Introduction
Background
Contemporary society is faced with the need to bring nature to urban residents due to its salutary effects on mental health as well as broader promotion of environmentalism (Kruizse et al., 2019). Gardens are a particularly important form of nature that provides easy access to therapeutic and educational benefits for urban populations (Adevi and Mårtensson, 2013). Motivations for gardening included pleasure, health improvement, and self-identity, supported by empirical evidence of positive associations between gardening frequency and well-being indicators (Chalmin-Pui et al., 2021). Even being in a garden, without actively working on the landscape, can provide mental health benefits available in other types of nature. Horticultural therapy programs often use gardens as their settings to amplify their therapeutic effects on mental well-being (McCaffrey and Liehr, 2016). Urban botanical gardens create opportunities for visitors to immerse in nature and relieve stress and depression from their hectic urban lives (Kohlleppel et al., 2002). Due to its urban proximity and refined natural landscapes, botanical gardens may play an important role in promoting the well-being of general public.
Nature’s benefits depend on the intensity and amount of exposure to nature. The “dose” of nature has gained increasing research attention due to its management implications for cost-effective public health improvement through contact with nature (Cox et al., 2017). While there exists evidence that nature’s well-being benefits increase with the dose of nature to a certain extent (Shanahan et al., 2015), this dose-response framework needs to be considered with caution due to the diversity of social and individual characteristics that may impact how nature is experienced and interpreted (Bell et al., 2019). Therefore, understanding how nature exposure impacts different social groups can advance knowledge of the intensity and amount of natural stimuli appropriate in specific contexts. In this study, we aimed to understand how individuals involved in an environmental field respond to added exposure to a natural environment in terms of their psychological well-being, connection to nature, environmental values, and proenvironmental behavior as expected benefits.
Documented benefits of exposure to nature
Research on nature’s benefits has shown that direct exposure to natural environments improves human well-being. Attention restoration theory (ART; Kaplan & Kaplan, 1989) and stress reduction theory (SRT; Ulrich et al., 1991) are among the most referenced theoretical accounts of how human cognitive capacity and physiological stress are affected by interfacing with nature. While ART posits that natural stimuli evoke involuntary attention that allows cognitive capacity to retain or restore, SRT relies on a psycho-evolutionary perspective that humans have developed an affinity with nature as a resourceful survival setting. Several reviews to date have documented extensive evidence that viewing or being in nature has therapeutic effects on mental health (Berto, 2014; Bowler et al., 2010; Jimenez et al., 2021; Korpela et al., 2016; Moll et al., 2022; Ohly et al., 2016). Such mental health effects of outdoor nature have been found to be replicable to some extent in virtual environments that may increase accessibility for broader populations (Browning et al., 2020; Shin et al., 2022).
In addition to the cognitive and emotional benefits, general human well-being can be enhanced through exposure to nature. Previous research drawing on positive psychology suggests that interacting with nature can meet individual psychological needs and thus contribute to long-term happiness such as life satisfaction and eudaimonic well-being (Cleary et al., 2017; Jo et al., 2022; Neill et al., 2019). Thus, natural environments have potential to benefit mental health in the short term as well as provide psychological well-being that improves human functioning.
Contact with nature can also encourage people to engage in pro-environmental behavior, defined as behavior that reduces the human impact on the environment or improves the environmental quality (Steg and Vlek, 2009), through fostering the psychological basis of environmentalism. Humans develop connection to nature by building affective, cognitive, and experiential relationships with nature through meaningful interactions (Tam, 2013). Previous research has shown that frequent exposure to nature can empower human-nature relationships (Chawla, 2020; Mayer et al., 2009) which were then positively related to environmental concern and behavior (Whitburn et al., 2020).
