In the face of escalating climate change, global pandemics, and social unrest, the importance of planting trees cannot be underestimated.
Trees are fundamental to life. They are ecosystem engineers for the great forests, providing habitat for innumerable plant and animal species. They help to filter rainwater and improve water quality, and provide a host of other ecosystem services.
Trees also represent a form of natural capital and a key tenet of green infrastructure.
We are now beginning to discover (and rediscover) many of the benefits associated with being surrounded by trees.
Natural capital providing a range of ecosystem services
At its most basic, natural capital is defined as a stock of natural assets. These natural or environmental assets can provide a range of direct and indirect ecosystem services.
Tree ecosystems directly provide a number of products, ranging from timber to food and water. We also gain critical benefits from the environmental regulation they provide for environmental processes like climate regulation, pollination, and air quality. The world’s rainforests, for example, are some of the largest reservoirs for sequestering atmospheric carbon.
Trees also help to reduce flood damage and erosion and provide intermediate services to support other ecosystems. These internal processes include soil formation and rehabilitation, photosynthesis, and nutrient cycling.
People enjoy a variety of aesthetic experiences, recreational activities, and associated wellbeing and health benefits in green areas – and areas with trees in particular.
The interrelationship between natural capital and green infrastructure
According to the European Commission, green infrastructure is “a strategically planned network of natural and semi-natural areas with other environmental features designed and managed to deliver a wide range of ecosystem services such as water purification, air quality, space for recreation and climate mitigation and adaptation.”
The concepts of natural capital and green infrastructure are thus clearly interrelated. Natural capital places an emphasis on the benefits the natural environment provides to humans. Green infrastructure, on the other hand, emphasises the benefits we gain by incorporating natural elements and environmental processes into human-dominated landscapes.
The creation of green infrastructure has been shown to provide a host of benefits in urban areas, and planting trees can provide a host of ecosystem services, depending on the context.
Health and wellbeing benefits
The creation of green infrastructure in urban areas strengthens community bonds and reduces socio-economic health inequalities. Green spaces provide a place where people can learn about nature as well as exercise, relax and reduce stress levels. Increased social interaction is frequently highlighted as a key benefit of green spaces.
Public green spaces have been significantly associated with greater mental wellbeing, as well as reductions in crime – especially violent crime. A 2018 study in Chicago, for example, associated a 10% increase in tree cover with a 10.3% reduction in battery and 11.3% fewer assaults and robberies.
The very structure of areas populated by trees helps to reduce noise pollution, and enhance attention and cognitive function. Studies have also shown that increased access to trees and green spaces can change the structure of the brain, prevent neurodegeneration, and increase resilience.
In a previous Food & Trees for Africa (FTFA) blog, we explored the various mental health benefits associated with planting trees, including the reduction of stress and anxiety. Trees are not only good for our mental health, though, they can also help to speed up recovery from surgery and illness.
Unsurprisingly, then, trees are associated with better academic performance. A Canadian study found that by increasing tree cover, urban school districts were able to improve primary school learners’ academic performance. This effect was particularly profound when focusing on socio-economically disadvantaged schools.
With thoughtful urban planning, planting trees can reduce infrastructure maintenance costs. One way they do this is by catching, cleaning, and diverting rainwater into natural waterways. This reduces pressure on sewerage systems and stormwater drains.
“Shifting our view to perceive public trees as assets rather than liabilities is an important aspect of maintaining and enhancing the benefits that trees provide in an urban setting,” says Climate-KIC, a knowledge and innovation community working to accelerate the transition to a zero-carbon, climate-resilient society. Part of this, says the organisation, is to stop fixating on the number of trees planted, and to focus instead on results-based metrics like cost benefit analyses.
The presence of trees, for instance, can reduce energy use in your home by providing cooling shade in summer and windbreaks in winter. Trees have also been shown to increase property values by between five and 18%.
Taking this all into account, surely the question we should be asking is not whether to plant trees, but rather, how do we plant and maintain more trees in the right places?