The overall aim of this investigation is to investigate the different species of plants in a stretch of land stretching from where the sea comes up to on the beach then over the first dune and up to the peak of the second dune in from the sea. On the way I will have to investigate the area the different species thrive in to be able to conclude what factors affect the growth of them and prove that marram grass only grows on certain parts of the sand dunes and if it has a factor of keeping the embryo dune together.From doing past work in biology I have learned that marram grass is a xerophyte so this plant is basically keeping the dunes together but I will have to investigate if the levels are changing as I go over the dune or if its stays at a constant level.
Throughout this investigation I will have to keep a fair test to make the results as accurate as possible. In a fair test only one factor is changed at a time whilst all other factors are kept the same at their best value. So I will vary one factor to keep it a fair test as possible and this factor is the site and this will be moving over the embryo dune (dune closest to the sea) and to the peak of the mobile dune (this is the second dune in from the sea). I controlled the way I recorded the air temperature, soil temperature, % coverage and the % of different species as well as moisture levels, Ph of the soil and the nutrient content; which I show how I controlled them in my planning.
The area that I have chosen for my investigation is an example of an ecosystem; this is a relatively self-contained interacting community of organisms, and the environment in which they live and with which they interact. A community is a particular area where the different species of plants and animals interact with each other. In this community there are different populations of plants an animals but the actual specific part of the habitat decides where these different species live and I am going to investigate what factors in these parts of the habitat causes the growth of the different species.
After carrying out my preliminary work the equipment I decided to use was
* 2 ranging poles
* Spirit level
* Sample bags
* Identification cards (for plants)
In the laboratory;
* Bunsen burner
* Electric balance
* Nutrients test kit
* Ph test kit
Basically the preliminary work I carried out was just to organise the parameters of my actual investigation as after I carried out my preliminary work I was able to see factors that I should change for my investigation.
When doing my preliminary work I was using a tape measure to measure the distance between the ranging poles but for the proper experiment I found out it would be much easier to measure a string of just over 2metres to tie to the ranging poles so I was moving 2metres up the dune without using a tape measure which I found to be much easier. Another thing I also changed by doing my preliminary work was the distance between sites. For my preliminary work I was doing each site every 4metres, but later found out that this was not enough results for by belt transaction and I also needed more information.
The factors that I controlled or varied are as follows. Whilst carrying out my investigation I must remember to keep a fair test, which I stated in my introduction, which is to change one factor and keep all other factors the same. The factor that I will be changing will be the site and this is moving up the dune 2m at a time (this is the distance I choose after doing my preliminary work). The way I recorded the results was in the same way for each site. In this investigation the way recorded the results was in the same way but just moving up the dune 2m at a time for each site calculating steepness, air temperature, soil temperature, wind speed and % coverage recording the different species of plants that are there.
When taking the steepness I hovered the spirit level above the string and moved the string till it was level and then measured the displacement of the string to see how much it has moved, I carried out this procedure at every site. When taking the air and soil temperature I took them next to the first ranging pole. For the air temperature I held it in the air for 15seconds and for the soil temperature I put it in the soil for 30seconds. When recording the % coverage and the % of different I placed a quadrant directly in front of the first ranging pole, there are 25 squares so I was able to calculate the percentage by looking at how many squares were occupied by plants. Then for the percentage of different species I identified the different species and estimated the % of that certain plant. The moisture test, nutrients and Ph tests were all carried out in a lab under constant conditions.
There are some risk factors in this investigation. For the practical care has to be taken when handling the ranging poles due to them having pointed ends and to take care on steep slopes in case of falling. The risk factors in the lab are that when using the oven for the soil samples and when burning off the samples care must be taken when handling the hot apparatus by using gloves. When carrying out the nutrients and Ph tests it has to be taken in that I am handling chemicals so contact with them have to be avoided.
For this experiment I would expect the further you go over the dune the more % cover of plants will occur as well as more different varieties occurring. This prediction is backed up by my preliminary work that I carried out which can be found in the appendix.
My first prediction is that marram grass will be highly common on the embryo dune then will decrease as you go over and up the mobile dune and as well as this different species will be introduced as you go over.
I predict that as your at the peak of the dunes this is where the wind speed will be at its highest whilst in the trough of the embryo and mobile dune wind speed will be at its lowest.
I also predict that the air temperature should basically stay the same whilst the soil temperature should increase the further from the tide you go.