Another important concept that underlies pro-environmental behavior is the set of human values placed on the integrity and sustainability of the environment. The Value-Belief-Norm theory of environmentalism (VBN) posits that human values are a fundamental predictor of pro-environmental behavior (Stern, 2000; Stern et al., 1999). Values oriented toward the environment have been consistently found to guide behavioral decisions to benefit the environment (Bouman et al., 2021). As past experience in nature tends to positively influence environmental values afterward (Deville et al., 2021), contact with nature may potentially shape personal values placed on the environment.
The present study
Most studies examining nature’s health benefits focused on clinical, sub-clinical, and general populations (Coventry et al., 2021) to seek implications for addressing certain medical conditions and overall public health. However, the assumption that exposure to urban nature universally benefits all individuals overlooks the nuanced implications of human-nature interactions (Bell et al., 2019), particularly among those with a high baseline level of exposure. To date, little is known whether nature’s benefits are equally available for people who maintain close contact with nature, such as those in environmental fields. Students majoring in environmental disciplines are more likely to be environmentally concerned compared to those who are not (Arnocky and Stroink, 2011; Chuvieco et al., 2018), suggesting that this group of individuals might be more exposed to and familiar with nature than the average people.
Understanding how environmentally trained students benefit from nature exposure can inform programs that aim to foster leaders in nature-based recreation and therapeutic practices. This study sought to address this need by applying a pre- and post-test experimental design to assess the effects of nature exposure on university students who maintain regular engagement with nature through disciplinary activities. Although nature exposure can theoretically reach a saturation level (Shanahan et al., 2015), we posited that walking in a garden may provide unique experience that can add benefits for our target student population. Thus, we hypothesized that walking regularly in a botanical garden will increase psychological well-being, connection to nature, environmental values, and pro-environmental behavior among college students in an environmental discipline.
Methods
Study site
The study was conducted at Wonkwang University’s Natural Botanical Garden (see Fig. 1) in Iksan-si, Jeollabuk-do, South Korea. The garden is located at 126° 45′ east longitude and 35° 50′ north latitude and 10–20m above the sea level. It shows an annual average temperature of 13.3°C and an annual average precipitation of 1,280 mm in 2021. The garden contains about 2,000 species of plants in 150 families and 430 genera managed by horticulture professionals at the university. It contains a variety of vegetation types depending on thematic landscape sections such as wetland, rockery, and topiary.
Participants
We recruited participants from a dendrology course in Spring 2022 at Wonkwang University. All class enrollees were from an undergraduate program in Forest Science and Landscape Architecture. Among a total of 92 students invited to our study through in-class announcements, 74 students agreed to participate in the study. We randomly assigned the participants to treatment and control groups (37 participants each). Among these participants, 39 completed the full research protocol and thus comprised a final sample, with 21 remaining in the treatment group and 18 in the control group. In this final sample, participants were 24.67 years old on average, with a median of 23 years and a standard deviation of 6.76 years. All participants were Korean by ethnicity and 33% (n = 13) of them were female.
Procedure
The course began on April 4th and lasted for 15 weeks, ending on July 15th in 2022. On the first day of class, all participants were administered a pre-test survey designed to establish baseline metrics for their nature relatedness, psychological well-being, and pro-environmental behavioral intentions. The treatment session took place immediately after class. As the ideal amount of nature walks has not been fully understood (Kotera et al., 2021), we designed this intervention program by adapting the procedures used in previous studies that found significant effects of 15-minute nature walks walks (Fuegen & Breitenbecher, 2018) and 2-hour weekly nature walks for up to 8 weeks (Korpela et al., 2016). We asked the treatment group to take a 15-minute walk in the botanical garden. This activity entailed a leisurely stroll, wherein students were free to choose their individual routes. In the meantime, the control group stayed in an indoor classroom setting. Both groups were assigned simple dendrology-related tasks (e.g., tree species identification) during their sessions under the supervision of teaching assistants to ensure the provision of equal educational opportunities. Ethical standards of this research procedure were approved by the Wonkwang University Institutional Review Board (WKIRB-202204-HR-025).
