evidence
Common mistakes
- Describing climate without connecting it to ecosystem structure
- Listing adaptations without stating the survival pressure
- Assuming one management strategy solves every threat
- Ignoring local livelihoods and rights when evaluating protection
What can you explain now?
How can removal of rainforest vegetation affect soil and nearby rivers?
Compare with the explanation
Less canopy and root cover can increase runoff and soil erosion, carrying sediment into rivers
The explanation links vegetation removal to water and soil transfers.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
How do climate and soil influence ecosystem adaptations, and what two sides should sustainable management consider?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.