investigating populations

types of sampling

random and systematic

random sampling happens between

contrasting habitats

systematic sampling happens when there is

uneven distribution

what is a point quadrat

at set intervals along the horizontal bar there are ten holes, in which a long pin is placed. Species that touch pin are counted.

what is a frame quadrat

square frame divided equal subdivisions with string or wire, abundance within each quadrant is recorded

What are the factors to consider when using quadrats

• size of quadrat- depend on size of plant/animal counted + how they are distributed within the area

• the number of sample quadrats to record within the study area- needed for reliable results

• the position of the quadrat- random sampling

what should you do when species are not evenly distributed within an area?

a large number of sample quadrat will provide a more representative result

How to obtain a random sample

• lay down two long tape measures at right angles along two sides of the study area

• random number generator to obtain random coordinates

• place quadrat at intersection of coordinates obtained

belt transect is used when

there is a form of gradual change in the community

How is a belt transect used

• stretch a tape across the ground in a straight line, frame quadrat is placed alongside the line , recording the species within it,moves along , repeating measurements

What can be measured in quadrats (A/D)

• frequency- likelihood of a species occurring in a quadrat, hard to count, general distribution + quick, does suggest density and detailed distribution

• percentage cover- estimate of the area within the quadrat a particular plant species occurs, difficult to count, data collection rapid, less useful when overlapping layers