Scientists discover Europe's ancient forests were nothing like we imagined

Picture the wilderness of central Europe 100,000 years ago, or even a million years ago. You might imagine an endless expanse of towering trees, with thick canopies blocking sunlight from reaching the ground. But according to a major new study, that familiar image of Europe's ancient forests is probably misleading.

Instead, much of the continent was a vibrant landscape of scattered trees, open woodlands, grassy clearings, and colorful wildflower meadows. Birds and butterflies flourished in these sunlit habitats, while enormous grazing animals helped prevent trees and shrubs from taking over.

Researchers led by Aarhus University have found that this mixture of habitats dominated Europe's landscapes for more than 20 million years. Far from being the continent's original natural condition, the dense, dark forests common in many parts of Europe today appear to be a relatively recent development in its ecological history.

Published in Biological Conservation, the findings challenge a longstanding assumption about what Europe's wilderness looked like before widespread human intervention. They also raise important questions about modern reforestation programs, which often prioritize planting dense forests to combat climate change and protect biodiversity.

"The study shows that current reforestation practices are on the wrong track - both here in Denmark, where subsidies are only granted for planting dense forests, and elsewhere in Europe. This will not only be harmful for biodiversity; it will be in direct contradiction to the type of ecosystems that Europe's species have evolved in over millions of years," says Professor Jens-Christian Svenning from the Center for Ecological Dynamics in a Novel Biosphere (ECONOVO), Department of Biology at Aarhus University, senior author of the study.

Challenging the Myth of Europe's Ancient Forests

For decades, conservation strategies have been influenced by the "closed-forest paradigm." This is the belief that dense forests with nearly continuous tree canopies were Europe's natural landscape before humans began clearing land for agriculture and settlements.

Under this view, restoring nature often means allowing trees to reclaim open areas or planting forests where they no longer exist.

The new research suggests that this approach may overlook a crucial part of Europe's ecological history. Rather than being uniformly covered by dense forests, the continent was characterized by changing combinations of grasslands, shrubs, and woodlands with different amounts of tree cover.

These landscapes supported a rich variety of species adapted to both wooded and open environments. Large plant-eating animals also played a major role in maintaining this diversity by grazing, browsing, and disturbing vegetation.

What 23 Million Years of Evidence Reveals

To reconstruct Europe's ancient environments, the researchers examined an unusually extensive collection of evidence spanning millions of years.

Previous studies have generally concentrated on more recent periods. This investigation extended much further into the past, examining paleoecological records from the Miocene epoch (which began around 23 million years ago) through the pre-industrial era.

Paleoecology is the study of ancient ecosystems using clues preserved in fossils, sediments, and other natural records. Because no single type of evidence can provide a complete picture of the distant past, the team combined several independent methods.

These included fossilized pollen and larger plant remains, charcoal left by ancient wildfires, and chemical signatures preserved in the teeth and bones of plant-eating animals. The researchers also examined fossil insects and mammals, along with ancient environmental DNA recovered from sediments.

Environmental DNA consists of genetic material left behind by organisms in their surroundings. When preserved in ancient deposits, it can help scientists identify plants and animals that lived in an area long ago.

Together, these different sources of evidence allowed the researchers to reconstruct not only what types of vegetation existed, but also how ecosystems changed over time and how animals influenced their surroundings.

"Each type of proxy offers its own perspective, but together they let us see whether the landscapes were covered by dense forests, open grasslands, or a mix of the two. By combining these datasets across time - from the Miocene to the pre-industrial era - we could trace long-term changes in vegetation and the role of large herbivores with much greater confidence than earlier studies that used only one method," explains the study's lead author, ECONOVO PhD student Szymon Czyzewski of Aarhus University.

The evidence points to a consistent pattern. Across more than 20 million years, Europe's landscapes were typically a shifting mosaic of trees, open spaces, and flowering plants rather than continuous stretches of closed forest.

Importantly, these mixed landscapes were not limited to one particular climate. They existed under temperate conditions comparable to those in much of Europe today, as well as during warmer and colder periods.

Elephants, Rhinos, and Bison Shaped Europe's Wilderness

One of the most striking findings concerns the influence of large wild herbivores.

Ancient Europe was home to animals such as elephants, rhinoceroses, aurochs, and bison. By feeding on vegetation and disturbing the ground as they moved, these animals helped keep parts of the landscape open.

Their activities created opportunities for grasses, wildflowers, and other plants that might otherwise have struggled beneath dense tree cover.

This constant interaction between animals and vegetation helped sustain a diverse mixture of habitats, providing suitable conditions for many different species.

Modern Europe, however, is missing much of this ecological influence. Many of the large wild herbivores that once shaped its landscapes have disappeared, and traditional grazing practices have also declined.

"The ecosystems we see in Europe today lack the large wild herbivores that not only shaped landscapes but also sustained its biodiversity for millions of years. The most dramatic shift has largely taken place within the last hundred years, when traditional extensive grazing disappeared from large parts of the landscape," says Czyzewski.

This loss of grazing pressure has changed how vegetation develops across much of the continent, helping explain why present-day European ecosystems differ so dramatically from those of the distant past.

Europe's Ancient Woodlands Were Full of Wildflowers

The research also offers a different perspective on species commonly associated with farmland and other human-managed environments.

Birds such as larks and jackdaws, along with mammals such as the European hamster, are often regarded as characteristic of agricultural landscapes. Yet the researchers suggest that their evolutionary histories likely extend back to the open woodland environments that existed long before modern farming.

Even familiar wildflowers have connections to these ancient ecosystems.

Wild poppies, now frequently seen growing in agricultural fields, also thrived in areas where large grazing animals disturbed vegetation within ancient woodlands.

These findings challenge the sharp distinction between "forest" and "open habitats" that often guides conservation planning today.

In Europe's ecological past, trees, meadows, shrubs, and grazing animals were not necessarily separate parts of nature. They frequently existed together, forming interconnected habitats that supported a wide range of wildlife.

Why Planting More Trees May Not Always Help Nature

The findings arrive as European countries continue expanding forests to capture carbon dioxide, address climate change, and restore biodiversity.

Although forests can provide important environmental benefits, the researchers argue that planting large areas of uniformly dense woodland may not be the best approach when the goal is to restore Europe's native ecosystems.

Many European species evolved in landscapes containing a mixture of trees and open areas. Converting these habitats into continuous closed-canopy forests could therefore reduce the variety of environments available to wildlife.

The study suggests that restoration efforts should focus more strongly on maintaining diverse landscapes, including open grasslands, scattered woodland, and areas shaped by natural grazing.

"Instead, restoration efforts should place greater emphasis on creating and maintaining mosaics of woodland and open habitats - not least through the restoration of natural-living large herbivores," Svenning concludes.

The findings add to a growing body of research from the same scientific group suggesting that large animals played a far greater role in shaping Europe's ecosystems than previously recognized.

They also reinforce the idea that Europe's ancient landscapes were generally brighter, more open, and more varied than the dense primeval forests often depicted in popular imagination.

Rather than restoring nature by simply planting more trees, the researchers suggest that protecting biodiversity may require recreating the complex balance of woodlands, meadows, and grazing animals that shaped the continent for millions of years.

The familiar image of Europe as a vast, dark, unbroken forest may be deeply rooted in our understanding of nature, but millions of years of evidence are painting a very different picture.