Directions: Ecology is “The branch of biology concerned with the relations between organisms and their environment,” (http://wordnetweb.princeton.edu/perl/webwn?s=ecology).  Ecology deals with the big picture and research in ecology is often at the ecosystem level or even higher.  As such, ecological research is difficult – it is almost impossible to control all variables completely and you can almost never include an entire population of organisms in your study.  Ecological sampling techniques are necessary in order to conduct ecological studies.

Ecological sampling techniques allows a researcher to take samples of different populations of organisms, habitats or ecosystems and draw conclusions about the whole system from those samples.  The assumptions are that multiple samples are representative of the system as a whole and that samples are collected randomly.  A researcher cannot choose which areas of a system/which organism should be sampled.  A researcher instead must use random sampling to ensure fairness and reliability of results.  If the researcher is interested in looking at one area of an ecosystem with particular attributes, or at an environmental gradient, then systematic sampling (which is not necessarily random) may be appropriate in certain circumstances.

For this tutorial you are going to be looking at different sampling techniques used in ecological research.  You will read several articles and then answer the questions below.  You will then be using some of these techniques for data collection in class.  Read the articles and answer the questions carefully, and make sure that you ask if you have any questions!

Articles: Read all of the information in the articles below to understand random sampling, line transects and belt transects.

1. Ecological Sampling Methods: Random Sampling
2. Ecological Sampling Methods: Systematic Sampling – Line Transect
3. Ecological Sampling Methods: Systematic Sampling – Belt Transect

Questions: Answer the questions below on a separate sheet of paper.  You should keep these answers as they will help you choose the right sampling techniques for your field research.

1. List the benefits and limitations of random sampling using quadrats.
2. Explain why randomization is essential when using random sampling with quadrats.
3. Describe at least three differences between random sampling and systematic sampling.
4. Compare line transect sampling with belt transect sampling.
5. Explain why taking many samples from the same ecosystem is more reliable than only taking a few samples.