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The Influence of Forest Activities in a University Campus Forest on Student’s Psychological Effects

International Journal of

Environmental Research

and Public Health

Article

The Inﬂuence of Forest Activities in a University Campus Forest

on Student’s Psychological Effects

Jin Gun Kim 1, Jinyoung Jeon 1 and Won Sop Shin 2,*

1 Graduated Department of Forest Therapy, Chungbuk National University, Cheongju 28644, Korea;

jingun0308@naver.com (J.G.K.); forest-bb@naver.com (J.J.)

2 Department of Forest Sciences, Chungbuk National University, Cheongju 28644, Korea

* Correspondence: shinwon@chungbuk.ac.kr; Tel.: +82-43-261-2536

Abstract: This study aimed to examine the psychological effects of forest activities in a campus forest.

A pre-test and post-test control group design was employed to evaluate the psychological effect of

forest activities in a campus forest. A total of 38 participants participated in this study (19 in the

forest activities group; 19 in the control group). The Proﬁle of Mood State (POMS) questionnaire, the

Concise Measure of Subjective Well-Being (COMOSWB), and the modiﬁed form of the Stress Response

Inventory (SRI-MF) were administered to each participant to assess psychological effects. This study

revealed that participants in the forest activities intervention group had signiﬁcantly positive increases

in their mood, stress response, and subjective well-being, comparing with those of control group

participants who did not partake in any forest activities. In conclusion, the implementation of forest

activities in a campus forest is an efﬁcient strategy to provide psychological well-being beneﬁts to

college students.

Citation: Kim, J.G.; Jeon, J.; Shin,

W.S. The Inﬂuence of Forest Activities

in a University Campus Forest on

Student’s Psychological Effects. Int. J.

Environ. Res. Public Health 2021, 18,

2457. https://doi.org/10.3390/

ijerph18052457

Academic Editor: Paul Tchounwou

Received: 21 January 2021

Accepted: 25 February 2021

Published: 2 March 2021

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Attribution (CC BY) license (https://

creativecommons.org/licenses/by/

4.0/).

Keywords: forest therapy; campus forest; proﬁle of mood state; subjective well-being

1. Introduction

The world has become an urban society, with many populations becoming alienated

from the traditional people–nature relationship. According to the World Health Organiza-

tion [1], more than half of the world’s population lived in urban environments in 2014, and

this will increase to 65% by 2030. Urbanization, deﬁned as the increase in the number of

cities and urban population, is a demographic movement and includes social, economic,

and psychological changes that constitute the demographic movement. It is a process

that leads to the growth of cities due to industrialization and economic development [2].

Urbanization provides us with many opportunities, such as rapid economic growth, but

overexposure to stress causes mental health problems [3,4]. Namely, urbanization affects

mental health by increasing stressors and factors such as overcrowding and polluted

environment, high levels of violence, and reduced social support [5].

In such a situation, mental health is an increasingly urgent public health problem,

highlighted by an increase in mental illness such as depression and anxiety [6,7]. This men-

tal health crisis is a particular concern on college campuses. Students encounter stressors,

including academic and extracurricular demands, relationships, ﬁnancial concerns, familial

expectations, identity development, and racial and cultural differences. In recent years,

there has been an increase in reported symptoms of mental health in college student popu-

lations. According to the 2019 National College Health Assessment [8], 87% of students felt

overwhelmed in the past 12 months by all the work they had to do. In addition, 65% of

students reported feeling overwhelming anxiety, and 70% of students felt very sad and,

45% of the students suffered from depression. Gallager [9] and Mackean [10] reported that

college students had increased mental health problems such as depression, anxiety, suicidal

thoughts, and other chronic psychiatric disorders compared to the general population.

Research suggests that students have mental problems due to the pressure of academics,

Int. J. Environ. Res. Public Health 2021, 18, 2457. https://doi.org/10.3390/ijerph18052457

https://www.mdpi.com/journal/ijerph

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taking exams, transitioning into college life [11], relationship problems with a peers and

romantic partners [12], ﬁnancial concerns, and familial expectations [13]. Hence, mental

health issues among college students can negatively affect academic performance [14,15],

relationship dysfunction [16], a high rate of drinking [17,18] and substance abuse [19,20],

and increased incidence of suicide [21]. Therefore, it is important to employ effective

interventions for coping with a college student’s mental health problems.

