Indicators of the Psychosocial and Physiological Effects of Forest Therapy: A Systematic Review

Research on forest therapy and health outcomes is insufficient and involves the limited unification of various health indicators. Information on the natural therapeutic elements of forests and forest-therapy programs is insufficient. We investigated forest-therapy programs, the natural therapeutic elements of the forest environment, and health-outcome measures to standardize the health indicators of forest therapy. A systematic review was conducted on the health outcomes of forest therapy from 2010 to 2021. We summarized natural therapeutic elements and forest-therapy sites, characteristics, and health outcomes. Twenty-nine articles were analyzed. Among them, forest therapies of walking and physical activity were conducted most frequently. Additionally, a positive improvement in general sentiment condition was substantial in all vegetation environments, and a reduction in depression, psychological enhancement, stress alleviation; and an enhancement in the cardiovascular system and the endocrine system occurred in both narrow- and broad-leaved forests. Walking, five-senses stimulation, physical activities, and meditation benefited psychological and physiological outcomes. We evaluated natural therapeutic elements of the forest-environment program and health outcomes. This systematic review can be used as a reference for the planning and operation of forest-therapy programs.