In the latest instalment of Diss Diaries, Kit Shoebridge tells us all about his project in Sussex. Kit attended Homerton College and graduated last year so he has some great tips and inspiration!
1. What is your dissertation about?
I attempted to measure the extent and distribution of the spread of an invasive plant species (Rhododendron ponticum) within an SSSI in Sussex over a ten-year period (2009-2019). I used the environmental characteristics measured in areas of new plant growth to predict which uninvaded areas that might be at risk to future invasion.
To do this, I first looked at a wintertime LiDAR survey of the forest taken in 2009 and identified any areas where the laser was not being blocked by evergreen shrubs. I took fifty samples of these areas in the summer of 2019 using 20x20m quadrats, measuring the percentage cover of any new growth and taking measurements of soil pH, soil moisture, and light intensity. The percentage cover data was used to produce a map showing which areas had been invaded over the past ten years, whilst the other three measurements were used in a statistical technique called ‘discriminant function analysis’ to predict the likelihood of future invasion, based upon the closeness of those environmental factors to the plant’s optimum growth conditions.
Image: a picture of the plant species I studied
2. Why is this important?
The results could have been used to help the local authorities with their invasion control efforts, given the rapid and aggressive nature of the plant’s spread. This plant disperses up to one million seeds per year, can grow in a relatively wide range of environments, causes the decline of native wildlife species (e.g. by blocking sunlight), and is very expensive and time-consuming to remove. As such, using a predictive statistical method to forecast the areas most susceptible to future invasion could save time, money, and effort, and would help preserve native species. This was particularly important at the site I studied, which was both an SSSI and an AONB.
Image: heatmap showing uninvaded areas by their susceptibility to future invasion
3. How did you find conducting your research remotely? (Methods, experience, etc)
I did my fieldwork before COVID-19, so I don’t have personal experience. However, the good thing about biogeography is that much of the data is remotely sensed anyway, taken from satellites and aeroplanes etc. So, if I had to conduct research remotely, I might have tried to find another LiDAR survey from 2019 that I could compare with the 2009 survey I already had, in order to examine areas of potential new growth. Admittedly, it would have been difficult to find another high-quality LiDAR survey of my exact research site, so I may have had to change my project more drastically.
Image: A map showing my study site
Image: the steps I took to get my sampling coordinates
4. What would be your advice to current second years planning their dissertation?
For some people, the academic topic(s) they are best at are also the ones they enjoy the most. However, if you’re not only of those lucky people, I think picking your dissertation topic can be really difficult. You might ask yourself: is it better to follow your academic passion, or your academic ability?
I went with the former, and it didn’t really work out. I really enjoy physical geography but it has never been my forte. Although the idea for my dissertation was really good according to my supervisor, the execution wasn’t great, and despite spending a year working on it, I received a 2.2. I didn’t really know much about the subject area, I hadn’t previously used these research methods, and I think my execution was a bit “unscientific”. So I would advise anyone planning their dissertation to consider both their interests and their skills when formulating their idea. You need to find it interesting enough to work on it for a year, whilst aligning as best you can with your existing academic knowledge.
Image: % cover of the plant in each quadrat
Image credits: Kit Shoebridge
DISCLAIMER: THE VIEWS EXPRESSED IN THIS ARTICLE ARE THOSE OF THE AUTHOR ONLY AND DO NOT REPRESENT THE VIEWS OR OPINIONS OF COMPASS MAGAZINE AS A WHOLE OR THE UNIVERSITY OF CAMBRIDGE DEPARTMENT OF GEOGRAPHY