The use of forests and forest therapy is increasingly recognized as an effective in-

tervention for dealing with physical and psychological problems [22,23]. Many studies

demonstrated that using forests helps to reduce stress and enhance physiological relax-

ation [24–27]. For instance, forest activities, such as walking through a forest or viewing

the landscape, can also increase parasympathetic nervous activity [26–28], suppress sym-

pathetic nervous activity [29,30], reduce the cortisol concentration [24,31], pulse rate, and

blood pressure [28,31], and improve the immune system [32–34]. Park et al. [31] reported

that the forest walking group demonstrated reduced cortisol levels, blood pressure, heart

rate, and sympathetic nervous activity and improved parasympathetic nervous activity

compared to the city walking group. Studies by Li et al. [32] investigated the impact of

forest trips on natural killer (NK) cell activity for two nights and three days on 12 men

with weakened immune function. The results demonstrate that forest activities improve

weakened immune function. A further study conducted on women also reported that

weakened NK cell activity positively affected male and female participants [33]. In addition,

increased NK cell activity was maintained for one week for both men and women, and in

the case of men, the long-term effect of forest healing was revealed through the results, in

that it was maintained until 1 month later [34].

In addition, regarding psychological relaxation aspects, the effects of forest therapy

were associated with improved mood state [35,36], self-esteem [37,38], and quality of

life [39,40], decreased psychological stress [41,42], depression and anxiety [43–45]. For

example, Kaplan and Kaplan [46] argued that individual mental fatigue could be restored

through contact with the natural environment, such as the forest. Ulrich et al. [47] demon-

strated that natural scenery, such as forests, relieves psychological stress. Shin et al. [48]

assessed the impact of forest environment on individual psychological health and well-

being and the forest experience contribution to emotional and cognitive health promotion.

Regarding the more direct impact of natural environments, such as forests, Pretty et al. [49]

reported that participants’ mood and self-esteem improved signiﬁcantly after forest ex-

ercise. Park et al. [50] showed that walking through a forest reduces negative emotions

such as tension, anxiety, depression, anger, fatigue, and improves positive emotions such

as vigor. In a similar study, Morita et al. [51] reported that staying and walking in the

forest reduces hostility and depression and increases vigor, and further study showed

that walking in the forest improves the amount of sleep and reduces the anxiety of partici-

pants [52]. To further clarify the psychological effects of forests, Song et al. [36] divided

624 college students into 52 groups to walk through the forest and urban environment.

The results show that participants who walked in the forest environment experienced

decreased negative emotions such as depression, tension, anger, fatigue, and confusion

and increased positive emotions such as vigor, compared with participants who walked in

the city environment, and participants with high anxiety experienced a greater effect from

the forest in improving depression than those with general or low anxiety.

Many studies demonstrated that exposure to nature, such as forests, improves cogni-

tive tasks that require direct attention. For example, Tennessen and Cimprich [53] showed

that the student who can see the natural environment through dormitory windows per-

formed better in tasks requiring concentration than those who did not. Taylor et al. [54] also

reported that children who could see urban forests near their apartments performed better

in tasks relating to memory, impulse control, selective attention, and concentration than

those who did not. Similarly, it has been shown that walking in the natural environment,

such as forests, provides advantages in language work memory and cognitive control

compared with walking in an urban environment [55–57].

Int. J. Environ. Res. Public Health 2021, 18, 2457

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However, due to the busy college life of students, interaction with forests far away

from cities is limited. Therefore, we need to utilize the campus forest to improve students’

quality of life. Campus forests are forests in the university campus space [58]. Campus

forests are considered meaningful places for experiencing everyday life, with the poten-

tial to support healthy campus planning [59,60]. Campus forests are pre-existing, easily

accessible, and effective resources for health [60]. Students who spend most of their time

on campus walk by and through these spaces daily. Therefore, it could be a good idea to

use campus forests to manage university students’ mental health. Campus forests have

recently been placed on the list of important urban green spaces, drawing more attention

to them than in the past [61,62]. Campus forests can connect green networks in the inner

city and contribute to forming a community with residents. On university campuses, green

space is desirable, and represents a precious amenity to help recruit and retain students,

promote student loyalty and pride, attract donors, and improve campus quality of life [63].

Some studies suggest the use of campus forests to help college students. Tudorie et al. [64]

reported that a campus forest provides a place to relax, meet friends, and pass through. It also

has a high potential to provide cultural, provisioning, and regulation landscape services.

The content and greenness of the view from indoors on campus can improve indoor

settings’ perceived restorativeness [65]. Campus forests also can improve the quality of

life and mental health beneﬁts for college students. For example, McFarland et al. [66]

showed that college students’ use of campus forests is associated with their quality of life.

