Black Death Rewilding Devastated Plant Diversity Across Europe as Forests Spread on Abandoned Farms

The heavy casualties of the Black Death gave plants free rein to retake landscapes across Europe, but their return to abandoned lands didn’t exactly do wonders for their diversity. After widespread “rewilding” — in which nature is restored in an area that humans have left — one might expect biodiversity to soar. But for plants that took over after the Black Death, the opposite turned out to be true.

A new study published in Ecology Letters shows that rewilding has its drawbacks when it comes to plant diversity. Plant diversity had flourished in Europe throughout the Middle Ages, but once the bubonic plague hit in 1347, plant diversity declined despite the spread of forests. This demonstrates how rewilding, a popular conservation strategy nowadays, may not always be the perfect approach, and that humans and nature sometimes depend on each other to prosper.

Read More: Black Death Bacterium Evolved to be Less Aggressive to Kill Victims Slowly

Rewilding After the Black Death

The Black Death had Europe reeling after wiping out potentially as much as half of the continent’s population (around 50 million people) between 1347 and 1353. The plague swept though larger port cities — trading hubs like Venice, Florence, and London — shocking local economies. While the effects of the plague weren’t as catastrophic in the countryside, rural economies suffered nonetheless, as farms and cultivated fields were abandoned.

Large swathes of land that were no longer used for farming experienced unfettered plant growth, as “rewilding” took effect. But while they grew in numbers, plants weren’t necessarily becoming more diverse.

“As farmland was abandoned, traditional land management practices ceased and forests spread,” said study author Jonathan Gordon, a postdoctoral research associate at the University of York, in a statement. “Rather than driving an increase in plant biodiversity, biodiversity plummeted. We only started to see a recovery once human populations rebounded and agricultural activity resumed — a process that took roughly 300 years to return to pre-plague levels.”

Hitting a Snag in Plant Diversity

The researchers involved in the new study examined the unexpected consequences of rewilding during and after the Black Death by collecting data from over 100 fossilized pollen records across Europe.

The data showed that plant diversity had actually been increasing from 0 B.C.E. to 1300 C.E., peaking in the High Middle Ages. But after the Black Death struck, plant diversity declined for the next 150 years.

The researchers found that plant diversity had been greatly affected in areas where crop production ceased. Areas where farming continued, on the other hand, saw a comparative increase in plant biodiversity.

This suggests that humans can have a positive impact on plants with the proper farming practices. At the time of the Black Death, for example, European landscapes were dominated by mixed agricultural systems, in which farmlands were separated by woods, grazing lands, and uncultivated plots. This allowed a wide variety of plant species to thrive.

“Our work offers a more nuanced perspective on the relationship between humans and nature, indicating that biodiversity and human land use do not have to be in conflict. In many cases, they actually depend on one another,” said co-author Chris Thomas, an ecologist and evolutionary biologist at the University of York.

Help From Humans

Rewilding has been considered an approach to conservation, yet researchers note caveats: eliminating human impact in certain landscapes may harm, rather than support, biodiversity.

They emphasize the importance of preserving Europe's mixed agricultural systems. And while intensive framing practices can wreak havoc on the land, low-intensity land management practices could be the key to preventing the loss of plant diversity.

“To maintain the many different types of biodiversity that have been associated with European ecosystems over the last few millennia, we have to take a ‘patchwork approach,’ where we have a mosaic of crops, woodlands, pastures, ponds, and lakes and so on, co-existing in the same landscape,” said Gordon.

Read More: Scientists Reveal the Black Death’s Origin Story

Article Sources

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• This article references information from a study published in Ecology Letters: Black Death Land Abandonment Drove European Diversity Losses