On the other hand it is not just the amount of light which reaches a plant that depends whether it can survive, but also the quality of it too. If the light which reaches a plant does not contain much blue or red light, then it will not be able to photosynthesise well. One way in which plants are adapted to live in the old coppice at Nower Wood is that the colour of the leaves are dark green, meaning that they contain many chloroplasts and therefore the absorption of light is great. Some plant species, such as honeysuckle, are climbers. They can climb up bigger, taller trees to get closer to the light entering the woodland. Bluebells, in the old coppice, grow in Spring where there are no leaves on the trees and more sunlight is able to pass through to them and they are adapted to survive in Summer when leave are present. Bluebells are adapted to grow earlier than other plant species to avoid dark surroundings.
→Wind can influence the abundance and distribution of plant species as it can act as an agent for dispersal of seeds. The growth of plant species may also be affected in case of high wind speeds in which the plant cannot tolerate. I expect this factor to be different in both coppices for the reason that being more trees in the old coppice, then this will therefore reduce wind speed. As a result, there should be low abundance and distribution of plant species in the old coppice as less seeds will be dispersed. But this may also be the case for plants in the young coppice, as there are no trees to act as wind breakers, and thus some plants may not be able to survive against high wind speeds. When there is more wind, then plants are able to transpire at a faster rate and thus they lose water through their leaves so therefore again I would expect less abundance and diversity of plant species in the young coppice.
→Humidity can affect the rate of transpiration, especially in the old coppice where there are more trees. The fact of there being more trees, suggests that the transpiration rate is higher as is the humidity levels. As it is more shaded in the old coppice by all the tall trees, this indicates that the air in the area will be moister, not only by transpiration occurring in the trees, but also by the ground flora transpiring below the trees in the old coppice. This in turn will allow the air around the plants to become moister and more humid too, and most of this most air will be unable to escape out of the old coppice with the big trees covering a large percentage of this coppice.
→Temperature can influence the abundance and distribution of plant species and affect the growth of the plant species as higher temperatures can speed up the rate of reactions (photosynthesis). However this is until a certain point, as too high temperatures can denature the enzymes present. Plants cannot grow much if the temperature is low, which is why plants do not grow in Winter.
I assume the temperatures in both coppices should be rather similar, as the young coppice and old coppice are relatively close to one another. Therefore the temperatures should not vary too much in both coppices.
→Altitude will not affect the distribution and abundance of plant species as there is a small difference in height above sea level for both coppices.
→Aspect is similar in both coppices as the young coppice and old coppice basically face in the same direction. The coppices would be affected by the aspect if one coppice was situated on a windier sloped side and the other on a sheltered one. But as this is not a problem, then there should be little difference in which the aspect causes for the distribution and abundance of plant species.
Edaphic factors (soil)
→Soil moisture will affect the distribution and abundance of plants because if there is more soil moisture in one of the two coppices, then the plants will be able to grow better than in the other coppice as there will be more nutrients and water in the soil. But if the soil is less moist in one coppice, then the plant species will not be able to draw up much nutrients and as much water, therefore the plant will not grow to its best due to there being less energy for the plant.
→Soil pH should not affect the distribution and abundance of plant species too much in each of the coppices, as I expect the soil pH to be quite similar in both coppices. However if the soil is very acidic or alkaline, then this I believe, will prevent some plants from growing, although the majority of plant species grow best at pH 7.
→Soil type/texture is not a major factor in this coursework, but the size of a soil grain can influence the amount of water and movement. This may result in some soils to have more moisture than others. The various types of soil, of different shapes, can affect distribution and abundance of plants for the reason that it has an impact on water movements, aeration and penetration of the roots. But the soil type will not be affected in our investigation, as the soil type in both coppices is that of loamy type.
Biotic
→Insects can influence the distribution and abundance of plant species as they cause plant reduction by consuming on them and insects, such as bees, pollinate transferring seeds from one place to another.
Worms aerate soil by burrowing. This oxygen can be used by plants in respiration- a process which plants undertake 24 hours a day.
→Trampling and mowing will definitely affect the distribution and, most likely, the abundance of plants as humans may trample or mow plants. This results in the plant species to be crushed and not survive. This is because the soil will become compact and the roots will have less space to spread out and grow. As a result, they cannot collect as much water from the soil and plant species will be unable to grow and may be killed.
→Weed killer can affect the distribution and abundance of plant species, as plants can be killed. Damage can also be done to other plant species by the appliance of weed killer.