Hipp et al. [67] also reported that college students who have higher levels of greenness

on-campus show a higher quality of life. In addition, Bang et al. [68] also reported that a

campus forest walking program signiﬁcantly increased health-promoting behaviors and

parasympathetic nerve activity and decreased depression. Using 558 voluntary college

students, Ibes et al. [60] investigated the psychological impact of green micro-breaks on

stress reduction. This study revealed that green micro-break interventions provided a

signiﬁcant psychological impact—most commonly, relief from stress. Therefore, utilizing

campus forests may serve as an effective strategy to help students to alleviate mental

health problems.

Even though a few studies positively evaluated campus forests for alleviating mental

health problems, there is still a lack of research in this area. More research evidence is also

needed on the health beneﬁts of the use of campus forests. Therefore, this study aimed to

investigate whether students’ forest activities inﬂuenced their psychological states.

The following research hypotheses were formulated and tested in the study:

(1) Campus forest activities will have a positive effect on mood (on the POMS: The Proﬁle

of Mood State scale);

(2) Campus forest activities will have a positive effect on stress response (on the modiﬁed

form of the Stress Response Inventory: SRI-MF scale);

(3) Campus forest activities will have a positive effect on happiness (on the COMOSWB:

Concise Measure of Subjective Well-Being scale).

2. Materials and Methods

2.1. Participants

Thirty-eight university students (mean age, 22.1 ± 1.6 years) were recruited for the

ﬁeld experiment. The distribution of participants was 24 males (mean age, 22.7 ± 1.4 years;

63.2%) and 14 females (mean age, 21.2 ± 1.4 years; 36.8%). Recruitment posters were posted

throughout the university buildings to recruit volunteers. No incentive was provided to

the volunteers. The inclusion criteria required the participants to be current students at the

speciﬁed university. Participants who met the following inclusion and exclusion criteria

were considered for study: (1) no diagnosis of a reaction to severe stress and/or depression;

(2) did not suffer from drug or alcohol abuse. The participants were randomly distributed

into two groups (i.e., 19 in the campus forest activities group and 19 in the control group).

The details of participants’ characteristics are shown in Table 1.

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Table 1. Instructions given to the two groups of participants during the study period.

Group

Activity group

Control group

Direct Request

Read and follow the instructions on the guide signs for each

activity installed on the course.

Do individual activities, not group activities, when performing

forest activities

Keep normal life during the experiment

Avoid alcohol and tobacco during the experiment

Do forest activities regularly (At least once a week)

Keep normal life during the experiment

Avoid alcohol and tobacco during the experiment

The experiment was conducted during the 2nd semester of 2019 (September–November).

A total of eight sessions of forest activities were performed. Before starting the experiments,

we explained the study’s purpose and procedures and obtained their written informed

consent. The Institutional Review Board of Chungbuk National University (IRB number:

CBNU-201910-SB-945-01) approved this study.

2.2. Experimental Site

The ﬁeld experiment site was conducted in the Chungbuk National University cam-

pus forest in Korea. The size of campus forest is about 315,000 m2, covered mainly by

Metasequoia glyptostroboides (DBH 44cm; tree height 22–27 m; 0.2 ha), Chamaecyparis pisifera

(DBH 34 cm; tree height 12–18 m; 0.25 ha), and mixed forest species (pitch pine, oak,

chestnut, oriental cherry; 2.7 ha), and the stand age ranged between 40 and 90 years old.

The study area was a suitable place for conducting forest activities in terms of accessibility,

distribution of a variety of vegetation, and gentle slope. During the eight sessions in

the experiment, the weather was pleasant and not raining, with a mean temperature of

16.2 ± 1.3 ◦C.

2.3. Procedure

The study employed a pretest-posttest control group experimental design [69]. Partici-

pants’ psychological states were measured before and after the intervention. The participants

were instructed to perform forest activities for eight sessions (one hour-long session per week).

We designed the forest activities to be performed voluntarily (see Figure 1). To perform forest

activities, an instruction booklet was administered to each participant. The instruction

leaﬂet was developed based on consultation from experts in the forest therapy ﬁeld, includ-

ing researchers and practitioners. Five forest activities were selected in this study to apply

as the campus forest activities intervention: stretching, respiration, walking, meditation,

and exercise.

The forest activities interventions were provided from September to November of

2019. The interventions were performed once a week during the daytime, depending on

participants’ preferred schedule. During each of the eight sessions in the intervention,

participants were asked to walk along the designated route in the campus forest, visit

speciﬁc locations where explanatory panels on forest activities were installed, and return to

the starting point at an appointed time. (see Figure 2). In the ﬁrst session of the intervention,

the leaﬂet was distributed to each participant. We asked the participants to perform the

forest activities intervention at least once a week according to the leaflet’s instructions. Details

regarding the instructions used for each activity are included in Appendix A. The participants

in the control group did not receive leaflets, lectures, or any forest activities, and were asked

to follow out their routine activities during the experimental period. The requests provided to

both groups of participants during the intervention are shown in Table 1.

