Sampling Organisms Flashcards

All 6 cards in this deck

What is the equation for the mean number of organisms per quadrat?

mean number per quadrat = total number of organisms counted ÷ number of quadrats

How do you estimate the total population of an organism in an area from quadrat data?

Multiply the mean number of organisms per $1\ \mathrm{m^2}$ quadrat by the total area in $\mathrm{m^2}$.

What are the steps to use a belt transect to investigate how light intensity affects plant growth?

e.g. stinging nettles at the edge of a wood

1. Lay a tape measure in a line at 90° from the edge of the wood.
2. Place a quadrat against the line and measure light intensity with a light meter.
3. Record the growth of the nettles (e.g. height or number of plants) in the quadrat, then move along the line and repeat at different distances.

Give two ways to improve the quality of data from a quadrat sampling investigation.

Use more (or larger) quadrats and sample other areas of the habitat; also repeat on different dates and calculate a mean.

True or false? Quadrats should be placed where you can see the most organisms.

False. Quadrats must be placed randomly so the sample is representative and unbiased.

What is a belt transect used to investigate?

How the distribution or abundance of a species changes across a habitat along a gradient in an abiotic factor, e.g. light intensity from shade into full sun.