What is the link between biodiversity and psychological well-being?

We know green spaces are associated with higher well-being, but what evidence do we have about the link between biodiversity and well-being?

While the systemic benefits of biodiversity are well documented — from food supplies to climate regulation, nothing short of sustaining life as we know it — far less is known about the psychological benefits of nature. Because the majority of research focuses on nature as “green spaces”, the evidence is even slimmer when we look for the benefits of dwelling in more biodiverse green spaces.

In other words, we’re asking:

• Are we happier when green spaces are more biodiverse?
• Does our brain somehow perceive and benefit from more biodiversity?

The idea here is to summarise the knowledge showing that people’s well-being improved both:

1. in green spaces; and
2. with variety and novelty

Resulting in the intriguing (yet very little studied) possibility that people would benefit more from more diverse green spaces and the implications this could have for both research efforts and landscape management public spending.

1. What are the benefits of green spaces?

Green spaces have been shown to improve mood disorders, reduce stress-related illnesses, boost attention capacity, and promote socialising. Additionally, nature can potentially combat hedonic adaptation up to a point, as evidenced by the long-lasting benefits of moving to greener areas. Check out the annexe below for detailed research references about all of the above.

2. Why would biodiverse spaces increase happiness more than green space?

Well-being and happiness may evoke powerful emotions, but they are, in fact, pretty stable and predictable states. Over a lifetime, despite major ups, downs, or life changes, we always tend to return to a steady, base level of happiness. The culprit you can trust — without fail — to ruin a good bout of happiness is called hedonic adaptation. No matter how enjoyable an experience or a major life change is, we eventually grow accustomed to it, and the novelty fades. What was novel becomes mundane. We adapt, mainly because our brain needs to stay alert to newer experiences and events that we should be paying attention to.

That’s also why our brains are also naturally curious and drawn to novelty. Although our happiness keeps fading, we have an eagerly curious brain to make up for it, which is a quasi-constant desire for novelty, for seeing, experiencing, and learning new things. That’s why we believe that varied stimuli in biodiverse spaces help people experience continuously novel environments, fight hedonic adaptation, and increase human well-being in the long run.

3. Why does the link between biodiversity and well-being matter?

Ecosystem services

Nature provides a variety of “services” for us, known as ecosystem services, including providing water, food, and raw materials, regulating the quality of the soil and air, storing carbon, and supporting pollination and photosynthesis.

Those benefits do not stop at supporting our basic needs. Nature also fulfils a “cultural” service by contributing to our mental health through aesthetics, inspiration, or building spiritual connections. However, research has not yet explored many of the mechanisms and pathways allowing nature to support mental health and well-being.

Landscape management

While green spaces and nature have a positive impact on human well-being, are all green spaces created equal? Do they increase the wellbeing of urban dwellers? As policymakers encourage municipalities to create more green spaces in towns, it raises the question of how those green spaces should be designed. If we find out there is value (need we remind the cost of stress and mental ill health?), then we should use this knowledge to design more biodiverse green spaces. It can also be relevant for land management and development at large.

The economic cost of depression and anxiety disorders:

According to the Organisation for Economic Co-operation and Development (OECD), mental health conditions such as depression cost the United Kingdom £70 billion (US$100 billion) annually in healthcare spending and lost productivity. This is an alarming figure that highlights the need for increased investment in mental health resources and support.

Implications

Landscape management and development represent significant budgets for governments across the globe. While this is important for maintaining the beauty and functionality of outdoor spaces, there may be opportunities to optimise these efforts and resources. By exploring ways to integrate mental health initiatives into landscape management and development, we can potentially improve the overall well-being of individuals and communities. This could include promoting the use of outdoor spaces for physical activity and relaxation, incorporating natural elements into urban design, and creating green spaces that are accessible to all members of society.

Overall, while the cost of mental health conditions and landscape management may seem disparate, there may be ways to use these two areas to complement and enhance one another. By adopting a holistic approach that considers both the physical and mental well-being of individuals and communities, we can work towards creating a healthier and more sustainable society.

Annexe

A summary of research on how green spaces promote human well-being.

1. Mood disorders: According to a 2010 meta-analysis, urban dwellers are roughly 20% more likely to develop anxiety disorders than their rural counterparts, and nearly 40% more likely to develop mood disorders. Similar results are found (in twin studies), which show a reduction in depressive symptoms.
2. Stress: Green spaces can relieve occupational stress (McDonald 1994), decrease stress-related illnesses (Grahn & Stigsdotter 2003), improve physiological recovery from stress (Ulrich 1991), and increase children’s resilience (Wells and Evans 2003). Stress Reduction Theory started in 1979.
3. Attention: Exposure to green settings consistently boosts a person’s capacity to pay attention, the potential mechanisms are laid out in Attention Restoration Theory. This effect is observed in various settings such as large and small forests (Park et al., 2011, Doimo, 2020), rural areas (Roe & Aspinall, 2011), wilderness settings (Hartig, Mang, & Evans, 1991), and prairies (Miles Sullivan & Kuo, 1998). The same effect is observed in more modest settings such as community parks (Fuller, Irvine, Devine-Wright, Warren & Gaston, 2007), schools (Li & Sullivan, 2016), and neighbourhoods (Engemann et al., 2019). One of the most striking studies, conducted by Berman, Jomides & Kaplan, 2008, ran a controlled trial and showed that a walk through the university arboretum improved participants’ attention by 20%. However, no gain in performance was observed when they walked in town. A 20% improvement in one’s capacity to pay attention is far from being trivial, it is comparable to the effect of attention deficit drugs such as Ritalin, Adderall, or Dexedrine. The beneficial effect of nature is not limited to a certain portion of the population. A wide variety of people benefit from exposure to green spaces. Studies have demonstrated links between green spaces and higher performance on attentional tasks for public housing residents, AIDS caregivers, cancer patients, college students, prairie conservation volunteers, and employees of large organisations.
4. Socialising: We are hardwired to connect with people. Countless evidence shows that having social ties is one of the most important pillars of well-being. People who are more socially connected are healthier, behave in healthier ways, recover from illnesses faster, and live longer than their more isolated peers. The built environment can have a profound impact on the formation and maintenance of social ties. It can either discourage or promote them. For example, areas with more greenery have lower reported crime rates (Ogletree, Larson, Powell, White, Brownlee, 2022). Increases in natural features or perceived greenness in these neighbourhoods are associated with higher levels of social contact and an increased sense of social support among residents (Kim Kaplan 2004, Maas, van Dillen, Verhieß & Grovenwegen 2009). Additionally, community gardens, hospital green spaces, and school playgrounds are all associated with increased interaction and a sense of community.
5. Nature could potentially beat hedonic adaptation to a point: For example, winning the lottery, typically makes people happier for up to one year (Brickman, Coates & Janoff-Bulman, 1978), whereas the benefits of moving to greener areas may last even longer than 3 years (Alcock, White, Wheeler, Fleming, Depledge, 2013).