Hello! This is Li Si, a recent graduate from NTU ASE and today I’m wrapping up my trilogy of blogposts by sharing about the Final Year Project (FYP) which I did under the Tropical Ecology & Entomology (TEE) Lab.
In the earlier two blogposts (check them out here and here), I shared about how I studied the diversity and community composition of arthropods/invertebrates in the soil and leaf litter. For my FYP, I decided to take things a step further and look into the roles that these invertebrates play in decomposition. My project was titled “Flavours of life: Assessing the feeding activity & preferences of soil-leaf litter invertebrates across a forest disturbance gradient”.
Bait lamina sticks (L) and cards (R), which were used to assess feeding activity in the soil and leaf litter respectively.
For this project, I adopted the bait lamina test to answer my research questions. The bait lamina test method is a well-established method of assessing soil feeding activity by using bait lamina sticks with holes that were filled with bait. However, since we were interested in leaf litter as well, we decided to also test this method out for the leaf litter. To do that, I designed bait lamina cards (the first of its kind!) and mass produced over a hundred of them using 3D printing. 3D printing is an extremely affordable method of producing simple tools such as these cards, with each card costing only several cents. On the other hand, the bait lamina sticks can easily cost several dollars per stick, which can be extremely costly (for this project, I was lucky to have inherited the sticks from our postdoc Li Yuen).
Deployment of bait lamina sticks (top) and cards (bottom) in the field. Bait lamina sticks are buried into the ground while bait lamina cards are placed in a mesh bag and underneath leaf litter.
There were two main research questions that I wanted to answer. Firstly, I wanted to find out whether feeding activity is different across a forest disturbance gradient. Secondly, I wanted to find out whether there was a difference in bait preferences when we use bait made of leaf litter from different plant species.
These questions are important because the findings of this project can potentially contribute towards forest restoration efforts. For instance, if a particular species of leaf litter has high decomposition rates, using them as an organic fertilizer or mulch can promote nutrient cycling and growth of saplings. This encourages a holistic approach towards forest restoration, which shouldn’t just be about planting trees. Rather, we should also look into restoring faunal communities (especially invertebrates) and the roles they perform.
TEE Lab team members out in the field: Li Si, Prof Eleanor Slade, Xuan Xu (left to right)
Reflections
At first glance, this project seemed simple – place sticks in forest, count holes, write a report. However, as I started thinking about the experimental design and the analysis I had to conduct to answer my questions, things started getting complicated. I was presented with a wide array of options to analyse my results, such as using linear mixed effect models, generalised linear mixed effect models, or transforming my data using arc-sine square root transformation, square root transformation, exponential transformation, etc. These methods all sounded the same to me and I struggled to tell the difference between them. It also did not help that existing publications often do not elaborate much on their method of choice. Fortunately, I was also reading the ES3307 Experimental Design & Analysis for Ecology course by Prof Eleanor Slade during the same semester, which helped me greatly with the developing a plan for analysing my results. For ASE juniors who are keen to pursue the ecology specialisation, this will be one of the most important and useful modules to take in ASE! (In case anyone is wondering, no I wasn’t paid to say this 😅).
After a tiring day of fieldwork, the next step is to count the number of holes that were perforated (this represents the feeding activity). Holding them upwards against the light helps to visualize the perforations better. This is the crucial step of transforming the field experiment into data which is used for analysis. Coincidentally, this also makes me look like I’m praying for success for my FYP, which was is also true I suppose!
Another big takeaway from this project was the power of using simple and low-cost methods such as 3D printing to conduct research. In an age of technological advancements, tools such as LiDAR and next-generation sequencing are becoming more and more commonplace. However, I believe that there is still a place for using simple tools such as sticks and stones to help answer our questions. In this study, an important finding was that the 3D printed bait lamina cards were also just as effective in assessing feeding activity, as compared to the OG bait lamina sticks. If I had spent the money to purchase enough sticks in place of 3D printing them, I would’ve spent the equivalent of several 3D printers. Therefore, this finding is highly encouraging because it shows the potential for researchers and citizen scientists of all experiences to make use of these methods to mass produce field equipment.
Lastly, to conclude this post, I would like to extend my heartfelt gratitude to everyone who have contributed to this project in one way or another, be it through offering advice for the project or joining me for fieldwork. Without their support and feedback, this project wouldn’t have been possible.
Thank you!