On an individual level, trees and urban woodlands are beneficial to people.
To name a few examples, they:
* Produce oxygen (a mature beech Fagus sylvatica produces sufficient oxygen over a year for ten people)
* Release many compounds into the atmosphere including monoterpenes which seem likely to have positive health effects.
* Absorb noise, dust, pollution and carbon dioxide.
* Reduce skin cancer.
*Reduce mental health problems.
* Improve post surgery recovery rates in hospital wards which overlook wooded settings.
Reference: Ecology of woodlands and forest book