Ecology of the past

Looking at a time capsule from Twente

By Dobrochna Delsen (currently studying for BSc Biology at the University of Amsterdam)

An unusual early morning.

It is 8:15. My train arrives at Science Park. After a ten-minute walk accompanied by other students I arrive at the university. After a short contemplation about whether I should take the elevator, I decide to take the stairs. The stairs are a bit exhausting, especially since the microscope room is at the top floor, but it gives me the necessary ‘exercise’ for the day. As I walk to the room at the end of the corridor I can see that the coat rack is still empty, except of the one lab coat that hangs there since the day my bachelors project started. I take out my student card and hold it against the door handle. The sound of the unlocking door gives me feeling of satisfaction and power. I step into the empty room with a feeling of superiority and go to my microscope where I will sit for the rest of the day.

At the time of writing this blog post I have now walked the stairs on numerous mornings, unlocked the door a few more times, finished counting (and recounting) all my pollen and phytolith slides, and started with analysing the data.

The ‘time capsule’ I am looking at is the top metre of a sediment core obtained from a pingo in Twente and the results of my identification of the micro-fossils contained within the sediments are looking starting to provide new insights into past vegetation change. The pollen and phytoliths contained within the top slide correspond with the modern vegetation I saw at Krakenven last year; the onset of agriculture in that area is possibly visible; and the phytoliths show some interesting trends as well. However, there are lots of things to think about when analysing and thinking about the at pollen and phytolith data.

For example, you have to think about which taxa to include in the pollen sum. This was also one of the discussion points related to the paper of Verbruggen et al. (2019) during the Amsterdam Palaeoecology Club (APC) meeting on April 16^th. Verbruggen et al. present a multi-proxy analysis on a Holocene peat sequence in a palaeochannel in a natural depression North Belgium. The researchers excluded trees (Salix and Alnus) from the regional pollen sum, which surprised me at first, but there was a logical reason for this. The samples came from a depression, making the local region the only place that was wet enough for Alnus and Salix to thrive. If these water-loving tree taxa were included in the regional pollen sum, the other taxa would have been underrepresented in the pollen diagram. For my data it is important to exclude the aquatic pollen and spores from the pollen sum. Betula was also a possible local resident that I would exclude, but since Betula can also thrive outside the local region of Krakenven and did not represent slides over 50% I chose to leave it in the pollen sum.

The data analysis scared me off in the beginning, but I’m starting to get more confident with it. So hopefully I’ll finish this project with a nice paper.

REFERENCE

Verbruggen, F., Bourgeois, I., Cruz, F., Boudin, M. & Crombé, P., 2019. Holocene vegetation dynamics in the Campine coversand area (Liereman, N Belgium) in relation to its human occupation. Review of Palaeobotany and Palynology, 260, pp.27-37. DOI: 10.1016/j.revpalbo.2018.05.004