Another prediction is that the moisture level will be high closest to the sea then will decrease but will increase in the trough between the dunes, this leads me on to say that there will be more plant life here so in turn there will be more nutrients in this part of the dune.
Scientific explanation for my predictions
My first prediction saying that marram grass will be highly common on the embryo dune then other species will be introduced as you go over as well as the % of marram grass decreasing. This is due to the desert like factors of the embryo dune. Marram grass (Ammophila arenaria) is a xerophyte that colonises the embryo sand dune and exists in the mobile dune. The marram grass stabilises the sand dunes due to the extensive underground network of rhizomes that binds sand to stabilises the dunes. Marram grass is able to thrive in these conditions because of its xeromorphic features they are as follows.
They have a layer stiff interlocking hairs, which are situated on the inner epidermis which reduces transpiration because of its ability to trap air. Another feature is that the leaves are able roll up into a cylindrical shape that is able to trap air to reduce transpiration. As well as this the stomata are sunken in grooves, reduced in numbers and only exist on the surface of the leaf so this again lowers the rate of transpiration. The marram grass stabilises the sand, which prepares the dune for colonisation of other plants. So this is how there is an increase of other species as you go further away from the sea. (This is research from advanced biology).
I also predicted that the wind speed on the peaks would be the highest in the trough would be the lowest this is basically just due to that on the peaks it is more exposed whilst in the trough it is far more sheltered so the wind cant get to this area.
The air temperature should basically stay the same whilst the soil temperature should increase, as you get further away from the sea this is due to the coolness of the North Sea. The air temperature doesn’t really change due to that it is not really in a long range of time so it doesn’t really change.
Due to the increase of plants in the trough the moisture levels are higher here the sand is more of a soil base so it can soak in water. Therefore if there is a increase in plant life in this area then this would in turn mean there are more nutrients in the soil sample. Its also high is higher in moisture nearest to the sea due to when the tide is coming in makes the sand moister.
I predict that as the levels of marram grass decrease there will be constant increase of hawkweed.
* Measuring a piece of string to over 2metres and tying it to the ranging poles so there is a 2metre gap between the ranging poles.
* The first ranging pole will be placed where the tide comes up to this can be seen because in the difference in moisture of the sand. So the distance between the ranging poles are always 2metres.
* The steepness is recorded by having a point on both the ranging poles at the same height and these points are where the string is tied to these points. Then by moving the string up or down the second ranging pole using a spirit level move it till it is level. Then the distance the string has moved on the second ranging pole is recorded so a profile can be drawn.
* The air temperature is recorded by holding a thermometer up for approximately 15seconds then recording it for that site.
* For the soil temperature I put the thermometer in the gap between the ranging poles and left it in for 30 seconds then recorded the result.
* When using the quadrant I laid it down directly in front of the first ranging pole and recorded the percent of the different species of plants.
* This procedure was carried out at each site, which is moving over the dune 2m at a time.
* I first took a crucible and weighed it then added some soil sample then re-weighed it thus working out how much sand is in.
* I then labelled the crucible saying what sample it was and put it in the oven overnight.
* When taking the crucible out I used oven gloves then left it to cool. Once cool I then weighed it taking off the weight of the crucible so I could see how much water was evaporated off.
* This value gives you the water content of the soil sample.
Analysis When looking at my results basically I can see that there is no plant life to start with for the first three sites this is the part that is very close to where the tide comes into when it is at its highest. Then the majority of plants at site 4 until site 17 is marram grass with small amounts of lyme grass and even smaller amounts of rest harrow. Then after site 17 new species are introduced whilst the levels of marram grass is decreasing the new species that start to occur are yarrow, common cats ear and hawkweed.
The area of land between sites 16 and 17 are very low in % coverage of plants this is due to this was used as a path (I recorded this whilst taking my results) so no plants are able to grow here except from small amounts of marram grass due to being able to grow in harder conditions. The profile of the dune basically shows the embryo dune followed by the mobile dune up to the peak. This shows how the marram grass is really dominant on the embryo dunes and then decreases then new species are introduced as heading onto the mobile dune.
I can also see that the embryo dune is smaller and less steep than the mobile dune. I noticed that when getting to the peak of the mobile dune there is a bit of marram grass I would expect this will be due to there being a higher level of wind nearer the top and less water will be able to get to this part of the dune so its long extensive roots will be needed and less water will have to be used at the plants at the top. In this investigation I have to prove that marram grass only grows on certain parts of the sand dune.