Method
Apparatus List:
- Quadrats
- Auger
- Environmental meter
- Tape measure- X Y coordinates
- I.D key for plant species
- Soil pH test equipment
- Record sheet
Firstly a 20m by 20m area, using two tape measures, had been set up in both coppices. Within this area, we had to work in groups of 3 and using a quadrat, 10 squares by 10 squares instrument, we first had to take a representative sample. This was the case as it would take far too long to count all the different plant species in both sites. This sample was done for us and we were provided with a sheet with 5 sets of random numbers which were to be used as coordinates. The numbers we were provided with decided where the quadrat would lie on the ground. For example, if the numbers were 12, 15, then you would need to find 12 across one tape measure along the x-axis and 15 across the other along the y-axis. You would walk along these points until they meet, and this would be where the quadrat is placed. However with trees (old coppice) and other groups in the way, and possibly not walking straight, it was easy to get sidetracked slightly. But luckily the coordinates we were provided with were ones which ensured that there would be no trees in the way, and the coordinated had already had wooden stands as to where the quadrat was to be placed on top of. This not only ensured that there were no trees in the way, but also that we did not need to worry about not walking straight, as the quadrat stands were already fixed into position.
The point of the quadrat is that it covers ground surface area as a percentage (1 square in a quadrat is 1%). We would look down through the quadrat, which was placed on stands of about 1 metre off the ground, and then count the number of plant species present in that quadrat space. Having done this, the next step was to record the different plant species observed onto a record sheet (green sheet).
Everyone used 5 quadrats in each coppice, ensuring a fair test had been undertaken. Our group teacher provided us with a key for identifying the various different plant species within the quadrats. Using random number sampling (sheet with random coordinates on it) ensured that the results were not bias, and this also eliminates human selectivity, but were reliable because if chose the areas myself, then I would most likely choose an area with many plant species in it.
We were all familiar with the above method for placing the quadrats where they were supposed to be placed, as we had practiced a trial coursework experiment at School in the Head’s garden and on the School field. We could therefore use the skills and knowledge to our advantage that we had so far acquired from our practice school investigation, and then combine this with our real Nower Wood coursework.
As we had practiced so far the above method at School, we also had to record the light intensity, humidity, temperature, and soil pH in each of the two coppices. To obtain the light intensity, humidity and temperature in the coppices, we benefited from an Environmental meter. The light intensity was measured in ‘lux’, humidity in ‘%’, and temperature in ‘°C’. When we were doing this we had to make sure that we were covering the Environmental meter with our shadow so that the sunlight would not affect the temperature too much.
To find the soil pH, we had to place an auger (drill like tool) into the ground and then twist it. After this procedure, the auger was twisted back out of the ground, and a sample of the soil collected, was placed into a test tube for the soil pH test to be performed (see below):
- Place about 2cm of soil into the test tube
- Add about 0.5cm of barium sulphate
- Add distilled water up to half of the test tube
- Shake well with thumb covering the opening of the test tube
- Add about 0.5cm of indicator solution into the test tube
- Tilt the test tube slightly
- Tap the test tube lightly
- Check the colour of the contents to see what it looks best like on the soil pH chart.
Having found all the results in both coppices, we had to show our plant species results on a table and then clearly on pie charts for both coppices to make it easier to understand and so that they could be easily compared by the different number of plant species found in each coppice. These pie charts can be seen in the obtaining evidence section. For our light intensity, humidity, temperature, and soil pH results, we showed the results on bar graphs where there were two columns, one for the young coppice and the other for the old coppice.
Fair Test
For the investigation to be mostly fair, we tested out other factors (soil pH, temperature, relative humidity). This helped us ensure that light was the only major difference in abundance and diversity of ground flora in the young and old coppice.
Some variables were controlled. This helped to make the investigation fairer and not influencing our results. These controlled variables included having the same sample size area, gradient, aspect and also altitude. In both coppices, we followed the exact same method and used the same equipment, including using the same number of samples and finding averages in our readings.
Obtaining Evidence
Results
Analysis
The pie charts shown on the previous page clearly give the different amounts of percentage cover by the various plant species. From them, I can tell that the results have easily been interpreted and now I can identify the comparisons in both coppices.
From part of my hypothesis, I believed that there would be greater abundance and diversity of ground flora in the young coppice rather than the old coppice. Clearly this has proven to be correct, as the pie chart which shows average percentage cover of flora in the young coppice illustrates that there is more diversity and abundance of plants species, with the exception of bluebell’s abundance in the old coppice. Our group recorded 21 different plant species in the young coppice but only 9 different plant species in the old coppice. Obviously Hazels seedling, tufted haired grass and Bramble responded most significantly to the sunlight entering the young coppice, and this may have been due to more light entering this coppice as there are no trees (coppiced recently) to shade the ground flora. With there being more light, more photosynthesis can take place which results in more biomass. In the young coppice, plants compete against each other to maximise the amount of light they can take in.
