mgr Niklas Hohmann

@article{Hohmann2022,

title = {Global compilation of surface mixed layer parameters (sedimentation rate, bioturbation depth, mixing intensity) from marine environments: The SMLBase v1.0},

author = {Niklas Hohmann},

url = {https://www.frontiersin.org/articles/10.3389/feart.2022.1013174/full},

doi = {10.3389/feart.2022.1013174},

year  = {2022},

date = {2022-12-06},

urldate = {2023-12-06},

journal = {Frontiers in Earth Science},

volume = {10},

pages = {1013174},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Hohmann2021,

title = {Incorporating information on varying sedimentation rates into paleontological analyses},

author = {Niklas Hohmann},

url = {https://doi.org/10.2110/palo.2020.038

},

doi = {10.2110/palo.2020.038},

issn = {1938-5323},

year  = {2021},

date = {2021-02-24},

journal = {Palaios},

volume = {36},

number = {2},

pages = {53–67},

abstract = {Stratigraphic changes in the clustering of first or last taxon occurrences are a joint expression of evolutionary, ecological, taphonomic, and sedimentological processes. Sedimentation rates control the degree of sedimentary dilution and condensation and thus alter the time contained in a given thickness of sediment. However, it remains poorly explored quantitatively how distinct the stratigraphic patterns in the first and last occurrences can be under different deposition models with a constant thickness of accumulated sediment. Here, I present an algorithm that translates ecological or evolutionary signals between time and stratigraphic height. It is implemented for R Software as the package DAIME and complemented by tools to quantify the uncertainties associated with the construction of deposition models. By modeling the stratigraphic expression of the K/Pg extinction and an earlier extinction pulse potentially linked to Deccan volcanism on Seymour Island under varying sedimentation rates, I show that (1) clustering of last occurrences ∼ 250 kyr prior to the K/Pg boundary can be equally explained by a stronger earlier extinction pulse or prolonged intervals with reduced sediment accumulation rate, but (2) when the temporal variability in sedimentation rate is known, the most plausible extinction dynamics can still be identified. The approach is applicable for any type of information transported as a part of the sedimentary record (e.g., fossils or trace elements) or data derived from it (e.g., isotope ratios and rates of morphological evolution).},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{https://doi.org/10.1029/2020PA003979,

title = {Reconstructing Depositional Rates and Their Effect on Paleoenvironmental Proxies: The Case of the Lau Carbon Isotope Excursion in Gotland, Sweden},

author = {E. Jarochowska and T. Nohl and M. Grohganz and N. Hohmann and T.R.A. Vandenbroucke and A. Munnecke},

url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020PA003979},

doi = {https://doi.org/10.1029/2020PA003979},

year  = {2020},

date = {2020-01-01},

journal = {Paleoceanography and Paleoclimatology},

volume = {35},

number = {12},

pages = {e2020PA003979},

abstract = {Abstract Variations in depositional rates affect the temporal depositional resolutions of proxies used for paleoenvironmental reconstructions; for example, condensation can make reconstructed environmental changes appear very abrupt. This is commonly addressed by transforming proxy data using age models, but this approach is limited to situations where numerical ages are available or can be reliably inferred by correlation. Here we propose a new solution, in which relative age models are constructed based on proxies for depositional rates. As a case study, we use the onset of the late Silurian Lau Carbon Isotope Excursion (LCIE) in Gotland, Sweden. The studied succession is a gradual record of shallowing upward in a tropical, neritic carbonate platform. As proxies for depositional rates we tested thorium concentration, carbonate content, and the concentration of pelagic palynomorphs. These three proxies were used to create relative age models using the previously published DAIME model. We applied these models to transform the δ13Ccarb values as well as concentrations of selected redox-sensitive elements. The three relative age models yielded qualitatively similar results. In our case study, variations in depositional rates resulted in peaks of redox proxies appearing up to 76% higher when taken at face value, compared to when accounting for these rates. In the most extreme cases, our corrections resulted in a reversal in the stratigraphic trend of elemental concentrations. This approach can be applied and developed across depositional setting and types of paleoenvironmental proxies. It provides a flexible tool for developing quantitative models to improve our understanding of the stratigraphic record.},

note = {e2020PA003979 2020PA003979},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{10.7717/peerj.8011,

title = {Enforced symmetry: the necessity of symmetric waxing and waning},

author = {Niklas Hohmann and Emilia Jarochowska},

url = {https://doi.org/10.7717/peerj.8011},

doi = {10.7717/peerj.8011},

issn = {2167-8359},

year  = {2019},

date = {2019-01-01},

journal = {PeerJ},

volume = {7},

pages = {e8011},

abstract = {A fundamental question in ecology is how the success of a taxon changes through time and what drives this change. This question is commonly approached using trajectories averaged over a group of taxa. Using results from probability theory, we show analytically and using examples that averaged trajectories will be more symmetric as the number of averaged trajectories increases, even if none of the original trajectories they were derived from is symmetric. This effect is not only based on averaging, but also on the introduction of noise and the incorporation of a priori known origination and extinction times. This implies that averaged trajectories are not suitable for deriving information about the processes driving the success of taxa. In particular, symmetric waxing and waning, which is commonly observed and interpreted to be linked to a number of different paleobiological processes, does not allow drawing any conclusions about the nature of the underlying process.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}