The Black Death Reduced Biodiversity in Europe, Study Finds

The Black Death killed millions of people across Europe—and new research suggests the epidemic also caused a major decline in biodiversity. The findings reveal that human activity can sometimes increase biodiversity by creating a patchwork of habitats, offering lessons for improving biodiversity in modern agricultural landscapes.

How the Black Death changed Europe’s landscape

The 14th century was a tumultuous period for Europe. Cold, wet weather early in the century contributed to widespread agricultural failure and unprecedented starvation during the Great Famine of 1315 to 1317.

Following the famine, the Black Death—an outbreak of bubonic plague caused by bacteria—killed more than a third of Europe’s population. Vast areas of farmland were abandoned as a result of the death toll and the social upheaval that followed. Europe’s population did not begin to recover until the 16th century, according to economic research.

The period provides researchers with an opportunity to study the long-term effects of human activity—and the sudden removal of people—on biodiversity.

Researchers examined more than 4,600 pollen samples

“We’re trying to figure out what’s going on,” Jonathan Gordon, a paleoecologist at the University of York’s Leverhulme Center for Anthropocene Biodiversity and the study’s lead author, told Live Science.

In a study published March 4 in the journal Ecology Letters, researchers compared more than 100 European pollen records containing approximately 4,600 samples. The records came from locations ranging from the lowlands of France and the highlands of southwest England to the Swiss Alps.

Pollen records provide evidence of past plant diversity and historical land use. Grains such as wheat, barley and rye were common components of medieval agriculture, so the presence of their pollen indicates that land was being used to grow crops.

The researchers divided the records into three categories according to changes in grain pollen: areas where agricultural production increased, areas where it decreased and areas with no evidence of grain cultivation.

Biodiversity fell by about 40% where farming declined

“We found an overall decline in biodiversity, but the overall decline was driven by landscapes with reduced agricultural production,” Gordon said.

In landscapes where agricultural production declined, biodiversity fell by about 40%. Approximately 150 years later, as populations began to recover and landscape disturbance increased again, biodiversity rose to slightly above its previous levels.

Why abandoned farmland may have reduced biodiversity

The results challenge the assumption that removing people from a landscape always benefits nature. According to Elle Ellis, an agroecologist at the University of Maryland, Baltimore County who was not involved in the research, scientists have long recognized that the relationship between people and biodiversity is complex.

When people manage landscapes in varied ways over long periods, they can create diverse habitats known as “mosaics.” These mosaics may support more species than a uniform landscape.

Medieval landscapes contained a range of farming practices and natural habitats, including old woodlands, heaths, ponds and areas of secondary forest. These habitats were interwoven with agricultural land, creating more opportunities for different plant species to thrive.

“There were many different types of farming in the same landscape,” Gordon said. “There was a lot of nature in that landscape that was left over from the middle or early Holocene.”

Modern monoculture can reduce biodiversity

The findings highlight the contrast between medieval and modern land-use practices. In the 20th century, global biodiversity declined by up to 11%, while land-use change, pollution and climate change became major causes of biodiversity loss.

Modern agriculture often relies on monoculture—the cultivation of a single crop species across a large area—which can reduce biodiversity, according to research on agricultural systems.

“This study shows that even in Europe until relatively recently very different forms of land management and interaction were practiced than today,” Patrick Roberts, head of the Department of Coevolution of Land Use and Urbanization at the Max Planck Institute for Geoanthropology, told Live Science in an email.

“The emphasis was on maintaining the ‘mosaic,’ rather than the monocultures, plantations or uniform landscape changes seen in the 20th and 21st centuries,” said Roberts, who was not involved in the study.

The research shows how people can use landscapes while preserving biodiversity and maintaining mixed ecosystem functions. Designing modern agricultural landscapes with a greater variety of crops and habitats could help support more species.

Species numbers are only part of biodiversity

Researchers still do not fully understand how the disappearance of people during the Black Death affected the natural world. Biodiversity is not only a measure of how many species live in a landscape; it also includes what those species do.

“Functional diversity is critical to how ecosystems adapt and how resilient they are to changes in climate, and this is what we need to future-proof our agricultural systems,” Gordon said.

Reference: J.D. Gordon, B. Fagan, J. Finch, L. Gilson, N. Milner and C.D. Thomas (2026). “Land abandonment during the Black Death caused a loss of diversity in Europe.” Ecology Letters, 29(3), e70325.