A Level Geography - Unit 4

These cards show the Unit 4 A2 Geography topics.


Biome Characteristics

Climate: Includes precipitation, temperature, light intensity and winds.

Precipitation: Whether it's seconds, reliable rainfall, type of rainfall and whether rain falls in the growing season.

Temperature: Major Influence on vegetation (growth-6°C, photosynthesis-10°C, stress-35°C).

Light Intensity: Affects photosynthesis - tropical ecosystems recieve more radiation and have higher energy inputs than polar ecostems.

Winds: Increases the rate of evapotranspiration and the wind-chill factor.

Endemism: Unique to a place/region. For example, Australia has species found nowhere else, such as Kangaroos.

Human Activity: Biodiversity is under attack from human activity e.g. habitat change, over-exploitation, introduction of alien invasive species, pollution, climate change, etc.

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Value of Ecosystems

  • Ecosystems have value
  • In some cases, a financial value can be calculated income from timber or tourism
  • Much of the value of ecosystems cannot easily be calculated in monetary terms
  • Healthy biodiversity ecosystems are essential for maintaining human wellbeing

Goods (provisioning services) - A product that we take from the ecosystem.


Regulating Services - Something the ecosystem does for us without asking and would do whether we were here or not.


Cultural Services - Something we take advantage of (like a service) but does not involve us physically taking anything (like a good).

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Biodiversity Under Threat

Hotspots - areas of species richness, which are under constant assault from human activity. About half of all plant and animal species on earth are found in these hotspots, which originally covered 15.7% of the earth's surface. Only about 10% of the original habitat remains.


Pivotal Areas - an area of crucial importance, which the world cannot do without, or it will cause serious negative impacts.


Distribution of Hotspots Under Threat- Biodiversity hotspots tend to be found along the west coast of the US, Brazil, Southern Europe, North and East Africa, South China, Sunderland, South West Australia and Japan. On average, they tend to be in developing countries.

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Ecosystems Under Theat - Case Study: Great Barrier

The Great Barrier Reef

  • The Great Barrier Reef stretches 2,300 kilometres along Queensland Coast, including 2,900 coral reefs and about 940 islands and cays.
  • It is home to more than 1,500 species of fish, 4,000 molluscs and 215 birds.
  • Higher sea temperature due to Global Warming means that many species are unable to breed (e.g. Clownfish).
  • Increased pollution has resulted in the loss of vegetation and wetlands.
  • Overfishing has meant that many species are endangered and extinct, including some species of Dolphin.
  • Increased tourism means that coral reefs are damaged.
  • Oil spills in the waters of the GBR kills coral reefs and other species.
  • Coral Bleaching due to El Nino periods means that coral tissue becomes blended or colourless due to warmer sea temperatures.
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Value of Ecosystems - 2

People of the Rainforest - indigenous people are the original owners of the tropical rainforests. It is used for their home, religion, spirituality, economic use and social & moral organisation.

Nutrient Cycling - storage, recycling, processing and acquisition of nutrients.

Fire, Timber & Fuel - production of timber, fuelwood, charcoal, fibres, dyes & other materials.

Insects - ecosystems are home to insects that are vital to the pollination processes. If they're lost, it would cost $0.5 trillion per year, and would be less succesful.

Medicine - about 25% of all medicines come from the rainforest plants. In tropical forest regions, over 2,000 tropical plants have been identified as having anti-cancer properties. However, scientists have only tested 1 in 10 plants and only intensively screened 1 in 100 up to today. With present day deforestation, thousands of plants would be extinct before they can be tested.

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Threats to Mangroves - Natural


  • Diseases
  • Hurricanes
  • Root clogging from increased water turbidity
  • Damage from boring organisms and parasites
  • Weeds
  • Insect pests e.g. wood borers, caterpillars, beetles.


