biodiversity

• • Biodiversity can be thought of as the variation that exists within and between all forms of life
• • Biodiversity looks at the range and variety of genes, species and habitats within a particular region
• • Biodiversity is very important for the resilience of ecosystems, in that it allows them to resist changes in the environment
• ecosystems


  all living and non-living components of particular area
• Ecosystem or habitat diversity

  • This is the range of different ecosystems or habitats within a particular area or region
  • If there is a large number of different habitats within an area, then that area has high biodiversity
  • A good example of this is a coral reef. They are very complex with lots of microhabitats and niches to be exploited
  • If there is only one or two different habitats then an area has low biodiversity
  • Large sandy deserts typically have very low biodiversity as the conditions are basically the same throughout the whole area
• Species diversity

  • The mix of different species that exist within a particular area or region can be measured to indicate levels of biodiversity
• species diversity

  It can be measured in different ways: species richness and species diversity

  species richness is the number of species within a community

  Species diversity looks at the number of different species in a community, and also the evenness of abundance across the different species present
• • The greater the number of species in an ecosystem, and the more evenly distributed the number of organisms is among each species, then the greater the species diversity
• community

  multiple populations of different species living and interacting in same area
• Ecosystems with high species diversity are usually more stable than those with lower species diversity as they are more resilient to environmental changes
• Maintaining biodiversity

  • There are many different reasons why maintaining biodiversity is beneficial
  • Biodiversity impacts all organisms (including humans) on a global scale
• reasons for maintaining biodiversity

  • moral and ethical: humans have a responsibility to reduce impact on planet and other species
  • ecological: biodiversity increases stability of ecosystems
  • environmental: organisms provide essential environmental services (water, nutrient cycle and absorption of carbon dioxide)
  • economic: range of organisms contributing to medicine, ecotourism, science, technology
  • aesthetic: visual beauty
  • agriculture: genetically diverse wild species can rescue crops from catastrophes
• Species richness is the number of species within a community
• • A community is a group of populations of different species living in the same place at the same time that interact with each other
• • Species richness is the simplest way to measure species diversity
• • Conservationists often favour the use of an index of diversity as it takes into account species number and evenness
• • Once the abundance of different species in an area has been recorded the results can be used to calculate the species diversity or biodiversity for that area
  • Species diversity looks at the number of different species in an area but also the evenness of abundance across the different species
  • An index of diversity is a measurement that describes the relationship between the number of species present and how each species contributes to the total number of organisms that are present in that community
• $d=$$N(N-1)/Σn(n-1)$

  calculating index diversity

  • n=total no. of organisms for a single species in community
  • N= total no. of organisms in community
  • Σ= sum of
  • larger number obtained, means higher level of diversity
• modern farming practices:

  • Farms became more specialised so they grew only one crop or raised one type of livestock (monoculture)
  • There was a switch to growing cereal crops rather than vegetables
  • Fields were made bigger to accommodate machinery via the removal of hedgerows and stonewalls
  • More land was made arable by draining wetland and filling in ponds
  • The use of pesticides and fertilizers massively increased
• Biodiversity


  The range and variety of genes, species and habitats within a particular region
• In relation to farming the biodiversity of insect, animal and plant species is often measured and studied
• Some modern farming techniques have had a major negative impact on the level of biodiversity present in farming areas
• Conservationists have made strong efforts to try and maintain or improve biodiversity around farmlands
• Rewilding

  1. Removing all human interference

  2. Reintroducing native species
• Organic farming has been largely promoted and encouraged
• Nutritious, fast-growing grass

  Essential for raising healthy livestock
• A dairy cow is capable of eating almost 20kg of dry biomass in one day
• Grazing pasture

  • Mixture of ryegrass and white clover species
  • Grows on drained, fertilised land
• Improving grazing land

  1. Farmers deliberately fertilise and drain the land

  2. Sow the seeds of ryegrass and white clover species
• Other plant species

  Either outcompeted or the changes to the land mean it is no longer a suitable habitat for them
• Natural grazing land that hasn't been interfered with

  • Large variety of plant species present
  • Can support a much greater range and number of insect species and bird species
• Wet grasslands have declined steeply in the last 100 years and are now regarded as biodiversity hotspots
• Ploughing and harvesting of crops

  • Points in the year when food is plentiful for farmland bird species
• Ploughing


  Brings invertebrates to the surface
• Harvesting

  Provides spilt grain from the crops and seeds from weeds, as well as making invertebrates more accessible by removing their cover
• Traditional crop sowing

  1. Plough fields in March

  2. Sow grains in late April

  3. Harvest in September
• The gap between harvesting and ploughing was significant - five or six months
• Modern farming crop sowing


  1. Plough fields in August

  2. Sow grains in September

  3. Harvest in July
• The gap between harvesting and ploughing is very short - one or two weeks
• Shorter gap between harvesting and ploughing


  Very short period of time during the year when food is plentiful for birds