The Impact of Open Forest Habitats on Psychological Well-Being

Abstract

Open habitats in forests perform several important functions. In addition to enriching biodiversity, they have an impact on the diversification of the forest landscape, and through complex processes and trophic relationships, they provide greater sustainability in forest communities. It turns out that they are also important not only for the functioning of nature, but also due to their regenerative properties, through which people can improve their well-being and recover their mental balance. The purpose of this study was to determine whether and to what extent mid-forest open dunes and wetlands are able to provide people with feelings of relaxation and mental renewal. The study was conducted in June 2024 in one of the forest complexes located in the suburban zone of Warsaw. The experiment was conducted with the participation of 52 young adult volunteers. The experiment used a pre–posttest method. The subjects’ mood and well-being were determined using four psychological questionnaires: the Positive and Negative Affect Schedule (PANAS), Restorative Outcome Scale (ROS), Subjective Vitality Scale (SVS), and Profile of Mood States (POMSs). The key findings from the research conducted are as follows: compared to the control sample (before entering the forest), exposure to all three variants of greenery had a restorative effect on the experimental participants; the water environment had the most favorable effect compared to the control sample (before entering the forest); and exposure to this environment provided the greatest increase in positive feelings and the greatest decrease in negative feelings. Research has shown that areas important for preserving forest biodiversity are also important for humans because of their high restorative properties. Preserving non-forest enclaves in forests and promoting their regenerative values for humans can be one nature-based solution to improve people’s health and well-being, especially for people living in urban areas.

1. Introduction

In today’s world, it is a fundamental human right and aspiration to achieve optimal physical, mental and social well-being, and therefore to maintain one’s health. Good health and well-being are among the important goals of the 2030 Agenda for Sustainable Development [1], achievable not only through disease prevention and treatment, but also through the promotion of mental health and well-being. Nature is as important to people’s physical well-being and mental health as it is to society’s ability to cope with global change, health threats, and disasters [2]. The COVID-19 pandemic made a striking contribution to raising awareness about the links between human health and the health of ecosystems. Its occurrence showed that the risk of infectious disease outbreaks and the spread of these diseases increases as nature is destroyed, and made people realize that it is precisely the protection and restoration of biodiversity and properly functioning ecosystems that are crucial to increasing human immunity and preventing the emergence and spread of diseases in the future. People need nature in their lives. Contact with nature is available via publicly accessible green spaces, primarily including parks, green spaces, and sports areas, but also forests used for recreation. A growing body of scientific evidence confirms nature’s positive, regenerative effects on human well-being. Despite extensive research exploring the significance of nature in human recovery, the specific physical characteristics that an environment should possess to effectively restore equilibrium between our physical and mental well-being remain somewhat ambiguous. Particularly concerning forests, there is a notable gap in understanding how various spatial features influence mood enhancement, the boosting of positive emotions, and overall vitality. In particular, few studies on this topic have looked at open habitats in the forest. It is not known whether the level of regenerative benefits derived from exposure to different open habitats, such as wetlands and unforested dunes, for example, is comparable to that offered by mature forest stands. Hence, in this article we fill the knowledge gap on this subject. We present methodological assumptions and the results of a randomized experiment, which provides indications of the positive impact of open habitats on people’s psychological well-being.

2. Literature Review

2.1. Green Spaces’ Importance for Mental Health

Public green spaces, both in cities and those bordering urban areas that are managed or used for recreational purposes, are of great importance to an ever-growing group of urban residents in Europe and worldwide. By 2030, more than 80% of Europe’s population will live in urban areas [3]. There is already a proven network of links between access to green spaces and human health. According to Hartig et al. [4], nature or green space can contribute to health by improving air quality, encouraging more physical activity, reducing stress, and increasing social cohesion. Currently, one public health challenge is the fight against mental health disorders, including affective disorders such as depression. Depression is becoming an increasingly significant health and social issue, affecting approximately 3.8% of the global population [5,6,7]. A report from the World Health Organization indicates that, by 2030, depression is projected to be the most prevalent disease worldwide [8]. This underscores the urgent need for more scientific research to safeguard individuals and effectively address mood disorders. In the face of growing mental health problems, there is also a growing body of evidence pointing conclusively to the regenerative psychological effects of interaction with green space or the natural environment [9]. It has been shown that people living in urban areas with more green space have reduced stress levels and better well-being compared to controls with poorer green space availability [10]. Nature can assist individuals in rebuilding and renewing their physical and mental strength. By providing essential adaptive resources to navigate life’s challenges, nature can lower the likelihood of developing chronic stress-related illnesses [10,11,12,13,14]. Additionally, it fosters various positive outcomes, including enhanced subjective well-being [15,16,17,18,19,20].

