Elephants, aurochs and bison kept ancient Europe a patchwork, not one dark forest, scientists say

A synthesis of 23 million years of European fossil, pollen and chemical evidence from Aarhus University concludes that large grazing animals kept the continent’s temperate landscapes open, a shifting mosaic of woodland, scrub and grassland. Elephants, aurochs and bison were among the animals credited with the work, alongside rhinoceroses. Dense, dark forest, by this reading, is a relatively recent arrival.

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The authors draw a policy conclusion from that history: reforestation schemes that favor a closed canopy, they argue, are heading in the wrong direction.

Pollen, charcoal and tooth chemistry as witnesses

The paper appeared in Biological Conservation on Feb. 23, 2026, and Aarhus issued its press release on March 2. Szymon Czyżewski, a PhD student at the university’s Center for Ecological Dynamics in a Novel Biosphere, is lead author, and Prof. Jens-Christian Svenning of the same center is senior author among 21 contributors, according to the ScienceDaily write-up that circulated on Nov. 7. The work is a synthesis of existing palaeoecological evidence, not new fieldwork, spanning the Miocene, which began about 23 million years ago, to the pre-industrial era. ScienceDaily’s summary line says the mosaic dominated for more than 20 million years, while its body text cites 23 million years of evidence; both describe the same record.

The team combined fossil pollen and larger plant remains, charcoal from ancient wildfires, chemical signatures preserved in the teeth and bones of plant-eating animals, fossil insects and mammals, and ancient environmental DNA from sediments. Czyżewski said that stacking independent lines of evidence let the researchers trace long-term vegetation change and the role of large herbivores with much greater confidence than any single record would allow, since no one type of evidence gives a complete picture. The picture held in cool, temperate and warm climates alike, and dense closed-canopy forest shows up mainly in the recent Holocene, linked to the loss of herbivores or to heavy livestock and agricultural use.

In the release’s description, the typical landscape was a mosaic of grassland, scrub and open-to-moderately dense woodland, rich in flowers. The closed-forest picture many people carry of prehistoric Europe is what the authors call the closed-forest paradigm, and they set out to challenge it with evidence spanning the whole Neogene, Pleistocene and Holocene.

Elephants, aurochs, bison and rhinoceroses as landscape engineers

Through grazing, browsing and ground disturbance, elephants, rhinoceroses, aurochs and bison kept parts of the vegetation semi-open, per the Aarhus summary, which credits the four animals together rather than assigning each a separate share of the openness. The aurochs is the clearest case of a lost partner. Britannica records a wild ox about 1.8 meters (6 feet) tall at the shoulder, probable ancestor of domestic cattle, whose last known population survived in central Poland until 1627.

Bison came closer to following it. The last wild bison in Poland was killed in 1919 and the last in the world died in 1927 in the Russian Caucasus, according to Rewilding Europe, which says reintroductions began in 1951 and that about 8,500 animals exist today, roughly 6,200 of them living free. The organization calls the species an umbrella species, because by grazing excess vegetation it helps maintain a mix of wooded and open landscape for invertebrates, birds and small mammals.

Some familiar farmland species may carry the same history. Larks, jackdaws and the European hamster likely evolved in these ancient open woodlands, the release says, and wild poppies grew in woodland disturbed by herbivores.

Danish forest subsidies and the restoration argument

Svenning said the study shows that current reforestation practices are on the wrong track, and he singled out Danish subsidies that only fund the planting of dense forest. He added that uniform, dense forests are not the answer for restoration and that planting them will not only be harmful for biodiversity. The authors argue that closed-canopy planting of that kind may reduce habitat variety. The summary adds that the most dramatic loss of these influences, traditional extensive grazing among them, happened mostly within the last hundred years, so modern forest cover reflects a very recent baseline. The researchers recommend putting greater emphasis on creating and maintaining mosaics of woodland and open habitat, including bringing back wild large herbivores. Czyżewski noted that the most dramatic shift in grazing influence has largely taken place within the last hundred years.

Those policy claims are the authors’ interpretation rather than direct measurements. The summary hedges accordingly: dense forests “appear to be” a recent development, and current practices “may” harm biodiversity. It offers no site counts, geographic coverage, effect sizes or dating uncertainties, and each proxy has limits of its own, which the authors acknowledge. The lead image on the report is an artist’s reconstruction, not a photograph. The work was funded by Villum Fonden, the Danish National Research Foundation and the Independent Research Fund Denmark, and the release lists no competing interests.

European countries are expanding forests to capture carbon dioxide and restore biodiversity at the same time. How much open mosaic that climate goal can accommodate is the question the Aarhus team’s argument leaves for foresters and policymakers, and the summary does not put a number on it.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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