Final 1: The Wonderful World of Lichens

Introduction
The main purpose of our research was to determine how the growth of
lichens is affected when exposed to air pollutants. We planned to conduct a
full-scale study, researching the different types of area lichens and the kinds
of environments they thrive in. We decided to study lichens for our final
project because we all share a common fascination with nature and concern
for the affects of pollution on our environment. We hypothesized that all
types of lichen are indeed adversely affected when exposed to air pollution
There are five specific questions that we formulated to help us get
started on our research. First of all, we wanted to find out the ideal type of
environment in which lichens grow. Secondly, we wanted to find out how to
identify lichens. Obviously, we needed to know what they look like. In
addition, we hoped to find out the effects of temperature changes on lichens.
Would our study still be valid if it was freezing cold outside? We wanted to
study the growth patterns of them. How fast do they grow? How long do
lichens live? We also wished to be able to identify the three different types
of lichens (crustos, folios, fruiticose) and the differences between them. Most
importantly, we needed to find out what the effects of air pollution and
certain chemicals are on lichens. This question was central to our hypothesis
and we felt it would help us form a more valid conclusion. We decided on
these specific questions because we feel they are essential to the overall
understanding of lichens and our project.
We were concerned about the effects of pollution on our environment,
and we hoped to show the lab participants how the growth of lichen
decreases in the midst of automobile pollution. The more research
conducted, the better the chance humanity will have to find a solution to the
problem of pollutants in the air. Our project is relevant because it is essential
to a better understanding of the effects of pollution on nature.

Relevance
We selected three references from the many we have found that deal
with our lab. Most involve Internet resources from science journals but we
have also found some reference books as below stated.
In the book Lichens of North America, by Irwin M. Brado, Sylvia Duran
Sharnoff, and Stephen Sharnoff (Yale University Press, 1997), several studies
on the effects of pollution on lichens were conducted. We discovered that
scientists on occasion use lichens themselves to study the air quality. In one
specific study, nearly 80% of the original lichen species were found to be
missing from the Indiana Dunes National Lakeshore.
B.W. Ferryís book entitled, Air Pollution and Lichens (Athlone Press,
1973), gives an extensive commentary on how pollution alters the growth and
chemical makeup of certain lichens. We learned from his book that it has
been successfully proven that certain lichens are changed by the affects of
air pollution.
We also found an extremely informative website named Lichen.com.
This helped us in finding what the three main types of lichen actually look
like and what factors differentiate them.
Our research relates to the larger question of global pollution and how
it negatively affects all living things in general. We hope that in some way,
our research will promote further exploration in the way chemicals brought
on by pollution can be quelled, so that wildlife will not be destroyed.

Materials and Methods
For this lab, we constructed an experimental design to determine the
quantities of lichens and how they were affected in certain areas. First, we
determined that in order to conduct a thorough experiment, we had to
choose trees from three different general locations on the campus. We
decided that these areas should be different so that we could take
observations from places in which there might be varying amounts of lichen.
For instance, lichens growing near a road would be more susceptible to air
pollutants because of heavy traffic flow and exhaust. Lichens growing in a
secluded field away from congested traffic might be less prone to the same
type of pollution constantly exposed to the other type of lichens. We
selected three different locations in Oxford. The first area was Pfeffer Park,
an area in which there would be absolutely no traffic, and therefore, less
overall pollution. The second area was near McKee Hall on Western
Campus, an area of relatively minimal traffic. The third area was along
Patterson Avenue, near a busy intersection where there would most likely be
the highest amount of air pollution.
For the student-generated lab, we needed a few materials: twenty
meter-long pieces of string, colored markers, and measuring tape. First, we
identified and marked five random trees in each of the three areas. We
measured one meter up on the tree and attached a string to the side which
we perceived had the highest amount of lichen. Then we proceeded to
examine the different types of lichens and identify which ones were present.
After these observations, we continued by labeling the string with a colored
marker which corresponded to the type of lichen we identified. We marked
the string according to how much lichen was present on the tree. In this way,
we were able to compare the amounts of the different types of lichen we
found, and how much lichen we discovered overall in each area.
Prior to taking the class out to the three sites, we introduced to them
the goals of our lab and the three different types of lichen. On our
worksheet, appropriately titled ìFun with Lichens,î we recorded the species
of tree that we examined, the location, circumference, and the types of lichen
that were present. The three of us then determined the percentage of the
meter-length of the tree that was covered in the different types of lichen, and
arrived at our results.

