Sustaining Ecosystems

What you'll learn

This guide covers everything you need to know about sustaining ecosystems for OCR GCSE Geography. You'll explore why ecosystems matter, how human activities threaten them, and the strategies used to protect and manage them sustainably. This topic connects to larger themes of resource management and environmental challenges that appear across your GCSE specification.

Key terms and definitions

Biodiversity — the variety of living organisms in an ecosystem, including the number of different species, genetic variation within species, and the range of habitats present.

Ecosystem services — the benefits humans obtain from ecosystems, including provisioning services (food, water, timber), regulating services (climate regulation, flood control), supporting services (nutrient cycling, soil formation), and cultural services (recreation, spiritual value).

Sustainable management — using natural resources in a way that meets current needs without preventing future generations from meeting their own needs, maintaining ecosystem health over time.

Deforestation — the permanent removal of forest cover, usually for agriculture, logging, or urban development, resulting in habitat loss and reduced carbon storage.

Conservation — the protection and preservation of ecosystems and species through various strategies including protection, restoration, and sustainable use.

Ecotourism — responsible travel to natural areas that conserves the environment, sustains local communities, and involves education and interpretation.

Carbon sequestration — the process by which ecosystems (particularly forests and oceans) absorb and store atmospheric carbon dioxide, helping to regulate climate.

Invasive species — non-native organisms introduced to an ecosystem that cause harm to native species, often outcompeting them for resources and disrupting food webs.

Core concepts

Why ecosystems need sustaining

Ecosystems worldwide face unprecedented pressure from human activities. Understanding why they need protection helps justify conservation efforts.

Value to humans:

• Provide essential resources including food, freshwater, medicines, and raw materials
• Regulate climate through carbon storage and oxygen production
• Control flooding through water absorption and slow release
• Purify water and air by filtering pollutants
• Support economies through tourism, fishing, and forestry
• Offer cultural and spiritual significance to communities

Intrinsic value:

• Every species has a right to exist regardless of usefulness to humans
• Complex food webs depend on biodiversity at all levels
• Loss of one species can trigger cascading effects through entire ecosystems
• Genetic diversity provides resilience against disease and environmental change

Global biodiversity trends:

• Species extinction rates are 100-1000 times higher than natural background rates
• Habitat loss affects approximately 75% of terrestrial ecosystems
• One million species face extinction within decades according to IPBES assessments
• Tropical rainforests lose an area equivalent to 27 football pitches every minute

Threats to ecosystems

Human activities pose multiple interconnected threats that degrade ecosystem health and reduce biodiversity.

Direct habitat destruction:

• Deforestation for agriculture (soy, palm oil, cattle ranching) removes 10 million hectares of forest annually
• Urban expansion converts natural habitats to concrete and infrastructure
• Mining operations destroy vegetation and contaminate soil and water
• Infrastructure development (roads, dams) fragments habitats and disrupts wildlife movement

Climate change impacts:

• Rising temperatures shift species ranges and disrupt breeding cycles
• Extreme weather events (droughts, floods, hurricanes) damage ecosystems faster than they can recover
• Ocean acidification from absorbed CO₂ threatens coral reefs and shellfish
• Melting ice reduces habitat for polar species like polar bears and penguins

Pollution effects:

• Agricultural runoff causes eutrophication in water bodies, creating dead zones
• Plastic accumulation in oceans harms marine life through ingestion and entanglement
• Air pollution damages plant tissues and reduces photosynthesis rates
• Chemical contamination bioaccumulates up food chains, affecting top predators

Overexploitation:

• Overfishing depletes fish stocks faster than they can reproduce
• Hunting and poaching drive species like rhinos and elephants toward extinction
• Illegal wildlife trade threatens thousands of species globally
• Unsustainable logging removes old-growth forests with high biodiversity

Invasive species introduction:

• Non-native species outcompete indigenous organisms for food and space
• Predatory invasives eliminate native prey species with no evolutionary defences
• Diseases carried by introduced species devastate populations
• Example: grey squirrels in the UK outcompete native red squirrels and carry squirrelpox

Conservation strategies

Multiple approaches exist to protect ecosystems, each with strengths and limitations suited to different contexts.

