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My investigation took place in a small woodland close to the Heatree Activity Centre which is located on the edge of Dartmoor National Park in Devon.

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Effect of aspect on lichen size. My investigation took place in a small woodland close to the Heatree Activity Centre which is located on the edge of Dartmoor National Park in Devon. Introduction: In the plant kingdom lichens are unique, consisting of two totally unrelated life forms one an alga and the other a fungus, living together in a complex but balanced state of symbiosis. A symbiosis is a life form where both the partners benefit from each other. In the case of the lichen, the fungus delivers water, minerals and gases from the environment to the algae, while the algae, which contains the green pigment chlorophyll, photosynthesises to supply the fungi with sugars and carbohydrates. The algal cells are either green or blue-green, while the fungal threads or hyphae are colourless. The fungal partner forms the body of the plant within which the algal cells are arranged, in many species, in a well defined layer 10-30m� thick just below the surface, but in others scattered between the fungal threads. The fungus also plays a role in the structure and the protection of the lichen. The algal cells, through the process of photosynthesis provide the lichen with its organic nutrition. Lichens are photoautotrophs, so they obtain their organic nutrients using energy from sunlight. 1. The Cortex 2. The Algae Layer 3. The Pith 4. Under Cortex 5. ...read more.


During the procedure I will be using the following equipment: o A thirty centimetre ruler so I am able to measure the lichens. I chose a thirty centimetre ruler as I thought that it would be easier to measure the lichens than with a meter ruler. o A light meter, this will help me control the variable of the light, so that the lichen on the north side and the south side of the tree are getting the same amount of light. o I will be using a compass to determine the north and the south side of a tree. o I will be using two identification books at the beginning of the study so I am able to determine the species of lichen I am looking at and what tree they are living on. Whilst taking precautions for my own health, it is also important to consider the well being of other organisms. Whilst walking around I will take care not to trample any flora unnecessarily. I will also tread carefully around hollow ground as the vibrations from my footsteps may disturb any animals living underground. My chosen lichen to investigate is the Parmeliopsis hyperopta. This was the most common occurring lichen when I did a preliminary investigation. Method: Before I can take the measurements I will need to measure the light intensity in Lux, this will determine which trees I will be looking at so that each tree has approximately the same amount of light on the north side of each tree and on the south side of each tree. ...read more.


This would perhaps provide more reliable substantial results. Also another change that I would make would be to increase the number of samples I took from each tree. I was only able to take the diameter of one lichen from each tree. Perhaps if I had taken at least three the out come of my results would have been supported or the extra sets of results would have enabled a differing outcome. Another procedure I could have chosen to do would be to compare the size of the lichen on one species of tree, in my case the sycamore tree, with the size of lichen on a different species of tree to see whether this produced any different more analytic results. There are, however other factors that I have overlooked. This is the effect environmental pollution has on lichens. Although lichens are able to survive extreme environmental conditions, most lichens are subject to contamination. This is due to the lichens efficient absorption system. Air pollution, particularly Sulphur Dioxide (SO2), has the greatest effect on lichens. This type of pollution can kill lichens but in many cases will affect the rate of growth in lichens. Lichens are also affected by agricultural sprays. Despite possible errors and procedures which could be done to improve the investigation the method was carried out efficiently and enabled me to accept my original hypothesis. From my results I am able to draw a firm conclusion that the amount of light available and the aspect of a tree has an effect on the size of lichen. ...read more.

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