grasses | Ecology of the past

Fieldwork in the Drakensberg

December 11, 2024
WDG

South African research trip (part 3 of 3)

As part of my MSc Biological Sciences research project at the University of Amsterdam I travelled to Africa, where I first presented the early findings of my research at the SASQUA congress (blog post 1) in Oudtshoorn (Western cape), before heading to the University of Kwa-Zulu Natal (blog post 2). Here I met up with local experts and prepared for the upcoming fieldwork, which the previous parts of this blog series covered. Now, the time has come for the final and best part, about my fieldwork in the absolutely gorgeous Drakensberg mountains.

Aims: As the samples for my research had already been collected earlier by my supervisors Prof. Dr. Jemma Finch & Prof. Dr. Trevor Hill for the University of Kwa-Zulu Natal, our initial goal was to collect various samples (charcoal, sediment cores, etc) for the next students. During my time at the university of Kwa-Zulu natal, however, we realized that it would be great to collect a bunch of C3 and C4 grass species, to extract phytoliths (amorphous silica particles formed in plant tissues) from, which would help with the interpretation of our data. This then became our new focus. To achieve this goal we visited the Drakensberg twice, one day trip in the weekend, and one trip with an overnight stay.

Day 1

After a night of utterly terrible sleep (I was alone on the AirBnB property, the gate did not lock due to the cold, and our dogs started barking at something (someone!?) at 2AM), I woke up at 6AM to get ready for the long day ahead of us. Jemma came to pick me up at the, bringing coffee with her, which I really appreciated. We then picked up Trevor at their place and began our drive towards the mountains. I had not seen much of the landscape in the Kwa-Zulu Natal province, which turned out to be very compared to the Western Cape. Whereas the western cape had fynbos vegetation (very similar to the Mediterranean, KZN was more savanna like. There was grass everywhere the eye could see, except for the patches of spruce, planted by humans. Halfway through the drive the Drakensberg mountains came into view, which was stunning. We then drove through some small villages, until we finally arrived at the Berg.

Introducing: Jelle Kraak

June 5, 2024
WDG

Hello Ecology of the Past readers, my name is Jelle Kraak and I’m currently doing a research project for my MSc Biological Sciences (University of Amsterdam) supervised by William Gosling (University of Amsterdam), Jemma Finch (University of KwaZulu-Natal), and Trevor Hill (University of KwaZulu-Natal). The project is entitled: “Assessing the effect of human induced fire regime changes on vegetation in the Drakensberg mountains”. During the project I will visit South Africa to work at the University of KwaZulu-Natal and visit field site thanks to partial funding from the Amsterdam University Funds.

Research project outline

As many of you know, humans have been interacting with the environment for millennia in various ways. One of the ways in which humans interact with the environment is through the ignition of fires. By doing so, humans may change fire regimes (fire frequency, severity and/or intensity), which in turn can cause changes in vegetation composition and structure. By using a combination of phytolith (local vegetation) and charcoal (fire) data from two sediment cores obtained from wetland environments in the Drakensberg mountains, we aim to assess the effect of fire regime changes on vegetation over the last 6000 years.

The phytoliths (biogenic silica microfossils) allow for the reconstruction of the past vegetation. Charcoal fragments characterize all aspects of past fire regimes: (i) frequency (time series analysis of charcoal data), (ii) severity (abundance of charcoal in samples reflecting biomass consumed), and (iii) intensity (spectral properties of individual charcoal fragments reflecting combustion temperature).

The most interesting part of this project (in my humble opinion) is that this study is the first to use micro-Fourier Transformed Infrared Spectroscopy (µFTIR) to reconstruct fire temperatures from field samples ánd combine these accurately reconstructed temperatures with local vegetation data! It is important to accurately estimate fire temperatures, as the temperature of a fire dictates the type of plant materials which are consumed in a fire (the higher the temperature, the greater the proportion of woody material burning up). Similar studies have been conducted previously, however, these studies compared fire severity i.e. total burnt biomass with vegetation data. Although this works decently, total burnt biomass is not an accurate representation of fire intensity or temperature, as at very high temperatures biomass turns to ash, which cannot be detected in sediment cores. Through parameterizing both the vegetation changes and the fire regime we will provide a comprehensive picture of how changing human fire use practices modified the vegetation. We anticipate that: (i) a decrease in fire intensity resulted in woody encroachment of the surrounding vegetation, which was concomitant with the arrival of agropastoralists c. 600 years ago, and (ii) a shift in the proportion of C3 and C4 grass species in reaction to temperature changes in the Drakensberg mountains.

In search for the historical roots of grasses

August 11, 2020
WDG

In search for the historical roots of grasses: A review of Neogene grass history in the Amazon drainage basin

Corresponding article: Kirschner, J. A., & Hoorn, C. (2019). The onset of grasses in the Amazon drainage basin, evidence from the fossil record. Frontiers of Biogeography. DOI: 10.21425/F5FBG44827

The onset of grasses in the Amazon drainage basin, evidence from the fossil record

March 23, 2020
WDG

Kirschner, J.* & Hoorn, C. (2019) The onset of grasses in the Amazon drainage basin, evidence from the fossil record Frontiers of Biogeography DOI:10.21425/F5FBG44827

*Judith conducted this work as part of her MSc Earth Sciences: Geo-ecological Dynamics degree at the Institute for Biodiversity & Ecosystem Dynamics, University of Amsterdam.