Preprints
https://doi.org/10.5194/egusphere-2023-2266
https://doi.org/10.5194/egusphere-2023-2266
10 Oct 2023
 | 10 Oct 2023

The optimum fire window: applying the fire-productivity hypothesis to Jurassic climate states

Teuntje P. Hollaar, Claire M. Belcher, Micha Ruhl, Jean-François Deconinck, and Stephen P. Hesselbo

Abstract. Present day fire frequency has been suggested to relate to a productivity/aridity gradient on a regional and global scale. Optimum fire conditions occur at times of intermediate productivity and aridity, whereas fire is limited on the high productivity (moisture) and aridity (no fuel) endmembers. However, the current global fire activity pattern is biased by the predominant burning of grasslands. Here we test the intermediate fire-productivity hypothesis for a time period on Earth before the evolution of grasses, the Early Jurassic, and explore the fire regime of two contrasting climatic states: the Late Pliensbachian (LPE) cooling Event and the Sinemurian – Pliensbachian Boundary (SPB) warming. Palaeo-fire records are reconstructed from fossil charcoal abundance, and changes in the hydrological cycle are tracked via clay mineralogy, which allows inference of changes in fuel moisture status. Large fluctuations in the fossil charcoal on an orbital eccentricity time scale indicate two modes of fire regime at the time. Wildfires were moisture limited in a high productivity ecosystem during eccentricity minima for both the SPB and LPE. During eccentricity maxima, fires increased, and an optimum fire window was reached, in which heightened seasonality led to intermediate states of productivity and aridity. The LPE experienced more extreme climatic endmembers compared to the SPB, with the fire regime edging closer to ‘moisture limitation’ during eccentricity minima, and more pronounced seasonality during eccentricity maxima, explained by the overall cooler climate at the time. This study illustrates that the intermediate-productivity gradient holds up during two contrasting climatic states in the Jurassic.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Teuntje P. Hollaar, Claire M. Belcher, Micha Ruhl, Jean-François Deconinck, and Stephen P. Hesselbo

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2266', Anonymous Referee #1, 15 Nov 2023
    • AC1: 'Reply on RC1', Teuntje Hollaar, 22 Dec 2023
  • RC2: 'Comment on egusphere-2023-2266', Patrick Bartlein, 05 Dec 2023
    • AC3: 'Reply on RC2', Teuntje Hollaar, 22 Dec 2023
    • AC4: 'Reply on RC2', Teuntje Hollaar, 22 Dec 2023
  • RC3: 'Comment on egusphere-2023-2266', Anonymous Referee #3, 08 Dec 2023
    • AC2: 'Reply on RC3', Teuntje Hollaar, 22 Dec 2023

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2266', Anonymous Referee #1, 15 Nov 2023
    • AC1: 'Reply on RC1', Teuntje Hollaar, 22 Dec 2023
  • RC2: 'Comment on egusphere-2023-2266', Patrick Bartlein, 05 Dec 2023
    • AC3: 'Reply on RC2', Teuntje Hollaar, 22 Dec 2023
    • AC4: 'Reply on RC2', Teuntje Hollaar, 22 Dec 2023
  • RC3: 'Comment on egusphere-2023-2266', Anonymous Referee #3, 08 Dec 2023
    • AC2: 'Reply on RC3', Teuntje Hollaar, 22 Dec 2023
Teuntje P. Hollaar, Claire M. Belcher, Micha Ruhl, Jean-François Deconinck, and Stephen P. Hesselbo
Teuntje P. Hollaar, Claire M. Belcher, Micha Ruhl, Jean-François Deconinck, and Stephen P. Hesselbo

Viewed

Total article views: 462 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
330 91 41 462 51 24 24
  • HTML: 330
  • PDF: 91
  • XML: 41
  • Total: 462
  • Supplement: 51
  • BibTeX: 24
  • EndNote: 24
Views and downloads (calculated since 10 Oct 2023)
Cumulative views and downloads (calculated since 10 Oct 2023)

Viewed (geographical distribution)

Total article views: 442 (including HTML, PDF, and XML) Thereof 442 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 26 May 2024
Download
Short summary
Fires are limited in year-round wet climates (tropical rainforests, too wet), and in year-round dry climates(deserts, no fuel). This concept, the intermediate-productivity gradient, explains the global pattern of fire activity. Here we test this concept for climate states of the Jurassic (~190 Myr ago). We find that the intermediate-productivity gradient also applies in the Jurassic, despite the very different ecosystem assemblages, with fires most frequent at times of high seasonality.