Spending time in natural settings contributes to reducing cortisol, a hormone linked to stress [11,12,13,14]. Moreover, being surrounded by nature boosts serotonin, a chemical in the brain that promotes happiness and well-being [17], leading to an uplift in mood and a reduction in anxiety and depression [18]. Research by Beyer et al. [15] indicated that living near greener areas correlates with decreased levels of stress, anxiety, and depression. Engaging with nature can significantly diminish mental exhaustion, irritability, anger, and anxiety, while enhancing attention, interest, concentration, and overall enjoyment [21,22].

Korpela et al. [23] found that the restorative effects of natural settings, especially forests, are much more effective than those of urban parks or other recreational areas in cities. Bielinis et al. [24] and Jung et al. [25] revealed that people tend to have fewer negative feelings in forested environments compared to urban areas. Moreover, Takayama et al. [26] found that feelings of vigor, along with a sense of subjective invigoration and vitality, were more pronounced in forest areas—which was attributed to the combined effects of walking and observation—than in urban environments. Forests are of great importance in the context of recovery and emotional balance. In Asia, as well as in other regions of the world, including Europe, there is growing interest in nature-based practices that promote mental health, such as forest bathing and forest therapy. Forest bathing, known as shinrin-yoku (literally “forest immersion”), is a practice that aims to improve health and well-being through direct contact with nature, engaging all of the human senses: smell, touch, taste, hearing, and sight [27]. Although both approaches acknowledge the positive effects of nature on human health, forest therapy provides a more intentional and healing structure for care and assistance [28,29]. Forest therapy can provide more structured interventions for specific health conditions, or in times of unexpected crises, experiences of loneliness or depression, while forest bathing is broadly beneficial for general stress reduction and mood enhancement. In recent years, there have been many publications on the positive effects of forest contact on human health [25,30,31,32,33,34]. A study by Tsunetsugu et al. [13] suggests that even short-term forest viewing is relaxing. Studies by Hartig et al. [35], Korpel [36], Tyrväinen et al. [37], Pasanen et al. [38], Jung et al. [25] have shown that people’s moods and positive feelings increase in natural areas. Recreation in forest areas contributes to increased vitality [39,40]. Recreation in the forest contributes to increased feelings of vitality [41,42]. Forest bathing is the best form of relaxation that can be obtained from contact with the forest [43].

2.2. Forest Space Features and Mental Wellness

Since the beginning of the 21st century, there have been many publications on the positive impact of contact with forests on human health [13,25,30,31,32,33,34,35,36,37,38,39,40,42,43]. More and more scientific attention [23,24,25,26] is being directed towards forest areas, which are being seen as a source of stronger and more lasting health benefits than those provided by the green and blue infrastructure of cities. Although there is an increasing amount of research focused on how green areas impact human health, there is still a lack of substantial evidence indicating that certain characteristics of green spaces provide varying health benefits. The distinct designs of green spaces, the terrain’s characteristics, and various management approaches can create diverse opportunities for physical exercise and mental refreshment [3]. Larger green spaces promote relaxation, release negative emotions, and allow a quietening of the senses, as reflected in the findings of Jin and Wang [19], Subiza-Pérez et al. [16], and Janeczko et al. [20]. Studies by Martens et al. [44] and Herzog et al. [45] indicate that a manicured forest, as opposed to a natural one, has greater regenerative value. Simkin et al. [46] proved that old-growth and mature economic forests have the most regenerative effect on humans. Also, a study by Janeczko et al. [47] showed that contact with a forest, only in the case of a mature stand, provides the greatest mood-enhancing benefits. In contrast, exposure to clear-cutting resulted in a decrease in positive feelings and an increase in negative ones, leading to a total mood disturbance, an increase in “tension” and “depression”, and a decrease in the sense of “vigor”. Clearcuts have significantly worse regeneration properties compared to mature stands and second-growth forests. Another study [48] on the perception of dead wood in the forest shows that the regeneration value of a managed forest is lower than that of a forest reserve. Exposure to a bark beetle-infested stand caused more stress in study participants than exposure to a managed forest with fallen logs. This scant evidence suggests that more research is still needed to identify green space attributes that are associated with specific health benefits [49].

