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03/2021: Four ways biodiversity influences our health

Author: Dr Melissa Marselle, Helmholtz Centre for Environmental Research; German Centre for Integrative Biodiversity Research; University of Surrey

Biodiversity, the variability of species, genes, and ecosystems, is essential for our health and wellbeing. But this biodiversity, on which we depend for the water we drink, the food we eat and clean air we breathe, is declining at an unprecedented rate. The economic and health risks from biodiversity loss will be enormous.

But why does biodiversity loss matter for human health? How is biodiversity important for our health? Our research identifies the three ways biodiversity keeps us healthy, and one way it does not.

Reducing harm

Biodiversity crucially contributes to human health by reducing ill health. By providing us with medicines, food and clean water, biodiversity protects us from diseases. Nearly 75% of all approved medical drugs come from nature. The food we eat comes from the biological diversity of animals and plants — and the work of bees and butterflies that pollinate those plants. Much of the world’s freshwater is provided from forests. The diversity of organisms in forests clean and filter water. Some plant species are better at removing heavy metals, like lead, from water than others. Biodiversity can also foster human health by reducing exposure to extreme heat. Urban greenspace with high diversity in the types of trees can reduce heat in cities, compared to urban greenspace with the same type of trees. This is because traits of certain trees – like the amount and size of leaves or the shape of the canopy – can influence the amount of cooling trees can provide during a heat wave.

Restoring capacities

Biodiversity also contributes to our health by restoring our capacities to deal with the demands of everyday life. Daily life can stretch our ability to handle stress, focus our attention and solve problems, which puts us at risk of being stressed and mentally ill. Biodiverse environments can help us restore these depleted capacities. For example, people living in a neighbourhood with more birds report being less stressed. A study had stressed people look at a meadow of varying species richness of plants for two minutes. People were most relaxed (measured as a decrease in their blood pressure) when looking at meadows with 32 different species of plants, but not when viewing meadows with 1 or 64 different species. Another study, looked at the views people have from the windows in their homes. People whose homes had views of a high amount of diverse vegetation had significantly lower cortisol, the stress hormone. While people whose window views in their homes with a high amount of vegetation that is all the same had the highest cortisol levels.

Building capacities

Biodiversity also fosters human health by building or strengthening our capacities for meeting the demands of everyday life. For example, a study in the US found that people reported doing less outdoor exercise in areas that lost ash trees, compared to US areas with ash trees. Sights and sounds of the diversity in nature – like seeing hundred of seabirds in flight or being in a forest – inspire strong emotions of awe, amazement and wonder. Such transcendent experiences of awe can give us a sense of perspective and help us to reflect on one’s life goals. People report that they were able to reflect and gain perspective on life more often when in a greenspace with a high number of species richness of plants and birds.

Causing harm

Biodiversity is not always good for us. It can also negatively impact our health by causing harm. Infectious diseases, like Ebola or Malaria, are good examples of the risks of biodiversity. Such diseases require a pathogen (like a virus) to transmitted to humans through host species, like bats, ticks or mosquitos. Unsustainable management of biodiversity (e.g. through habitat loss or wildlife trade) can increase the risk of interactions with animals that carry these infectious diseases. Allergies, animal attacks, and nettle stings are other examples of how contact with biodiversity is also harmful to human health.

Dr. FOREST project

In the Dr.FOREST research project, we will investigate the ways tree diversity in forests impact human health and well-being. In particular, we have work packages assessing the influence of tree diversity on human health via the reducing harm pathway (WP2 and WP4) looking at medicinal plants, food and air pollution; the restoring capacities pathway (WP1) looking at stress reduction and attention restoration; and the creating harm pathways (WP3) looking at ticks and other disease vectors. We do this by studying temperate forests in Austria, Belgium, France, Poland and Germany.

One million species are at risk of going extinct. This biodiversity loss has a negative impact on human well-being and health. We hope our research in Dr. FOREST can underpin the urgency of why we need to protect biodiversity for our own health and well-being, as the economic and health costs of biodiversity loss to society would be enormous.

Disclosure statement: The Volkswagen Foundation provided funding for this research via a Symposia grant to Dr Melissa Marselle & Prof Aletta Bonn. This was authored by 26 leading scientists from biology, ecology, epidemiology, psychology, geography, medicine, and public health, as well as experts from the WHO Europe and the German Nature Conservation Agency.