Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Surprising findings on forest fires

21.02.2019

Lake Van in eastern Turkey is considered a unique climate archive. Several years ago, an international team of scientists led by the University of Bonn raised sediments from the bottom of the lake reflecting the past 600,000 years. An interdisciplinary group of soil scientists and paleobotanists from the University of Bonn has now evaluated the drill cores for residues of early fires - with surprising findings. The fires did not mainly occur during particularly dry periods as assumed, but in comparatively humid and warm periods - because then the forests grew particularly lush and provided fuel for fires. The results are now published in the journal “Quaternary Science Reviews”.

Every summer there are more and more reports of bush and forest fires in the south. But even long before man adapted earth’s vegetation to his purposes or started fires, large fires occurred at regular intervals.


Dr. Arne Kappenberg from the Institute of Crop Science and Resource Conservation (INRES) at the University of Bonn equids the gas chromatograph.

(c) Photo: Volker Lannert/Uni Bonn


Prof. Dr. Thomas Litt and Manuela Rüßmann with drill cores from Lake Van at MARUM, the Center for Marine Environmental Sciences in Bremen, where the cores were stored.

(c) Photo: Nadine Pickarski/Uni Bonn

Researchers at the University of Bonn have investigated the frequency and intensity of these steppe, bush and forest fires over the past 600,000 years using drill cores from the bottom of Lake Van in eastern Turkey. During this period, rainfall washed the soil and pollen from the surrounding area into the lake, which thus became a unique archive.

In 2010, an international team of scientists led by the paleobotanist Prof. Dr. Thomas Litt from the Institute of Geosciences and Meteorology had already drilled the deposits of Lake Van with a floating platform. “In the 220-meter thick sediment profile, we were able to reconstruct the vegetation of the past 600,000 years using pollen,” says Litt.

On the basis of the composition of the pollen in the individual layers, the paleobotanist determined which plants grew particularly frequently during particular epochs. Based on the temperature and water requirements of these plant species, the scientists were able to draw conclusions about the respective climate.

Together with soil scientists from the Institute of Crop Sciences and Resource Conservation (INRES) at the University of Bonn, the researchers analyzed the fire residues in the drill cores. The fire residue particles are partly microscopically small and finely distributed in the sediments. “We therefore used a method that works independently of the visibility of the charcoal residues,” explains soil scientist Prof. Dr. Wulf Amelung from INRES.

Benzene polycarboxylic acids served as a biomarker for the fire residues, respectively as biomarker for Black Carbon. The age of the layers in the drill cores, the pollen contained therein and the content of benzene-polycarboxylic acids made it possible to reconstruct the predominant vegetation and the fire events.

“Our thesis was that fire activities were highest during dry climate periods,” says lead author Dr. Arne Kappenberg, who was a doctorate student of Prof. Amelung. After all, even today, fires frequently occur in summer in the dry forests and shrub heaths of the Mediterranean region, while the forests of the cool and damp temperate latitudes are largely spared.

Fires were particularly violent between the ice ages

The data of the past 600,000 years from the drill cores of Lake Van, however, show the opposite. “The forest fires increased during the phases where a lush steppe oak forest with coniferous trees grew in a relatively humid and warm climate,” summarizes Litt. It was thus not dry brushwood as tinder that was decisive for the early fires, but the quantity of plants (biomass) that was produced depending on temperature and precipitation.

The biomass was particularly large in the warmer episodes between the ice ages. Since it was only about 11,000 years ago that man made a more extensive appearance in the Middle East through agriculture and livestock breeding, the fires were largely natural.

The fires show a peculiar cycle: About every 100,000 years there were particularly violent fires. This is probably related to the so-called Milankovic cycles. These refer to the regular fluctuations of the Earth's orbit, which result in higher irradiation on our planet in this rhythm. “This is regarded as a driving force for the change between warm and cold periods,” says Amelung.

The researchers suspect that these differences in irradiation led to an accumulation of forest fires not only locally, but globally. Data from Japan indicate that. “This assumption has to be tested on the basis of further studies,” says Kappenberg.

So far, there have been studies on steppe and forest fires that date back a maximum of 150,000 years. The drill cores from Lake Van cover the past 600,000 years. The data also allows derivations for the future. Litt: “If the trend of increasing summer drought continues to persist in Germany, then the danger of forest fires will also rise significantly here.” After all, there are lush forests in Germany - and according to the results of the study, the fire risk increases with the biomass.

