Europe Was Mostly Open Woodland and Meadow for 20 Million Years, Study Finds

Europe's natural landscape was probably not the endless dark forest many people picture. A large new study reports that open woodlands, grassy clearings and wildflower meadows dominated the continent for more than 20 million years, according to Aarhus University, which led the research.

The authors say the finding calls into question reforestation programs that favor planting dense forests. They argue such programs could harm the very biodiversity they aim to protect. The work was published in the journal Biological Conservation.

What the researchers say Europe looked like

According to the university, much of the continent, even 100,000 years ago or a million years ago, was a patchwork of scattered trees, open woodland, grassy clearings and flowering meadows. Birds and butterflies thrived in these sunlit habitats. Large grazing animals helped keep trees and shrubs from taking over.

By this account, the dense, shaded forests common in many parts of Europe today are a relatively recent development in the continent's ecological history, not its original state.

The idea being challenged

For decades, conservation thinking has been shaped by what the researchers call the “closed-forest paradigm.” It holds that dense forests with nearly continuous canopies covered Europe before humans cleared land for farming and settlements. Under that view, restoring nature often means letting trees reclaim open ground or planting forests where none stand.

The new study suggests that approach overlooks a key part of the story. Instead of uniform forest, Europe had shifting combinations of grassland, shrubs and woodland with varying amounts of tree cover. These landscapes supported species adapted to both wooded and open settings, and large plant-eating animals helped maintain that variety by grazing, browsing and disturbing vegetation.

How the team reconstructed the past

Earlier studies mostly focused on more recent periods. This one examined paleoecological records from the Miocene epoch, which began around 23 million years ago, up to the pre-industrial era. Paleoecology studies ancient ecosystems through clues preserved in fossils, sediments and other natural records.

Because no single type of evidence gives a full picture, the team combined several independent methods:

• fossilized pollen and larger plant remains
• charcoal left by ancient wildfires
• chemical signatures in the teeth and bones of plant-eating animals
• fossil insects and mammals
• ancient environmental DNA recovered from sediments

Lead author Szymon Czyzewski, a PhD student at Aarhus University, said each type of evidence offers its own perspective. Combining them, he said, let the team trace long-term changes in vegetation and the role of large herbivores with much greater confidence than studies that relied on one method.

The researchers report a consistent pattern: across more than 20 million years, landscapes were typically a shifting mosaic of trees, open spaces and flowering plants rather than unbroken closed forest. They say this held under temperate conditions comparable to much of Europe today, as well as in warmer and colder periods.

Why it matters for tree-planting and conservation

Many reforestation programs aim to fight climate change and protect wildlife by planting dense forests. The study's authors say this may work against nature in Europe, since the continent's species evolved in mixed, open habitats shaped by large grazers.

Senior author Jens-Christian Svenning, a professor at Aarhus University's Center for Ecological Dynamics in a Novel Biosphere, said current reforestation practices are “on the wrong track.” He said that applies in Denmark, where, according to him, subsidies are granted only for planting dense forests, and elsewhere in Europe. In his view, this is harmful for biodiversity and contradicts the type of ecosystem European species evolved in over millions of years.

These policy conclusions are the researchers' own interpretation of their findings. The study describes the long-term pattern of European landscapes; how governments design forest and nature restoration programs is a separate question.

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Around Prague, based on reporting by ScienceDaily