2.3. Open Habitats in the Forest and Their Regeneration Potential

Forests on the outskirts of the city and in its suburban zone are characterized by a certain spatial diversity, which is reflected both in the vertical structure (different stand compactness, age class diversity, etc.) and horizontal structure, which is reflected in the mosaic of forest stands and open areas. The term “open” here means, as in the study [50], a non-forested area. Open habitats are open land habitats and open water aquatic habitats. Open areas in forests, located among or at the edge of forest ecosystems, are permanent or temporary areas created by natural or anthropogenic factors [51]. They include, in particular: non-forest land that is an ecological land use; non-forest land that has natural values related to the non-forest character of the biocenosis, such as thermophilic grasslands, meadows, swamps or bogs not overgrown with trees and shrubs, clearings in the mountains, scenic spots, water bodies, as well as agricultural land or forestless military training grounds, etc. [51]. There are many works indicating the enormous ecological and protective importance of this type of surface [52,53,54,55]. Mid-forest open areas have an important function of enriching biodiversity; through complex trophic processes and relationships, they provide greater sustainability for forest communities. In addition, wetlands and peatlands play a role in regulating water supply, actively storing carbon, and at the same time, protecting the vast stores of carbon already deposited in the form of peat.

Open habitats offer a range of essential ecosystem services in addition to their role in supporting biodiversity. They enhance the beauty and diversity of landscapes, preserve scenic views, such as those from trails and key vantage points, and give visitors the chance to observe wildlife [50].

Establishing open habitats within existing forests and thoughtfully planning new ones can greatly enhance both their biodiversity benefits and overall visual appeal. For visitors to forested areas, the aesthetic quality of these “natural” landscapes is often just as important as their conservation value. This significance is amplified in rural settings, where the experiences of walking and observing nature differ markedly from those in urban environments [50]. Water is an important and attractive feature for people to use and enjoy [56,57,58]. According to research on the characteristics of green spaces in the city [20], the leisure effect achieved in contact with a blue environment is higher than that achieved due to exposure to green areas. The restorative effect achieved due to contact with an open area, offering opportunities for landscape perception, was higher than when in contact with a tree canopy site. But does this observation apply to open habitats in forests? The purpose of our study was to determine whether and to what extent mid-forest marshes with water tables and unforested dunes are able to provide people with relaxation and mental renewal. The study adopted the following hypotheses:

Hypothesis 1. 

Contact with the forest positively affects people’s psychological relaxation, expressed by an increase in perceived regenerative effects, subjective vitality, positive emotions, and a decrease in negative emotions.

Hypothesis 2. 

All three analyzed spatial features—wetland, mid-forest non-forested dune, and mature forest stands—have regenerative, restorative properties.

Hypothesis 3. 

Exposure to the swamp with an open water table leads to increased regenerative benefits compared to the other analyzed forest space options.

3. Materials and Methods

3.1. Participants

The invitation to participate in the experiment was extended to adult students of Warsaw University of Life Sciences who were of Polish nationality and without mental health conditions or problems. Participation in the study was voluntary. Participants were guaranteed full anonymity, were informed of the purpose of the study, were instructed on the course of the experiment, and were assured of the possibility of discontinuing the study protocol at any time during the study. The invitation was accepted by 21 men and 31 women, according to the declaration, who were between the ages of 21 and 25. During the experiment, the participants were not allowed to communicate with each other, and the use of telephones was prohibited, as was the consumption of products containing caffeine, theine, or other energizing substances. The experimental protocol was in accordance with the ethical standards of the Polish Committee for Ethics in Science and the 1964 Declaration of Helsinki (as amended).

3.2. Study Sites

The survey was conducted in June 2024 (3 June 2024) in the public forests managed by the Drewnica Forest District, at a distance of about 0.4–2.5 km from the borders of the city of Warsaw and at a distance of about 13 km from the center of the capital city (Figure 1). The pine stand (site A, compartment 207 g) was composed of 86-year-old pine, with 56-year-old oak, maple, and robinia also present in places (https://www.bdl.lasy.gov.pl/portal/mapy-en; accessed on 6 January 2025). The habitat type of the forest was fresh mixed coniferous forest. The canopy density was moderate, and the forest cover was 0.9. The wetland (location B, compartment 130 g) had an area of 1.59 ha. Sporadic tree species were present, such as alder (46 years old), willow (46 years old), and birch (71 years old). The dune (location C, compartment 167 g) covered an area of 9.56 ha. In places, there were volunteer pine and birch trees (21 years old). The plant communities here belong to the class Sedo-Scleranthetea and two orders: Corynephoretalia and Festuco-Sedetalia.

