Conservation and maintaining biodiversity

What you'll learn

This revision guide covers conservation and biodiversity maintenance as tested in AQA GCSE Biology. You'll understand why biodiversity matters, explore threats to ecosystems and species, and examine practical conservation strategies including breeding programmes, habitat protection, and sustainable management. These concepts link directly to human impacts on ecosystems and are frequently examined through data analysis and case study questions.

Key terms and definitions

Biodiversity — the variety of different species of organisms in an ecosystem; higher biodiversity indicates healthier, more stable ecosystems

Conservation — the protection and management of species and ecosystems to prevent extinction and maintain biodiversity

Extinct — a species that no longer has any living individuals anywhere on Earth

Endangered — a species at serious risk of extinction due to very low population numbers

Captive breeding programme — breeding animals in controlled environments (zoos, reserves) to increase population numbers before potential reintroduction to the wild

Habitat — the natural environment where an organism lives, providing food, shelter and suitable conditions for survival

Sustainable development — development that meets current needs without compromising the ability of future generations to meet their own needs

Ecotourism — tourism directed toward natural environments that supports conservation efforts and provides income for local communities

Core concepts

Why biodiversity matters

Biodiversity provides essential benefits to both ecosystems and humans. Ecosystems with high biodiversity are more stable because:

• Many species contribute to nutrient cycling and energy flow through food webs
• If one species declines, others can fulfill similar ecological roles
• Greater genetic variation within species allows adaptation to environmental changes
• Complex interactions between species create resilient ecosystems

Human dependence on biodiversity includes:

• Food sources: crops, livestock, fish and wild species provide nutrition and genetic material for breeding programmes
• Medicine: many drugs originate from plants, animals and microorganisms (e.g., aspirin from willow bark, antibiotics from fungi)
• Raw materials: timber, fibres, oils and other natural products support industries
• Ecosystem services: pollination, water purification, climate regulation and soil formation
• Cultural and aesthetic value: recreation, tourism and spiritual significance

Threats to biodiversity

Human activities pose significant threats to biodiversity worldwide. Understanding these threats is essential for developing effective conservation strategies.

Habitat destruction represents the most serious threat:

• Deforestation for agriculture, urban development and timber removes species' homes
• Draining wetlands eliminates specialised habitats supporting unique species
• Coastal development destroys mangroves and coral reef ecosystems
• Fragmentation divides populations, reducing genetic diversity and mating opportunities

Pollution damages ecosystems through:

• Pesticides and herbicides reducing insect populations and contaminating food chains
• Plastic waste causing entanglement, ingestion and habitat degradation (particularly marine environments)
• Air pollution (sulfur dioxide, nitrogen oxides) causing acid rain that damages forests and aquatic ecosystems
• Water pollution from sewage, agricultural runoff and industrial chemicals creating toxic conditions

Climate change affects species distribution and survival:

• Rising temperatures force species to migrate to cooler regions or face extinction
• Changing precipitation patterns alter habitats and food availability
• Ocean acidification threatens coral reefs and shellfish
• Extreme weather events increase mortality rates

Overharvesting depletes populations:

• Overfishing reduces fish stocks below sustainable levels
• Poaching threatens species like elephants, rhinos and tigers
• Collection of wild plants reduces genetic diversity
• Unsustainable logging removes ancient forests

Introduction of non-native species disrupts ecosystems:

• Invasive species outcompete native organisms for resources
• Introduced predators threaten species that evolved without such threats (e.g., rats on island bird populations)
• New diseases can devastate populations lacking immunity
• Hybridisation with native species reduces genetic distinctiveness

Conservation methods: protecting habitats

Habitat conservation prevents biodiversity loss by maintaining functioning ecosystems. Key strategies include:

Protected areas and nature reserves:

• Designating areas where human activity is restricted or managed
• National parks, marine reserves and wildlife sanctuaries provide refuge for species
• Buffer zones around sensitive habitats reduce external impacts
• UK examples: New Forest National Park, Snowdonia, North Yorkshire Moors

Habitat restoration:

• Replanting native vegetation in degraded areas
• Removing invasive species to allow native species recovery
• Restoring natural water flow in drained wetlands
• Creating wildlife corridors connecting fragmented habitats to allow species movement

