the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Comparison of paleobotanical and biomarker records of mountain peatland and forest ecosystem dynamics over the last 2600 years in Central Germany
Carrie L. Thomas
Boris Jansen
Sambor Czerwiński
Mariusz Gałka
Klaus-Holger Knorr
E. Emiel van Loon
Markus Egli
Guido L. B. Wiesenberg
Abstract. As peatlands are a major terrestrial sink in the global carbon cycle, gaining understanding of their development and changes throughout time is essential to predict their future carbon budget and potentially mitigate negative influences of climate change. With this aim to understand peat development, many studies have investigated the paleoecological dynamics through the analysis of various proxies, including pollen, macrofossil, elemental, and biomarker analyses. However, as each of these proxies are known to have their own benefits and limitations, examining them in parallel potentially allows for a deeper understanding of these paleoecological dynamics at the peatland and for a systematic comparison of the power of these individual proxies. In this study, we therefore analyzed soil cores from a peatland in Germany (Beerberg, Thuringia) to a) characterize the vegetation dynamics over the course of the peatland development during the late Holocene and b) evaluate to what extent the inclusion of multiple proxies, specifically pollen, macrofossil, and biomarkers, contributes to a deeper understanding of those dynamics and interaction among factors. We found that, despite a major shift in regional forest composition from primarily beech to spruce as well as many indicators of human impact in the region, the local plant population in the Beerberg area remained stable over time following the initial phase of peatland development up until the last couple of centuries. Therefore, little variation could be derived from the paleobotanical data alone. The combination of pollen and macrofossil analyses with the elemental and biomarker analyses enabled further understanding of the site development as these proxies added valuable additional information including the occurrence of climatic variations, such as the Little Ice Age, and more recent disturbances such as drainage and dust deposition.
Carrie L. Thomas et al.
Status: open (until 17 Jun 2023)
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RC1: 'Comment on bg-2023-57', Anonymous Referee #1, 30 Apr 2023
reply
This manuscript presents an interesting dataset comprising pollen, spores, microcharcoal, plant macrofossils and geochemistry data, as well as sedimentary biomarkers from a mountain peatland in Beerberg (Germany). The time interval of the peat core goes back to ca. 2600 cal yr BP. The main goal of the study is to reconstruct vegetation dynamics over the last 2600 years and assess how the biomarker record adds to the understanding derived from the combined classical palaeoecological proxies in the reconstruction of past environmental conditions and peatland development.
I really liked reading this manuscript. The text is clear and nicely structured, methods are presented in sufficient detail, while the idea behind this study is definitely worth exploring. I have two main observations though. The first is that, in my opinion, the manuscript needs a stronger justification for its novelty. The second observation concerns the biomarker dataset which, despite being one of the fewest of such kind in the temperate Europe, is discussed somewhat superficially. I would have liked to see an extension of the discussion towards exploring potential sources of these biomarker compounds in the study area, backed by some statistics, as pollen and macrofossil data are already available in sufficient resolution.
Some specific comments below:
Abstract
L. 14-16: I didn’t see any evidence in the proxy record for dust deposition. Perhaps consider rephrasing?
Methods
2.1. Study area
It would have been nice to see a map with the study area, given that this is a mountainous region and local topography is important in the interpretation of the proxy signals.
Sampling: It was not explained how the overlapping peat sequences were correlated. Based on stratigraphy? Furthermore, what is the reason behind reporting the averages of geochemistry and biomarker data for the overlapping sequences?
2.2 Elemental analysis: please add the sample volume for the samples used for elemental geochemistry.
L. 99-100. You mentioned that there are some lithological transitions. I would suggest to add a lithological column to one of the figures (e.g., the geochemistry figure, or the agedepth model).
L. 102. Consider highlighting more in the introduction the use/purpose of analysing the stable isotopes of N and C. The same suggestion for n-alkanols and n-fatty acids.
2.7.3 Radiocarbon dating: What is the reason for exclusion of the uppermost radiocarbon date?
Results
Suggestion: When describing the results, focus on time, not on zones. In my opinion, it is more interesting for the reader to know when something happened, rather than the depth intervals.
Figure 2. d15N is missing from the figure, although it was mentioned as a performed analysis in the Methods.
Figure 3. It would be useful to see the phases in the macrofossil record drawn on the figure.
Discussion
L. 325-329. ‘The disappearance of Neurospora and Gelasinospora together with the rapid decline in CHAR-micro […] This may also indicate drier conditions on peatlands.’ This interpretation is confusing.
L.402-403. Paq and Pwax basically mirror each other. Is this situation site-specific? If not, why are both indices necessary? Also, there is no discussion around the n-alkanols and n-fatty acids.
Citation: https://doi.org/10.5194/bg-2023-57-RC1
Carrie L. Thomas et al.
Carrie L. Thomas et al.
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