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20 December 2012

Die neue Weltordnung der Tiere: Wallace-Karte nach fast 150 Jahren aktualisiert...

18 December 2012

(Fleder)Mäuse als Krankheitsüberträger - Untersuchungen zu Vektoren in Hessens Wäldern...

03 December 2012

Rapid test to save lives of snakebite victims . New diagnostic test awarded 1st prize at the Göttingen Innovation Competition...

22 November 2012

Online-Portal zum Klimawissen wächst...

20 November 2012

Midges in a heat-based test of endurance – evolutionary history determines adaptability to high temperatures...

11 October 2012

„Feed the World 2050“ – Veranstaltung zum Welternährungstag 2012: Wie ernährt man neun Milliarden Menschen nachhaltig? Ernährungssicherung der Zukunft...

21 September 2012

Schutz für die Heimat der Drachenblutbäume: BiK-F, Senckenberg, GIZ und jemenitische Umweltagentur vereinbaren Zusammenarbeit im UNESCO-Weltnaturerbe Sokotra...

17 September 2012

Veranstaltungdreiklang: Vorträge und Diskussionen zur Nachhaltigkeit ...

14 September 2012

Teamwork in the tropics – pollinators and frugivores are less choosy at the equator...

04 September 2012

Pinguine in der Patsche: Neue Zahlen zu Pinguin-Rückgang auf sich erwärmender Antarktischer Halbinsel...

30 August 2012

Klimaentwicklung ist keine Einbahnstraße - Tiefsee-Bohrungen zeigen langfristige Entwicklung des CO2-Kreislaufs...

01 August 2012

Tropical climate in the Antarctic: Palm trees once thrived on today’s icy coasts 52 million years ago...

06 July 2012

Outstanding for the past 15 million years – the Swiss Alps have influenced Europe’s climate since the Miocene ...

05 July 2012

Pilze für die Zukunft: Neuer LOEWE-Schwerpunkt „Integrative Pilzforschung (IPF)“...

28 June 2012

Tree trumps grass to rule the savannas...

26 June 2012

Auf Mückenfang im Auftrag der Wissenschaft - Frankfurter Wissenschaftler unterstützen „Jugend forscht!“ Projekt in Bad Vilbel...

25 June 2012

Vortrag: Tropenkrankheiten – jetzt auch in Europa?...

11 June 2012

Vortrag im Senckenberg: Toxische Lebensretter - Einsatz von Tiergiften in der modernen Arzneiforschung ...

04 June 2012

Unscheinbar und doch gewaltig: Flechten, Algen und Moose sind Großspeicher für Stickstoff und Kohlendioxid...

31 May 2012

Biodiversität und Klima Forschungszentrum vereinbart Kooperation mit Nationalpark Kellerwald-Edersee...

25 May 2012

Allergie durch Klimawandel? - Vortrag aus der Reihe „Natur wirkt!?“...

14 May 2012

Vortrag: Gesundes Stadtgrün – wie Park und Co. unsere Lebensqualität steigern...

10 May 2012

Globaler Online-Atlas der Arten – Großprojekt „Map of Life“ geht an den Start...

07 May 2012

Der BIOTA West Atlas – 10 Jahre Biodiversitätsforschung in einem Buch ...

26 April 2012

Gefährliche Gäste – Parasiten: Vortrag aus der Reihe „Natur wirkt!?“...

24 April 2012

Ein genetischer Personalausweis für Pilze...

20 April 2012

Polar bears are evolutionarily older and genetically more distinct than previously known: ancestry traced back to 600,000 years ago...

17 April 2012

Evolution: Vangas beat Darwin’s finches in diversity ...

10 April 2012

Vortrag: Medizin am seidenen Faden – neue Anwendungsgebiete für Spinnen...

22 March 2012

Viren aus dem Regenwald - Vortrag aus der Reihe „Natur wirkt!?“...

12 March 2012

Neue Senckenberg-Vortragsreihe „Natur wirkt?!“...

29 February 2012

Standing still in running water - Lotic dragon- and damselfly species are less able to track climate change...

24 February 2012

Blick aufs große Ganze – Jahrestagung des Arbeitskreises Makroökologie der Gesellschaft für Ökologie ...

06 February 2012

Klimawandel: Warum aus Wissen so wenig Handeln wird – Podiumsdiskussion mit Harald Welzer und Hans-Werner Sinn...

24 January 2012

Where there’s a worm there’s a whale – First distribution model of marine parasites provides revealing insights...

23 January 2012

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10 January 2012

Rettet uns Geo-Engineering vor dem Klimawandel? ...

