Measuring the distribution and abundance of organisms Flashcards
1
Q
How does distribution of organisms change?
A
- usually not even
- found where favourable abiotic and biotic factors favour them
- survival rate high as all the resources to live are available and predation pressure from consumers is low
2
Q
How is distribution measured?
A
- line transect
- tape then take samples at regular intervals
- belt transect
- two parallel lines marked and samples are taken of area between points
- systematic, non-random sampling
3
Q
What is the advantage of this systematic sampling?
A
- allow scientists to study how the differing abiotic factors in different areas of the habitate aaffect the distribution of a species
- e.g. in land from sea, view successional changes
4
Q
HOw does abundance of organsims change?
A
- increase
- immigration
- births
- decrease
- emigration
- deaths
5
Q
Why do you not count all members of a piopulation?
A
- couting process coulod damage environment
6
Q
How are accuracy of sampling techniques increased to estimate abundance?>
A
- almost never representative
- large sample size
- greater number of indiiiudlalds, lower the probability that chance will influence the result
- random sampling to reduce change of bias
7
Q
How is plant abundance measured?
A
- quadrates placed randomly in area
- count indiviudals
- estimated population number m-2 = number of individuals in sample / area
8
Q
How is animal anundance measured?
A
- quadrats used for slow moving
- capture mark release recapture
- capture as many in sample area
- mark or tag
- release - allow time for residstribution
- recapture as many individual in sample area
- record number of marked and unmarked individual present in the sampel
9
Q
How is animal abundance calculated?
A
- Lincoln index
- estimated population size = (number of individuals in first sample x number of indiviudals in second sample) / number of recaptured marked individuals
