Evaluate biodiversity conservation
Explain biome, succession and biodiversity pressures, then evaluate conservation strategies for forests, Antarctica and named ecosystems.
Section 4.3 · Impacts of human activity on ecosystems
Exam scope and assessment notes
Original StudyForA teaching and practice, not Cambridge-authored questions, mark schemes or official grades. Cambridge expects candidates to study all eight topics, carry out investigative work and learn teacher-selected case studies. This course does not replace a centre's named case-study examples, current local environmental data, supervised fieldwork or the candidate's own investigation. Practice datasets are illustrative, not observations from a real place. No official assessment or certification is provided. The examples and practice datasets in these lessons are fictional and formative; learners must add their centre's verified case studies and current local evidence.
Before you begin
- Cambridge recommends prior environmental/science study equivalent to IGCSE or O Level. This is an AS-only qualification; use the exam-year syllabus and confirm centre entry details.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What makes environmental evidence useful?
What you will learn
- Describe biomes, succession and ecosystem productivity
- Explain human pressures and conservation strategies
- Evaluate ecological, social and economic evidence for a named ecosystem
Ecosystems vary and change
The syllabus focuses on desert, forest, grassland and tundra biomes. Compare their climate, soil type and vegetation. Primary and secondary succession move from different starting conditions through pioneer and intermediate stages toward a climax community; soil, timescale and starting point affect the sequence.
Competition, grazing and predation interact with abiotic conditions. A general stage model does not mean every ecosystem follows an identical timetable. Ecosystem productivity is the rate of biomass production; connect this idea to GPP and NPP in the energy lesson.
Biodiversity has ecological and human value
A native species occurs naturally in a place; an invasive species spreads and causes harm there. Invasive species can compete with, prey on or alter habitats used by native species, changing abundance and diversity.
Conserving biodiversity can protect potential medicines, food, wood, fibres, oils, fuels, genetic diversity, ecological services, and cultural or recreational value. Evaluation should include people and ecosystem outcomes, not only species counts.
Compare conservation methods
The syllabus includes legislation and protocols, regulation of sustainable harvesting, CITES, the International Whaling Commission, the EU Common Fisheries Policy, the International Tropical Timber Organisation and the IUCN Red List; detailed treaty knowledge is not required. The EDGE programme prioritises Evolutionarily Distinct and Globally Endangered species.
Captive breeding and release may support a threatened population but depends on genetic diversity, suitable habitat, survival after release and continued threat reduction. Habitat conservation and creation include rewilding, extracted reserves, protected areas, conservation zones and national parks; assess enforcement, connectivity, costs and local participation.
Sources for this lesson
Pause and explain
What evidence is needed to evaluate a protected area?
Worked example
A protected area reduces logging but limits a community's customary resource access. Outline a balanced evaluation.
Show the worked solution
- State the conservation objective.
- Assess habitat outcomes and enforcement.
- Include community rights, livelihoods and alternative management.
Answer Protection may reduce habitat loss, but effectiveness depends on enforcement and whether extraction shifts elsewhere. Include local access and livelihoods, community participation, alternatives and ecological indicators over time; designation alone does not prove conservation success.
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.
An introduced predator spreads on an island and native bird numbers fall. Explain a possible biodiversity impact and a follow-up measure.
Give me a hint
Trace a mechanism, then measure the affected population and habitat.
Compare my reasoning
- Identify the relevant data, place or process in the prompt.
- Apply describe biomes, succession and ecosystem productivity to the stated context.
- Explain the inference and one limitation or trade-off.
The introduced predator may prey on native birds or their eggs, lowering breeding success and changing food-web relationships. Repeat comparable nest or population surveys and record predator abundance; check other pressures before attributing the entire decline to one cause.
Look for these in your work
- Describe biomes, succession and ecosystem productivity
- Uses relevant evidence and explains the environmental mechanism
- Distinguishes observation, inference and limitation
A conservation plan combines an EDGE priority species, captive breeding and habitat protection. Explain the role and one limitation of each.
Give me a hint
Separate prioritisation, population support and ecosystem management.
Compare my reasoning
- Identify the relevant data, place or process in the prompt.
- Apply explain human pressures and conservation strategies to the stated context.
- Explain the inference and one limitation or trade-off.
EDGE highlights species with high evolutionary distinctiveness and global endangerment so limited attention can be prioritised. Captive breeding may raise numbers but release can fail if habitat or the original threat remains. Habitat protection addresses conditions for multiple species but needs enforcement and local support.
Look for these in your work
- Explain human pressures and conservation strategies
- Uses relevant evidence and explains the environmental mechanism
- Distinguishes observation, inference and limitation
Compare a wildlife-trade rule with habitat restoration as biodiversity strategies.
Give me a hint
Compare the pressure each addresses and the evidence of success.
Compare my reasoning
- Identify the relevant data, place or process in the prompt.
- Apply evaluate ecological, social and economic evidence for a named ecosystem to the stated context.
- Explain the inference and one limitation or trade-off.
A trade rule such as CITES controls international trade in listed species, but effectiveness depends on implementation and enforcement. Habitat restoration can improve habitat area or connectivity, but takes time and may not remove hunting or pollution. Assess population trends, habitat condition, compliance and affected communities.
Look for these in your work
- Evaluate ecological, social and economic evidence for a named ecosystem
- Uses relevant evidence and explains the environmental mechanism
- Distinguishes observation, inference and limitation
Common mistakes
- Treating protected-area status as proof biodiversity is secure
- Describing succession as a fixed schedule for every ecosystem
- Ignoring local communities in conservation decisions
What can you explain now?
What evidence is needed to evaluate a protected area?
Compare with the explanation
Ecological outcomes, management and effects on affected communities
A policy designation is not the same as a measured outcome.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Why is the area of a protected zone not enough to prove successful conservation?
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.