Int. J. Environ. Res. Public Health 2021, 18, x FOR PEER REVIEW

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Int. J. Environ. Res. Public Health 2021, 1f8o,r2e4s5t7activities, and were asked to follow out their routine activities during the experi5- of 16

Int. J. Environ. Res. Public Health 2021, 1m8, exnFOtaRlPpEeErRioREdV.ITEWhe requests provided to both groups of participants durin5gotfh1e6 interven-

tion are shown in Table 1.

forest activities, and were asked to follow out their routine activities during the experi-

mental period. The requests provided to both groups of participants during the interven-

tion are shown in Table 1.

FFigiguurree11..MMaappss ooff tthhee ccaammppuussfoforereststaactcitviivtiietisetsratrial iinl itnhitshsistusdtuyd. y.

Figure 1. Maps of the campus forest activities trail in this study.

(A)(Astr)esttcrheitncghing

(B) respi(rBa)tiroenspiration

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(D) exercise

(E) meditation

FFiigguurree22. .CCamampups ufosrefostraecsttivaitciteisviintiteersvienntteiornv.ention.

2.4. Psychological Measurement

The psychological evaluations used the Profile of Mood States (POMS), the modified

form of the Stress Response Inventory (SRI-MF), and the Concise Measure of Subjective

Well-being (COMOSWB) questionnaires. The POMS is a well-established measure of

emotional state and is a reliable and valid instrument for assessing psychological distress

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2.4. Psychological Measurement

The psychological evaluations used the Proﬁle of Mood States (POMS), the modiﬁed

form of the Stress Response Inventory (SRI-MF), and the Concise Measure of Subjective

Well-being (COMOSWB) questionnaires. The POMS is a well-established measure of

emotional state and is a reliable and valid instrument for assessing psychological dis-

tress [70,71], and has been used previously to estimate the inﬂuence of a forest experience

on mood states [71–74]. It simultaneously evaluates six mood states: “tension-anxiety

(T–A)”, “depression-dejection (D)”, “anger-hostility (A–H)”, “fatigue (F)”, “confusion

(C)”, and “vigor (V)” [70,71]. A ﬁve-point Likert scale (0 = strongly agree to 4 = strongly

disagree) was used for each item to evaluate each participant’s mood state. In this study,

we employed the short form of the Korean version of the POMS (30 items) [75]. The Korean

version of POMS was revealed to have relatively high reliability (Cronbach’s α = 0.85).

The SRI-MF was used to assess the participants’ stress response levels. The SRI-MF

is a self-reported tool that measures the participant’s stress response levels, including

somatization, anger, and depression [76,77]. The SRI-MF is a key measurement tool con-

cerning stress, particularly the mental health and physical symptoms related to stress [78].

It has been used previously to estimate the effect of a forest therapy program on stress [79].

The SRI-MF has 22 items, and each item has a 5-point Likert scale (1 = strongly disagree;

5 = strongly agree). The SRI-MF was revealed to have relatively high reliability (Cronbach’s

α = 0.93) [77].

The COMOSWB was used to assess each participant’s subjective well-being states.

The COMOSWB measures three sub-scales: life satisfaction, positive emotion, and negative

emotion [80]. It has been used previously to estimate the effect of a forest therapy program

on happiness [81]. The COMOSWB has a total of nine items with a 7-point Likert scale

(1 = strongly disagree; 7 = strongly agree). The COMOSWB was revealed to have relatively

high reliability (Cronbach’s α = 0.86) [80].

2.5. Data Analysis

The statistical analyses were performed using SPSS 18.0 Windows (SPSS, Chicago,

IL, USA). Descriptive statistics comprised means, standard deviation, frequency, and

percentage to present socio-demographic information and outcome variables. Paired t-tests

were used to compare participants’ psychological states between pre-and post-tests for

each group (forest activities intervention and control groups). All statistical tests used a

p-value of <0.05 as the signiﬁcance level.

