Measuring Biotic Factors

• Dichotomous key• Estimating abundance• Lincoln Index• Quadrats

Biotic…it’s alive!

• So when looking at an ecosystem, whilst in your amazing ecology quest…

• It is super important to identify the various species, and to do it correctly…– Otherwise your results & conclusions will be invalid (and

you will look like a fool)• Because you are probably not an expert in all the

species out there….There is a good chance you will not know which specific ones you are looking at.

• You will need a key…but not just any key…

A Dichotomous Key

• Dichotomous means divided into 2 parts. • Subconsciously you have already come to the realization that the word “Parts”

means steps. Because you really are just that smart!

• At each step, you are given options, normally 2, that are based on the species characteristics

• The option you chose will lead you to another set of options which you will chose from which will lead you to another set of options, and so on until you are able to determine the species.

• Remember those books…if you want Kate to go to the river, turn to page 2 if you want her to go back inside, turn to page 4

Dichotomous Key

• If 1 go to 4 if 2 go to 5…• Its basically that way of organizing information so

you can walk through identifying a species• Does it live in water or on land

If land…– Is it warm or cold blooded– If warm blooded does it have 2 legs or 4– 2 legs…does it fly? Yes…birdIt’s a very dumb and simple example but you get the point

Your Turn

• You will do a few things:1. familiarize yourselves with dichotomous keys

by using the website listed on your worksheet.

2. Answer the questions as you move through the DicoWebsite

3. Obtain 2 mystery keys and identify the species by using the key (don’t cheat)

Be Aware…

• You will need to be able to make a dichotomous key for up to 8 species