Legal protection:

• International agreements like CITES (Convention on International Trade in Endangered Species) regulate trade
• National legislation protects specific habitats and species
• Enforcement of fishing quotas and hunting restrictions prevents overharvesting
• Environmental impact assessments required before major developments

Sustainable land management:

• Controlled grazing prevents overgrazing while maintaining grassland habitats
• Coppicing woodlands provides timber while preserving forest ecosystems
• Traditional farming methods (hedgerows, crop rotation) support biodiversity
• Agroforestry combines agriculture with tree conservation

Conservation methods: protecting species

Species-specific conservation targets organisms at risk of extinction through focused interventions.

Captive breeding programmes:

• Zoos and conservation centres breed endangered species in controlled conditions
• Genetic management prevents inbreeding and maintains diversity
• Reintroduction programmes return captive-bred individuals to suitable wild habitats
• Example: Arabian oryx recovered from near-extinction through captive breeding and reintroduction

Successful captive breeding requires:

• Sufficient breeding pairs to maintain genetic diversity
• Expertise in species biology, nutrition and veterinary care
• Suitable habitat available for eventual reintroduction
• Control of original threats in the wild

Seed banks:

• Storing seeds from rare and endangered plant species at low temperatures
• Millennium Seed Bank (Kew Gardens, UK) preserves seeds from thousands of species
• Seeds remain viable for decades or centuries, protecting genetic diversity
• Seeds can regenerate species or restore populations if extinction occurs in wild

Monitoring and research:

• Population surveys track species numbers and distribution
• Radio tagging and satellite tracking study movement patterns and habitat use
• Research identifies threats and tests conservation interventions
• Citizen science programmes engage public in data collection

Legislation and enforcement:

• Trade bans protect species from exploitation (e.g., ivory trade prohibition)
• Protected species lists make harming or collecting illegal
• Wildlife crime units investigate poaching and trafficking
• Penalties deter illegal activities

Sustainable resource management

Sustainable development balances human needs with environmental protection, ensuring resources remain available for future generations.

Sustainable fishing:

• Fishing quotas limit catch sizes to sustainable levels
• Minimum net mesh sizes allow young fish to escape and mature
• Closed seasons during breeding periods protect reproduction
• Marine protected areas serve as breeding grounds
• Sustainable fishery certifications inform consumer choices

Sustainable forestry:

• Selective logging removes only certain trees, maintaining forest structure
• Replanting ensures forest regeneration
• Long rotation periods allow forest maturity before harvesting
• Certification schemes (FSC - Forest Stewardship Council) verify sustainable practices

Ecotourism generates income while supporting conservation:

• Entry fees fund habitat protection and anti-poaching efforts
• Local employment provides alternatives to unsustainable practices
• Education programmes raise awareness about conservation
• Carefully managed to prevent habitat damage from excessive visitors
• Caribbean examples: turtle watching in Tobago, rainforest tours in Dominica

Reducing consumption and waste:

• Recycling reduces demand for virgin materials
• Reducing plastic use decreases pollution
• Energy efficiency lowers carbon emissions
• Sustainable agriculture minimises environmental impact

Conflicting pressures

Conservation efforts often face conflicts between environmental protection and human development needs.

Economic vs environmental concerns:

• Logging provides jobs but destroys habitats
• Mining generates wealth but pollutes ecosystems
• Agricultural expansion feeds growing populations but reduces wilderness
• Development projects improve living standards but fragment habitats

Balancing local and global interests:

• Local communities may depend on resources that conservation restricts
• Compensation schemes and alternative livelihoods help gain local support
• International funding supports conservation in developing nations
• Community-based conservation involves local people in decision-making

Long-term vs short-term benefits:

• Conservation provides long-term ecosystem services
• Short-term economic gains often outweigh distant future benefits in decision-making
• Education about ecosystem value encourages sustainable choices
• Government policies can prioritise long-term sustainability

Worked examples

Example 1: Evaluating conservation strategies

Question: The Javan rhino is critically endangered with fewer than 80 individuals remaining. Evaluate the use of captive breeding versus habitat protection for conserving this species. [6 marks]