3. Results

3.1. Psychological Measurements

3.1.1. Proﬁle of Mood States (POMS)

The results of paired t-tests between pre-and post-tests POMS scores for each group

are presented in the Table 2. As shown in Table 2, there was a signiﬁcant decrease in Total

Mood Disturbance scores for the campus forest activities group after eight sessions of

the forest activities intervention (t = 3.976, p < 0.01). The results of paired t-tests indicate

that there were signiﬁcant positive changes in ﬁve subscales of the POMS, except for

one subscale, entitled “anger-hostility” (t = 1.882, p > 0.05): “tension-anxiety” (t = 2.419,

p < 0.05), “depression-dejection” (t = 2.468, p < 0.05), “fatigue-inertia” (t = 5.050, p < 0.001),

“confusion-bewilderment” (t = 5.175, p < 0.001), and “vigor” (t = -2.733, p < 0.05).

However, there were no signiﬁcant changes in the control group participants’ changes

in Total Mood Disturbance and all six subscales of the POMS: “tension-anxiety”, “anger-

hostility”, “depression-dejection”, “fatigue-inertia”, “confusion-bewilderment”, and “vigor”.

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Table 2. The results of paired t-test analyses of subjective Proﬁle of Mood State (POMS) scores.

CFA

Cont.

TMD

T–A

A–H

Before

25.16 ± 4.32

7.11 ± 0.96

4.68 ± 0.93

5.42 ± 1.04

8.95 ± 0.86

8.37 ± 0.67

9.37 ± 0.72

After

10.68 ± 4.35

4.68 ± 1.12

3.11 ± 0.62

3.16 ± 0.64

5.42 ± 0.88

5.74 ± 0.70

11.42 ± 0.85

3.976

2.419

1.882

2.468

5.050

5.175

-2.733

0.001 **

0.026 *

0.076

0.024 *

0.000 ***

0.014 *

Before

20.79 ± 3.12

5.95 ± 0.84

5.79 ± 0.90

4.26 ± 0.68

8.16 ± 0.53

7.00 ± 0.54

10.37 ± 0.60

After

21.84 ± 3.85

6.42 ± 0.87

5.37 ± 0.92

4.58 ± 0.74

8.32 ± 0.77

7.11 ± 0.60

9.95 ± 0.76

−0.355

−0.590

0.671

−0.480

−0.221

−0.244

0.522

0.726

0.563

0.511

0.637

0.828

0.810

0.608

Notes: T–A, tension-anxiety; A–H, anger-hostility; anger-hostility; D, depression; F, fatigue; C, confusion; V, vigor; TMD, Total Mood

Disturbance. Campus forest activities group (CFA) and control group (Cont.). *** p < 0.001, ** p < 0.01, * p < 0.05.

3.1.2. Modiﬁed Form of the Stress Response Inventory (SRI-MF)

The results of paired t-tests between pre-and post-tests SRI-MF scores for each group

are presented in the Table 3. As shown in Table 3, there was a signiﬁcant decrease in

total stress response scores for the campus forest activities group after eight sessions of

the campus forest activities intervention (t = 3.745, p < 0.01). The results of paired t-tests

indicate that there were signiﬁcant positive changes in three subscales of the SRI-MF:

“somatization” (t = 3.481, p < 0.01), “anger” (t = 2.645, p < 0.05), and “depression” (t = 2.955,

p < 0.01).

Table 3. The results of paired t-test analysis of modiﬁed form of the Stress Response Inventory (SRI-MF) scores.

CFA

Cont.

Before

After

Before

After

Total

Somatization

Anger

Depression

54.16 ± 3.35

22.05 ± 1.46

13.84 ± 1.01

18.26 ± 1.27

43.53 ± 3.34

17.11 ± 1.44

11.53 ± 1.04

14.89 ± 1.17

3.745

3.481

2.645

2.955

0.001 **

0.003 **

0.016 *

0.008 **

49.42 ± 2.90

21.47 ± 1.37

10.89 ± 0.78

17.05 ± 1.19

52.05 ± 3.90

23.74 ± 2.07

11.58 ± 0.88

16.74 ± 1.33

−0.795

−1.320

−0.646

0.317

Notes: Total, Total happiness. Campus Forest activities group (CFA) and Control group (Cont.). ** p < 0.01, * p < 0.05.

0.437

0.203

0.527

0.755

However, there were no significant changes in the control group participants’ total stress

responses and other sub-scales of the SRI-MF: “somatization”, “anger”, and “depression”.

3.1.3. Concise Measure of Subjective Well-Being (COMOSWB)

The results of paired t-tests between pre-and post-tests COMOSWB scores for each

group are presented in the Table 4. As shown in Table 4, there was a signiﬁcant increase

in total happiness scores for the campus forest activities group after eight sessions of the

campus forest activities intervention (t = −3.202, p < 0.01). The results of paired t-tests

indicate that there were signiﬁcant positive changes in two subscales of the COMOSWB:

“life satisfaction” (t = −2.996, p < 0.01), “negative emotion” (t = 2.750, p < 0.05). However,

there were no signiﬁcant changes in the subscale titled “positive emotion.”

