Purpose- To investigate my aims, test my hypothesis and compare Druridge Bay to the theory of idealised dune system formation. Aims-To find out how vegetation type and quantity varies across the dune system. To identify factors which affect vegetation type and quantity as we move inland and to assess the extent to which the sand dunes at Druridge Bay compared with a typical system of sand dune development. Hypothesis- With increasing distance inland there will be a greater variation and quantity of vegetation/ plant species growing in the dune system.
Geographical Theory Used
In my investigation I was looking at the theoretical or typical system of dune development as described in texts and websites. This model suggests that as distance from the shore increases, a number of variables should change. For example the first dunes we should have encountered would be the embryo dunes. These dunes are small and at the early stage of development. Embryo dunes are harsh environments with low moisture content and alkaline conditions so only robust species of pioneer plants colonise. The ph decreases, soil moisture increases and the conditions become more favourable to more vegetation can grow and the vegetation variety increases as well. Plants like Oak and Pine colonise grey dunes and if undisrupted by human influence dunes can reach climatic climax vegetation.
My fieldwork location was Druridge Bay located on the coastline of Northumberland in the North-East of England which has a Psammosere ecosystem. This is a suitable location because it was in close proximity to my school in Newcastle. This made travel costs affordable as we used the school mini bus and avoided expensive private hire costs. This location was suitable because it had a well developed system of dunes that allowed us to study the aspects of dune morphology and vegetation diversity that we were interested in. It also allowed us insight into the way that humans interact with and impact on the system of dunes as it is a well used location with many accessible footpaths and roads. This allowed us to gather evidence about not only the physical processes and features which we expected to be present but also the ways that humans cause erosion and trampling and what impact this has.
In order to carry out my fieldwork investigation safely, I had to respond to a number of risks. For example, as the location was close to the sea and exposed to the elements, there was a degree of risk related to the weather conditions on the day we visited. In order to manage this risk we took appropriate clothing and food etc to ensure that the elements did not pose a risk to our health. In addition, the unfamiliar terrain of the dunes was steep and difficult to walk on in places. It would have been easy to suffer injuries from falls etc, especially when carrying equipment such as ranging poles. In order to manage this we wore appropriate footwear to help with grip and balance and we also were careful to carry equipment in such a way to minimise hazards. For example, ranging poles were carried with the spike pointing at the ground at all time Also getting lost to manage this we conducted regular head counts, agreed on a meeting place of the car park in case individuals did get lost and informed the ranger of Druridge Bay that we were working on the sand dunes on the day of our fieldwork.
I conducted a vegetation survey. This survey looked at the % cover of vegetation and the variety of species. As the dunes at Druridge are large and cover a wide area, we conducted a number of transects along a stretch of the beach so we were looking at a number of line samples as a whole group. Starting at the High water mark, I used 2 ranging poles to mark out each of my data collection points. I measured an equal distance each time of 4m and my vegetation survey was carried at the central point between my two poles each time. This systematic sampling would ensure that any bias would be removed from the results. I placed a quadrat on the ground each time and used it to measure the % cover and then analysed its contents to record the different species that were present. However my plant species knowledge was limited and this made it difficult for me to identify the true species variety in each of our quadrats. Also the species directory was hard to understand which added to the inaccuracy of my identifications. To improve this we could have took photos and compared them to plant literature when we returned to school which would have made sure we identified the species correctly. However, overall this is a cheap easy method of data collection which if completed correctly by geographers with good plant knowledge would obtain accurate results.
Primary and Secondary Data
Primary Data- Research collected by asking questions,conducting fieldwork and collating results. Secondary Data- Based on findings from other peoples research i.e textbooks and websites I used a range of primary data, collected by myself from fieldwork, in my investigation. For example, I carried out a vegetation survey to look at the quantity and diversity of vegetation across the dunes. I also used some secondary data sources, for example I used the GIS package Google Earth to interrogate satellite imagery of the dunes and the bay before undertaking the fieldwork. This allowed me to identify good locations to carry out my transects and also it allowed me to identify some initial characteristics of the area such as the level of human influence.