05 January 2012

Inselhopping zahlt sich aus - Studie unterstreicht Bedeutung des Verbreitungsgebiets bei der Artbildung ...

Press Releases

Tree trumps grass to rule the savannas

Frankfurt am Main, Germany, June 28, 2012. A new study published today in “Nature” by authors from the Biodiversity and Climate Research Centre and the Goethe University Frankfurt suggests that large parts of Africa’s savannas may well be forests by 2100. The study suggests that fertilization by atmospheric carbon dioxide is forcing increases in tree cover throughout Africa. A switch from savanna to forest occurs once a critical threshold of CO2 concentration is exceeded, yet each site has its own critical threshold. The implication is that each savanna will switch at different points in time, thereby reducing the risk that a synchronous shock to the earth system will emanate from savannas.

Tropical grasslands, savannas and forests, areas the authors call the savanna complex, are expected to respond sensitively to climate and atmospheric changes. This is because the main players, grasses and trees, differ fundamentally in their response to temperature, carbon dioxide supply and fire and are in an unrelenting struggle for the dominance of the savanna complex. The outcome of this struggle determines whether vast portions of the globe’s tropical and sub-tropical regions are covered with grasslands, savannas or forests.  In the past such shifts in dominance have played out in slow motion, but the current wave of atmospheric changes has accelerated the potential rate of change. 

Experimental studies have generally shown that plants do not show a large response to CO2 fertilization.  “However, most of these studies were conducted in northern ecosystems or on commercially important species” explains Steven Higgins, lead author of the study from the Biodiodversity and Climate Reseach Centre and Goethe-University. “In fact, only one experimental study has investigated how savanna plants will respond to changing CO2 concentrations and this study showed that savanna trees were essentially CO2 starved under pre-industrial CO2 concentrations, and that their growth really starts taking off at the CO2 concentrations we are currently experiencing.“

The vegetation shifts that the Higgins and Scheiter study projects are an example of what some theorists call catastrophic regime shifts. Such catastrophic regime shifts can be triggered by small changes in the factors that regulate the system. These small changes set up a cascade of events that reinforce each other causing the system to change more and more rapidly. The study demonstrated that the savanna complex showed symptoms of catastrophic regime shifts.  “The potential for regime shifts in a vegetation formation that covers such vast areas is what is making earth system scientists turn their attention to savannas” comments Higgins. 

Knowing when such regime shifts will occur is critical for anticipating change. This study discovered that locations where the temperature rise associated with climate change occurs rapidly, for example in the center of southern Africa, are projected to switch later to forest as the high rate of temperature increase allows the savanna grasses to remain competitive for longer in the face of rising atmospheric CO2 concentration. This means that even though a single location may experience its catastrophic regime shift, the vegetation change when averaged over a region will be smoother. Such gradual transitions in regional vegetation patterns will reduce the potential for shocks to the earth system. “While this may seem reassuring, we have to bear in mind that these changes are still rapid when viewed on geological time scales”, says Higgins.

The practical implications of the study are far reaching. For example, the study identified a belt that spans northern central Africa where fire suppression would encourage savannas to transition to forests. “So if you wanted to sequester carbon as part of a carbon mitigation action, this is where you should do it” explained Higgins “with the caveat that where this will work is shifting as atmospheric conditions change.” A worrying implication is that the grasslands and open savannas of Africa, areas with unique floras and faunas, are set to be replaced by closed savannas  or forests.  Hence it appears that atmospheric change represents a major threat to systems that are already threatened by over-grazing, plantation forestry and crop production.

Press images:

African Savannah

African savanna: Global climate change is shifting the odds in favor of trees in contrast to grasses, with the consequence that large parts of Africa’s savannas may well be forests by 2100. Copyright: Steve Higgins [Download in 300 dpi]

Terms of use:  Images may be used for editorial purposes only. Please state the copyright information as given in the image caption. Use of images for commercial purposes prohibited.

For further information, please contact:

Dr. Steve Higgins
LOEWE Biodiversität und Klima Forschungszentrum (BiK-F) & Goethe-Universität Frankfurt
Phone +49  69 798 40171
email: higgins@em.uni-frankfurt.de

oder

Sabine Wendler
LOEWE Biodiversität und Klima Forschungszentrum (BiK-F),
Press Officer
Phone: +49 69 7542 1838
email: sabine.wendler@senckenberg.de

Paper:
Steven I. Higgins and Simon Scheiter (2012). Atmospheric CO2 forces abrupt vegetation shifts locally, but not globally. Nature, DOI: 10.1038/nature11238

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