A2 Edexcel geography, unit 3- biodiversity under threat revision notes

Biodiversity under threat
Defining biodiversity

Key definitions
BIODIVERSITY-this is the variety of genes, species and ecosystems in an area.

BIOSPHERE-this is the thin veneer of living material on the planet's surface.

BIOME-this is a global scale ecosystem, e.g. tropical forest.

BIOMASS-this is the total weight of living matter.

ECOSYSTEM DIVERSITY-this…

Hotspots have lost 70% of their natural vegetation.

Types of hotspots
Examiner's tip: learn the names and locations of at least one of each of the three types of land-based biodiversity hotspots.

1. Continental hotspots, e.g. Brazil's Cerrado.
2. Large island hotspots, e.g. Madagascar.
3. Small island hotspots, e.g. Sri…

Physical

Light intensity
Altitude
There is a range of ecological zones as a result of altitude and each with its own endemic species. Commonly, biodiversity is high on
large, high tropical (low latitude) islands, e.g. Madagascar.

Large areas
This is because of the complex food chains.

Latitude
Decay and nutrient…

Energy flows
Primary producers convert sunlight into chemical energy and as energy is lost, the volume of biomass decreases.

Goods and services of an ecosystem
Goods Services
Medicine Habitats
Timber Carbon sink
Water cycle
Services
PROVISIONING SERVICES-they are products, e.g. food.

REGULATING SERVICES-they are benefits, e.g. climate.

CULTURAL SERVICES-they are…

Disease

EXTINCTION-this is a natural event of death of all members of a species but humans are accelerating the rate of extinctions.

Examiner's tip: candidates often confuse the destruction of an ecosystem (e.g. shrimp farming) with the more gradual
degradation of an ecosystem (e.g. by over-exploitation or tourism).

Human threats…

Cycle of decline




Players and stakeholders
Key player Opinion expressed
The Wet Tropics Management Authority It is responsible for managing the World Heritage Site. It wishes
to research and monitor the state of the World Heritage Site. Its
aim is to develop management agreements with landholders
and Aborigines.
Cairns council…

World Biodiversity Reserve

Physical geography
18 main islands, 3 smaller islands and 107 rocks.
Upwelling of nutrients as a result of the cold currents.
El Nino and La Nina: El Nino causes temperature rise and La Nina vice versa.

Threats to the Galapagos Islands
1. Invasive species (e.g. goats) are…

It is a fragile and vulnerable ecosystem. The tundra has very low organic productivity (primary productivity) is a measure of how
quickly vegetation grows. The ANWR lies in the Arctic tundra and has a polar climate. The winters are long, dark and cold with short
summers. Precipitation is low (known…

should use areas that are already being exploited and although this may be difficult in terms of the security and reliance- it prevents
the exploitation of an area.

4. When was the ANWR created?

The region first became of federal protection in 1960

Western Arctic Reserve
They are known as…

Regional organisations, e.g. TVE Asia Pacific
Advantages Disadvantages
Raised awareness of the importance of mangroves. Doesn't provide enforcement, it is only advice.
Use of the media and so equal access.
Allows local communities to reach the initiative and do it
themselves.



NGOs, e.g. Wetland International
Advantages Disadvantages
Provides further support…