The study was carried out in the Collaborative Research Center SFB 806 “Our Way to Europe” of the Universities of Cologne and Bonn and the RWTH Aachen.

Wissenschaftliche Ansprechpartner:

Prof. Dr. Thomas Litt
Institute for Geosciences and Meteorology
University of Bonn
Tel. +49 (0)228/732736 or 733103
E-mail: t.litt@uni-bonn.de

Dr. Arne Kappenberg
Institute of Crop Science and Resource Conservation (INRES)
University of Bonn
Tel. +49(0)228/732194
E-mail: arne.kappenberg@uni-bonn.de

Prof. Dr. Wulf Amelung
Institute of Crop Science and Resource Conservation (INRES)
University of Bonn
Tel. +49(0)228/732780
E-mail: wulf.amelung@uni-bonn.de

Originalpublikation:

Arne Kappenberg, Eva Lehndorff, Nadine Pickarski, Thomas Litt, Wulf Amelung, Solar controls of fire events during the past 600,000 years, Quaternary Science Reviews, DOI: 10.1016/j.quascirev.2019.02.008

Johannes Seiler | idw - Informationsdienst Wissenschaft
Further information:
http://www.uni-bonn.de/

Further reports about: Meteorology acids biomass forest fires forests geosciences

More articles from Earth Sciences:

nachricht Strong storms generating earthquake-like seismic activity
16.10.2019 | Florida State University

nachricht The shelf life of pyrite
14.10.2019 | MARUM - Zentrum für Marine Umweltwissenschaften an der Universität Bremen

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Solving the mystery of quantum light in thin layers

A very special kind of light is emitted by tungsten diselenide layers. The reason for this has been unclear. Now an explanation has been found at TU Wien (Vienna)

It is an exotic phenomenon that nobody was able to explain for years: when energy is supplied to a thin layer of the material tungsten diselenide, it begins to...

Im Focus: An ultrafast glimpse of the photochemistry of the atmosphere

Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have explored the initial consequences of the interaction of light with molecules on the surface of nanoscopic aerosols.

The nanocosmos is constantly in motion. All natural processes are ultimately determined by the interplay between radiation and matter. Light strikes particles...

Im Focus: Shaping nanoparticles for improved quantum information technology

Particles that are mere nanometers in size are at the forefront of scientific research today. They come in many different shapes: rods, spheres, cubes, vesicles, S-shaped worms and even donut-like rings. What makes them worthy of scientific study is that, being so tiny, they exhibit quantum mechanical properties not possible with larger objects.

Researchers at the Center for Nanoscale Materials (CNM), a U.S. Department of Energy (DOE) Office of Science User Facility located at DOE's Argonne National...

Im Focus: Novel Material for Shipbuilding

A new research project at the TH Mittelhessen focusses on the development of a novel light weight design concept for leisure boats and yachts. Professor Stephan Marzi from the THM Institute of Mechanics and Materials collaborates with Krake Catamarane, which is a shipyard located in Apolda, Thuringia.

The project is set up in an international cooperation with Professor Anders Biel from Karlstad University in Sweden and the Swedish company Lamera from...

Im Focus: Controlling superconducting regions within an exotic metal

Superconductivity has fascinated scientists for many years since it offers the potential to revolutionize current technologies. Materials only become superconductors - meaning that electrons can travel in them with no resistance - at very low temperatures. These days, this unique zero resistance superconductivity is commonly found in a number of technologies, such as magnetic resonance imaging (MRI).

Future technologies, however, will harness the total synchrony of electronic behavior in superconductors - a property called the phase. There is currently a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Symposium on Functional Materials for Electrolysis, Fuel Cells and Metal-Air Batteries

02.10.2019 | Event News

NEXUS 2020: Relationships Between Architecture and Mathematics

02.10.2019 | Event News

Optical Technologies: International Symposium „Future Optics“ in Hannover

19.09.2019 | Event News

 
Latest News

Energy Flow in the Nano Range

18.10.2019 | Power and Electrical Engineering

MR-compatible Ultrasound System for the Therapeutic Application of Ultrasound

18.10.2019 | Medical Engineering

Double layer of graphene helps to control spin currents

18.10.2019 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>