Urbanization has been progressing rapidly, with the global population having approximately doubled in the last 40 years (OECD/European Commission, 2020), which contributes to environmental and noise pollution in cities. These factors can have psychological and physical impacts on humans, leading to severe stress and potentially threatening to their health (Shin, 2009). Previous studies have reported positive effects of visiting natural environments, such as forests, on human health (Wendelboe-Nelson et al., 2019). Thus, people have been visiting forests for recreation and relaxation, as well as for health benefits such as stress reduction (Korea Forest Service, 2020).

In response to this demand, in March 2010, the Korea Forest Service partially amended the Forestry Culture and Recreation Act (hereinafter referred to as the “Forest Recreation Act”) (Act No. 10116) and defined a “healing forest” as a forest that is developed for the utilization of a variety of elements of the forest, including fragrance and scenic view, in order to raise the immunity level of human bodies and enhance health, thereby establishing a legal basis for forest therapy (also known as forest healing). In July 2011, the Forest Recreation Act was partially amended (Act No. 10845) to legally define “forest therapy”, establish a system for training “forest healing instructors”, who are experts in developing and providing forest healing programs, and prepare standards for “forest healing programs” to effectively utilize the therapeutic functions of forests. As of 2022, 2,510 forest healing instructors have been trained (Korea Forest Welfare Institute, 2022). They are deployed in natural recreation forests, forest baths, healing forests, and forest paths to develop and disseminate various forest therapy programs.

A forest therapy program comprises activities that promote human health by utilizing various natural elements to maximize the therapeutic function of the forest (Kim, 2015). Therefore, the first step in the program development process should consider the gender, age, occupational characteristics, diseases, and purpose of the visit, and the program should be developed based on forest healing factors and therapies to maximize their effects (Yoo, 2009). However, the development and dissemination of customized forest therapy programs that consider user characteristics are insufficient, and extensive reviews and guidelines for target persons and applied therapies are needed (Lee et al., 2015).

As the demographic targeted for forest therapy broadens to encompass various fields, the scope of associated research is likewise expanding (Korea Forest Service, 2022). In order to present the health and medical effects of forest therapies for different groups of people, it is necessary to conduct research supported by systematic and scientifically produced evidence. Accordingly, many quantitative studies related to forest therapy programs have been conducted in South Korea, employing objective effectiveness verification aligned with evidence-based medicine principles. To ensure medical safety and the reliability of clinical outcomes, it is necessary to accumulate and socially disseminate research results on the effectiveness of forest therapies by targeting people and diseases (Yoo et al., 2015).

We reviewed the studies that comprehensively examined the effectiveness of forest therapy programs for each category of target people and found that Park (2020) focused on children, Yi and An (2021) on adults, and Lee (2022) on the elderly. In terms of patient category, Lee et al. (2016) focused on atopic children, while Chae and Lee (2020) focused on adult patients. Based on the results, we observed that the effectiveness of forest therapy programs was mainly examined in the healthy general population. However, despite the wide range of target participants in forest therapy programs, studies that examine the current status of populations in forest therapy programs and the effectiveness of forest therapy programs based on the situations and specific diseases of study populations are lacking.

Therefore, if we identified research trends and the status of study subjects by reviewing the previous studies on forest therapy programs, the results can be used as a basis for setting the direction for future studies on forest therapy programs for each target category. Furthermore, identifying the characteristics of programs organized by disease type can be used to develop target-specific forest therapy programs.

In this study, we systematically gathered forest therapy program studies conducted to date with the aim of identifying research characteristics (such as year and type of publication, and study subjects) and examining program features (including site type, implemented season, schedule type, and structure) based on disease type.

In this study, we systematically collected forest therapy program studies using the scoping review methodology to analyze research trends and the status of study subjects and examine the characteristics of forest therapy programs by disease type.

Upon examining the research trends, we found that the number of academic papers has been steadily increasing in South Korea since 2006, starting with the first study in 1996. In particular, since 2011, the number of academic papers and theses has increased dramatically in South Korea, accounting for the majority of the total research. This finding can be attributed to the fact that in 2006, forestry and medical experts established the Korea Forest Healing Forum through interdisciplinary cooperation to explore ways of utilizing the healing functions of forests (Yeom, 2009), followed by developing of healing forests and disseminating forest therapy programs under the leadership of the Korea Forest Service in 2007, leading to their popularization. Since then, forest therapy has been introduced as a legal concept through a partial revision of the Forest Recreation Act in 2011, and policy conditions have been set, including “the active implementation of forest therapy programs to improve public health.” Furthermore, studies confirming the medical effects of forest therapy have been conducted actively through the establishment of forest therapy-related majors in regular university courses in 2010 (Chungbuk National University, 2024). In the case of studies in other countries, the number of publications has been steadily increasing since 2015. Therefore, evidence-based research should be continuously expanded by establishing policy conditions appropriate to the current situation, such as the enactment of independent forest therapy-related laws and the preparation of plans to implement forest therapy actively. This will contribute to disseminating the effectiveness of forest therapy within society and establish a foundation for collaboration with the health and medical sectors, fostering the international promotion of forest therapy.

