sampling in ecology Flashcards
why do we sample?
= sampling is more time efficient, butis more accurtae
= random sampling in uniform areas to eliminate bias
= line transects to examine a change in distance
= large number of samples 30+
what is random sampling used for?
= a plant or a slow moving animal
= used to estimate population that are evenly distrubuted
= line 2 tape measures at right angle to create a grid
= use a random number generator, to generate two coordinates
= place the quadrat and collect the data
= repeat at least 30 times- represenative sample and calculate a mean
=
What is a line transect used for?
= used to estimate population sizes, when they are unevly disturbuted
= place the transect at rught anglrs to the shore line, pkac the wuadrat at every 5 m
= collect the sata
= repeat by placing another 0 traaudrats on the transect
How to calculate local frequency?
= percenatge of squaes with the species present
= as there are 100 squares we represent as a percentage
% local frequency repeat 30 times and calculate the mean and whatever the percenyage is the estomate for the entitrefield
How do we find the density?
% the number of one species in a given area
= the size of the field/ the size of the quadrat
= x the number of one species
What is percenyage cover?
= porportion of the ground occupied by the species
What are the advantages and disadvantages of local frequency?
= quick method to sample a large area
= useful if difficult to identify indivual organism
= poor accuracy doesnt consider overlap
= plants or the size of plans
what are the advantages and disadvantages of density?
= more accurate if you can easily distinguish an indivual plant,
= there are not too many to count
= can be used to estimate species richess,
= more time consuming
What are the advantages and disadvantages of percentage coverage?
= quicker method than density useful if too difficult to idensity individual organism
= subjectivve limitive accuracy
= doesnt consider overlapping plants or size of plants