Environmental conditions, including atmospheric weather conditions, as well as those related to noise and illumination during the experiment, were controlled. To determine the atmospheric conditions, data from the meteorological station MiGW-PIB Warsaw-Bielany (252200150), located closest to the experiment site, were relied upon (location: 52°16′53′′ N 20°57′48′′ E. Commonly used, free, iOS-based applications such as UX Light Meter FREE and Sound Level Analyzer Lite were used to measure light. Similar apps have been used in other studies by Tsunetsugu et al. [46] and in our earlier work by Janeczko et al. [43]. The collected data from measurements made in the field are summarized in

Table 1. Conditions during the experiment.

Atmospheric Conditions
average daily temperature	cloudiness	humidity	pressure	wind speed
20.5 °C	3	60–90%	1000 hPa	3 m/s
sound level:
53–65 dB
average light intensity
Forest	dune	wetland
12,124–28,743	133,847–159,197	54,283–86,414

.

3.3. Procedure

The experiment began at 10 a.m. All participants met at a common point located on the edge of the forest. At this point, they were asked to answer questions via psychological test questionnaires (pre-test). Participants completed the POMS, PANAS, SVS, and ROS psychological tests.

In the next step, everyone was randomly divided into three groups (Groups A and B had 17 people each, and Group C had 18 participants). The experiment involved 3 researchers. Each group, led by a researcher, moved in rotation through the forest from point to point of exposure. Group A first observed a pine stand, followed by a wetland and a sand dune (Figure 2). The time spent moving from point to point averaged about 15 min.

Group B began the experiment by being exposed to a wetland, a dune, and a pine stand. Group C started with the dune and then observed the pine stand and the wetland. As a result, only one participant group was present at each exposure site. The exposure time was 15 min. A number of other studies on the regenerative properties of short recreation programs in natural environments have followed a similar approach [20,33,48]. During the observation, each participant was at a distance of about 5 m from the next participant. During the exposure, participants were not allowed to exercise physically; they could sit, stand, and observe the space. Then, after 15 min of observation, using psychological tests, information was collected on the emotional state and mood of the study participants. The general scheme of the procedure is shown in Figure 3.

3.4. Measurements

The mood and well-being of the participants in the study were determined by the pre–posttest protocol, which was based on four psychological tests, namely:

• Positive and Negative Affect Schedule (PANAS) (the Polish version was published by Brzozowski in 1991 [59]). The test consists of ten questions relating to positive feelings and another ten to determine the level of negative feelings. This questionnaire is accurate and reliable [60].
• Restorative Outcomes Scale (ROS)—a test consisting of seven questions, developed by Korpela et al. [36] and used in Poland by Bielinis et al. [24].
• Subjective Vitality Scale (SVS)—the test contains four questions measuring vitality, and this scale is valid and reliable [61].
• Profile of Mood State (POMS), a test adapted to Polish conditions by Dudek and Koniark [62]. It is based on six subscales measuring levels of tension (T), Anger (A), Fatigue (F), Depression (D), Confusion (C), and Vigor (V). POMS is a reliable and contemporary measure of mood state, which was previously used by, for example, Furuyashiki et al. [63] and Yu et al. [64] to assess the impact of nature on mood.

A previous study showed that all of these questionnaires have moderate (Cronbach’s α = 0.794) to high (Cronbach’s α = 0.921) reliability with young Polish adults and could be used with adequate precision in this study [65].

3.5. Data Analysis

All data collected from participants were coded in Excel (Microsoft, Redmond, WA, USA), and mean values and standard deviations (SDs) were calculated using this program. Further analysis was performed using STATISTICA version 13.3 (TIBCO Software Inc., Palo Alto, CA, USA). A paired t-test was used to compare pre- and post-exposure measurements. The distribution of the data was similar to a normal distribution. A parametric one-way ANOVA with repeated measures was used to assess the level of benefit derived from individual exposures on human well-being. The ANOVA was followed by post hoc comparisons using Tukey’s HSD test. Results for which “p > 0.05” was statistically significant in both ANOVA and post hoc tests were included in the analyses.

4. Results

4.1. Reliability of Scales

The internal consistencies of all scales and subscales are shown in

Table 2. Verification of internal consistency.