Protected areas:

• National parks restrict harmful activities while allowing sustainable tourism
• Marine protected areas ban fishing in critical breeding grounds
• Wildlife reserves provide safe habitats for endangered species
• Success depends on adequate funding, enforcement, and local support
• Example: Yellowstone National Park (USA) protects diverse ecosystems across 9,000 km²

Legal protection:

• CITES (Convention on International Trade in Endangered Species) regulates wildlife trade
• National legislation like the UK Wildlife and Countryside Act 1981 protects species and habitats
• Fishing quotas limit catches to sustainable levels
• Enforcement challenges include illegal poaching and insufficient penalties

Habitat restoration:

• Reforestation replaces lost forest cover and sequesters carbon
• Wetland restoration improves water quality and provides flood protection
• Coral reef restoration transplants healthy corals to damaged areas
• Requires long-term commitment as ecosystems take decades to fully recover
• Example: Great Green Wall initiative aims to restore 100 million hectares across Africa's Sahel

Captive breeding programmes:

• Zoos breed endangered species in controlled environments
• Individuals reintroduced to wild populations increase genetic diversity
• Maintains species on brink of extinction until habitats can be secured
• Limitations include high costs and animals may struggle to adapt to wild conditions
• Example: California condor numbers increased from 27 (1987) to over 500 today

Sustainable management approaches:

• Ecotourism generates income for local communities while protecting nature
• Selective logging removes only mature trees, allowing forest regeneration
• Sustainable fishing practices use appropriate gear and respect breeding seasons
• Agroforestry integrates trees with crops, maintaining some forest benefits
• Community-led initiatives ensure local people benefit from conservation

Case study: Tropical rainforest sustainability

Understanding specific examples demonstrates how sustainability principles apply in practice.

Amazon Rainforest threats:

• Deforestation for cattle ranching and soy production
• Logging (legal and illegal) removes valuable hardwoods
• Mining operations for gold and other minerals
• Road construction opens previously inaccessible areas
• Climate change reduces rainfall, increasing fire risk

Sustainability strategies in action:

Brazil's Forest Code:

• Requires landowners to preserve 80% of rainforest on their property
• Establishes buffer zones along waterways
• Enforcement remains inconsistent due to political and economic pressures

REDD+ scheme:

• Pays developing countries to reduce deforestation rates
• Monitors forest cover using satellite technology
• Provides economic incentive to maintain forests for carbon storage
• Ecuador received $18 million for reducing deforestation by 50,000 hectares

Indigenous land rights:

• Indigenous territories show lower deforestation rates than unprotected areas
• Traditional knowledge supports sustainable resource use
• Legal recognition of land rights protects both people and ecosystems
• Covers approximately 28% of the Amazon basin

Selective logging certification:

• FSC (Forest Stewardship Council) certifies sustainably managed forests
• Only mature trees harvested, protecting younger growth
• Maintains forest structure and biodiversity
• Provides premium prices incentivising sustainable practices

Case study: Coral reef sustainability

Coral reefs demonstrate ecosystem fragility and the need for integrated conservation approaches.

Threats to coral reefs:

• Ocean warming causes coral bleaching when symbiotic algae expelled
• Ocean acidification weakens coral skeletons
• Overfishing disrupts food webs and removes herbivores that control algae
• Coastal development increases sedimentation and pollution
• Destructive fishing practices (dynamite, cyanide) physically damage reefs

Great Barrier Reef protection:

• Marine park zoning designates no-take areas (green zones) covering 33% of reef
• Water quality improvement programmes reduce agricultural runoff
• Crown-of-thorns starfish control programmes protect coral from predation
• Climate change adaptation research develops heat-resistant coral varieties
• Tourism management limits visitor numbers and anchoring damage
• Challenges: 2016-2017 bleaching events killed 50% of corals in northern sections

Caribbean coral reef initiatives:

• Belize Barrier Reef removed from UNESCO endangered list after oil drilling ban
• Marine protected areas established across Jamaica, Bahamas, and Trinidad
• Coral restoration nurseries grow fragments for transplantation
• Lionfish culling programmes remove invasive predators
• Sustainable fishing regulations include seasonal closures and size limits

Global cooperation and governance

International action addresses threats that cross national boundaries.

International agreements:

• Paris Agreement commits countries to limit climate change
• Convention on Biological Diversity sets targets for habitat protection (30% by 2030)
• Ramsar Convention protects wetlands of international importance
• Montreal Protocol demonstrates successful cooperation (ozone layer recovery)

Funding mechanisms:

• Global Environment Facility provides grants for biodiversity projects
• Debt-for-nature swaps cancel debt in exchange for conservation commitments
• Green Climate Fund supports climate adaptation in developing countries
• Private sector initiatives include corporate sustainability pledges

Challenges to cooperation:

• Economic interests conflict with conservation goals
• Sovereignty concerns limit enforcement of international law
• Unequal distribution of costs and benefits between developed and developing nations
• Short-term political cycles undermine long-term conservation needs

Worked examples

Example 1: 4-mark question

Explain how deforestation reduces biodiversity. [4 marks]

Model answer: Deforestation directly removes habitats that species depend on for food and shelter (1). This causes local extinctions of species unable to survive in other environments (1). Forest removal also fragments remaining habitat, isolating populations and reducing genetic diversity (1). Additionally, loss of forest canopy affects microclimates, making conditions unsuitable for species adapted to stable temperature and humidity (1).

