Expert: Florence M Rollwagen - 5/3/2008

Question
QUESTION: i need help for my extended essay and i'm not sure how im gonna carry out my experiment for this particular topic on the distribution and growth of lichens on urban pavements. any pointers? its considered under biology right?

ANSWER: Hi Vernon:  Thanks for your question.

A lichen is a mutualistic pair organisms consisting of an alga and a fungus.  Usually, you find them on tree trunks and rocks.  They are very sensitive to urban pollution, which is probably why you're asking this question.  Lichens can be considered a "canary in a coal mine" because they are indicators of pollution.

So, is this an essay or an experiment?  You mention both in your question.  

If it's an essay, just look up "lichens urban pavement" and you will get lots of information.

If it's an experiment or survey, you'll have to do much more work searching the environment for lichens.

I know you want me to write your essay for you, but I won't do that.  Look up some of the sources on the internet and ask me more questions.

FM Rollwagen, PhD

---------- FOLLOW-UP ----------

QUESTION: its an essay but i have to do experiments too to back up my essay. no not asking you to but just wondering how am i gonna test for the gases, for instance, sulphur dioxide concentration in the particular area, and how to correlation it to the lichen growth in the specific area.

Answer
AHA, that explains it!  Testing for gases in the atmosphere is far too complicated for a study of this type.  Perhaps you can estimate the pollution levels in various ways.  For example, the amount of traffic per hour.   Or proximity to factories, coal plants or other.  I don't know where you live, but try to look in a number of different locations and try to estimate the number, size and variability of the lichens found there.  Make sure to keep accurate records, such as date and time, weather conditions (temp, humidity), suspected pollutants.  Measure the diameter of the lichens, record their color.  Probably it will take a number of weeks to do this project, perhaps the whole summer!

This is about the right time of the year to do this (assuming you don't live in Minnessota or Maine!), since the weather is turning nice and it's been wet.

You can get some climate estimates at
the National Oceanic and Atmospheric Administration
www.noaa.gov
and
the Environmental Protection Agency
http://www.epa.gov/ttn/chief/net/2002inventory.html

You'll have to hunt around on these sites for your area and what information you want.  It's the government, so it's complicated!

Hope this helps.  You can check with your teacher about your approach to the problem.

FM Rollwagen, PhD