Table 4. The results of paired t-test analyses of Concise Measure of Subjective Wellbeing (COMOSWB) scores.

Total

happiness

Life

satisfaction

Positive

emotion

Negative

emotion

Before

19.05 ± 1.61

CFA

After

23.21 ± 1.87

−3.202

0.005 **

Before

21.42 ± 1.65

Cont.

After

24.00 ± 1.23

14.74 ± 0.68

15.16 ± 0.75

10.84 ± 0.82

16.26 ± 0.64

15.63 ± 0.72

8.68 ± 0.93

−2.996

−1.027

2.750

0.008 **

0.318

0.013 *

16.05 ± 0.60

14.84 ± 0.80

9.47 ± 0.78

16.79 ± 0.48

15.95 ± 0.49

8.74 ± 0.81

Notes: Campus Forest activities group (CFA) and Control group (Cont.). ** p < 0.01, * p < 0.05.

−1.784

−1.099

−1.293

0.915

0.091

0.286

0.212

0.372

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On the other hand, there were no signiﬁcant changes in the control group partici-

pants’ total happiness and other sub-scales of the COMOSWB: “life satisfaction”, “positive

emotion”, and “negative emotion”.

4. Discussion

This study evaluated the psychological effectiveness of forest activities in a campus

forest. This study revealed that campus forest activities intervention participants had

signiﬁcantly positive mood states, stress responses, and happiness after the intervention.

The results of this study indicate that the campus forest provides effectiveness in improving

college students’ psychological health.

To date, many empirical research results have shown that forest therapy programs

carried out in forests far away from the city provide a wide range of psychological health

beneﬁts to the program participants [82,83]. However, few studies on the psychological

effects of campus forest activities have been reported. Therefore, this study suggests that

campus forests can help to promote psychological well-being among university students.

This study showed that the negative mood states of “tension-anxiety”, “depression-

dejection”, “fatigue”, and “confusion” were lower, and the positive mood states of vigor

were signiﬁcantly higher after campus forest activities intervention. These results, which

demonstrate the psychological beneﬁts of campus forest activities, are consistent with

previous ﬁndings demonstrating improvements in mood states after walking through

urban green space [84–86] and forest areas [87,88].

This result also found that the total stress responses and other subscales of the SRI-

MF such as “somatization”, “anger”, and “depression” were significantly lower after the

campus forest activities. This study confirms that campus forest activities had a significant

effect on stress reduction. This is consistent with the results of previous studies showing

a reduction in psychological stress after viewing a forest and forest walking [88–90]. For

example, Morita et al. [89] reported that forest walking could improve self-rated health

status and reduce psychological stress. Marselle et al. [90] showed that nature-based walking

reduced perceived stress, depression, and negative emotion and improved positive emotions

and mental health. Im et al. [78] reported that forest walking signiﬁcantly decreased stress

response scores compared to city walking. In addition, Khianman et al. [91] demonstrated

the stress-reduction effect of forest therapy on various subjects. These ﬁndings show

that the beneﬁts of forest therapy activities in stress relief are consistently evaluated as

signiﬁcant results.

This study also shows participants’ increased happiness levels in the campus for-

est activities intervention group. The results of this study are consistent with previous

studies’ improvement of happiness after partaking in forest activities, such as playing

in the forest and the forest therapy program. Park et al. [81] reported that employees’

subjective happiness increased after participating in four sessions of a forest therapy pro-

gram. Happiness increased in children who played in forests comparing with those who

played in classrooms [92,93]. Similar studies have shown that green spaces, including

forests, promote a sense of happiness [94]. For example, Luck et al. [95] reported that

vegetation cover had the strongest positive relation with personal well-being. According

to Lohr and Pearson-Mims [96], people felt more positive emotions and happiness when

viewing trees than inanimate objects. Van Herzele and De Vries [97] and MacKerron and

Mourato [94] reported that people living adjacent to green space were happier than people

living in urban environments. People more related to nature tend to seek more experiences

with nature, and beneﬁt from the well-being outcomes from those experiences, such as

feelings of positive mood and happiness [98,99]. Promoting participants’ happiness offers

signiﬁcant beneﬁts. Happiness can create pleasant moods, positive emotions, positive atti-

tudes toward oneself and others [100], and is known to be signiﬁcantly linked to reduced

heart disease rate [101,102] and mortality [103,104], health and longevity [105,106], and

improved sleep [107].