Mark scheme guidance:

• Each valid point explaining a different mechanism receives 1 mark
• Link cause (deforestation) to effect (reduced biodiversity) clearly
• Specific mechanisms score higher than vague statements

Example 2: 6-mark question

Assess the effectiveness of ecotourism as a strategy for sustaining tropical ecosystems. [6 marks]

Model answer: Ecotourism can effectively sustain tropical ecosystems by providing economic incentives for conservation (1). In Costa Rica, ecotourism generates $2.6 billion annually, demonstrating that intact rainforests have greater economic value than cleared land (1). This income funds protected areas and employs local communities as guides and rangers, reducing pressure for destructive activities like logging (1).

However, effectiveness depends on proper management as tourism can damage what it aims to protect (1). Excessive visitor numbers cause erosion, wildlife disturbance, and pollution (1). Without regulation and equitable benefit sharing, local communities may not support conservation, and "greenwashing" can allow environmentally harmful tourism to continue (1).

Mark scheme guidance:

• Balance strengths and limitations for "assess" questions
• Use specific named examples to support points
• Conclusion or judgment strengthens answer
• 6 marks typically require developed points (3 × 2 marks) or more basic points

Example 3: 9-mark question

"Conservation strategies can only succeed with local community involvement." To what extent do you agree? [9 marks + 3 SPaG]

Model answer structure: Introduction: State your position clearly (agree, disagree, or balanced view).

Arguments supporting the statement:

• Community-based conservation in Namibia shows communal conservancies reduced poaching and increased wildlife populations because locals benefited from tourism revenue
• Indigenous Protected Areas in Australia demonstrate traditional knowledge improves ecosystem management
• Top-down conservation often fails when communities resent restricted access to resources they depend on
• Local people provide enforcement, monitoring, and sustainable use practices that external agencies cannot

Arguments against the statement:

• Some conservation requires government action communities cannot provide (legal frameworks, international cooperation)
• Short-term economic pressures may override long-term conservation even with involvement
• Scientific expertise from external organizations contributes essential knowledge
• Protected areas can succeed despite local opposition if properly resourced and enforced

Conclusion: Weigh both sides and provide reasoned judgment based on evidence presented.

Mark scheme guidance:

• Level 3 (7-9 marks): Detailed points, named examples, balanced evaluation, clear conclusion
• Level 2 (4-6 marks): Some development, may lack balance or examples
• Level 1 (1-3 marks): Basic points, limited development
• SPaG: 3 marks for spelling, punctuation, grammar, and specialist terminology

Common mistakes and how to avoid them

• Confusing conservation with preservation: Conservation allows sustainable use of ecosystems; preservation protects them from all human use. Use the term that matches the strategy described.

• Listing threats without explanation: Don't just state "climate change threatens ecosystems." Explain the mechanism: "rising temperatures cause coral bleaching as corals expel symbiotic algae, leading to starvation."

• Vague case study references: Avoid "in tropical rainforests..." Instead write "In the Amazon rainforest, Brazil's Forest Code requires..." Specific places, schemes, and data score higher marks.

• One-sided assessment answers: "Assess" and "evaluate" command words require balanced consideration of strengths AND limitations. Structure answers to show both sides before concluding.

• Mixing up ecosystem services categories: Know the difference between provisioning (products obtained), regulating (benefits from processes), supporting (necessary for other services), and cultural (non-material benefits).

• Ignoring scale in answers: Specify whether discussing local (community reserves), national (protected areas), or international (CITES, Paris Agreement) strategies. Different scales suit different contexts.

Exam technique for "Sustaining Ecosystems"

• Command word focus: "Explain" requires reasons/causes (because/this leads to); "Assess/Evaluate" needs weighing pros and cons with judgment; "To what extent" demands balanced argument with clear conclusion supported by evidence.

• Mark allocation guides detail: 2 marks = 2 developed points or 4 basic points; 4 marks = substantial explanation with linked points; 6+ marks = extended writing requiring examples, balance, and possibly judgment.

• Case study specificity: Learn at least two ecosystem examples with specific data (percentages, costs, areas, dates). Names of schemes, places, and organisations demonstrate geographical knowledge worth marks.

• Link human and physical geography: Strong answers connect ecosystem sustainability to other specification areas—population pressure, economic development, climate change, resource management. Show understanding of interconnections.

Quick revision summary

Ecosystems provide essential services but face threats from habitat destruction, climate change, pollution, overexploitation, and invasive species. Conservation strategies include protected areas, legal frameworks, habitat restoration, and sustainable management like ecotourism. Success requires balancing environmental protection with human needs, particularly through local community involvement. International cooperation addresses transboundary issues through agreements and funding mechanisms. Specific case studies (tropical rainforests, coral reefs) demonstrate how strategies apply in practice with varying effectiveness depending on context and implementation.