Cambridge IGCSE Environmental Management: Ecosystems, Biodiversity and Fieldwork — Revision Notes

Topic 5 of Cambridge IGCSE Environmental Management (0680) covers how ecosystems work, why forests matter, how biodiversity is conserved and how fieldwork data is collected. Expect definitions, food-web and pyramid interpretation, the 10% energy rule, and “discuss” questions on conservation strategies and sampling methods. Fieldwork skills are also tested through source material on Paper 2.

For full explanations use the ecosystems study guide; practise with the ecosystems practice questions.

Syllabus coverage (0680, 2027-2029)

Ref	Learning outcomes
5.1.1-5.1.9	Ecosystem components; biotic and abiotic factors; interactions; pollination; photosynthesis; energy flow; pyramids; respiration; carbon cycle
5.2.1-5.2.4	Causes and impacts of deforestation; sustainable forest management and why it is needed
5.3.1-5.3.2	Conservation strategies; benefits and limitations
5.4.1-5.4.5	Scientific method; random and systematic sampling; sampling techniques; benefits and limitations

Key ecosystem terms (5.1.1)

Term	Definition
Habitat	The place where an organism lives
Species	A group of organisms that can breed to produce fertile offspring
Population	All the organisms of one species in an area
Community	All the populations of different species in an area
Niche	The role of a species in its ecosystem
Prey / predator	The organism eaten / the organism that hunts and eats it
Apex predator	A predator at the top of a food chain with no natural predators

Biotic (living): producers, primary, secondary and tertiary consumers, decomposers. Abiotic (non-living): temperature, water, oxygen, carbon dioxide, salinity, light, pH.

Biotic interactions (5.1.3): native vs invasive species; competition (for food, light, space); predation; pollination.

How do pollination, photosynthesis and respiration fit together?

• Pollination: transfer of pollen from an anther to a stigma, by insects or wind; leads to fertilisation, then seed and fruit formation. (Flower structure is not required.)
• Photosynthesis: carbon dioxide + water → glucose + oxygen, using sunlight energy captured by chlorophyll.
• Aerobic respiration: glucose + oxygen → carbon dioxide + water, releasing energy.

Notice that the two word equations are reverses of each other: an easy check in the exam.

How does energy flow through an ecosystem? (5.1.6-5.1.7)

• Only about 10% of energy passes from one trophic level to the next.
• The rest is lost in movement, respiration, digestion and excretion.
• Pyramid of energy: always pyramid-shaped, because energy is lost at each level.
• Pyramid of numbers: can be inverted, for example one tree supporting many caterpillars.

Worked example. Grass fixes 20 000 kJ. Energy reaching each level at 10%: grasshoppers 2 000 kJ → frogs 200 kJ → snakes 20 kJ. The tertiary consumer receives 0.1% of the producer’s energy, which is why food chains rarely have more than four or five levels.

The carbon cycle (5.1.9)

Process	Carbon moves
Photosynthesis	Atmosphere → plants
Respiration	Organisms → atmosphere
Feeding	Plants → animals
Decomposition	Dead matter → atmosphere and soil
Fossil fuel formation	Dead organisms → coal, oil, gas (over millions of years)
Combustion	Fuels and wood → atmosphere

Why are forests cleared, and why does it matter? (5.2)

Causes: logging and timber; subsistence and commercial farming; roads and settlements; rock, ore and mineral extraction; hydro-electric power stations (flooding of valleys); climate change.

Impacts: habitat loss; loss of biodiversity; soil erosion and desertification; silting of rivers and flooding; global warming; changes to rainfall patterns; genetic depletion.

Sustainable management of forests = balancing the needs of the environment, wildlife and humans while conserving forests for future generations. It is needed because forests:

• regulate climate as carbon sinks and stores;
• support the water cycle through interception, water uptake, transpiration and reduced surface run-off;
• control floods and prevent soil erosion;
• are a genetic resource and supply food, medicine and raw materials;
• offer recreation, ecotourism and education.

How can biodiversity be conserved? (5.3)

Strategy	Benefit	Limitation
Sustainable harvesting	Income continues without wiping out the species	Quotas are hard to enforce
Sustainable forestry	Timber with replanting	Replanted forest is less diverse than the original
National parks and reserves	Protect whole habitats	Need funding and guards; may displace local people
Wildlife corridors	Link fragmented habitats so animals can move and breed	Land is costly; corridors can be narrow
Seed banks	Store genetic material for the future	Seeds do not adapt to changing conditions in storage
Zoos and captive breeding	Rebuild numbers of endangered species	Expensive; reintroduction can fail
Ecotourism	Funds conservation and local jobs	Visitors can disturb wildlife
International cooperation against animal trade; regulation of trade	Reduces poaching demand	Illegal trade continues
Threat classification (threatened, endangered, extinct)	Targets effort at the species most at risk	Data for many species is incomplete

How do you plan a reliable fieldwork investigation? (5.4)

Scientific method (5.4.1): aim and hypothesis → plan methods (sampling strategy and technique, questionnaires, surveys, pilot study) → identify independent, dependent and control variables → repeats and replicates → record → analyse → identify and process anomalies → conclude.

Strategy	How	Benefit	Limitation
Random	Coordinates from random numbers	Avoids bias	May miss parts of the area
Systematic	Samples at regular intervals, e.g. every 5 m along a transect	Shows change along a gradient	Can miss patterns between the intervals

Technique	Used for
Pitfall trap	Ground-dwelling invertebrates
Pooter	Small insects, sucked into a container
Sweep net	Insects in long grass
Quadrat	Plants and slow-moving animals (percentage cover or count)
Transect	Change across an area, with quadrats along a line
Aerial photography and drones	Large or inaccessible areas, such as forest cover
Automated sampling	Camera traps or sensors collecting data continuously

Common mistakes and exam traps

• Confusing population (one species) with community (all species).
• Writing that energy is “used up” - it is transferred and lost as heat and in life processes.
• Calling a pyramid of energy inverted; only pyramids of numbers can be.
• Giving “more samples” as the only improvement: say repeats increase reliability and explain why.
• Forgetting that a seed bank conserves genetic resources, not habitats.

Frequently asked questions

What does the 10% rule mean? About 10% of the energy at one trophic level passes to the next. The rest is lost in movement, respiration, digestion and excretion.

What is the difference between random and systematic sampling? Random sampling chooses sample points by chance to avoid bias. Systematic sampling places them at regular intervals, often along a transect.

Which conservation strategies are on the 0680 syllabus? Ten are named, from sustainable harvesting and national parks to seed banks, ecotourism, trade regulation and threat classification.

Official syllabus

Cambridge IGCSE Environmental Management (0680) syllabus for 2027, 2028 and 2029 - official syllabus PDF, Topic 5.