Biodiversity Flashcards
Biodiversity
The variety of living organisms present in an area
Habitat biodiversity
Number of different habitats found within an area
Species biodiversity
Number of species in a community
And is made up of 2 components:
-Species richness
-Species evenness
Genetic biodiversity
Variety of genes that make up a species
Random sampling
Selecting individuals by chance, each individual in population has equal likelihood of selection.
-samples in habitat randomly selected
-random numbers can be used as coordinates for position to sample
-quadrat use
Advantages and disadvantages of random sampling
Advantages
-avoids bias
Disadvantages
-may not cover all area
-species with low abundance may be missed (underestimating biodiversity)
Examples of non-random samping
Opportunistic, stratified, systematic
Opportunistic sampling
-uses organisms that are conveniently available
-researcher decides on areas to sample during process of collecting data
Advantages and disadvantages of opportunistic sampling
Advantages
-easier and quicker than random sampling
Disadvantages
-data biased and can lead to overestimate
Stratified sampling
-Study area is divided into non-overlapping sub-areas, and samples obtained from each sub-area
Advantages and disadvantages of stratified sampling
Advantages
-all areas sampled in habitat so less of underrepresentation
Disadvantages
-disproportionate numbers of samples means small areas may be overrepresented
Systematic sampling
Line transect:
-marking a line along the ground between two poles
-taking samples at specified points
-can include describing all organisms touching the line or distances of samples from line
Belt transect:
-2 parallel lines are marked, samples taken of area between the lines
Advantages and disadvantages of systematic sampling
Advantages
(line transect)
-only shows types of plants, not how many
(belt transect)
-provides more info
-No. and type of plant recorded
-shows how abiotic (non-living) factors affect distribution
Disadvantages
-only species on line recorded and other may be missed leading to underestimate
What is sampling used for
-estimating No. of organisms in an area without having to count them all
-used to measure a particular characteristic of an organism
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Sweep netting (to catch insect in long grass)
-walk through habitat with stout net
-sweep net through vegetation
-small animals caught
-empty onto white sheet to identify and count
Advantages and disadvantages of sweep netting
Advantages
-helps estimate biodiversity easily
Disadvantages
-cannot be used in wet, flattened or very short vegetated areas
-difficult to use in some trees or very tall/ dense vegetation
-species living very close to ground tend to be passed over
Pooter (to catch small insects)
-sucking on a mouthpiece, insects drawn into holding chamber via the inlet tube
-a filter before the mouthpiece prevents them from being sucked into mouth
Advantages and disadvantages of pooter
Advantages
-can be used in low vegetation and in water
-chamber can hold large samples of insects before needs to be emptied
Disadvantages
-predators small enough to be sucked in may affect other organisms in jar
Pitfall trap (to catch small, crawling invertebrates)
-hole dug in ground ->insects fall in
-must be deep enough so insects can’t crawl out
-covered with a roof-structure so doesn’t fill with rainwater
Advantages and disadvantages of pitfall trap
Advantages
-gives an estimate of biodiversity
Disadvantages
-not all organisms fall
-some may escape
