Europe’s forest plants thrive best in light-rich, semi-open woodlands kept open by large herbivores

Before Homo sapiens arrived, Europe’s forests were not dense and dark but shaped by open and light-rich woodland landscapes. A new study from Aarhus University shows that most native forest plants are adapted to semi-open, light-filled woodlands—formed over millions of years by the influence of large, free-ranging herbivores such as bison, elk, and wild horses.

The study, published in Nature Plants, adds another chapter to a growing body of research challenging the traditional idea of Europe’s forests as closed-canopy wilderness.

The researchers analyzed 917 native forest plant species in Central and Western Europe and found that more than 80% prefer high-light conditions—environments traditionally created by large herbivores. This suggests that dense forests only became widespread after humans eliminated the large herbivores.

“Our results provide strong evidence that the closed-forest model commonly used in restoration does not match the evolutionary history or ecological preferences of most temperate forest plants,” says lead author Szymon Czyżewski, a Ph.D. student at the Center for Ecological Dynamics in a Novel Biosphere (ECONOVO) at Aarhus University who conducted the study with the center’s director, Professor Jens-Christian Svenning.

The evidence is mounting

The new study builds on a series of earlier ECONOVO results that, based on different data, point in the same direction. Together, the research paints a picture of a Europe where large herbivores, for millions of years, created light-rich woodland landscapes that have now largely disappeared.

The researchers also uncovered a worrying link between herbivore decline and the extinction risk of plants. Forest plants that are most strongly adapted to heavy grazing pressure are significantly more threatened today.

According to Svenning, this development has had serious consequences for biodiversity. “Our study shows that the plants most dependent on grazing are also the ones most at risk today. When large herbivores disappear, the forest closes in, and many light-demanding plants struggle to survive.”

Implications for forest management

The study has far-reaching implications for conservation, forest management, and reforestation across Europe. It challenges the prevailing “closed forest paradigm” and supports a shift toward restoring or maintaining heterogeneous, semi-open woodlands through trophic rewilding and low-intensity grazing.

The researchers thus call for a new approach to ecological restoration that actively includes large herbivores—either through rewilding or extensive woodland grazing—to recreate the varied, light-rich woodland landscapes.

“We should be cautious about simply planting trees everywhere and thinking that will promote biodiversity. It can actually be harmful if we don’t also preserve and restore the natural dynamics that large herbivores have maintained for millions of years,” says Czyżewski.