The Positive Impact of Planting Trees Under an Urban Afforestation Program on Mental Health

Abstract

The growing body of evidence highlights the beneficial effects of passive nature exposure on mental health parameters, such as affects and subjective vitality. However, there is a lack of empirical data associated with the effects of active involvement in afforestation activities on affects and subjective vitality levels, particularly in urban areas. The current study aimed to evaluate the effects of hands-on participation in urban afforestation activity on affects and subjective vitality in adults. One hundred fifty-two adults participated in a 90-min urban afforestation program. The primary outcome, affect levels, is measured by the Positive and Negative Affect Schedule. The secondary outcome was the subjective vitality, which was analysed by the Subjective Vitality scale. Mediator and moderator effects of participants’ connectedness to nature, perceived restorativeness of the environment, exerted physical effort during the activity, menstrual cycle phase, and hours spent walking, exercising, and sleeping were analysed by bivariate correlation and multiple regression. Results showed significant pre-post improvements in positive affect (t = −9.165, p < .001), negative affects (t = 7.473, p < .001), and subjective vitality (t = −5.881, p < .001). The effect sizes of these differences are moderate for positive affects (d = .734), negative affects (d = .554), and small for the subjective vitality (d = .439). Regression models successfully predicted the variances in positive affects (adjusted R2 = .169, F = 10.560, p < .001), and subjective vitality (adjusted R2 = .150, F = 9.285, p < .001). The results suggest that adults may benefit from participating in a 90-min urban afforestation program by improving affects and subjective vitality.