11) Biodiversity

• biodiversity:

  • the variety of living things found in an area
  • includes all living organisms
  • organisms are interconnected, they depend on each other
  • generally higher in areas near the equator (rainforests)
• importance of biodiversity:

  • maintaining the balance of the ecosystem
  • recycling and storage of nutrients
  • combatting pollution
  • stabilising climate
  • protecting water resources
  • forming and protecting soil
  • maintaining eco-balance
• main importance of biodiversity:

  • genetic variation
  • interdependence
• habitat diversity - refers to the number of different habitats within an area
• species diversity:

  species richness - the number of different species living within a particular area

  species evenness - a comparison of the number of individuals of each species within a community
• genetic diversity - the variety of genes that make up a species
• measuring biodiversity:

  • distribution
  • abundance
  • quadrats
  • transects
• measuring abundance:

  • percentage cover (quadrat)
  • abundance scale

  ACFOR scale: abundance, common, frequent, occasional & rare

  • species frequency
• non-random sampling:

  opportunistic - weakest form, uses organisms that are readily available

  stratified - population divided into subgroups. A sample of a subgroup is then taken to estimate its size

  systematic - can be done with line transects or belt transect
• Simpsons diversity index:

  D = 1-(Σ(n/N)²)

  n - number of individuals of a particular species

  N - total number of all individuals of all species

  the closer to 1 the higher the diversity
• species - a group of similar organisms able to reproduce to give fertile offspring
• 3 levels of biodiversity

  species diversity - the number of different species and the abundance of each species in an area

  genetic diversity - variation of alleles within a species

  habitat diversity - number of different habitats in an area e.g beaches, sand dunes, mudflats etc
• factors increasing genetic biodiversity

  mutation - new alleles are creating increasing genetic diversity

  interbreeding - alleles are transferred between the two populations (gene flow) increasing genetic diversity
• factors decreasing genetic biodiversity

  • genetic bottlenecks - few individuals within population survive an event or change - reduce gene pool
  • founder effect - a small number of individuals migrate away or become isolated from population, gene pool is small
  • genetic drift - alleles randomly passed through generations & some may disappear by chance
• factors decreasing genetic biodiversity

  • selective breeding (artificial selection) - humans choose organisms with advantageous characteristics
  • captive breeding - programmes in zoos, where a small number of individuals are bred in captivity
  • artificial cloning - using asexual reproduction to produce large numbers of a particular species
  • natural selection - species evolve to contain primarily the alleles which code for advantageous characteristics
• measuring genetic biodiversity

  • measuring polymorphism
  • polymorphic genes have more than one allele e.g blood type

  proportion of polymorphic gene loci = number of polymorphic gene loci/total number of loci

  the greater the proportion of polymorphic gene loci, the greater the genetic biodiversity within the population
• human factors affecting biodiversity

  • deforestation
  • agriculture - large amount of land cleared and some planted with a single crop (monoculture)
  • climate change
• impact of climate on biodiversity

  • variation in the earths climate
  • a change in climate means that an area previously inhabitable becomes inhabitable
  • may cause a decrease or increase in the range of some species
  • some species may be forced to migrate or become extinct
  • e.g melting of ice caps = extinction of the few plants & animals living in these regions
  • rising sea levels from melting ice caps & thermal expansion = flood low lying land - reduce availability for terrestrial habitats
  • higher temperatures & less rainfall = plant species failing to survive, xerophytes become more dominant
• impact of deforestation on biodiversity

  • directly reduces the number of trees present in an area
  • if only a specific type of tree is felled, the species diversity is reduced
  • reduces the number of animal species present in an area as it destroys their habitat, this reduces the number of animal species
  • animals are forced to migrate to other area to ensure their survival
• impact of agriculture on biodiversity

  farmers try to maximise the amount of food and yield that they can produce from a given area of land

  reducing biodiversity:

  deforestation - increase area of land available for growing crops or rearing animals

  hedgerow removal - turn small fields in large fields - use large machinery

  pesticides - chemicals that kill pests that feed on crops - reduces species diversity

  herbicides - chemicals that kill unwanted plants e.g weeds - reduce plant diversity & animal diversity for those feeding on weeds

  monoculture - grow fields with one type of plant
• maintaining biodiversity

  economic reasons

  • food and drink - plants and animals are the source of almost all food and drinks
  • clothing - fibres and plastics are made from plants and animals
  • drugs - many are made from compounds from plants
  • fuels - produce renewable fuels
  • regulation of atmosphere and climate
  • industry and raw materials like timber
  • wildlife and natural scenery is a source of income e.g ecotourism
• maintaining biodiversity

  ecological reasons

  • disruption of food chains and species are interdependent on one another
  • disruption of nutrient cycles e.g decomposers like worms improve quality of soil by recycling nutrients. If worm numbers decline, soil quality will be affected. This will affect the growth of plants and amount of food available to animals
  • key stone species are vital - keep ecosystems balanced
  • loss of habitats
  • habitat destruction can also affect climate
• maintaining biodiversity

  ethical reasons

  • organisms have the right to exist
  • moral responsibility to conserve biodiversity for future human generations
• maintaining biodiversity

  aesthetic reasons

  • areas rich in biodiversity provide a pleasant, attractive environment that people can enjoy
  • recover more rapidly from stress and injury
  • more visitors = economic advanatages
• maintaining biodiversity - agriculture

  • protection against disasters
  • pest control
  • source of food
  • pollinators
  • new varieties
• conservation - preservation and careful management of the environment and of natural resources
• in situ conservation - protects species in their natural environment
• in situ conservation

  • national parks and wildlife reserves - controlling grazing, restricting human access, feeding animals
  • marine conservation zones - such as coral reefs
• advantages of in situ conservation

  • species and habitat conserved
  • larger populations can be sustained
  • chances of recovery greater than ex situ conservation
  • scientific research
• disadvantages of in situ conservation

  • climate change still remains at risk
• ex situ conservation - relocating species that are facing threat
• ex situ conservation

  • relocation to safer area
  • captive breeding - create a stable, healthy population of a species and then reintroduced species back into natural environment
  • botanic gardens - plants grown successfully (provided with the best resources to grow such as soil nutrients and water availability)
  • seed banks - seeds can be frozen and stored in seed banks without losing their fertility
• ex situ advantages

  • predation and hunting more easily managed
  • reduce chance of extinction
  • reintroduction into the wild
• ex situ disadvantages

  • only small number of individuals cared for
  • difficult and expensive to sustain the right environment
  • less successful than in situ
  • struggle to survive when reintroduced into natural environment
• conservation agreements

  international union for the conservation of nature (IUCN)

  • assist in securing agreements between nations
  • publish a red list detailing current conservation status of threatened animals
  • involved in establishing international trade in endangered species (CITES) - increase international cooperation in regulating trade in wild animals and plant specimens
• conservation agreements

  rio convention

  • aims to develop international strategies on the conservation of biodiversity and how to use animal and plant resources in a sustainable way
  • convention made it part of international law that conserving biodiversity is everyones responsibility
  • provides guidance to governments on how to conserve biodiversity
• conservation agreements

  countryside stewardship scheme

  at a local level

  • Protecting hedgerows.
  • Grazing control.
  • creating wildlife habitats
  • sustaining beauty and diversity of the landscape
  • restoring neglected land