Trees can contribute to the increase of local food and nutrition security, providing food such as fruits, nuts and leaves for both human consumption and fodder. Their wood, in turn, can be used for cooking and heating. Trees play an important role in increasing urban biodiversity, providing plants and animals with a favorable habitat, food and protection. A mature tree can absorb up to 150 kg of CO₂ per year. As a result, trees play an important role in climate change mitigation. Especially in cities with high levels of pollution, trees can improve air quality, making cities healthier places to live in.

Strategic placement of trees in cities can help to cool the air between 2 and 8 degrees Celsius, thus reducing the urban “heat island” effect, and helping urban communities to adapt to the effects of climate change. Large trees are excellent filters for urban pollutants and fine particulates. They absorb pollutant gases (such as carbon monoxide, nitrogen oxides, ozone and sulfer oxides) and filter fine particulates such as dust, dirt or smoke out of the air by trapping them on leaves and bark. Research shows that living in close proximity of urban green spaces and having access to them, can improve physical and mental health.

Mature trees regulate water flow and play a key role in preventing floods and reducing the risk of natural disasters. A mature evergreen tree, for instance, can intercept more than 15 000 liters of water per year. Trees also help to reduce carbon emissions by helping to conserve energy. Planning urban landscapes with trees can increase property value, by up to 20 percent, and attract tourism and business.

A city with well-planned and well-managed green infrastructure becomes more resilient, sustainable and equitable in terms of nutrition and food security, poverty alleviation, livelihood improvement, climate change mitigation and adaptation, disaster risk reduction and ecosystems conservation. Throughout their lifetime, trees can thus provide a benefit package worth two to three times more than the investment made in planting and caring for them.