Measures
All outcome variables were measured using a 5-point Likert scale. Participants’ environmental values were measured using the value scale developed by Stern et al. (1999) and translated into Korean. Respondents was asked to rate how important each of the following items were as a guiding principle in life: unity with nature, respecting the earth, and protecting the environment. To measure the psychological connection between participants and nature, we used the original 21-item Nature Relatedness scale (Nisbet et al., 2009) translated into the Korean language (Seo and Jeong, 2016) to measure participants’ affective, cognitive, and experiential aspects of connection to nature. These items include “I am not separate from nature, but a part of nature”, “The state of nonhuman species is an indicator of the future for humans”, and “I take notice of wildlife wherever I am”. To measure psychological well-being, we translated and administered the Psychological Well-Being scale (Ryff and Keyes, 1995) which includes six core dimensions of self-acceptance, autonomy, environmental mastery, positive relationships with others, purpose in life, and personal growth. Example items are “I like most parts of my personality”, “I am good at managing the responsibilities of daily life”, and “People would describe me as a giving person, willing to share my time with others”.
To measure intentions to engage in pro-environmental behaviors that are widely accepted in the context of South Korea, we used a pro-environmental behavior scale developed by Korea Environment Institute (Ahn et al., 2021) for a national environmental awareness survey. This 8-item scale asks how willing one is to do the following behavior items: using more environmentally friendly transportation mode; reducing the use of disposable products; separating trash; saving water; saving energy; buying products with green certification; buying local products close to home; and reducing the use of personal vehicles.
Analysis
We used R Studio version 4.1.3 for all statistical analyses. All variables in our survey data did not follow a normal distribution as shown by Shapiro-Wilk normality test (p < .05). In this case, population characteristics cannot be inferred using parametric estimation. Thus, we took a nonparametric approach using the Wilcoxon signed-rank test which is used to compare the statistical locations of two dependent samples and examine if there is a significant difference in data measured at two different time points (Rey and Neuhäuser, 2011). This decision-making process was primarily attributed to our small sample size which is often found in quasi-experimental studies targeting specific groups such as clinical populations (Korpela et al., 2016; Lesser et a l., 2020) or the elderly (Jo et al., 2022). Pre- and post-participation mean values of the variables were used for each test to see if the median of these values were significantly different before and after study participation.
Results and Discussions
Results showed that walking in a botanical garden for 15 minutes twice a week for 15 weeks did not significantly affect the outcome variables (Table 1). In both treatment group and control group, the median values of participants’ biospheric values, nature relatedness, psychological well-being, and pro-environmental behavior intentions were not significantly different between the pre- and post-participation measurements, as shown by the absolute z-values of non-parametric comparisons smaller than 1.96 (significance level of p = .05). The graphical representation of the results within the treatment group is shown by the box plot in Fig. 2.
The conceptualization of nature exposure that improves quality of life and encourages pro-environmental behavior has gained traction in landscape research and management with an assumption that it will have universal and consistent benefits for all. However, the dose-response model can be further nuanced by closer investigation of the effects of added nature exposure on environmentally engaged groups. This study’s findings draw attention to a critical examination of the generalized claims following ART (Kaplan and Kaplan, 1989) and SRT (Ulrich et al., 1991). Results from our study involving bi-weekly 15-minute walks for 15 weeks did not demonstrate a significant impact on environmental values, connection to nature, psychological well-being, or pro-environmental behaviors among students in an environmental discipline.
The lack of a salient effect of walking in a botanical garden shown in our study indicates that the benefits of nature exposure may not be universal but rather contingent upon participants’ baseline exposure to nature. This result extends previous findings that people working in forestry fields were less likely to reap nature’s restorative benefits compared to non-forestry professionals because forestry professionals’ daily exposure to forests may have masked nature’s novelty effects characterized as “being away” and “fascination” as in ART (von Lindern et al., 2013). Similarly, university students in a forestry-related degree program typically engage in field work in natural environments on a regular basis, which may set a high baseline level of exposure to nature. Our study suggests that students engaged in an environmental field could have also experienced a lower level of restoration during the botanical garden walks, which might have limited the benefits provided by natural stimuli. Given the significant role of environmental professionals in planning and managing urban green spaces spaces (Ugolini et al., 2022), it is timely to reconsider the extent of nature’s benefits to individuals in close contact with natural environments.
