Edexcel A2 contested planet - Biodiversity

breif outline of everything on biodiversity


Defining Biodiversity

 genetic diversity = range of genes found in a particular species                                                          species diversity = variety of plant and animal species present in an ecosystem                                        ecosystem diversity = number of different ecosystems within a given area

factors influencing biodiversity

human:                                                                                  Global:

  • level of protection/managment                                      -  size of area
  • level of economic development                                     -  history and age
  • population growth                                                         -  Isolation
  • eutrophication/pollution                                                 -  lattiutde and altitude


  • succession
  • interaction between species
  • disturbance
  • dispersal and colonisation
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strongly correlated with lattitude -> highest levels in tropical areas (near to equator) 

gradual decrease in biodoversity towards higher lattitudes -> due to presence of limiting factors e.g. light


area containing a high number of endemic species

cover less that 2% of the Earths surface but contain 44% of the worlds known plant species and 35% of animal species

currently 34 hotpsots including 11 marine hotspots

e.g. New Zealand

—30,000 indigenous land species

—- 29 indigenous fish species - —8000 marine species

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Value of an ecosystem

provisoning services (goods) -> materails obtained directly from ecosystem e.g wood, usually sustainable

Regualting services -> carbon sinks -> vital for functioning of the Earth, also ecosystems can protect against flooding and soil erosion

Cultural services -> provide aesthetic and spiritual enjoyment and opportunities for recreation

Supporting services -> e.g nutrient cycling -> essential for ecsystem well being

e.g value of a coral reef (Great Barrier Reef, Australia)

—Occupies only 0.15% of marine environment, consists of 3000 reefs —                                                    

Home to over 25% of all known fish species —

Protects coastline from erosion -> acts as a wave break 

—Provides food for locals -> 25% of fish catch from coral reef                                                              

—Medicine -> new treatments for bacterial infections —Education and research —Tourist magnets

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Threats to biodiversity

factors influencing biodiversity

The WRI has identified major factors that influence biodiversity:

  • unsustainable population growth and natural resource consumption
  • inequality in ownership and management
  • lack of knowledge and understanding

Local factors:

deforestation -> cleared for farming or urbanisation

tourism -> lead to ecosystem degradation e.g. soil erosion

 eutrophication/pollution -> surface run off from farms due to use of fertilisers

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global factors:

climate change -> the stern review claimed that climate change is likely to occurr too rapidly for many species to adapt

phenological studies show that seasonal events such as flowering and egg laying have been advanced by several days

coral bleaching also shows that temperatures have increased

1 degree rise = 10% of land species face extinction, coral reef bleaching common

2 degree rise = 15-40% of land species face extinction, including 25-60% of South Africa's mammals, coral reefs bleach annualy

3 degree rise= 20-50% of land species face extinction, massive losses of hotspots, loss of coastal areas, coral reefs die

deforestation ->  clearance reduces biodiversity and resources for local people , knock on effects for food webs and nutrient cycling

pollution ->  acidificaiton of oceans, airbourne pollution and ozone depletion

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Disruption of ecosystem processes

energy flows -> primary producers convert light energy into chemical energy via photosynthesis, energy is lost through respiration at each stage 

human activity can affect energy flow by changing the number of organisms at each trophic level by huntung/harvesting

nutrient cycling -> circulation of chemicals through an ecosystem, when organisms die nutrients are returned to the soil where other organisms can use it

human activity can affect nutrient cycling by adding fertilisers which changes to chemical property of the soil -> can lead to eutrophication in lakes and streams

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Movement of species

world is becoming increasinlgy connected -> movement of species from one part of the world to another becoming increasingly common, often happens accidently

alien species have enhanced survival rates because:

  • have no natural predator
  • not susceptible to disease

therefore alien species reproduce and spread fast and can have many negative effects on native species

they can arrive by:

