Desertification Threatens Mediterranean Forests

Heidelberg Earth scientists study natural climate fluctuations of the past 500,000 years –

With a view towards predicting the consequences of human-made climate change for Mediterranean ecosystems, Earth scientists from Heidelberg University have studied natural climate and vegetation fluctuations of the past 500,000 years. Their primary focus was the effects of these fluctuations on the forests in the Mediterranean region. To this end, researchers led by Dr. Andreas Koutsodendris analyzed fossil pollen preserved in a sediment core from Greece. Their investigations suggest that in long-standing drought conditions—as the latest climate models predict—desertification of the forests in the Mediterranean region is likely in the near future.

Mediterranean forests are not only hotspots of biodiversity, but they also provide critical ecosystem services. They protect against soil erosion, regulate the regional climate, and hydrological conditions, and supply food and timber. “Because they are exceptionally sensitive to climate change, concern for their survival is growing in light of anthropogenic CO2 emissions and associated global warming,” explains Koutsodendris. He is a member of the research group of Dr. Jörg Pross, which investigates the Earth’s environmental and ecosystem dynamics at Heidelberg University’s Institute of Earth Sciences.

To trace how Mediterranean forests reacted to climate changes in the past, the Heidelberg researchers, in cooperation with colleagues from France, Germany, Greece, and the United Kingdom, took drill cores from Tenaghi Philippon—a terrestrial climate archive in the northeast of Greece—that provide a complete record of the past 500,000 years, and in which fossil pollen grains are preserved. The data on vegetation development in this period gained from the pollen grains was correlated with geochemical data on contemporaneous fluctuations in precipitation. The results of the team led by Koutsodendris show that, in the past, the Mediterranean forests transformed into steppes within a few decades as soon as specific precipitation thresholds were crossed.


Author: Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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