Mark scheme answer:

Captive breeding advantages:

• Protects individuals from poaching and habitat loss threats [1 mark]
• Allows controlled breeding to maintain genetic diversity [1 mark]
• However, very low population numbers mean limited genetic variation, risking inbreeding [1 mark]

Habitat protection advantages:

• Preserves natural behaviours and ecosystem interactions [1 mark]
• Protects entire ecosystems benefiting multiple species [1 mark]
• More cost-effective than maintaining captive populations [1 mark]

Conclusion should acknowledge that both approaches are needed: habitat protection is essential for long-term survival, while captive breeding might be necessary if wild populations continue declining.

Example 2: Interpreting biodiversity data

Question: Scientists surveyed two woodland areas. Woodland A contained 15 different bird species with similar population sizes. Woodland B contained 15 different bird species, but one species comprised 70% of all birds observed. Which woodland has higher biodiversity? Explain your answer. [3 marks]

Mark scheme answer:

• Woodland A has higher biodiversity [1 mark]
• Both have the same number of species (species richness) [1 mark]
• But Woodland A has more even distribution of individuals across species, whereas Woodland B is dominated by one species, meaning lower overall biodiversity [1 mark]

Example 3: Sustainable fishing practices

Question: Describe how fishing quotas and minimum net mesh sizes help maintain fish populations. [4 marks]

Mark scheme answer:

Fishing quotas:

• Limit the total number/mass of fish caught [1 mark]
• Prevents overfishing, allowing populations to maintain sustainable numbers [1 mark]

Minimum net mesh sizes:

• Allow smaller/younger fish to escape through nets [1 mark]
• Ensures fish can mature and breed before being caught, maintaining reproductive population [1 mark]

Common mistakes and how to avoid them

• Confusing biodiversity with population size: Biodiversity refers to variety of species, not just numbers. A forest with 1000 individuals from 50 species has higher biodiversity than one with 10,000 individuals from 5 species.

• Thinking conservation only means "leaving nature alone": Many conservation strategies involve active management (controlled breeding, habitat restoration, invasive species removal). Explain specific actions, not vague statements.

• Claiming captive breeding always works: Address limitations — requires suitable habitat for reintroduction, sufficient genetic diversity, control of original threats, and expertise. Mention these when evaluating effectiveness.

• Overlooking economic/social factors: Exam questions often ask you to consider conflicting interests. Acknowledge that local communities may depend on resources, and conservation must balance human needs with environmental protection.

• Using non-specific examples: When asked for examples, give precise ones (e.g., "Millennium Seed Bank at Kew Gardens" rather than "some seed banks exist"). AQA rewards specific knowledge.

• Not reading data carefully: Questions involving graphs or tables require precise interpretation. Check axes, units and scale. State what the data shows before explaining why.

Exam technique for "Conservation and maintaining biodiversity"

• Command words matter: "Describe" requires stating what happens without explanation (2-3 marks). "Explain" needs reasons/causes (3-4 marks). "Evaluate" requires weighing up advantages and disadvantages with a conclusion (5-6 marks).

• Use data when provided: If a question includes a graph, table or case study, reference specific figures in your answer. Marks are allocated for interpreting data, not just general knowledge.

• Structure longer answers: For 4-6 mark questions, organise your response clearly. Consider: point 1, evidence/example, point 2, evidence/example, conclusion if evaluating. This demonstrates developed scientific reasoning.

• Link to the specification: Questions may ask about specific threats to biodiversity, methods of conservation, or sustainable development. Know examples of each category and be ready to apply them to unfamiliar contexts.

Quick revision summary

Biodiversity — the variety of species in ecosystems — faces threats from habitat destruction, pollution, climate change, overharvesting and invasive species. Conservation strategies include protecting habitats through reserves and legislation, species-focused interventions like captive breeding programmes and seed banks, and sustainable resource management including fishing quotas and certified forestry. Successful conservation balances environmental protection with human development needs, often involving conflicting pressures between economic benefits and long-term ecosystem health. Specific examples and understanding evaluation skills are essential for exam success.