This is shown to be true as there is a high presence of it on the embryo dune whilst far less on the mobile dune but there is a bit on the way to the peak of the mobile dune. By seeing that the marram grass thrives on the embryo dunes shows that the marram grass is the pioneer species. Basically I can see that the other species of plants are able to grow due to the marram grass. The marram grass holds together the embryo dune by its extensive root system of rhizomes which bind the sand. This is the only plant that is able to thrive in these condition which is due to its xeromorphic characteristics.
Towards the start of the embryo dune where there are no plants present is due to that this is the place where the high tide comes up to and this makes the salt content of the sand very high even the marram grass is not able to grow here. It cant grow here due to water can’t be gained by the plant but only lost due to water will be leaving the roots due to osmosis. There is a higher salt concentration in the sand so water will leave by osmosis to try and balance this in balance of concentration.
The marram grass is able to grow further up the dune whereas other plants cant grow due to the salty wind from the sea and their roots are not extensive enough so could be blown away. This is why other species are able to grow in the trough due to it being sheltered by the wind and the soil being more suitable for plant life with more water content and nutrients. When getting towards the peak of the mobile dune there is some marram grass present again this will be due to the salty sea air from the sea and not much water will be able to get to the plants here.
At this point if I had more time I would go further over the mobile dune to look at the levels of marram grass to help it back up my theory of where the marram grass grows. What I would expect to happen is that the levels of marram grass will decrease when over the peak because it will be sheltered from the wind again. When looking at my kite diagrams it agrees to what I have just said about the marram grass is common on the embryo dune but when it is decreasing new species are being introduced.
I have noticed on my kite diagram there is a very high reading for marram grass at site17 which is 100% This was due to there being a path there and do only thing that that could grow there even though in small amounts was the marram grass. My predictions that I made about the air temperature and soil temperature that the soil temperature should increase a bit the further you get away from the sea and the air temperature should stay roughly the same was mostly true in my results as the soil temperature shows an overall increase going from 15i?? C to 17i??
C but the air temperature shows a very similar pattern this will be due to it took quite a long time to carry out this investigation so it would eventually increase. Also what is shown that there is a decrease of moisture in the soil but there is a bit of an increase when you are in the trough between the embryo and the mobile dune. This is also what I predicted and will be due to that water will be soaked into the sand from the sea so it will be high at this point and also higher in moisture in the trough due to water will be able to build up here more because of everything slopping towards it.
I also saw what I predicted would happen with the wind speed that it is higher as you go up to the peak of the embryo dune and higher when you get to the peak of the mobile dune as well as much lower in the trough between the embryo and mobile dune. This is just quite obviously because it is more sheltered. In the trough where there is the most plant life I have noticed that there is more nutrients at these points this will be the reason for why more and different species will be able to grow. Evaluation I would agree that the method I used was quite accurate to collect a firm set of results that I could conclude from.
My procedure was thought out so there was no real anomalous results except for when at site 16 to 17 where there is not much plant life but this was due to that it was being used as a path so plant life would be very hard to grow here. There was one problem that I thought I had with the equipment and that was that I was using a pond thermometer for recording the temperature readings which I thought was not very suitable for reading the soil temperature as I would or liked it to have a more direct contact with the sand.
So this could be said to be a limitation of this experiment so I would change this if I were to do it again. There were limitations to my experiment for example when I was recording the % coverage of each plant the values were definitely not accurate due to that I was just estimating the % of each plant that was growing there just by looking at it. I found when doing the profile of the dune it was quite accurate even though it wasn’t accurate to the last mm I was able to look at the sand dunes pretty accurately and it showed a good profile of the embryo dune and mobile dune that I was able to use in my analysis.
My statistical test was not proven to be correct, as it was not close to1 because this would mean that there was correlation present but this was down to taking the % coverage by estimate which is not that accurate. If I were to carry out this experiment again I would of done more belt transactions of the sand dune so it could compare them as well as going over the mobile sand dune to see if this also agreed to my predictions.
Another thing that I would of also did was to use more quadrants at each station so I could get a average of plant species in that area which I would think would make it more accurate due to not all of the area at each station was exactly the same so a average would be better. So to conclude from to this investigation I can say that the marram grass plays a big part of the formation of the embryo dune so other species are able to be introduced further on.