Upon examining the study subjects from the selected papers, we found that the main subjects were health clients. Specifically, they included workers such as teachers, counselors, social welfare and mental health workers, and healthcare workers, as well as those who were socially vulnerable and exposed to stressful situations, such as young individuals in child welfare facilities, individuals with an addiction to the internet and smartphones, and families of patients. The second main group was mental health patients, including children with intellectual, developmental, and speech disabilities, as well as individuals with depression. The last group comprised physical patients, including menopausal women and patients with cancer patients and atopic dermatitis. This suggests that forest therapy has been utilized as part of preventive medicine and alternative therapies for unhealthy conditions attributed to lifestyle and environmental stress (Korea Forest Service, 2022), and studies have been conducted to identify the medical effects of forest therapy on patients. The relationship of diseases with certain occupations, caregiver roles, and social circumstances such as poverty has been reported (Wilhelm et al., 2004; Kuruvilla and Jacob, 2007). Moreover, individuals in socioeconomically and psychosocially disadvantaged situations have higher levels of stress than the general population and higher morbidity rates for depression and other diseases (Korean Women’s Development Institute, 2010). Therefore, there is a need to analyze the effectiveness of forest therapy programs comprehensively through systematic literature reviews and meta-analyses of forest therapy programs for health clients who are the main target. In the case of mental health and physical patients, this study shows similar results as a study by Park et al. (2012), in which a Delphi survey was conducted among experts in the fields of forestry and medicine to identify diseases suitable for forest therapy; however, there is a lack of research on this topic. The lack of research can be attributed to limitations in the process of recruiting special study subjects, namely patients, without cooperation from the health and medical fields. Therefore, it is necessary to continue to expand effectiveness research on patients through collaboration with the healthcare and medical sectors.

The sites of forest therapy programs primarily included general forests and forest welfare facilities. In addition, such programs were conducted in various locations such as parks, urban forests, university research forests, and national parks, and differences in the locations depending on the type of disease were noted. It is believed that nature recreation forests (Korea Forest Service, 2015a), healing forests (Korea Forest Service, 2015b), and other forest welfare facilities consider Barrier-Free design and Universal Design elements in their facility construction, making them suitable as forest therapy activity sites for health clients and individuals with physical patients in terms of safety. The effects of forest therapy may vary depending on the type of forest space (Kim, 2012). However, while most studies have conducted an overall analysis of available forest therapy resources, forest environments, forest compositions, and climatic conditions, etc., at the study sites, there has been a lack of discussion on the correlation between research subjects and forest environments. Therefore, research should be conducted on the appropriate forest therapy environment according to the characteristics of the subjects, and studies are needed to determine the correlation between the types of sites and the subjects.

In terms of the implemented seasons, summer accounted for the highest proportion overall, and spring and fall had similar proportions. This is likely due to the fact that spring, summer, and fall are considered for outdoor activities. These results are consistent with the findings of Park et al. (2021), who analyzed a forest therapy program operated by the Korea Forest Welfare Institute. South Korea has four distinct seasons due to its geographical characteristics (Lee, 1979), thus showing diverse ecological characteristics of the forest environment. Due to these characteristics, the concentration of non-volatile organic compounds in the forest environment varies depending on the season (Park et al., 2018), and diverse scenic views of forests are recorded in different seasons, eliciting psychological and physiological recovery effects (Chen et al., 2023; Kim and Lee, 2023). Specifically, winter has been associated with decreases in human physical fitness and activity levels (Shephard and Aoyagi, 2009), as well as reductions in serum BDNF levels (Molendijk et al., 2012), and increased rates of diagnosis for depression and anxiety (Winthorst et al., 2011). However, despite research on the impact of winter forest environments on human recovery, studies on winter forest therapy programs have been lacking (Bielinis et al., 2018a; Bielinis et al., 2018b; Bielinis et al., 2021; Peterfalvi et al., 2021). Therefore, it is necessary to conduct research to verify the effectiveness based on the characteristics of forest therapy resources existing in each season, and research on forest therapy programs utilizing winter forest environments needs to be expanded.

Upon scrutinizing the structures of forest therapy programs, we noted that the primary types of schedules included one-day multiple session type and lodging type. For the one-day type programs, 120 min showed the highest frequency, followed by 60 min, and 180 min. The lodging type programs were mainly 3 days and 2 nights programs and 2 days and 1 night programs, and the session type programs were mainly based on a once-a-week cycle, with 6 to 10 sessions. In particular, one-day multiple session type programs predominated among mental health patients (74.4%), with programs of 16 sessions or more being attempted. It is interpreted that such programs aim to provide repetitive and long-term interventions for mental health patients. Generally, it has been reported that the effectiveness of forest therapy varies depending on program schedules, lengths, durations, cycles, and sessions (Cho, 2019; Kwon, 2023), and greater changes and effectiveness can be observed when participation is continuous (Yeon, 2007; Kim and Jeon, 2019). However, there has been a lack of discussion on the correlation between the characteristics of subjects and forest therapy program attributes. Therefore, it is necessary to expand the research on various types and schedules of forest therapy programs, in addition to the ones that are currently being studied, and to verify the appropriate program structures according to the type of disease. This will allow for more options and appropriate structures when developing forest therapy programs for specific populations.

This study applied the scoping review methodology to extensively review the studies on forest therapy programs conducted to date and provided an overview of the research characteristics and program characteristics in the selected papers. This study is significant in that we have suggested the study subjects of forest therapy programs objectively by summarizing them according to the KCD-8 and identifying the scope of research conducted to date. We hope that this study serves as a reference for developing target-specific forest therapy programs in the future by segmenting the targets according to their characteristics and collaborating with the stakeholders in the healthcare and medical fields. Nevertheless, it is essential to acknowledge a limitation in this study, as it relies on a literature review, which might introduce potential gaps in the research results. Therefore, it is necessary to review more cases of forest therapy programs and current program data of public and private forest therapy organizations to analyze and summarize the results more broadly. This will contribute to the discussion on the relationship between diseases and forest therapy programs.