Humans not all bad for biodiversity, new science study finds
Humans are often blamed for a decline in biodiversity, but a new study has shown that sometimes, humans can actually have a positive impact.
Humans have played an important role in vegetation change for thousands of years. Often we are at fault of disrupting the delicate biodiversity balance, but in some places and over longer periods of time, humans have been good for biodiversity.
Global pollen clues
Researchers from the University of York found humans are an important driver of vegetation change. They used a global pollen dataset to evaluate the variety of plant communities dating back to the beginning of the Holocene period, 12,000 years ago. From then until the beginning of the Industrial Revolution, the speed at which different types of plants changed within a community accelerated with increased human land use in all continents. However, analysis also revealed the nature of these changes varied geographically.
Human activity caused plant communities to diversify across most of the northern hemisphere, but in Africa, South America and some parts of North America, greater human land use caused a drop in plant diversity, while increases in diversity were seen in areas with more limited human land use.
“When we read headlines about threats of extinction to animal or plant life, human activity is often cited as one of the main reasons for the decline,” says study leader Jonathan Gordon, a postdoctoral researcher from York’s Leverhulme Centre for Anthropocene Biodiversity. “While it is absolutely true that the vast majority of extinctions taking place since 1500 have been driven by humans, over longer time periods the effects of humans on local and regional biodiversity are positive in many areas.”
Diversity increased in once-forested areas of the northern hemisphere as farming and forestry practices interacted with regionally specific plant communities. The partial clearing of trees to make way for animals, crops and homesteads increased the diversity of habitats and made space for light-loving plants.
Gordon says: “We see a slightly different picture in open grasslands and savannas, compared to forested areas, however, and this could be because it is more challenging for humans to diversify plant life by planting trees, compared with chopping trees down in forested regions. In these areas, biodiversity only benefited with less intense forms of human use.”
Varied approach
The research suggests a more varied approach to increasing biodiversity globally, with evidence from thousands of years of human interactions with the Earth’s ecosystems being considered in new and future environmental policy.
“The common assumption when tackling biodiversity issues is that human influence needs to be removed in order for the environment to thrive as nature intended it to,” Professor Chris Thomas, from the Leverhulme Centre for Anthropocene Biodiversity. “In many places biodiversity thrives because of many thousands of years of human activities, and in others it can suffer, and so it is important to know the differences in order to develop appropriate conservation policies.”
“In a European context, for example, this work suggests that low-intensity, traditional farming methods practised over multiple millennia resulted in elevated biodiversity levels,” adds Gordon. “Encouraging traditional methods and reintroducing them in locations where they have now been abandoned, could be part of future conservation strategies that seek to include, rather than reject out of hand, humans from diverse ecological systems.”
News reference
Gordon, J,D. et al. (2024), Floristic diversity and its relationships with human land use varied regionally during the Holocene, Nature Ecology & Evolution.