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The results of this study reveal a positive relationship between students’ forest activ-

ities and their psychological effects. However, it is not clear whether the psychological

effects resulted from the activities the participants performed, the forest activities, or expo-

sure to nature and the forest. Further studies are needed to clarify this relationship. The

inﬂuence of each forest activity performed by the participants on the psychological effects

should also be investigated in further research. In particular, forest walking is one of the

most representative activities of forest therapy.

Numerous studies have shown that walking in a forest improves mood state [87,88]

and alleviates perceived stress [89,90]. Walking in the forest has also been demonstrated to

be more effective in improving mental health than walking in the city environment [108].

Diaphragmatic breathing [109,110] and meditation [111–113] in the forest have also re-

ported positive psychological effects in some previous studies. Meditation with deep

breathing in the forest increases the connection with nature and improves mental, physical,

and emotional well-being [114]. The health promotion effects of outdoor activities were

signiﬁcantly enhanced when meditation was incorporated into nature activities [115,116].

Holt et al. [117] showed that students who engaged in the use of campus forests in passive

ways, such as sitting, studying, or eating were not associated with health and wellbeing

beneﬁts, while students who actively engaged in the use of green space, such as being

physically active outdoors, were strongly associated with a higher quality of life, better

overall mood, and lower perceived stress. As mentioned above, previous research suggests

that time spent in nature in energetic activity can promote restoration and reduce stress

and improve happiness [87–93]. Therefore, forest activities’ psychological effects through

campus forests can be an efﬁcient strategy to improve mental health.

Recent research showed that college students are constantly exposed to stressors and

that the college period is an important time, during which young people adopt lasting

healthy lifestyle habits, and is associated with increased chronic disease risk [118,119]. In

particular, mental health problems are important. Across all countries combined, 21.2%

of college students have major depression disorders and 18.6% have generalized anxiety

disorder [120], and they have a higher rate of being diagnosed or treated by a profes-

sional for anxiety, depression, panic attacks, and attention deﬁcit hyperactivity disorder

(ADHD) [8]. Universities have been increasing their efforts to address this problem in

various programs. The programs for students have included initiatives such as mindfulness

programs, yoga classes, and pet therapy [121–123]. Although a variety of programs has

been used to address students’ mental health, the ability of campus forests to help the

student is often overlooked. Students, faculty members, and others use campus forests for

a walk every day. However, the potential psychological beneﬁts of campus forests are not

widely acknowledged [60]. Therefore, this study can demonstrate the psychological health

potential and suggest campus forests for health promotion resources to university students

and other campus members.

Forest activity in campus forest is an effective and convenient way to escape busy

college life and focus only on oneself. Undertaking activities in natural environments

reduces stress and anxiety and thus promotes health [124]. Our study suggests promoting

opportunities for students to use campus forests and inform ways or activities for students

to utilize campus forests to promote mental health. In addition, staff or faculty of the uni-

versity can use campus forests in leisure activities whenever they can, such as lunchtime or

rest time during work, which will help to relieve work stress. In this regard, the university

should continue to maintain well-managed campus forests and expand convenient access

to paths through natural areas, promoting campus forest or green space use. The university

should also support education to increase students’ awareness around existing campus

forests and the potential mental health beneﬁts from regular use [117].

However, we acknowledge the several limitations of this study. Firstly, this study

employed ﬁve forest activities (stretching, respiration, walking, meditation, and exercise).

It is not clear which activity contributed the most to the results and how the differential

effect of each of the activities affected the participants. Further studies are needed to clarify

Int. J. Environ. Res. Public Health 2021, 18, 2457

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and compare the various types of forest activities. Secondly, the sample size of this study

was small, and the participants for this study were limited to healthy university students

in their 20s. To generalize the ﬁndings, further studies are needed create a large sample

using different groups of the population with different socio-demographic characteristics.

Thirdly, this study was conducted in a campus forest to validate the psychological effect of

campus forest activities. The potentials of different forests are not all the same and vary

based on forest features. The effects according to the various characteristics of the forests

(i.e., tree species composition, forest stand, structure, canopy cover, forest element-related)

must be examined in the future. Fourth, participants’ prior expectations and experiences

with forests may inﬂuence the results. Further study is needed considering the extent of

exposure to nature in childhood and patterns of visits to forests. Firth, in this study, the

control group conducted their usual activities. Some of the control group may use forests

for their leisure, and those experiences may inﬂuence the results of this study. Therefore,

further studies are needed with participants who spend time in forests without giving

them any instructions. Sixth, for an overall discussion, verifying the effects of campus

forests using other psychological methods is necessary to demonstrate the new possibility

to promote students’ health. In a further study, it is necessary to investigate in depth what

are the important variables that contribute to the psychological effects of campus forests.

