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Geography Revision Guide
Biodiversity Under Threat

What influences it?

Primary Ecological

Size of an area ­ bio increase when the area increases as there is room for more species =
migration encourages
History and age ­ greatest bio found in oldest and least disturbed ecosystems especially the tropics
= few…

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Habitat heterogeneity­ varied physical environment great Bio as it provides a WIDER range of


Succession­ BIODIVERSITY increases as species establish themselves, interact and subtly the
environment. E.g. succession in SAND DUNES or POND

Interaction ­ leads to competition =EXTINCTION when EXOTIC species are involved
Disturbances ­ environmental disaster…

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½ Earths species are found in the Tropical rainforest = only 7% of the Earth's surface


HOTSPOTS = BIODIVERSITY HOTSPOT = areas threatened by humans contain a large number of biodiversity
(Large % = ENDEMICS)

Must have 1500 endemic vascular plants ­ not found anywhere else!

30% or less…

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7. Oil and gas development
8. Climate change


LOCATION: Pacific approximately 1,000 km from Ecuador
The islands belongs to Ecuador
They are volcanic archipelago (chain of islands)
Belongs to Ecuador's national park systems and a UNESSO World Heritage Site
Fame ­ Charles Darwin `origins of species'…

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Intensive Use: 25 zones, maximum of 90 people (4/5 groups of 20 authorised daily)

Extensive Use: 16 zones ­ only approximately 12 people daily = no large groups

Primate Use: Special permit required to visit

Primate Scientific: Only scientific researchers

Special Use: Next to colonised…

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Energy Flows = the sun is the driver of most systems on our earth. Primary producers (green plants) tropic level
one convert sunlight energy by PHOTOSYNTHESIS

The Tropic Pyramid

Summary of the energy flows through the TRF ecosystem

Primary Consumers (herbivores) = GAIN ENERGY = Primary Producers (eating)

Primary Production…

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The Nutrient Cycle

NUTRIENT CYCLE = circulation of elements from environment to organism

Nutrient Cycles ­ Nutrients found in the soil and litter the cycled between these stores ­ usually shown in a flow
diagram: size of circles represent amount of nutrient: width of the arrow represents the importance of…

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IMPORTANT ­ The concentration of nutrients in the through fall different to that in the original rain. Nutrient
inputs and Outputs ­ nutrients dissolved in rainwater = important input.

BIODIVERSITY THREATS:Distribution of threatened areas:

Ecosystems scorecard ­ identifies freshwater ecosystems as the most eco-stressed
Living Planet Index Card ­ identifies…

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SUGGESTS: there might be some hope for threatened ecosystems if attempts are made to conserve them

As levels of development fluctuate they don't always follow the same patterns. This is a generalised graph to show
the state of ecosystems. When development levels increase there are examples of ecosystems suffering.


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Problems with CC = it varies seasonally and is expected to be reduced by climate change.

Sustainable Yield = the safe level at which the goods and services of an ecosystem can be `harvested' without
harming it.

Carrying capacity = the maximum human population that can exist in equilibrium with…


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