Ecosystems Under Stress

What Ecosystems Under Stress covers

Ecosystems from trophic structure and nutrient cycling up to the global biomes, then the pressures on rainforest, savanna, coral reef and local habitat, and what sustainable management involves. One of two Section C options in Component 1.

The 27 subtopics

Each one has its own page.

• Biodiversity Levels and Causes of DeclineRecall questions on genetic, species and ecosystem diversity, species richness and evenness, local trends, extinction rates and threatened hotspots, and on overexploitation, invasive species, pollution and climate change as causes of decline, phenological mismatch and metrics of loss.Open →
• Biodiversity Loss and Ecosystem ServicesRecall questions on resilience, trophic cascades, the shrinking genetic pool and what ecosystem services provide.Open →
• Ecosystem Structure, Trophic Levels and Food WebsRecall questions on what an ecosystem is, its biotic and abiotic components and the flow of energy, on producers, primary, secondary and tertiary consumers and decomposers, and on food chains, food webs and energy transfer between trophic levels.Open →
• Ecosystem Inputs, Outputs, Stores and TransfersRecall questions on solar energy, precipitation, weathered nutrients and atmospheric gases as ecosystem inputs, heat, water and nutrient losses as outputs, biomass, litter, soil organic matter and soil nutrients as stores, and photosynthesis, respiration, decomposition, root uptake and consumption as transfers.Open →
• Biomass, Net Primary Production and SuccessionRecall questions on biomass, net primary production and its formula, and on succession, seral stages, pioneer species, climatic climax and sub-climax.Open →
• Nutrient Cycling, Climate and SoilRecall questions on mineral nutrient cycling between soil, biomass and litter and why its rate varies, on how climate, vegetation and soil influence one another through nutrients, water retention, drainage and rooting depth, and on the effects of aspect, altitude and slope.Open →
• Environmental Controls and Ecosystem FeedbackRecall questions on why climate, vegetation, soil and relief are interconnected and on positive and negative feedback loops.Open →
• Biomes and the Tropical Rainforest EnvironmentRecall questions on biomes, the seven major terrestrial biomes and why latitude governs their distribution, and on the tropical rainforest's location, rainfall, temperatures, nutrient-poor soils, nutrient stores and cycling, and soil moisture budget.Open →
• Rainforest Stratification and AdaptationsRecall questions on the emergent, canopy, understorey and shrub layers and the forest floor of a tropical rainforest, and on adaptations including buttress roots, drip tips, lianas, epiphytes and the adaptations of rainforest fauna.Open →
• Savanna Climate, Soils and AdaptationsRecall questions on savanna latitudes, wet and dry seasons and the ITCZ, rainfall, temperatures, laterite soils and the soil moisture budget, grasses, thick bark, waxy leaves, tap roots, baobabs and deciduous trees as adaptations, fauna and large herbivore populations, and how savanna differs from rainforest in the amount and seasonality of rainfall.Open →
• Human Impacts on the Tropical RainforestRecall questions on how deforestation and logging affect rainforest soils, nutrient cycling and biodiversity, habitat fragmentation, slash and burn, cattle ranching and mining, population and economic pressures, agricultural extension and intensification, threatened ecosystem services and approaches to sustainability.Open →
• Human Impacts on the SavannaRecall questions on overgrazing and desertification, why frequent burning favours grasses over trees, poaching, population growth and economic development, agricultural extension and irrigation, the causes of biodiversity loss, and what sustainable land management in savannas requires.Open →
• Succession and Climatic ClimaxRecall questions on what succession is, why a climatic climax community persists and what a lithosere describes.Open →
• Temperate Deciduous WoodlandRecall questions on temperate deciduous woodland as the climatic climax of the British Isles, why its trees shed leaves, its canopy, sub-canopy, shrub, field and ground layers, seasonal light and spring-flowering ground flora, and its brown earth soils.Open →
• Plagioclimax and Heather MoorlandRecall questions on what a plagioclimax is, a British example, and how controlled burning holds moorland short of woodland.Open →
• Coral Reef Conditions, Services and StressesRecall questions on the latitudes, temperature, clear shallow water, zooxanthellae and salinity coral reefs need, their structure and ecology, their coastal protection, economic and nursery services, and stresses from bleaching, ocean acidification, salinity change, algal blooms and drainage basin schemes.Open →
• Human Pressures and Coral Reef ManagementRecall questions on onshore development, desalination discharges, agricultural runoff, industrial contamination and plastic, damage from boats, divers, tourism sewage and construction, overfishing and destructive fishing, the prospects for reefs and the Great Barrier Reef, and protected areas, regulation, pollution reduction and restoration.Open →
• The Great Barrier Reef: Extent and BleachingRecall questions on where the reef lies, how far it stretches and when mass bleaching occurred.Open →
• Crown-of-Thorns Starfish and Reef TourismRecall questions on why starfish outbreaks harm the reef, how nutrient pollution worsens them and why tourism needs managing.Open →
• Local Ecosystems: Heathland, Parkland, Ponds and DunesRecall questions on local ecosystems, heathland soils, shrubs and burning, managed parkland with its ground layer, old trees, woodland edges and maintenance, pond zonation and marginal and emergent plants, and the succession from embryo to yellow, grey and fixed dunes.Open →
• Adaptations to Dry EnvironmentsRecall questions on reduced and rolled leaves, waxy cuticles and sunken stomata, and on why animals become nocturnal.Open →
• Agriculture, Urbanisation and Invasive SpeciesRecall questions on habitat loss, monoculture, nutrient runoff and soil compaction from agriculture, on habitat fragmentation, impermeable surfaces and pollution from urban development, and on species introductions and how invasive species exclude natives, disrupt food webs, transmit disease and modify habitats.Open →
• Ecological Change and Conservation StrategiesRecall questions on how ecological change causes biodiversity loss and degrades ecosystem services, nutrient cycles and resilience, and on conservation through habitat restoration, wildlife corridors, invasive species management, stakeholder consultation, funding, monitoring, adaptive management, SSSIs and agri-environment schemes.Open →
• Sustainability and Stakeholder ConflictRecall questions on what sustainable development means locally and on the conflicting interests and funding limits it meets.Open →
• Studying Local Ecosystems and Ecological ChangeRecall questions on studying a distinctive local ecosystem, its characteristics, ecological responses, local factors, properties, human impacts, conservation and sustainable development, and on a case study of a region experiencing ecological change and the community responses it illustrates.Open →
• The Sefton Coast sand dunes case studyThe Sefton Coast dunes as the local ecosystem case study: succession and soils, natterjacks and red squirrels, pine planting, erosion at Formby Point, invasive scrub, designations and management evaluated.Open →
• Ecological change in BorneoEcological change in Borneo as a regional case study, covering the loss of rainforest and peat swamp forest to logging, oil palm and fire, the effects on orangutans and the carbon cycle, and responses from certification to conservation.Open →