Results
Our results were not exactly what we had hoped for or imagined we
would discover. Although trees in the high traffic area (US highway 27 along
Patterson Avenue) proved to have less lichen growth than those in minimal
traffic (along Western Drive) and no traffic area (Pfeffer Park), there was not
as great a difference as we had hypothesized before the experiment.
Surprisingly, trees in the low traffic zone rather than the no traffic zone
yielded the most lichens, although the difference in numbers was more or
less insignificant.
As for the types of lichens encountered on the trees, we did find a
significant difference in the amount of lichen growth located on trees near
Patterson Avenue versus the trees in Pfeffer Park and along Western Drive.
There were traces of lichens in the heavy traffic area, but in the minimal and
no traffic locations there was a greater abundance of lichens. Another
difference we discovered that occurred in the latter areas was that Pfeffer
park had much more of the foliose type of lichen than in any other location
that we researched. On the contrary, the trees along Western Drive had a
multitude of the crustose group of lichens. This added to our intrigue of how
lichens are altered by air pollutants. Why would there be more crustose in a
minimal traffic location and more foliose in an area with no traffic?
Obviously, with the short amount of time allotted and the small amount of
resources we used, we were not able to further our investigation on this and
other inquiries. Another question we shared involved the fact that none of
the fruiticose type of lichens were apparent in our research.
We used the ANOVA test to decide if there was a significant difference
between the growth of crustose and fruticose lichens. The P-value which we
received was .0043. Since it is below the number .05, we could not accept
our null hypothesis. The null hypothesis stated that there would be no
significant difference in lichens no matter what location the trees were in.
Other ANOVA tests between lichen locations revealed that there is a small
difference in lichen growth in the areas we researched. We were content
with these results because they coincided with our preliminary
presumptions. The only information that did not correspond with our first
hypotheses was the fact that the ANOVA test revealed that there was actually
more lichen growth in the minimal traffic area than in the area with no traffic
at all. Our first reaction was that the trees in Pfeffer Park were exposed to a
much higher amount of direct sunlight than the trees on Western Drive. The
trees in Pfeffer Park that were surrounded by shade did have a much higher
abundance of lichen and we believe that those in immediate sunlight more
than likely inaccurately affected the outcome of our results. Other than a
small amount of error involved with our research, the outcome we received
was enough information and proof to partially corroborate our prior
expectations.

Discussion & Conclusions:
Because of our research prior to our experiments for this lab, some
results we obtained were not all too unexpected. We were not expecting to
find any of the fruiticose type of lichen because we learned that it is much
more rare and harder to find in the Oxford area than the other two types
which we researched. We also researched how air pollution specifically
affects lichen populations and found several interesting pieces of
information. First of all, we found that the air pollutant Sulfur Dioxide (SO2)
does the most widespread damage to lower plants, even though it is only one
of several air pollution components in the atmosphere. SO2 is the result of
mostly city and industrial pollution. We also discovered that the reason
lichens are affected by pollution is because they act like sponges. They take
in everything that is dissolved in the rainwater and retain it. Lichens have a
very unusual makeup compared to many other green plants. They are a
combination of algae and fungus. Because of their exceptional composition,
lichens have extraordinary reactions to certain natural events. Since there is
no way to eliminate sulfur dioxide, the sulfur content accumulates within the
lichen and reaches a level where it breaks down the chlorophyll molecules
which are responsible for photosynthesis in the algae. Photosynthesis is the
process green plants use to convert sunlight energy to chemical energy
which in turn is used by the plant. We found that in the case of lichens, when
the photosynthetic process stops in the algae, the algae die and lead to the
death of the fungus.

Were we to do the experiment over, we would change a few aspects of
our research. For one thing, we would study more trees per area. It is very
likely that five trees per traffic area do not provide enough data to accurately
discern whether or not air pollution plays a large roll in lichen growth on
area trees. More trees would have also helped keep the test more random.
In retrospect, one spring per tree is not a very thorough study of lichen
growth. Perhaps if we used more strings and hung them at more random
points, we would have received more accurate results of the total growth of
lichens.
We could also have been more precise with the measurement of the
strings, and marking them for lichen growth. Because the marks on the
strings were so spread out and tiny at times, we had to estimate lengths at
times and add them together.
Finally, we noticed while measuring that lichens appeared to grow in
abundance in shady areas and less so in areas affected by direct sunlight.
This may have been the most important factor that we overlooked, and
should certainly be taken into consideration in any future lichen research.

Literature Cited:

Brado, Irwin M., Sylvia Duran Sharnoff, Stephen Sharoff.(1997) Lichens of
North America. Yale University Press.

Ferry, B. W. (1973) Air Pollution and Lichens . Athlone Press.

Gjesvik (1996) Air Pollution Project Europe. The Norwegian Society for
the Conservation of Nature, Oslo.

Huckaby, L.S. (ed.) (1993). Lichens as Bioindicators of Air Quality.
USDA Forest Service General Technical Report RM-224, Rocky
Mountain Forest and Range Experimental Station, Fort Collins

Http://www.lichen.com

Richardson, David, H.S. (1992). Pollution Monitoring with Lichens,
Richmond Publishing, Slough

Salanki, J., Jeffrey, D. & Hughes, G.M. (1994). Biological Monitoring of
the Environment: A Manual of Methods. CAB (Commonwealth
Agricultural Bureau) International, Farnham Royal.

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