Biodiversity Flashcards
Define ‘biodiversity’
The variety of species in an area, the variety of habitats and the variety of alleles.
Define ‘habitat biodiversity’
Give four examples of habitats
The number of different habitats within an area
E.g. woodlands, sand dunes, meadows, streams
Define ‘species biodiversity’
The number of different species living in a habitat (species richness)
The abundance of each species (species evenness)
Define ‘genetic biodiversity’
The variation of alleles within a species
Why is sampling important?
Extremely difficult and very time consuming to count every single individual of a species living in a habitat
Sampling provides an estimate of the total number of species living within an area - representative of whole habitat
State four sampling techniques
Random sampling
Opportunistic sampling
Stratified sampling
Systematic sampling
Explain random sampling
Give an example
Sample sites in habitat are randomly selected
E.g. sampling plants
- lay two 20m measuring tapes at 90’ angle to each
other
- randomly generate two numbers between 1-20 using
random num. generator
- two number act as coordinates to lay quadrat
Evaluate the use of random sampling
+ Avoids researcher bias
- May not cover all aspects of habitat equally
- Results may underestimate biodiversity as species
with lower presence may not be counted
Explain opportunistic sampling
Sample sites chosen by investigator
Evaluate opportunistic sampling
+ Easier and quicker than random sampling
- Biased data as researcher may be enticed to certain areas rather than others due to large/ colourful species
- Data may overestimate biodiversity as some areas
importance is overestimated
Describe stratified sampling
Different areas within habitat which appear different are identified, and separately sampled in proportion to their part of the habitat as a whole
Evaluate stratified sampling
+ All areas of habitat sampled
- so data does not underestimate biodiversity like
in ran. sampling as all species are counted for
- May lead to overrepresentation of some areas in sample
- i.e disproportionate number of samples taken in small areas that look different
Describe systematic sampling
Samples taken at fixed intervals across the habitat using line/ belt transects
Evaluate systematic sampling
+ Useful when habitat shows clear gradient of an environmental factor. E.g. land drier away from pond
- Species not on line missed - underrepresentation of biodiversity in data
How can species richness and species evenness be measured?
Species richness - Take random samples of habitat and count number of species
Species evenness - Take random samples of habitat and count number of individuals in each species
