Growing urbanisation is a threat to both mental ill health and biodiversity. As global urban cover is projected to increase to 1.9 million km² with 5.2 billion people expected to live in urban areas by 2030, action is needed to reduce future risks to both people and nature. Urban nature-based solutions, such as planting trees, might be a preventative solution to tackle both mental health challenges and biodiversity loss. 

This German study focuses on a specific type of the urban forest: individual street trees. Street trees are an important component of the urban forest because:

(1) they contribute to the conservation of native tree species,

(2) they are public amenities located throughout the urban matrix, and

(3) they can be easily retrofitted into urban areas where opportunities for growing the urban forest are limited.

Street trees also provide various ecosystem services for human health and well-being, such as air quality and climate change adaptation.

As mental health outcomes are influenced by the type of environment and its ecological quality, more knowledge is needed on the types and ecological qualities of the urban greenspace that have a benefit for mental health.

Such evidence can inform health professionals, urban foresters, city planners, and urban designers on the required policy, planning, and management decisions necessary to ensure the urban forest has a positive impact on both public health and nature conservation.

Read the study