To present my data related to vegetation variety, I used a kite diagram, which allowed me to present data of a variety of species on one graph. My horizontal axis was a distance scale from 0-100m, representing the distance we moved inland and on the vertical axis I have individual % scales for each type of vegetation, such as Marram grass.I plotted each type of vegetation separately, representing the % of ground they covered by the amount of width they took up. This allowed me to easily identify the the dominant species of Marram grass which was the only species to colonise between 0 and 20m from the high water mark. It also gave a clear visual representation of the different types of vegetation across the Druridge Bay dune system.
First of all we analysed our data using a scatter graph. The vertical axis represented % vegetation cover compared to the vertical axis which represented the distance across the dune system from the HWM. I plotted data from 2 transects separately and progressively from 4m from the HWM up to 64m from the HWM. I then placed a line of best fit on each graph. These showed me that there was a positive correlation which showed that as distance from HWM increased so did % vegetation cover. To test the strength of the positive correlation I used Spearmans Rank Correlation Coefficient so I would obtain detailed results. We then used a significance graph to remove any bias and obtained results of 0.78 and 0.63 which showed that my data was statistically significant.
One of my aims was to investigate the variations in type and quantity of vegetation. One of the things I found was that there was greater species diversity in the vegetation on the dune system further away/ inland from the HWM. This supported my Hypothesis. This was due to the pH level decreasing inland giving inland areas a more favourable, less harsh environment which encourages colonisation. We also found that Marram Grass was most dominant species along the transect, although I identified 7 species in total like Sea Spurge for example. However, erosion caused by visitors making their own paths across the dune system lead to some areas having no vegetation cover at all as it all had been eroded. The most startling feature was that there was a relatively high level of vegetation cover near the start of my transect on the embryo dunes. This was because the tank traps of the backshore acted as a coastal defence and protected the plants from erosion and trapping sediment.
Strengths The work that I have produced was generally successful in meeting the aim as I was able to come to a conclusion about the extent to which the dunes at DB reflected the typical dune model. However, there are a number of factors that have impacted on my work and influenced my overall findings. First of all, as we collected and collated a range of data across a number of transects, I do feel that the data gives a reasonably accurate idea about the dunes although some of the individual methods could have led to reductions in the accuracy of the data. Weaknesses A good example of this is the infiltration survey. The equipment we used for this was very basic and as a result there was little control over the amount of water that we were putting into the funnel, this means that the timings we took are probably affected by human error and make them less useful when discussing the findings and drawing conclusions. This could have been simply rectified by accurately measuring the amount before it was put into the funnel. When presenting my data, i used a kite diagram which allowed me to analyze the variation in vegetation in a lot of detail and make good comparisons between species; however my lack of good knowledge of vegetation type could have led to some incorrect identifications. This would mean that my overall conclusion about vegetation may be less valid than hoped. Improvements In order to improve the overall validity it would be important to make use of some better equipment to gain more accurate results and perhaps look at the data over a longer period of time to compare the effects of different weather conditions etc.
Evaluation- Weaknesses and Improvements
Weaknesses- A good example of this is the infiltration survey. The equipment we used for this was very basic and as a result there was little control over the amount of water that we were putting into the funnel, this means that the timings we took are probably affected by human error and make them less useful when discussing the findings and drawing conclusions. This could have been simply rectified by accurately measuring the amount before it was put into the funnel. When presenting my data, i used a kite diagram which allowed me to analyze the variation in vegetation in a lot of detail and make good comparisons between species; however my lack of good knowledge of vegetation type could have led to some incorrect identifications. This would mean that my overall conclusion about vegetation may be less valid than hoped. Improvements- In order to improve the overall validity it would be important to make use of some better equipment to gain more accurate results and perhaps look at the data over a longer period of time to compare the effects of different weather conditions etc.