Forests provide different health benefits based on their structure

A walk in the forest often brings peace, calm, and a deep sense of renewal. From ancient times to modern therapy practices, forests have stood as symbols of balance and healing. But not all forests heal equally.

As cities grow and public health concerns rise, scientists are uncovering how the design and structure of forests matter. The health benefits we get from green spaces, especially forests, depend not just on their presence, but on what they are made of.

A new study from the University of Surrey and the University of Ghent sheds light on this. Working with partners across Europe, the research team explored how specific features of forests influence human health.

The findings mark a major step in understanding the complex links between ecological structure and wellbeing.

Forest traits and human health benefits

The study, which is part of the larger Dr. Forest research project, included 164 forests across five European countries. The researchers focused on seven ecological characteristics and their influence on various health outcomes.

The forests were not selected at random. They varied in structure, species mix, and density, allowing researchers to draw comparisons. This wide range of forest types provided a rare opportunity to explore how real-world differences affect human experiences and health.

The goal was not to judge forests as good or bad, but to understand how their differences shaped people’s health responses. What emerged was a nuanced view. Forests benefit health, but their structure can amplify or limit those effects.

The power of tree diversity

One of the key traits studied was tree species diversity. The findings showed that more diverse forests offered modest but positive health outcomes. These effects were not dramatic, but they were consistent enough to support the idea that diversity is beneficial.

Tree diversity does not just matter for human health. It also supports broader biodiversity, helping insects, birds, and mammals thrive. This makes it a safe, low-risk strategy for forest managers aiming to enhance public health while improving ecosystem resilience.

More tree species create different textures, shapes, and colors, making forests more visually stimulating and ecologically stable. These aspects can subtly influence how people feel and behave when they visit such areas.

While the direct health impacts may be limited, the indirect ones, through enhanced engagement and ecosystem strength, are valuable.

Canopy structure: A major influence

Among the ecological features studied, canopy structure had the strongest impact. Dense canopies reduce heat by offering shade and help regulate the forest’s internal climate. They also provide larger leaf surfaces, which trap fine particulate matter and improve air quality.

These benefits are especially important in urban settings, where heatwaves and pollution are on the rise. In such contexts, a well-structured canopy becomes more than a luxury. It is a necessity. The cooling effect alone can reduce heat stress and the risk of heat-related illnesses.

Yet, there are trade-offs. Denser canopies create more humid conditions. While that is good for moisture-loving plants, it also creates ideal habitats for ticks, which carry Lyme disease.

In addition, less sunlight reaches the forest floor. This limits the growth of medicinal plants, reducing some of the forest’s potential healing properties.

Mental health gains beyond structure

Perhaps the most consistent finding across the study was the benefit of simply being in a forest. Regardless of structure or biodiversity, spending time in a forest improved mental wellbeing. People reported lower anxiety and stress, along with more positive emotions.

What enhanced these effects was how natural and biodiverse the forest felt to the visitor. Forests that looked wild, vibrant, and untamed tended to offer more psychological relief. This suggests that human perception plays a key role in shaping forest-based experiences.

“Our study shows that forests generally provide a mental health benefit, reducing anxiety and stress, regardless of their biodiversity or structure. As one in six people in England experience anxiety and depression each week, this research suggests that simply being in a forest can improve mental health,” noted Dr. Melissa Marselle, a lecturer in environmental psychology at the University of Surrey.

“For the UK, this means preserving urban forests so people can easily access forests where they live, work and play for their mental wellbeing. Contact with forests could be prescribed by the NHS, as research shows that NHS nature prescriptions are effective at improving mental health.”

Designing healthier cities with forests

The study points to a pressing need in urban planning. It is not enough to plant trees and call it a forest. The structure, layout, and biodiversity of these spaces must be considered. Urban forests should reduce heat, absorb pollution, and offer mental rest.

This involves difficult trade-offs. Canopy density must balance between cooling the environment and letting in enough light. Species choices should consider both ecological function and visual appeal. Forests must feel natural to the human eye while also being safe and accessible.

Planners and health professionals can now use this evidence to shape better public spaces. Health services could integrate forest access into mental health treatments. Parks could be designed not just for recreation but also for healing. In a time when stress-related disorders are rising, these changes could make a meaningful difference.

Forests are essential tools for public health

This research redefines the role of forests. No longer just natural assets or scenic spots, they emerge as powerful contributors to public health. But their power lies in their details. Forests must be built, preserved, and managed with intention.

Tree diversity adds depth and life. Canopy structure shapes the microclimate and air. Visitor perceptions tie it all together. Forests that feel alive and balanced bring calm and strength to those who enter them.

Nature has always played a quiet role in healing. Now, with evidence in hand, we have the chance to shape that role more deliberately. Managed well, forests can support both ecosystems and the people who rely on them for peace and mental clarity.

The study is published in the journal Nature Sustainability.

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