Alternative explanations should not be ruled out regarding the non-significant effects of nature exposure found in this study. There might have been a ceiling effect in the study variables among participants due to regular contact with nature. Positive correlations between outdoor activity participation and connection to nature have been found in cross-sectional studies (Lawton et al., 2017; Liu et al., 2022; Szczytko et al., 2020), suggesting that regular exposure to nature can keep one connected to nature and mentally healthy. This might have left little room for additional benefits for our participants during botanical garden walks. It is also possible that the amount and frequency of additional walks performed by our participants might have been marginal compared to their everyday contact with nature. Other possible factors that might have confounded the beneficial effects of nature walks include a lack of reflective and meditative experience (Høyem, 2020), semesterly fluctuations in students’ mental health (Browning et al., 2023), and the botanical garden’s insufficient configuration for restorative effects. Particularly, ART’s vague conceptualization of soft fascination as a restorative factor (Joye and Dewitte, 2018) still remained unresolved in our study because the nature-based intervention lacked design principles strictly guided by a clear theoretical framework.
Presenting non-significant effects of nature walks is not to downplay the inclusion of environmentally active populations in nature-based interventions. Despite the alternative scenarios, our results highlight the imperative for further investigation to delineate the characteristics of populations that might benefit the most or the least from nature exposure (Jimenez et al., 2021) as well as identify the right “dose” of exposure and landscape types (Shanahan et al., 2015). Furthermore, cultural differences among communities and social groups should be better understood to provide participants with nature experience that will be most meaningful and effective for them (Bell et al., 2019). With this knowledge, nature-based interventions can be carefully designed to meet the specific needs and circumstances of target populations.
We recognize several limitations of this study that are worth noting in interpretation. First, the small sample size likely restricted the power of statistical analysis and could have resulted in false negative results (i.e., Type II error). Although this is a common concern for clinical trials that target populations with rare conditions, our study participant pool could have been managed to reduce the drop-out rate. Second, the walking activities were not strictly structured, which could have created diverging types of nature experiences among participants. A more consistent walking program for all would be needed in further studies to control for personal differences in exposure to natural environments. Third, our data were restricted to psychological constructs which are parallel to the physical health benefits of nature walks. The positive association between physical and mental health during nature walks can be further explored in subsequent studies. Also, qualitative data such as interviews would enrich findings by providing explanations of how and why walking in a botanical garden over a prolonged period was (in)effective. Fourth, it was difficult to determine if the amount of nature exposure was effective for our study participants, so future experimental studies may consider including various engths, frequencies and activities in their treatments. Lastly, this study lacked a comparison group consisting of non-environmental majors or the general public, which obscures confounding factors and thus limits the validity of findings. Hence, further investigation with a two-by-two (i.e., major/non-major and treatment/control) experimental design is warranted. These methodological enhancements are essential for advancing our understanding of the intricate relationship between nature exposure and its psychological and behavioral outcomes across diverse demographic segments.
Conclusion
In the era of rapid urbanization, providing urban populations with proper nature contact is of growing importance in promoting public health. However, it is unlikely that the benefits of nature exposure are universal across social groups with different levels of engagement with nature. Environmental discipline students, often engaged in regular fieldwork that provides regular nature exposure for them, likely have established a strong baseline relationship with nature which may have reduced the potential for improvement in environmental values, connection to nature, psychological well-being, or pro-environmental intentions. Nevertheless, environmentally engaged individuals may still benefit from carefully designed nature programs that create meaningful experience or amplify the effects of exposure to nature for them.
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