Rye (Secale cereale) is a grass grown extensively as a grain and forage crop. It is a member of the wheat tribe and is closely related to barley and wheat. Rye is highly tolerant of soil acidity and is more tolerant of dry and cool conditions.
Nettles (Urtica dioica) are a herbaceous perennial, growing to 1-2m tall in the summer and dying down to ground level in the winter. It has widely spread roots. Humans and animal waste may be responsible for elevated levels of phosphate in the soil, providing an ideal environment for stinging nettles.
VARIABLES:
The controllable variable will be the area in which I will be conducting my experiment. The uncontrollable variables are: light, moisture, pH, temperature, carbon dioxide, oxygen, air movement and trampling.
METHOD OF CONTROLLING VARIABLES:
I will view all the possible areas in which I can conduct my experiment, which contain the vital component. It has to contain a substantial amount of different species in both areas of trampled and non-trampled land, to enable me to compare them. The areas have to be maintained by the people who visit the park, the non-trampled area has not been interfered with by the park rangers and the trampled area is not artificially trampled (i.e. lawn mowers). Both areas have to be 20metres long. I will carry out as many repetitions as I can in my time on the common, to ensure that my results are reliable and accurate as I can make them. All measurements will be double-checked.
RISK ASSESSMENT:
As the investigation has to take place on the common, insects and any other species in the common could cause an irritation. It will be a safe option to apply insect repelent before doing the preliminary work. Whilst walking on the grass insects, and any other species in the habitat of study, may get trampled on and killed. When taking the soil depth, the needle that is used could damage any undergroud habitats or insects in the grass, it would suitable to try to clear any insects on the surface before implanting them. These problems are unable to control and so it is obvious that to overcome them the best way is to just be careful. There could be some plants that are irritating and so gloves should be worn whilst performing the investigation. I should try to avoid working in slippery areas. However, if forced to do so, I should take my time.
The tape measure may move, resulting in the wrong area being investigated so it is a good idea to use ranging poles as markers for where the tape measure should begin and end making sure that these markers are regularly checked. I could accidently take down an innaccurate reading and so therfore my readings should not be rushed, otherwise I will make careless mistakes. I should recheck my readings to make sure I have read them correctly and should also be consistent with how I record them, e.g. if I round upa number I should carry this on throughout the whole investigation.
PRELIMINARY WORK:
For my preliminary work, I measured a line transect of 20m long, with some of the tape measure running through a non-trampled area and a trampled area. I took 10 readings by placing the quadrats down at 2m intervals starting at 0m. I estimated the precentage of vegetation and identified each species of vegetation inside the quadrat. I also found out the depth of the soil in each quadrat by pushing the needle into the soil and measuring how deep it travels. A soil sample was taken to measure the pH. There was a bit of percipitation when the investigation was carried out. It was conducted at approximately 11 o’clock in the morning.
PRELIMINARY RESULTS:
TABLE SHOWING THE SPECIES DIVERSITY IN A TRAMPLED AREA.
COMMENTS:
The preliminary work gave me the opportunity to work with different apparatus, so I could learn how to use them to gain the most accurate results for my own investigation.
METHOD OF MY INVESTIGATION:
My plan was to count the diversity of species on trampled and non-trampled ground to see if there is a correlation.
I will first gather all my equipment, so I can have it all at hand when it is required. The equipment I will need is:
- A 20m measuring tape
-
0.25m2 quadrat
- 30cm ruler
- spatula
- containers
- needle
- notebook and pencil.
Tha venue for my investigation will be on Wimbledon and Putney Commons (see enclosed map). I will go to my chosen area on the common, which is where there is non-trampled and trampled land for 20m. I have chosen this length because it will produce enough data to get an average from and it gives a more accurate representation of each section that I am investigating. This length can compensate for any areas of grass that that do not contain a sufficient amount of different species. Having a large area to investigate will decrease that chances of any anomolies that might occur. I have also chosen this area, because it is a small enough area for me to complete investigating within the time allocated.
I will lay out my 20m tape measure along an area of trampled land. I will fix my tape in place with two ranging poles, preventing the tape measure moving out of place and also investigating the wrong area. The tape meaure will be laid no more than 10m away from where the non-trampled area will be measured. This distance is short enough between the two areas to ensure that the two areas have the same variables affecting them.
I will start my investigation in the trampled area. I will use my 20m long tape measure as a belt transect. A belt transect isa strip, usually 0.5m in width, located across a study area in such a way that the transitions in plant populations are highlighted. I will place the quadrat at 2m intervals starting at 0m. I will count the different amount of species in each sqaure and tally them down in my notebook. Using the quadrat helps me to see the different species because it splits it up into sections. In each quadrat I will push my needle directly into the centre to measure the soil depth. Having these readings will allow me to compare the soil depth ofboth areas of my investigation. I will then be able to see if there is a difference in the soil depth, which could explain if there is or is not a difference in species diversity. I have not chosen to measure the light intensity because I clearly know that there is a difference because there are more trees in the non-trampled area so I already know that this couls possible be a limiting factor.
