B6.1.1 & 6.1.2 Sampling Flashcards
Sampling?
Taking observations/ measurements from a small area which are representative of a larger area.
Pooter
Jars with rubber bungs sealing the top, two tubes stuck through the bung, one with net/mesh on
Suck on mouthpiece with net on end to trap insects into chamber from other tube.
Sweep nets
Sweep large net through air to catch flying insects
Kick sampling
Kick a river bed/bank to disturb habitat, hold net downstream to capture any organisms released into flowing water
Tree beating
Stretch a large white cloth under tree/bush, shake or beat tree to dislodge invertebrates which will fall into cloth
Pitfall traps
Steep sided containers sunk into hole in ground, cover hole with roof so it doesn’t fill with rain water, traps crawling invertebrates
Sampling animals
Capture-recapture technique:
- capture organisms from sample area
- mark individuals
- release back into community
- later recapture organisms
- record unmarked and marked organisms caught
Capture recapture equation
Estimated population size =
(first sample size X second sample size)/marked recaptured individuals
How to identify unknown organisms?
- Branched key (spider diagram)
2. Numbered key (dichotomous key)
How to sample plants?
Quadrat
Quadrat
A square frame divided into a grid of smaller same sized squares
Place onto ground and record how many of organism in each square
Estimated population
=mean population per m2 X total area
When to use non-random sampling?
When looking at distribution of an organism over a distance
How to random sampling?
Use random number generator to determine coordinates of where to place quadrat, preventing bias
Transect
A line across a habitat, along which samples are taken
