assessing species diversity

types of sampling

random and systematic sampling

random sampling

should be used when an area looks reasonably uniform…there is no clear pattern as to where the species are distributed…avoids bias

quadrats

a square frame that marks off areas of ground or water…used to measure species presence and abundance

species frequency

measure of chance of a particular species being found within any quadrat

species density

measure of how many individuals there are per unit area

percentage cover

the percentage of area inside the quadrat that is occupied by each species

mark-release recapture

estimates the population size of mobile organisms

steps to mark-release-recapture

catch as many organsisms as possible and mark them safely…count them and release them back into their habitats to free mix…after sometime recapture a large sample…count the number of marked and unmarked individuals

estimated number in population formula

intial marked X number of marked and unmarked / number of secondary marked

systematic sampling

investigates species distribution when physical conditions change

line transect

record the identity of organisms that touch the line at set distances…shown as drawing

belt transect

place quadrats at regular intervals along line…record abundance of species within quadrat…shown as bar chart or kite diagram

correlation

plot a scatter graph

strength of corelation

how close the points are to the straight line

pearsons correlation coefficient

used for 2 sets of data which is continuous and normally distributed

spearmans rank correlation

independant data which is correlated but not linear…rank data for each variable and assess the difference between the rankings…make a null hypothesis