  • ship -> attach to the bottom of boats or in ballast water e.g. Zebra muscle arrived from North America form the Casparian region
  • air -> responsible for introducing snakes into Guam (pacific island)

e.g. Galapagos island -> introduced new species to encourage fishing and tourism                                

60% of endemic plants are endangered                                                                                                      

—490 new insect species (49 considered at risk of causing damage)

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Managing biodiversity

Sustainable yield

the 'safe' level of harvest without having a negative effect on the ecosystem

there are two measures to assess this yield:

  • maximum sustainable yield -> greatest yeild that can be taken without harming the ecosystem
  • optimum sustainable yield -> compromise due to lower yield but doesn't destroy aethetic value

e.g. Southern Ocean Fisheries (Antartica)

accounts for 10% of the worlds ocean

creation of the Antartic Treaty System has meant that fisheries are now sustainably managed 

before overfishing had lead to the extinction of several species of fin fish

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Economic development and ecosystem degradation

very closely linked together -> high economic development allows investment into protection and conservation strategies

so, low development means little money to invest in protection and high risk of environmental degradation

—Soufriere Marine Management Area (St Lucia) -> protected area

home to many coral reefs, local people work in fishing, tourism and aggriculture, tensions between rival stakeholders has lead to a decline in water quality, depletetion of fish stocks and pollution

SMMA was developed to reduce tensions, divided are into 5 sections:

  • marine reserve
  • yaught mooring
  • fishing priortity
  • recreational use
  • multiple use
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Masai Mara (Kenya) -> degraded area

masia people own the park but a breakdown in managemnt meant to a decline in grassland ecosystem health

park fees supposed to go towards protecting the reserve but it never reached them

in 2008 the council was replaced by a private organisation -> lead to better organisation and money was dontaed to got towards purchasing proper equipment e.g. radios and 4 wheel drive vehicles

Udzungwa National Park (African Mountains) -> pristine area

—276 tree species -> 50 endemic —55 mammals —250+ species of birds —Provides locals with food and medicine -> access is highly controlled adopted strategies from Tanzanian National Park -> sustainable bottom up strategies e.g. tree nurseries and fuel efficient stoves

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Key Players

TNCs - responsible to innovation and development of technology, companies increasingly using green manufacturing methods to improve publics perception, invest in schemes

Scientists/researchers - find new ways to improve conservation e.g. genetic banks

International organisations e.g. UN - introduce laws to protect species

NGOs e.g. WWF & Greenpeace - promote conservation and protection by using sustainable strategies

National Governments - act as regulators (enforce laws) and facilitators by investin/fund schemes and have postive incentives 

local communities - often dependent of ecosystems for basic materials e.g. traditional medicine, provide detailed local knowledge that can be used to chose the most appropitate schemes

individuals - develop ethical consumerism (chose to buy environmentally friendly products), influence supermarket behaviour

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Protection Strategies

total protection -> popular in 60's, areas are completely fenced off from outside world, strict access for scientists/researchers

criticised due to conflict over conservation and cutting people off, areas concentrate on specific species, barriers don't follow natural ecosystem borders

biosphere reserves -> large reserves connected by open corridors so species can move polewards due to global warming 

people argue that they should concentrate on hotspots due to high levels of biodiversity but WWF argues a wide variety is better

restoration -> ultimate conservation challenge, can be costly as sometimes involves creating ecosystems from scratch -> depends on the state of the ecosystem

conservation -> re-establish species into the wild by establishing a captive population e.g. Pandas, used to educate people about endangerd species, endenism and hotspots

CITES ->  international agreements between governments to ensure international trade in animals and plants is sustainable (doesn't threaten thier existence)

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several problems with current strategies -> only 12% of the Earths surface is designated for protection (less than 1% is marine), mainly due to a shortage of funding


WWFs predictions:

buisness as usual - increased ecological footprint, no reduction in overshoot (degree to which consumption exceeds biological capacities)

slow shift - gradually reduce footprint by developing sustainable policies, biological capacities recover by 2100

rapid reduction - use of radical polices to reduce footprint, elimination of overshoot by 2040

shrink and share - break down world into regions and share responsibility of controlling overshoot

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