Europe’s natural landscape may have been far more open and varied than the dense, unbroken forests often imagined by people picturing the continent 100,000 or even 1 million years ago. A study led by researchers at Aarhus University suggests that, for more than 20 million years, much of Europe consisted of a shifting mosaic of scattered trees, open woodland, grassland, flowering meadows and shrubs, maintained in part by large herbivores.
Published in Biological Conservation, the research challenges the long-standing assumption that closed-canopy forest was Europe’s default wilderness before widespread human settlement. It also raises questions about modern afforestation programs that prioritize planting dense forests to capture carbon, address climate change and protect biodiversity.
“This study shows that current afforestation efforts are going in the wrong direction. Here in Denmark, subsidies are given only for planting dense forests, but also in other parts of Europe. This is not only detrimental to biodiversity, but also goes directly against the type of ecosystem in which European species have evolved over millions of years,” says Professor Jens Christian Svenning of the Center for Neobiosphere Ecodynamics (ECONOVO), a biologist at Aarhus University and the study’s lead author.
Challenging the closed-forest paradigm
For decades, conservation strategies have been influenced by what researchers call the “closed forest paradigm”: the idea that, before humans cleared land for agriculture and settlements, Europe was covered largely by dense forests with nearly continuous tree canopies.
Under this view, restoring nature often means allowing trees to reclaim open land or planting forests where they have disappeared. The new research suggests that this approach overlooks important parts of Europe’s ecological history.
Rather than being uniformly forested, the continent appears to have contained varying combinations of grassland, shrubs and woodland with different levels of tree cover. These environments supported species adapted to both forest and open habitats. Large herbivores helped preserve that diversity through grazing, browsing and disturbance of the vegetation and soil.
What 23 million years of evidence reveals
To reconstruct Europe’s ancient environments, the researchers examined an unusually broad paleoecological record, extending from the Miocene, which began about 23 million years ago, to pre-industrial times.
Paleoecology uses evidence preserved in fossils, sediments and other natural records to study ancient ecosystems. Because no single source provides a complete picture of the distant past, the research team combined several independent lines of evidence. These included fossilized pollen, large plant remains, charcoal from ancient wildfires, and chemical traces preserved in the teeth and bones of herbivores.
The researchers also examined insect and mammal fossils, as well as ancient environmental DNA recovered from sediments. Environmental DNA consists of genetic material left behind by organisms in their surroundings. When it survives in ancient deposits, it can help identify plants and animals that once lived in an area.
Combining these records allowed the researchers to reconstruct not only which types of vegetation were present, but also how ecosystems changed over time and how animals influenced their environments.
“Each type of proxy provides a unique perspective, but by combining them we can see whether a landscape is covered by dense forest, open grassland, or a mixture of the two. By combining these datasets across time (from the Miocene to the pre-industrial era), we were able to track long-term changes in vegetation and the role of large herbivores with much higher reliability than previous studies using only one method,” explains Simon Czeszewski, an ECONOVO PhD student at Aarhus University and the study’s lead author.
The evidence points to a consistent pattern: for more than 20 million years, European landscapes were typically a shifting mosaic of trees, open areas and flowering plants, rather than a continuous expanse of closed forest.
These mixed landscapes were not limited to one climate. They occurred during warm and cold periods as well as under temperate conditions comparable to those found in many parts of Europe today.
How elephants, rhinos and bison shaped the landscape
One of the study’s most significant findings concerns the influence of large wild herbivores. Ancient Europe was home to animals including elephants, rhinoceroses, aurochs and bison. By eating vegetation and disturbing the ground as they moved, these animals helped keep parts of the landscape open.
Their activity created opportunities for grasses, wildflowers and other plants that would otherwise have struggled beneath dense tree cover. This ongoing interaction between animals and vegetation maintained a diverse range of habitats and created suitable conditions for many species.
Much of that ecological influence is missing from modern Europe. Many of the large herbivores that once shaped the continent have disappeared, while traditional grazing practices have declined.
“Ecosystems found in Europe today lack the large wild herbivores that not only shaped the landscape but also maintained its biodiversity for millions of years. The most dramatic changes have occurred primarily within the last 100 years, when traditional large-scale grazing has disappeared from large parts of the landscape,” Czeszewski says.
The loss of grazing pressure has altered how vegetation develops across much of the continent and may help explain why many European ecosystems now differ so sharply from those of the distant past.
Ancient open woodlands were rich in wildflowers
The findings also offer a different perspective on species often associated with agricultural land and other human-managed environments.
Birds such as larks and jackdaws, along with mammals such as the European hamster, are frequently regarded as inhabitants of farmland. The researchers suggest that their evolutionary history may instead reach back to open woodland environments that existed long before modern agriculture.
Some familiar wildflowers also have links to these ancient ecosystems. Wild poppies are common on farmland today, but they may also have flourished where large herbivores disturbed vegetation within ancient forests and open woodlands.
These findings question the sharp distinction between “forest” and “open habitat” that often guides conservation planning. In Europe’s ecological past, trees, meadows, shrubs and grazing animals were not necessarily separate components of nature. They often occurred together, forming interconnected habitats that supported a broad range of wildlife.
Why planting more trees may not always benefit nature
European countries continue to expand forest cover to capture carbon, combat climate change and restore biodiversity. Forests can provide important environmental benefits, but the researchers argue that uniformly dense plantations across large areas may not be the best way to restore Europe’s native ecosystems.
Many European species evolved in landscapes combining trees and open spaces. Replacing these environments with continuous, closed-canopy forest could therefore reduce the variety of habitats available to wildlife.
The study suggests that restoration efforts should place greater emphasis on maintaining diverse landscapes, including open grasslands, scattered woodland and areas shaped by natural grazing.
“Instead, restoration efforts should focus on creating and maintaining a mosaic of forest and open habitat, especially through the restoration of naturally occurring large herbivores,” Svenning concluded.
The research adds to a growing body of work by the same scientific group indicating that megafauna played a much larger role in shaping Europe’s ecosystems than previously recognized.
It also supports the idea that Europe’s ancient landscapes were generally brighter, more open and more diverse than the dense primeval forests often depicted. Protecting biodiversity may require more than planting trees: it may mean rebuilding the complex balance among forests, pastures and herbivores that shaped the continent over millions of years.
Source: www.sciencedaily.com
