Soil Moisture- if there isn’t enough moisture in the soil, only certain plant species will survive as they have adapted to photosynthesise in those conditions. Also, lower soil moisture will prevent large numbers of a plant species from thriving in that area.
Soil pH- Whether the soil is alkaline or acidic and the extent to which they are can greatly affect the plant species which are able to grow there. If the soil is too acidic, many plants will not be able to survive, only those which have adapted to cope thriving due to the lack of inter-specific competition. Similarly, if the soil is too alkaline, only those that have adapted to those conditions will survive and thrive.
Type of Soil- soil types may greatly affect the chances of a plant species surviving and even striving, as different amounts of moisture will be held in it, with different types and amounts of nutrients. This can cause only species adapted to cope with these conditions to survive and thrive if there isn’t much competition, and others to die out due to the conditions and competition.
Soil Organic Matter- this was important as it showed the amount of available nutrients for the plants on the ground floor. The more organic matter or ‘humus’ present on the ground, the more nutrients available for the plants to use to grow, both individually and in abundance. It would also affect how concentrated the plants were.
Topography- the way that the land lies is quite important as it will determine which way the rain will run off, and in turn the abundance and the distribution of plant species within the area.
These factors were all checked to try and determine which factor was the most important. The two coppices were very near to each other, in order to try and keep the edaphic factors, temperature and the topography of the areas the same, concentrating on light as the key variable.
Hypothesis- I predict that there will be a greater abundance of plant species in the new coppice, due to the fact that there is more light present which will be used for photosynthesis, allowing many different species to grow. In the old coppice, I believe there will be less plant species, as only a few species will be able to photosynthesise in the darker conditions, as they will have adapted to those conditions.
Plan- I have already studied ecology at school, and in preparation for this investigation, we carried out an experiment on the school field, examining the distribution of broad-leaved plants in two differently managed areas. The sampling techniques used when carrying out this experiment were modified and improved for the investigation in Nower Wood, in order to achieve more accurate results.
In carrying out the investigation, a sample count was taken instead of a total count. This was because even though it isn’t as accurate, a total count would’ve taken too long. Therefore, to ensure the sample count taken was as representative as possible, we decided to take as many random samples, doing all the experiments at each quadrat, as we could, and then find their overall average.
Methods- First, a grid was created on each of the coppices. Random values were taken, which were then used to create a grid reference from where readings would be taken. At each grid reference, a group would lay a quadrat down, and the percentage cover of each different plant species present was noted, as well as the light cover and the percentage of organic matter present. At each quadrat, soil pH measurement and soil types were determined with the use of an auger, and the results were recorded. The soil temperature was also measure at each grid reference. Each group repeated this experiment five times at random grid references, and the results were combined to find an average for the entire coppice. This was then repeated in the other coppice.
Samples of the soil from each area were taken. These samples were taken back to a laboratory where the water content of the soil (soil moisture) was established and the results were recorded.
In each coppice, the experiments and the number of them carried out were the same, so as to make the investigation a fair test.
Apparatus- Quadrat
Tape measure
Auger
Plant identification sheets
Soil thermometer
Soil pH testing kit
Soil type key
Results And Analysis- The pie chart below shows the average amounts of plant species present in the old coppice from readings of our group.
Overleaf is a pie chart showing the percentages of plant species present in the new coppice from readings in our group.
Below is a bar graph displaying the amount of different species found within our group.
Below is a bar graph of the entire class’s results on the number of plant species in the two coppices.
Shown below is a table of the results we collected in our group concerning the edaphic factors.
Below is another table, showing the class average results concerning edaphic factors.
These results show that there is a link between light present and the soil temperature. We can say the higher the light level, the higher the soil temperature, as if more light reaches the ground, it will heat it up more.
We can also see that all the factors were the generally quite similar values, excepting light where there was a large difference in the values. From the class average, we can see that there was a larger diversity of plant species in the new coppice than in the old coppice. We can therefore derive from these facts that the new coppice contains more plant species as there is more light, allowing many different species to thrive, using it for photosynthesis. Therefore my hypothesis was supported, and only those plant species which have adapted to survive with little light thrived in the old coppice, e.g. bluebells.
Evaluation- These results give support to my hypothesis, though they don’t prove it, as the investigation didn’t use a total count, but a representative count. Also, these results aren’t necessarily representative of all old and new coppices across the world, and may in fact be false.
There were a few anomalous results, as shown in the fact that our group’s results discovered less plant species in the new coppice than in the old. These can be attributed to the fact that some of the quadrats had to be placed in areas where only one type of species was present (e.g. in a bush). Also, results from the quadrats may have been wrong since the two coppices had been used the previous day, resulting in much of the area being flattened by people walking over them. Another contributing factor to anomalous results may be that the areas examined aren’t simply 2-D surfaces, they have an upper layer of plants which covers up lower layers, which potentially ‘house’ many more plant species and also that it may have been the wrong time of year to see the full diversity of each of the coppices. Plant identification was also quite poor generally as many plants looked very similar to the untrained eye.
In order to ensure that the survey was a lot more accurate, we could watch many old and new coppices over time, recording the results and finding an overall average creating much more representative figures of old and new coppices.