I will take up the tape measure and ranging poles from the area of trampled grass, trying not to damage any species. I will then set up the equipment in the non-trampled area and repeat the measurements of species diversity and soil depth.
After collecting all the data that I need I have chosen to carry out a Mann Whitney U statistical test. I chose to do this statistical test because is asseses whether two samples of observations come from the same distribution. The null hypothesis is that the two samples are drawn from a single population, and therfore that their probablity distributions are equal. It requires the two samples to be independent, and the observations to be ordinal or continuous measurements. I am unable to use a t-test because it requires measured data wheras I am using counted data. The chi squared test requires comparing frequencies in categories which is unsuitable for my investigationn, aswell as the Spearman’s rank because I am not investigating whether two variables correlate.
RESULTS
TABLE SHOWING THE SPECIES DIVERSITY IN A TRAMPLED AREA.
TABLE SHOWING THE SPECIES DIVERSITY IN A NON-TRAMPLED AREA
ANALYSING EVIDENCE
Trends and patterns: From the results that have been collected, I have noticed that there does not look like there is a difference in species diversity in trampled and non-trampled areas. I found that similar plants grow in both these areas with a difference of mushrooms and nettles in the non-trampled area and clover in the trampled area. The soil pH was the same in the two areas of study but the soil depth differed.
I expected to find less species in more trampled areas, these were the areas, which had a low soil depth, but this was not necessarily true. There were no visible patterns found.
Anomalous results: there were two results that stood out for me in the second investigation. The two highest quadrats where there was the highest soil depth had the least species in them. This could be showing inconsistency with the readings on the soil depth where there could have been more pressure put in this area.
Statistical test:
Mann-Whitney U Test
R1=112.5
N1=10
N2 = 10
R2 = 97.5
U1 = N1N2 + N1 (N1 +1) – R1
2
U1 = 10 x 10 + 10 (11) - 97.5
2
U1 = 100 + 110 – 97.5
2
U1 = 100 + 55 – 97.5
U1 = 155 – 97.5
U1 = 57.5
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U2 = N1N2 + N2(N2 +1) – R2
2
U2 = 10 x 10 + 10 (11) – 112.5
2
U2 = 100 + 110 - 112.5
2
U2 = 100 +55 – 112.5
U2 = 155 – 112.5
U2 = 42.5
The critical value for N = 10 and the critical value for N2 = 10. the smallest U value is >23, so there is not a significant difference at p = 0.05, this means that my null hypothesis has been accepted.
DISCUSSION AND EVALUATION
Conclusion: My null hypothesis being accepted concludes that there is no significant difference between species diversity on trampled and non-trampled areas. There is relatively the same amount of species but there is not a wider range in the non-trampled area, than I first predicted. The species that were found were suited to their environment.
Explanation of conclusion: My research has led me to understand that the perfect conditions for plants such as nettles and mushrooms are areas where they will not get trampled on. Nettles have a protective barrier in the form of little hair-like structures on their leaves and stem that irritate the skin upon contact. This is their way of survival and allows them to grow freely without any other species disrupting its life cycle. They also have long roots, non-trampled areas are an ideal place for the requirements of nettles because after taking soil depth samples I found that the non-trampled area had more soil depth which meant that more diffusion could take place. The reason for there not being an increase in the number of species is that all the species that were found were all competing for nutrients in the soil. My non-trampled area was relatively close to a line of trees. This could be another reason why there was not a significant difference in species. Trees are large plants that have very thick, long roots. Having trees and small plants in the same area can inhibit diversity because the trees will be taking up more nutrients from the soil, which means that there is more competition for water and nutrients hence there not being a large amount of species.
The trees also provide shade, some of the species found prefer shaded areas but this may inhibit some other plants growing. For some plants, shade means that there is not enough photosynthesis happening. Photosynthesis is the process by which plants and some bacteria use the energy from sunlight to produce sugar, which cellular respiration converts into ATP.
Critical analysis: the reliability of my results was reduced by the fact that I only had a short period of time to complete collecting my data and had no chance to repeat it in other trampled and non-trampled areas, I could have possible used areas by a pond that are trampled and non-trampled because this would have provided moisture which would have brought about different species. The reliability of my results is further reduced by the variables that I could have studied and controlled. Although I did get a chance to measure the pH of the soil, I did not check it at every quadrat, for any reason there could have been a change in pH such as the spillage of a liquid or chemicals by some cars.
Limitations: There was not enough time or equipment to repeat the experiment. Repetition would have given me a wide range of results and maybe there might have been a wide range of species diversity. I should have read the pH in every station to give me more accurate results.
Reference:
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