• Biodiversity is the?range and variety of different species?of organisms on?Earth, or within an?ecosystem
• It considers not only the?species richness?but the?variation?within each species, its?distribution?and?population size
  • E.g. a?high biodiversity?would be found in an environment with?lots of different species?which show?a lot of variation?and are living in,?all?evenly distributed?across the study area

   

• Many?human activities?are?reducing biodiversity?in individual ecosystems and on a global level
  • E.g. waste production, deforestation and global warming

   

The importance of biodiversity

• Different species depend on each other for:
  • Food
  • Shelter?(eg. birds nesting in trees)
  • Maintenance of the physical environment?(eg. tree roots provide stability for soils, ensuring they do not get washed away. This in turn provides a stable habitat for other plant species)

   

• High biodiversity ensures the stability of ecosystems by?reducing?the?dependence?of one species on another for these three things
• Populations?with high levels of diversity are also more likely to be resilient to sudden?environmental impacts or disease
• Consider the food web below:
  • If the mouse population was suddenly wiped out, the fox and the hawk populations might decrease but would not be wiped out as mice are?not their only food source
  • This example ecosystem has?sufficient biodiversity?to?support?the fox and hawk populations
  • The fox population can still?depend on?the rabbit and frog populations for food
  • The hawk population can still?depend on?the frog and sparrow populations for food

   

A food web demonstrates the importance of biodiversity within an ecosystem

We can investigate biodiversity with quadrats using a similar method to the one used when investigating population size

Apparatus

• 2 tape measures
• Quadrat
• Random number generator
• Species key

Method

• Use 2 tape measures to lay out your?first survey area?(e.g. 10m X 10m)
• Use a?random number generator?to create a set of coordinates to place your first quadrat
  • E.g. for coordinates 4,5, you would place your quadrat 4m along on the x-axis and 5m along on the y-axis

   

• Count the?number of different species?found within that quadrat
• Repeat this process until you have collected the data for?10 quadrats
• Repeat these steps for the?second survey area

The method for how to investigate biodiversity using a quadrat

Results

• The simplest indicator of biodiversity in this investigation is simply to compare the?number of different species?found in each survey area
• A higher level of biodiversity would be indicated by a larger number of different species found in that area
• However, this measurement of biodiversity is very simplistic as it doesn't tell us about the?distribution?or?population size?in either survey area
• As with species abundance, the biodiversity?is likely to be influenced by?biotic factors?such as:
  • Competition
  • Predator-prey relationships
  • Interactions with other organisms within the food chain or food web

   

• Biodiversity will also be influenced by?abiotic factors?such as:
  • Light intensity
  • Mineral availability
  • Water availability
  • pH
  • Temperature
  • Salinity

   

Limitations

• As with the previous investigation (comparing abundance in 2 study areas), it can be easy to?miss individual organisms?when counting in a quadrat, especially if they are covered by a different species
  • Solution: Use a?pencil?or stick to carefully?move leaves out of the way?to check if there is anything else underneath

   

• Identifying species or distinguishing between species?may be tricky
  • Solution: Use a?species key?to identify the species

   

Applying CORMS to practical work

• When working with practical investigations, remember to consider your CORMS evaluation

CORMS Evaluation

• In this investigation, your evaluation should look something like this:
  • C?- We are changing the?study area?where we are collecting the data
  • O?- We will count?plant species?each time (not animal, fungi etc)
  • R?- We will?repeat?the investigation several times to ensure reliability
  • M1?- We will count the?number of different plant species?found across all quadrats
  • M2 -??this isn't really relevant in this scenario
  • S?- We will control the?size of the quadrat,?the?random?way that quadrats are placed on the ground, the day that the results were collected