From the second pie chart, we can observe that the plant species bluebells had the highest average percentage cover (81.6%) of flora in the old coppice. This is due to their method of growing in Spring, when there are no leaves present to block out the sunlight approaching the ground, and they are adapted to survive in Summer when the field layer is rather dark by storing their contents vital for growth in bulbs under the ground. In the old coppice there are very few plant species, as mentioned above, and this is simply due to the result that not much sunlight can enter to the ground flora in this coppice. Therefore the plant species are unable to photosynthesise at their best and some have died as a result.
Evaluation
Did The Investigation Work?
On the whole I think the investigation went well for the reason that we were prepared and we had a brief idea of what we were doing, as we had practiced the investigation at school. Everyone was clear about how the equipment should be handled and what the use of each apparatus was. Also most of the results seemed to be correct and the method, which was reliable, was quite successful and fair as we eliminated bias by using random sampling. We had help from the teachers and staff at Nower Wood to direct us into the right direction of carrying out the investigation correctly and this helped the investigation to work tremendously. Our results provided us with quite strong trends and solid feedback as to how the coppices differ from one another.
However
Are The Results Reliable?
The results can be said to be both reliable and unreliable. They were reliable as we carried out a fair test measured as many variable as possible and we used 5 quadrats in each area. For each of the factors, temperature, humidity and light intensity, we took 3 readings for them in each coppice but every reading was taken in different parts of that coppice. From these results, we obtained an average and reliable result.
However other factors such as wind and soil moisture were not taken into account and therefore not measured. This could have affected the whole investigation as the results may have been manipulated.
Anomalous Results
From the results, I have spotted an anomaly. This can be found in quadrat 3 (9,7) in the young coppice. The abundance of ground flora is strangely much lower than those in other quadrats. This could have been due to human trampling which then the flora was crushed by and the abundance of species becomes low. Also, as well as trampling, quadrat 3, with the coordinates of (9,7), was placed under a tree. This would cast a shadow over the ground flora and so less light is unable to reach them. As a result, the plants will not be able to photosynthesise at their best and then plant growth is slowed down. The abundance of ground flora in quadrat 3 is just 50% cover, but the average for abundance of ground flora in the young coppice is 83.6% cover.
Limitations Of The Methods Used
There were a few limitations of the method that we used at Nower Wood. One important limitation was estimating the percentage cover of plant species as we witnessed that some plants had been overlapped by other plants and this made it especially hard to observe any other plants buried underneath. Also, due to this overlapping, the percentage cover would sometimes reach over 100%. Another limitation was identifying the plant species. In our school investigation, we did not encounter as many different plants than at Nower Wood, but we were aided by an I.D Key. It was difficult to find the correct plant species in the key and to find the plant name for some of the plant species, it took time. Again for some of the plant species, we could not recognise them in the key, and so for this we had to ask the teachers. I found that the grasses were most difficult to identify, for the reason that they all looked similar and this might have lead us to identify them incorrectly.
As we only carried out the investigation once in the year in the Spring season, in May, this is only a snapshot of time and what we saw at that time will look completely different if we were to carry out the investigation again in Winter. Different plants would be growing and therefore the results will change enormously. Also the way in which we had to look at and count the plant species was rather tricky. As the quadrats were placed on wooden stands at about 1 metre off the ground, the angles at which we looked down through them might have affected the results.
Improvements
For the investigation to be improved, I feel that we should have had more practice when it came to identify plant species. This would save us time looking in the key for similar pictures of the plant name we are trying to find. Also instead of using just five quadrats in each coppice, perhaps if we used more, then this would show less impact on the anomalies on our results. If we used more sensitive equipment, such as a soil pH meter to calculate the soil pH rather than adding approximate ingredients, then the readings would be even more accurate. A soil pH meter is electronic and can be placed straight into the ground to record the pH of the soil in each coppice. By using this device, we do not have to worry about comparing the colour of the soil when tested, against a pH colour chart.
If the raised wooden posts, on which the quadrats were placed on, were lowered, then we would be given a better and clearer view of the plants within the quadrat. As mentioned in the limitations, the investigation should be done in Winter too so that results can easily be compared to one another. By this, we could also see what impact factors make in comparison with our current results.
For a final improvement, as the weather conditions changed while in each coppice, I think the experiments should be done at the same time as each other. This would ensure that the results are not affected by the weather while taking down readings in one coppice and then the other.
Further Work
For the investigation to be furthered, I can investigate one other hypothesis which might affect the diversity and abundance of ground flora. This new hypothesis could be that ‘if the diversity and abundance of fauna is high in a coppice, then the diversity and abundance of ground flora will also be high in that same coppice’. As fauna is animal species, such as insects, then if the abundance and diversity of plant species is high, then there is more food for animals to eat.