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Global soil erosion already a problem 4000 years ago, traffic champion ants and strategies for placing future hydropower dams

By 1st November 2019 February 10th, 2020 No Comments

Soil erosion reduces the productivity of ecosystems, changes nutrient cycles and thus directly impacts climate and society. An international team of researchers, including Pierre Francus at the Institut National de la Recherche Scientifique (INRS) and INRA at the Université Savoie Mont Blanc have now recorded temporal changes of soil erosion by analyzing sediment deposits in more than 600 lakes worldwide. They found that the accumulation of lake sediments increased significantly on a global scale around 4000 years ago. At the same time, tree cover decreased as shown by pollen records – a clear indicator of deforestation. The study published in PNAS (Proceedings of the National Academy of Sciences) suggests that human practices and land-use change have intensified soil erosion long before industrialization.

Staying with the ecology theme, dams planned for construction in the Mekong Basin of South East Asia would drastically and irreversibly reduce sediment flow, according to a new study published in Science Advances, which provides the framework to optimize where and how dams are built in this (and other) regions. If current dams remain on schedule in the Mekong Basin, it could devastate ecosystems and fisheries in the lower floodplains by the middle of the next decade, the authors say. The findings also suggest opportunities remain for strategic planning to minimize damage to the lower basin by concentrating future hydropower above large existing dams, although this strategy may conflict with the economic ambitions of bordering nations.

The French members of the team are from the Collegium–Lyon Institute for Advanced Study in Lyon and the University of Lyon.

Source: AAAS

On a lighter note: whether they occur on the road to our holidays or the daily commute, traffic jams affect cars as well as pedestrians. Scientists at the Research Center on Animal Cognition (CNRS/Université Toulouse III – Paul Sabatier) and the University of Arizona in the US  have now demonstrated that ant colonies, however, are spared these problems and circulate easily, even in the event of extremely dense traffic, thus ensuring consistent efficiency in their foraging. The findings are reported in eLife.

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© Emmanuel PERRIN/CRCA/CNRS Photothèque

Read the CNRS press release.