Scales	Subscales	Cronbach’s α
PANAS	Positive	0.842
	Negative	0.916
ROS		0.931
SVS		0.864
POMS	Tension	0.783
	Depression	0.940
	Anger	0.896
	Fatigue	0.882
	Confusion	0.824
	Vigor	0.870

n = 52.

. The Cronbach’ α was used as an internal consistency measure. The ROS had high internal consistency, while PANAS, SVS, and POMS (as a whole) had good internal consistency.

4.2. Positive and Negative Affect Schedule (PANAS)

Post-analysis of averages and standard deviations following ANOVA can be found in

Table 3. Mean and SD of psychological measurements in the analyzed space variants during the experiment (for PANAS scales).

Measures	Valid N	Total				Pre-Test (a)				Pine Forest (b)				Sand Dune (c)				Wetland (d)				F Ratio	Prob > F
		Mean	−95%	95%	SD	Mean	−95%	95%	SD	Mean	−95%	95%	SD	Mean	−95%	95%	SD	Mean	−95%	95%	SD
PANAS Positive	52	2.74	2.65	2.84	0.79	2.59 bd	2.42	2.76	0.62	2.87 a	2.62	3.12	0.90	2.60 d	2.38	2.83	0.80	2.94 ac	2.73	3.15	0.75	2.05	0.09
PANAS Negative		1.63	1.53	1.72	0.77	1.70	1.47	1.93	0.83	1.57	1.35	1.80	0.82	1.67	1.45	1.89	0.79	1.54	1.35	1.73	0.68	0.40	0.81

−95%—Confidence limits for means −95%; +95%—confidence limits for means +95%; SD—standard deviation.

. The letters signify notable statistical differences among the averages. No significant differences were observed across all averages for the negative component of PANAS. The positive component of PANAS showed a marked increase in the posttest, following exposure to both a pine forest and a wetland. Exposure to the wetland resulted in a significantly greater improvement (PANAS positive) compared to exposure to the sand dune.

The average magnitudes of favorable changes in mental well-being determined with PANAS (ΔPA, ΔNA) and their uncertainties (95% confidence level), which were determined for the analyzed variants of the experimental conditions, are shown in Figure 4.

4.3. Restorative Outcome Scale (ROS) and Subjective Vitality Scale (SVS)

The levels of ROS and SVS were significantly higher in the posttest after exposure to a pine stand and a wetland (

Table 4. Mean and SD of psychological measurements in the analyzed space variants during the experiment (for ROS and SVS).

Measures	Valid N	Total				Pre-Test (a)				Pine Forest (b)				Sand Dune (c)				Wetland (d)				F Ratio	Prob > F
		Mean	−95%	95%	SD	Mean	−95%	95%	SD	Mean	−95%	95%	SD	Mean	−95%	95%	SD	Mean	−95%	95%	SD
ROS	52	4.62	4.43	4.80	1.51	4.08 bd	3.72	4.43	1.27	4.93 a	4.49	5.37	1.57	4.39 d	3.96	4.82	1.53	5.08 ac	4.70	5.47	1.38	3.91	0.00
SVS		4.08	3.95	4.21	1.08	3.81 bd	3.51	4.11	1.08	4.20 ad	3.88	4.53	1.15	4.01	3.72	4.30	1.04	4.33 ab	4.04	4.62	1.04	1.77	0.13

−95%—confidence limits for means −95%; +95%—confidence limits for means +95%; SD—standard deviation.

).

It also turns out that the average value of benefits measured by the ROS test after exposure to the wetland is statistically significantly higher than after exposure to the dune (Figure 5).

4.4. Profile of Mood States (POMSs)

There were six subscales of the POMS scale, and almost all had lower values after exposure to the pine stand (pre-test vs. posttest)—

Table 5. Mean and SD of psychological measurements in the analyzed space variants during the experiment (for POMS scales).

