Lichen Lab - Lost e-mail ?

Andy Dyson andy at biology.demon.co.uk
Sat Dec 16 05:32:53 EST 1995


Hello everyone 

Many people heve requested details and I have sent many already.
However I seemed to have lost some e-mail along the way. If you sent
me a request and did not get a reply then please accept my apologies.
To ensure everyone can get a copy of the details here is what you
would heve recieved.:

Lichen Practical (Lab for colleagues 'across the pond')

The following exercise is based on lichen and conditions in the UK and
therefore may need slight modification to account for local
differences.


Two good lichens to study are Xanthoria parientina (a Yellow-Orange
variety) and Parmelia sulcata (Blue-Grey), both of these grow in a
circular pattern and therefore are useful for our purposes.

X parientina is fairly resistant to pollution and is common in the UK
at least, it can grow at rates of about 2.5mm (radial growth) per
year. P sulcata is equally tolerant but grows at about 1.2 to 2.2 mm
per year. The exercise depends on the assumption that the largest
specimen on the rock/gravestone colonised  soon after exposure.  Armed
with a hand lens and suitable measuring devises the students set about
recording the diameter of lichen on graves stones of known age. They
must then construct a calibration curve and from that a growth rate
can be calculated.

There are many factors which can affect the growth rate and I
encourage the students to comment on the possible errors with their
calculations.

A competition can then be set up whereby the students have to date a
building or monument based solely on the lichen growth and their own
calibration curve. (It helps if you have the exact age of the building
etc. from local records)


If you need more details or have any practicals/labs which you use to
'encourage' students the would be gratefully recieved.


Andy Dyson

andy at biology.demon.co.uk




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