What you need to know

Answer each one before you reveal it.

Take Ecosystems Under Stress further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Food chain vs Food web

  Food chain: linear sequence of feeding relationships. Food web: network of interconnected food chains.

• Primary succession vs Secondary succession

  Primary succession: community development beginning without soil. Secondary succession: community recovery where soil remains.

Questions from this topic

Each one with the model answer underneath.

1. 1

   What are the three levels at which biodiversity is measured?

   Model answer

   Genetic diversity within species, species diversity within communities, and ecosystem diversity across landscapes

2. 2

   Define genetic diversity as a component of biodiversity.

   Model answer

   The variation in alleles and genotypes within a population or species

3. 3

   What does species diversity refer to as a level of biodiversity?

   Model answer

   The variety of different species within a community, encompassing both the number of species present and their relative abundances

4. 4

   Define species richness.

   Model answer

   The number of different species present in a community or area

5. 5

   What is species evenness?

   Model answer

   The relative abundance of each species within a community

6. 6

   What is ecosystem diversity?

   Model answer

   The variety of different habitats, biological communities and ecological processes within a region

What is inside Levo

Six ways to work the same material.

Ecosystems Under Stress revision questions

What does Ecosystems Under Stress cover in AQA A-Level Geography?

27 subtopics: biodiversity levels and causes of decline, biodiversity loss and ecosystem services, ecosystem structure, trophic levels and food webs, ecosystem inputs, outputs, stores and transfers, biomass, net primary production and succession, nutrient cycling, climate and soil, environmental controls and ecosystem feedback, biomes and the tropical rainforest environment, rainforest stratification and adaptations, savanna climate, soils and adaptations, human impacts on the tropical rainforest, human impacts on the savanna, succession and climatic climax, temperate deciduous woodland, plagioclimax and heather moorland, coral reef conditions, services and stresses, human pressures and coral reef management, the great barrier reef: extent and bleaching, crown-of-thorns starfish and reef tourism, local ecosystems: heathland, parkland, ponds and dunes, adaptations to dry environments, agriculture, urbanisation and invasive species, ecological change and conservation strategies, sustainability and stakeholder conflict, studying local ecosystems and ecological change, the sefton coast sand dunes case study and ecological change in borneo. Each one has its own page with questions and model answers.

How is Ecosystems Under Stress organised?

By the AQA 7037 specification, subtopic by subtopic, so it matches the order you are taught it in.