exp 1.4 to carry out a quantitative survey of plants Flashcards
grid quadrat
square frame subdivided by wire/strings
limitations of grid quadrats
can only be used for small plants
fast moving animals wont stay in them
trees wont fit
how to use the quadrat to measure percentage cover and frequency
place quadrat randomly
repeat 9 times so there are 10 quadrats in total
how do we ensure quadrats are placed randomly
throw a pencil over your shoulder and place quadrat where it lands
percentage cover
an estimate of the amount of ground in a quadrat is covered by each species
how do you calculate the percentage cover
count the number of times each plant touches the point of intersection of each small square
express this figure as a percentage of the total grid points
frequency
the chance of finding a named species in any one throw of a quadrat
disadvantages of frequency
dependent on organism and quadrat size
assumes that organisms are evenly distributed
formula for calculating frequency
no of quadrats containing plant divided by the total no of quadrats x 100
line transect
rope market at intervals- record what touches the line and measure environmental conditions at each
disadvantages of line transects
not random as you choose where you place them
when are line transects usually used
when studying the changes in organisms as you go from shaded region to a more open field
