A2 Edexcel Geography BIODIVERSITY UNDER THREAT (Contested Planet)


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(3) Biodiversity Under Threat
3.1 Defining Biodiversity
Biodiversity (Biological Diversity) ­ the variability among living organisms of all sources: terrestrial, marine and aquatic
ecosystems and the ecological complexes of which they are part of, including:
1. Diversity within species
2. Diversity between species
3. Diversity of ecosystems
Type of diversity Examples
(1) Genetic diversity ­ the Genetic variability among populations or individuals can determine the degree of
diversity of genes found resistance to pests and diseases
within a species, e.g. a type of
A broad gene pool is vital to combat disease and climate change.
whelk or a plant such as cereal
Agro-ecosystems have been reduced by plant breeding to artificial monocultures
(genetic erosion).
(2) Species diversity ­ the Diversity of species bolsters ecosystem resilience to withstand threats such as
variety of plant/animals climate change. Removal of a key species, such as bees, has a huge impact on the
species in a given area functioning of an ecosystem, i.e. nutrient cycling and energy flows. Endemic species
(habitat), i.e. the numbers of (unique and rare) are especially important. Where there are few factors which limit
different organisms growth, as in tropical areas, high primary productivity leads to a complex and
diverse food web with many ecological niches leading to high biodiversity
(3) Ecosystem diversity ­ the The two ecosystems with highest biodiversity are tropical rainforests and coral
variety of different reefs. The high level of ecosystem diversity adds to the value of goods and services.
ecosystems and the habitats Equally in a SSSI such as Oxwich, South Wales, there are a wide variety of habitats
surrounding them in a given with the small reserve, which leads to a very high level of ecodiversity.
area; it includes biotic and
abiotic components
Agro-ecosystem - A dynamic association of crops, pastures, livestock, other flora and fauna, atmosphere, soils, and
water. Agro-ecosystems are contained within larger landscapes that include uncultivated land, drainage networks, rural
communities, and wildlife.
Primary productivity - Synthesis of organic materials (biomass) by green plants using the energy captured in
Ecological niche - The role an organism occupies and the function it performs in an ecosystem, specific to that particular
3.1.1 Factors influencing biodiversity
Globally, biodiversity levels vary widely across land and oceans. Both physical and human factors influence levels of
biodiversity and these factors operate at a variety of scales from local to global. Global physical factors such as
variations in climate, play a major role in controlling the presence or absence of limiting factors, such as:
Availability of light
Nutrient supply
An absence of limiting factors leads to high levels of primary productivity and the energy produced leads to high
levels of biodiversity. Conversely, where limiting factors are strongly evident, e.g. in cold temperatures such as the
Arctic, arid regions like deserts, darkness, etc. this will lead to low levels of biodiversity. The size of the area is another

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Hence the recent `size matters'
mantra, and the creation of huge transnational conservation areas such as the Peace Parks of Africa.
Locally, there are numerous factors that may have an impact on biodiversity:
Disturbance from a natural disaster e.g. hurricanes, volcanoes, tsunamis on both land and ocean ecosystems,
Asian tsunami 2004 ­ destroyed some mangrove forests
Quasi-natural disasters, e.g. wildfires (Victoria, Australia 2009), hunting, fishing, slash and burn farming
Eutrophication from high-tech agricultures
Physical factors Human factors
Climate, e.g.…read more

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The marine hotspots encompass future planning and
include some areas such as Chagos Island in the north Indian Ocean, which is currently a wilderness area with almost
pristine coral reefs. Here the threats are more global, with bleaching from global warming and the pursuit of specimens
for ornamental fish collections in the Far East.
3.1.3 The value of ecosystems
Ecosystems are of enormous value to human wellbeing because of the range of services and good that they offer.…read more

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GBO ­ 3 (Global Biodiversity Assesses the current status and trends of biodiversity to celebrate International Year
Outlook 3) www.cbd.int/gbo3 of Biodiversity in 2010. The Year of Biodiversity was marked by a world conference
in Aichi, Japan
3.2.…read more

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As a result of exploitation, many ecosystems are under threat. The state of biodiversity is such that 2010 was declared
the year of World Biodiversity in order to attempt to reverse the trend. Sustainable yield is a concept that is
increasingly used as a key to successful ecosystem management, especially for marine ecosystems.
Sustainable yield is the safe level of harvest that can be hunted, caught, utilized without detriment to the sustainable
management of an ecosystem.…read more

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Other NGOs' scientific Numerous NGOs support conservation and sustainable management schemes such as WWF in
research Udzungwa Forest, or Project Seahorse which carried out scientific research to manage marine
Local governments In the UK, they manage local reserves in cooperation with the Wildlife Trust and support
Biodiversity Action Plans
National There are various departments, such as DEFRA, which aim to provide a well-managed
governments, e.g. in countryside and conserve wildlife.…read more

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In-situ conservation to work alongside ex-situ conservation (e.g. seed banks, zoos, gene banks) in order to save
endangered species from extinction. Historically, some zoos experienced bad publicity with their conservation
role underrated Mechanics
There is potential conflict between top-down global strategies and other local, bottom-up initiatives and actions.
Indigenous people tend to value the biodiversity available to them. They rely on this for their subsistence and therefore
resent schemes imposed from afar.…read more

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A number of key players are involved in the future of biodiversity at all scales from global to local.…read more



thankyou so much!!!


your notes are amazingggggggggggggg

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