Analysis
Task 1
Using spreadsheet 1-dune transect vegetation data, create a kite diagram for the percentage cover of each species at each sampling point.
A kite diagram graphs the percentage cover data for each species at each sampling point either side of a central axis. The result is a series of parallel lines representing the distribution of each species along the transect with symmetrical 'kites' either side as the plants fade in and out according to their distribution. This can be drawn by hand, however, there are software packages, such as Merlin http://www.heckgrammar.kirklees.sch.uk/index.php?p=10310, that have been developed to produce these from Excel spreadsheets.
You can views an example of a kite diagram - we have drawn the data for bare ground to show you how data should appear.
Species can be ranked in alphabetical order or sorted in order of their first occurrence along the transect.
Soil analysis
The soil samples were analysed in the laboratory to determine sodium and organic content. Organic content was measured by incineration of a known weight of oven-dried soil in a muffle furnace. View a photo of crucibles. The subsequent loss of weight provides a measure of the soil's organic content. The results of this are given in spreadsheet 2-sodium and organic content. Sodium concentration was analysed by flame photometry - a sample of soil is washed with distilled deionised water and the solution and the water aspirated into a flame. The absorption of light at wavelengths characteristic for sodium is compared against a calibration curve of standards with a known concentration of sodium).
Task 2
Using the data from spreadsheet 2-sodium and organic content plot two further graphs which show the sodium and organic content of the soil at increasing points along the transect. Comment on the trends observed along the transect. You may also want to annotate your kite diagram with this.
Task 3
Firstly, examine the kite diagram. What type of succession is occurring? What patterns do you observe? Are there clear zones or are the transitions more gradual? If you were to place boundaries to designate different types of dune how might you do this? Can you identify species or groups of species characteristic of different parts of the sand dune? Which among them might serve as indicator species to inform you about the age and development of the dunes? You might want to view plant portraits to assist you here. What does the data for soil organic content and levels of sodium tell us about the dune?
Further Analysis
What insight does such a survey provide on the development of the dune? Consider the plant species: how are they adapted to their environment? What are the unusual features of these dunes and how might some of the data might be explained by these? Suggest a series of experiments which you might use to test your ideas.
