There are generally two types of forest therapy. One is to walk or view the forest alone without a guide, and the other is to be accompanied by a guide. This study aimed to investigate the healing factors and health benefits of self-guided forest therapy and guided forest therapy programs and examine the differences in characteristics between interventions. Thirty-seven undergraduate students participated in a randomized experiment (19 in the self-guided forest therapy and 18 in the guided forest therapy program). Data were collected from 111 self-reported essays after each intervention (three essays per person). Results revealed that the forest healing factors contained four categories in common: auditory element, visual element, tactile element, and olfaction element. Forest therapy's health benefits included five categories in common: change of mind and body, introspection, change of emotion, cognitive change, and social interaction. Among the typical differences, the self-guided forest therapy group mentioned more keywords related to introspection than the guided forest therapy program group. On the other hand, the guided forest therapy program group mentioned more keywords associated with the change of emotion and social interaction than the self-guided forest therapy. Our findings show that self-guided forest therapy provides an opportunity for self-reflection to focus on and think about one's inner self. On the other hand, guided forest therapy programs provide positive emotional changes and promoting social bonds through interaction with others. Therefore, because the effects that can be obtained vary depending on the type of forest therapy, participants can utilize forest healing to suit the desired outcomes.
Keywords: guided forest therapy program; healing factor; health benefit; self-guided forest therapy.