Experiment to Compare the Percentage Area Covered by Lichen on Gravestones and the Age of the Gravestone
The aim of this individual study was compare the amount of lichen found on gravestones in a graveyard and the first stated age printed on the gravestone. The initial hypothesis was that the older the gravestone, the higher percentage coverage of lichen. In this experiment 20 samples were taken at random out of a field of 87 gravestones in an open graveyard at Chaldon Church in Coulsdon, Surrey. The results collected will be collated into a spearman’s rank statistical test and analysed.
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There will be a higher percentage coverage of lichens present as the age of the gravestones increase.
The aspect of the gravestones.
Whether the gravestones would be covered by shade at any time.
The geology of the gravestone
The size and type of the gravestones.
The age of the gravestone
The amount and type of lichen found
The aspect of the gravestones, although not a problem in the case of the graveyard I will be measuring could have caused some concerns. In the Case of Chaldon Church the graveyard is completely open on the east side of the church. The whole grounds are part of the graveyard but other sections such as to the west and south were covered by the church or trees. All gravestones face east and so it is easy to control the aspect.
The same issue with the aspect applies for the shade. The east of the church is completely open and all the gravestones that will be sampled will be well away from the boundaries of the church, trees or fences and so there will be no problems with controlling of the light intensity.
I intend to find many different gravestone rock types when I take part in this experiment. The main groups come under the harder rocks such as metamorphic (marble) and igneous (granite) and softer rocks .ie. sedimentary (sandstone and limestone). My experiment is not aimed at percentage cover of lichen and rock type and so this will not be a variable of mine. Headstones in older graveyards tend to mostly be sandstone and so I am expecting very few hard rock headstones. There is no real way of controlling this experiement in this way, except by ruling out the other rock types and sticking to sandstone, but this would limit and disrupt the random sampling that needs to take place.
The gravestones that we will be sampling from will all be of a type that is standing upright. No horizontal gravestones will be measured, only those that have a vertical headstone will be accounted for in the random sample. As for the size of the gravestone there will be variations in size and to overcome this and keep it controlled I must take note of the height and width of each gravestone. As we will be using a 50cm2 quadrat, I will be taking the average of the height and width and place the quadrat over that area found in the middle of the headstone. For example, if the height is 100cm and the width 93cm, the 50cm2 quadrat will be placed 25cm from the top and 21.5cm in from the side. If a gravestone is not tall enough or wide enough then it will have to be removed from the sample and another random gravestone selected.
The age of the gravestone is one of the two variables that I intend to measure. This will not be controlled in any way. There is no age limit to the sample and if a gravestone is selected is 200 years old or just 2 years old then it will still be selected and used in my experiment. I will also only note the first date on the gravestone when the first person has been buried to keep the whole experiment constant.
The amount of lichen found is the other variable to my experiment. There will be many different types of lichen present on the gravestones but I will not be measuring these as they have no input into my experiment as I am not measuring diversification. However, all lichen that is located in the quadrat during the fieldwork will be measured and not controlled as it is all relevant to my investigation as a collective species. The measurements of percentage coverage will be taken as accurately as possible using the 100, 5cm2 boxes in the 50cm2 whole quadrat.
On Wednesday the 8th of March 2006 I will go to Chaldon Church in Coulsdon, Surrey. I will use a random sampling method to pick out the gravestones that I will be using in my experiment. For data calculations afterwards I will need at least 20 samples. I will draw a plan map from a birds eye view perspective of all the gravestones in the graveyard. I will then allocate a number to each gravestone. Using a random number generator on a calculator I will take the second two digits of the three shown on the screen to pick the gravestone samples from the numbered map previously drawn. Once the 20 gravestones have been sampled from the whole graveyard I will start to measure the lichen on each gravestone.
For each gravestone I will measure the height and width of the front of the gravestone (the front will be the side with the writing on) and calculate the middle 50cm2 for each one. For those that are not tall or wide enough for the 50cm2 quadrat they will have to be removed and another gravestone shall be randomly selected using the computer. Once the middle has been found I will accurately calculate the percentage coverage of lichens in the whole quadrat. 1% covereage would mean that one of the 5cm2 areas was completely covered. Next I will note down the percentage coverage and then note down the first stated age of the gravestone. This is in the case that more than one person is buried in the same grave, I will always take the first date to keep the experiment constant.
Once the first gravestone in the sample has had its age and percentage lichen coverage noted down then move on to the next in the sample and repeat the measuring process for all 20 gravestones.
In the case of a pilot study, before I undertake the whole experiment I will do a small random sample of 5 gravestones and pick three of the five. I will measure them in exactly the same method stated above and collate the data in tables. If anything needs to be changed for the real experiment then it can be as the pilot will be a test run and a buffer to see whether the whole experiment can work.
There are no hazardous chemicals involved in this experiment as I am only partaking in a measurement of natural ecology. However consideration must be give to any organisms that I come across and I must not interfere with the course of nature by touching or removing any of the lichens or any other vegetation or animals in the region. Ethical considerations on part of the church must be undertaken and I must ask for full permission from members of the church such as a pastor or reverend, if they are present, to use their graveyard as part of my studies. Also I must be careful not to tread on graves or disrupt any decorations of the graveyard such as flowers.
None of the procedures will be dangerous, although suitable footwear such as walking boots would be advisable as there is a slight slope to the graveyard and no footpaths, only grass. Anything that I take into the graveyard shall also be removed such as apparatus or litter.