Islands show human influence on nature

What is the impact of humans on nature? In Science an article appeared in which researchers try to give an answer to that question. Biogeographer and postdoc at LUCL Sietze Norder is one of its authors.

‘Nature is often considered to be a backdrop for humans’, says Norder. ‘Everything is unspoiled until humans arrive and change everything. We wanted to investigate how the degree of change that humans make in nature compares to pre-human changes.’

It is difficult to measure these changes on the continents, because these have often been inhabited for hundreds of thousands to millions of years. Islands are better suitable, because usually they have had a human population for ‘only’ a few hundred to thousands of years. That is why, the research team focused on such areas.

Eleven times faster

Using long drills they brought up different layers of earth and researched what pollen they contained. It turned out that the composition changed in every layer of earth, but the biggest shift occurred when humans arrived. ‘We can see that changes happened up to eleven times as fast as before’, Norder states. ‘One of the reasons is that humans tried to reproduce certain plants while they ignored others. Or they brought plants and animals with them when they settled. In this way, a cultural ecosystem with a clear interaction between humans and nature develops.’

The pattern turned out to be a consistent one: on all thirty islands that the team examined, ecosystems changed quicker after the arrival of humans. This result eventually led to the article in Science. ‘We were extremely happy. We worked on this with twenty-two people, each person with their own expertise and their own research. It is so cool when all the puzzle pieces come together at the end.’

Landscape versus culture

In the coming years, Norder continues to delve into the interaction between humans and nature. As a postdoctoral researcher at LUCL he is not focussing on the spreading of plants or animals, but on that of languages and cultures. ‘As a biogeographer, I always kind of roam between faculties. At Humanities I have the opportunity to look at how landscape influences languages and cultures. There exist for example languages that are only spoken near rivers or high in the mountains. That is what I want to delve into in the coming period.’

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