These limitations should be considered in future research. Despite these limitations, this

study provides a notable strength of the forest activities in a campus forest, which is that

they are easily accessible to students to use whenever they can.

5. Conclusions

This study showed that the campus forest activities intervention provided signiﬁcant

psychological effects on college students. More speciﬁcally, there were signiﬁcant positive

changes in participants’ emotional states, stress responses, and happiness. The study

results indicate the effectiveness of campus forest activities, suggesting the complementary

use of different types of forest areas in such a modern urbanized society. These ﬁndings can

provide guidance to decision-makers on the importance of the campus forest management,

and policymakers can utilize these results in order to enhance student’s mental health.

Author Contributions: J.G.K. performed data acquisition, statistical analysis, interpretation of the

results, and manuscript preparation. J.J. was involved with acquisition of data. W.S.S. had an

important a role in the overall performance of this research, particularly experimental design and

research idea. All authors have read and agreed to the published version of the manuscript.

Funding: This research received no external funding.

Institutional Review Board Statement: This study was approved by the Institutional Review Board

of Chungbuk National University (IRB number: CBNU-201910-SB-945-01).

Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.

Data Availability Statement: The data presented in this study are available on request from the

corresponding author. The data are not publicly available due to privacy.

Acknowledgments: We thank the forest healing lab members of Chungbuk National University for

their help. We also gratefully thank forest therapists for their valuable guidance.

Conﬂicts of Interest: The authors declare no conﬂict of interest.

Appendix A. Campus Forest Activities Signs Text

(1) Forest stretching signs

(1) Neck rotation: Stand upright with both hands on your waist and turn your

neck in one direction for eight beats. Turn it in the opposite direction.

(2) Shoulder rotation: Stand upright with your ﬁngertips on your shoulders and

turn your shoulders in a circle. Turn it in the opposite direction.

Int. J. Environ. Res. Public Health 2021, 18, 2457

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(3) Waist rotation: Stand upright with both hands on your waist and turn your

waist in one direction. Turn it in the opposite direction.

(4) Knees rotation: Bend your upper body, place your hands on your knees, and

turn your knees in one direction. Turn it in the opposite direction.

(5) Wrist and ankle rotation: Lightly rotate both wrists for eight beats while

rotating one ankle together.

(2) Forest respiration signs

(1) Stand your upper body in a suitable place in the forest with your spine straight-

ened.

(2) Put your hands on the sides and slowly count ‘1, 2, 3, 4’ (4 s) in your mind and

inhale deeply through your nose.

(3) Slowly exhale into your mouth, counting eight seconds in your mind.

(4) Repeat 20 times.

(3) Walking in the Forest signs

(1) When you walk, walk in the order of heel-sole-toe position with your back straight.

(2) Slowly inhale deeply through your nose, counting ‘1, 2, 3, 4’ (4 s) in your mind.

(3) Slowly exhale into your mouth, counting eight seconds.

(4) Forest exercise signs

(1) Push-ups: Stand facing a suitable tree nearby, put your palms on the tree. Bend

your elbows and lower your chest to the tree and push through the palms of

your hands to straighten your arms (Repeat 10 to 20 times).

(2) Arm pull: Stretch your arms forward, pull your arms backward as hard as

possible, and then stretch them forward again (Repeat 30 times).

(3) Squat: First, stand your feet shoulder-width apart. Second, squat down by

pushing your knees to the side while moving your hips back. Third, break

parallel by Squatting down until your hips are lower than your knees. Finally,

press into your heels and straighten your legs to return to an upright standing

position (Repeat 20 times).

(4) Core exercise: Keep your knees straight and raise your legs as high as possible

(Repeat 10 times on both sides).

(5) Heel raise exercise: Keeping your knees straight, raise your heels up off the

ﬂoor as far as you can go, and then slowly return (Repeat 30 times).

(5) Forest meditation signs

(1) Sit in a comfortable position with your spine straightened by standing your

upper body in a suitable place in the forest.

(2) Slowly inhale deeply through your nose, counting ‘1, 2, 3, 4’ (4 s) in your mind.

(3) Slowly exhale into your mouth, counting eight seconds in your mind.

(4) Now, I feel my thoughts and emotions calm as I ﬁnd the breathing rhythm and

focus on breathing.

(5) If you have miscellaneous thoughts, focus on your breathing.

(6) At this moment, focus fully on the present state.

(7) Close your eyes.

(8) Do it for 5 min.

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