Sampling Organisms Flashcards
All 7 cards in this deck
How is the size of a population estimated from quadrat samples?
population size = mean number of organisms per m² (from the quadrats) × total area of the habitat (m²)
How is randomness achieved when choosing where to place quadrats?
Use a random number generator to give random coordinates for the quadrat positions.
What is a belt transect used to investigate?
How the distribution of organisms changes across a habitat along an abiotic gradient, e.g. light intensity away from a wood.
What are the steps to carry out a belt transect?
e.g. nettle growth as light intensity changes away from a wood
- Lay a tape measure/rope in a line across the habitat.
- Place a quadrat at measured intervals along it and record the nettles in each.
- Measure light intensity at each distance with a light meter.
Name the instruments used to measure light intensity, temperature and soil water in a habitat.
Light/lux meter, thermometer and water (moisture) meter or sensor.
True or false? Taking more quadrat samples makes the estimate of population size more reliable.
True. A larger sample size reduces the effect of anomalies and makes the mean more representative.
In quadrat sampling, what is percentage cover and when is it used?
An estimate of the percentage of the quadrat's area covered by one species. It is used when individuals are hard to count, e.g. grass or moss.