Diversity of FORESTs affecting human health (Dr. Forest)

Forest ecosystems are an important reservoir for biodiversity in human-dominated landscapes within Central Europe, and deliver many ecosystem services. They are also a popular location for recreational activities, especially near urban areas. However, forests can also harbour threats and diseases. The Dr. FOREST project quantifies four important pathways explaining how forest diversity can improve, or reduce risks to human mental and physical health: (i) provision of visual aesthetics and enjoyable soundscapes, (ii) provision of nutritional and medicinal forest products, as well as a comfortable microclimate for recreation, (iii) dilution or reduction of disease vectors, and (iv) reduction of air pollution. The project makes use of existing research infrastructures for functional biodiversity studies and relies on a rigorous experimental design that allows quantification of tree diversity effects on human health. The empirical work will be done in controlled tree diversity experiments as well as in natural forests of differing diversity adopting a comparative design. The sites are located in contrasting climatic regions of Central Europe (France, Belgium, Germany, Austria, Poland). In three Case Studies in urban forests the consequences of forest diversification schemes for health-related risks and benefits will be elaborated together with local stakeholders (Sonian Forest Brussels, Bois de Bordeaux, Auwald Leipzig). All Work Packages and Tasks are handled by teams composed each of both natural and medical scientists, ensuring cross-disciplinary collaborations and synergies. Interactions with stakeholders to refine research questions and to promote the human health impacts of biodiversity in forests, as well as formulation of management guidelines, will ensure high relevance for health policy and forest administration. A final symposium will communicate the projects findings to high-level stakeholders and will support evidence- based decision-making for forest biodiversity and human health co-benefits and risks.

The research project Dr. FOREST explored the impact of forest biodiversity on human health across various settings, including natural forests, urban areas, and laboratory studies. The study sites were located in France, Belgium, Germany, Austria, and Poland. By conducting stakeholder workshops, we refined our research questions and raised awareness about the health benefits of forest biodiversity. We discovered that spending time in forest environments generally boosts mental health. Interestingly, the number of different tree species in a forest did not directly enhance mental health. Instead, people's perception of increased biodiversity, whether through sight or sound, was linked to better mental health outcomes. Forests also play a crucial role in regulating temperatures, reducing thermal stress. This effect is influenced more by canopy density than by the variety of tree species. Additionally, we found that tree diversity does not affect the nutritional value of medicinal plants and edible mushrooms. However, we did uncover a significant health benefit related to tick-borne diseases: higher tree diversity was associated with a lower proportion of ticks carrying Lyme disease-causing bacteria, highlighting the role of diverse forests in reducing health risks. We also investigated how different tree species and their mixtures capture dust, finding that both the type of tree and the leaf characteristics contribute to dust capture, which has implications for air quality. Our findings suggest that forest management practices focusing on biodiversity can enhance public health. However, different aspects of forest biodiversity affect various health outcomes, indicating potential trade-offs in management strategies. These insights will guide the development of management guidelines for health policymakers and forest administrators to optimize the health benefits of forests. In summary, promoting diverse forests can offer multiple public health benefits, from mental well-being to disease prevention. Our research underscores the importance of considering biodiversity in forest management to improve overall health and well-being.