  • Climate Change - very sensitive to sea level rise.
  • Browsing and trampling by wildlife damaged seedlings, leaves, flowers and roots.
  • Poor rainfall
  • High soil salinity
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Threats to Mangroves - Human


  • Logging
  • Costal development - loss of habitat
  • Dredging
  • Oil spills
  • Filling & diking
  • Human waste
  • Use of mangrove land for urban development


  • Sea level rise - 45cm rise will destroy 75% of forest over a 10,000 square km area.
  • Increased shrimp aquaculture causes a 50% loss of mangroves
  • Tourism
  • Climate Change
  • Human waste
  • Overfishing
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Alien Invasive Species

  • These are species which move out of their natural habitat and colonise new areas as a result of human activity.
  • Our globalised world has increased the threat from alien invasive species.
  • Some aliens are introduced deliberately, perhaps as a food source, predator or ornamental species, but then escape into the wild and have unattended consequences. 
  • Other alien invasive species are accidental introduction

Successful Invaders tend to be:

  • Capable of rapid reproduction
  • Able to disperse
  • Rapid growing
  • Tolerant to a range of environmental conditions
  • Able to eat a wide range of foods
  • Strong
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Alien Invasive Species Case Study - Cane Toad

  • The Cane Toad was introduced to Australia in the 1930s as a biological control (to control the population of the Cane Beetle as it was destroying sugar crops.
  • 90% of Goanna's have been killed by eating them and being poisoned.
  • Decline in Northern Quoll.
  • Snakes and freshwater Crocodiles are dying from eating the toads.
  • They have also been known to eat baby birds nests e.g. Rainbow Bee Eaters.
  • Other amphibians have to compete as the Toad is disrupting the food chain.
  • However, they have successfully controlled Cane beetle numbers and many birds are tolerant to the poison.

Control Methods:

  • Freezing
  • Gassing
  • Rewards for killing them
  • Even wacking them with golf clubs
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Sustainable Fishing - Solutions and Problems


  • Vary net sizes
  • No fishing zones (certain times of the year)
  • Limit profits
  • Incentives - subsidise fuels
  • Develop international treaties
  • Invest money into research
  • Encourage target specifit methods
  • Use fishing police, Navy and Coast Guard


  • There's still illegal fishing
  • Demand for fish
  • Varied net sizes don't always stop bycatch
  • Food web implications
  • Too many stakeholders
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Key Players in the Fishing Industry

  • Trawler companies
  • TNC
  • Fishermen
  • Marine tourism
  • EU
  • Companies such as 'Bird's Eye'
  • Fish mongers
  • Animal Activists
  • Inuits
  • Governments
  • Marine Biologists
  • NGOs such as 'Greenpeace'
  • Coast Guard/Sea Police
  • Consumers
  • Supermarkets
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Threats to Ecosystems

  • Consumerism
  • Pollution
  • Waste
  • Urbanisation
  • Pesticides/Fertilizers
  • Transport
  • Widening development gap
  • Agriculture of marginal areas
  • Demand for energy
  • Continued population growth
  • GM crops
  • Tourism
  • Instinction of species
  • Globalisation
  • Exploiting resources
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Ecosystem Key Players

  • Global - Countries get together to develop wildlife conservation treaties e.g. Ramsar Convention.
  • TNC - Determining which goods and services are produced and how e.g. the WTO.
  • NGO - Stops the degredation of the planet's natural environment and ensure a sustainable future e.g. WWF and Greenpeace.
  • National - Governments help to manage biodiversity, acting as regulators and facilitators.
  • Local - Local communities are often dependant on biodiversity for their survival e.g. Indigenous people.
  • Individuals - most diverse group of all in their demand for consumers of food, fuel, water and shelter. Ethical consumerism has led to people to choose to buy environmentall friendly products e.g. dolphin friendly tuna.
  • Total Protection Strategies - Biosphere reserves, tolerant forest conservation, extracting researves and ecotourism.
  • Restoration - Restoring highly degraded ecosystems and linking up small reserves to produce a larger, more climate-proof reserve e.g. Great Fan project in East Anglia.
  • Conservation - An alternative for endangered species to establish a captive population away from its natural habitat.
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The Millenium Ecosystems Assessment (MEA)

  • 2 development pathways - one in which the world becomes increasingly globalised and the other in which it becomes increasingly regionalised.
  • 2 different approaches to ecosystem management - one in which actions are reactions and most problems are addressed only after they become obvious, and the other in which ecosystem management is proactive and policies seek to manage ecosystem services for the future.

All 4 scenarios predict rapid conversion of ecosystems, especially of grassland and forests to farmland or for urbanisation. The rates depend on the changes in population, consumption and wealth.

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