Measures	Valid N	Total				Pre-Test (a)				Pine Forest (b)			Sand Dune (c)				Wetland (d)					F Ratio	Prob > F
		Mean	−95%	95%	SD	Mean	−95%	95%	SD	Mean	−95%	95%	SD	Mean	−95%	95%	SD	Mean	−95%	95%	SD
Tension	52	0.93	0.85	1.01	0.67	1.04 b	0.85	1.22	0.67	0.81 a	0.63	0.99	0.64	0.98	0.77	1.18	0.72	0.88	0.72	1.05	0.60	0.89	0.47
Depression		0.73	0.63	0.83	0.84	0.89 bd	0.64	1.15	0.92	0.63 a	0.39	0.87	0.85	0.78	0.54	1.01	0.83	0.63 a	0.42	0.83	0.73	0.91	0.46
Anger		0.84	0.75	0.93	0.75	0.96 bd	0.75	1.17	0.75	0.73 a	0.52	0.93	0.75	0.90	0.68	1.13	0.81	0.74 a	0.56	0.93	0.67	0.95	0.43
Fatigue		1.44	1.31	1.57	1.07	1.68 bd	1.39	1.96	1.01	1.28 a	0.95	1.61	1.18	1.61	1.30	1.91	1.10	1.24 a	0.96	1.52	1.01	1.71	0.15
Confusion		0.98	0.89	1.06	0.69	1.28 bd	1.07	1.48	0.73	0.88 a	0.69	1.06	0.66	0.99	0.79	1.18	0.70	0.85 a	0.69	1.01	0.58	3.50	0.01
Vigor		1.98	1.86	2.09	0.91	1.86 d	1.63	2.08	0.81	2.08	1.78	2.37	1.04	1.82	1.57	2.07	0.90	2.11 a	1.86	2.36	0.91	1.05	0.38
TMD		3.11	2.78	3.43	2.65	6.5 bcd	5.94	7.06	2.00	2.25 a	1.05	3.46	4.33	3.42 a	2.24	4.61	4.26	2.23 a	1.19	3.28	3.76	1.79	0.13

−95%—confidence limits for means −95%; +95%—confidence limits for means +95%; SD—standard deviation.

. The exception is the vigor subscale, which measures positive mood; however, this index did not increase statistically significantly after exposure to the pine stand. Instead, it was observed that its value increased significantly compared to the pre-test after exposure to a wetland with open water.

It was also found that all POMS subscale values, except for tension, statistically significantly decreased after exposure to the wetland—Figure 6. No statistically significant benefits were noted for dune exposure, either in comparison with pre-test values or between scales. However, TMD as a whole, dune exposure also provides significant benefits in terms of improved mood.

5. Discussion

Once again, we provide evidence that recreation in a natural environment increases positive feelings. Many other works have also proven that recreation decreases negative emotions [24,37,47]. But mostly these findings have been the result of comparing recreation in a forest area and a city [25,26,44]. This time, the experiment was conducted largely inside the forest, and the exposure subject was open, mid-forest areas and the mature stand. Hence, we found no clear reduction in the level of negative feelings. Being inside the forest caused the level of negative feelings to be low. Still, the average PANAS-negative value did not differ significantly from that established at the beginning of the experiment. Also, in the author’s earlier study conducted inside the forest [48], we did not note a decrease in negative feelings. The marked increase in positive feelings resulted from the greater richness and greater number of visual and auditory stimuli offered by the forest, including its non-forest enclaves. Walking in the forest and exposure to changing landscape features such as mature stands of trees, water, and a forestless expanse of sand offered significantly more pleasant and varied experiences. Hence, the level of positive aspects of PANAS was significantly higher after exposure to a pine stand and a swamp. Exposure to water provided a statistically significantly higher benefit (Panas-positive) than exposure to a sand dune. Environments with water are associated with higher preferences, greater positive effects and a more restorative effect [66,67]. Contact with water guarantees the highest level of regenerative benefit. The restorative value, and at the same time the level of vitality derived from exposure to water, are higher than in the case of exposure to mature pine stands. This is also confirmed by previous research on the restorative properties of green spaces in the city [44]. Exposure to water was found to be significantly mood-enhancing and led to greater improvements in mood compared to mature stands. Water is one of the important determinants of landscape attractiveness [68,69,70]. Tajima et al. [70] discovered that exposure to aquatic environments can enhance one’s mood. Notably, individuals who frequently experience these views report a more substantial positive impact on their mood compared to those with medium or low frequency of exposure. Interestingly, the differences in mood inventory scores based on frequency were more significant for men than for women. Those situated near water tend to exhibit a heightened sense of positivity and well-being. Gazing upon a tranquil body of water can evoke feelings of comfort, openness, and freedom. People who are in a relaxing environment are in a better mood and enjoy better mental health. In our previous research, we also found that exposure to water [44] led to improved mood. Also, Peng et al. [71] found that the effect of the water environment on mood was significant, especially for depressed mood and feelings of refreshment.

The current study found that a stand of pine trees also provided renewal, although to a lesser extent. Going to the forest and surrounding oneself with trees and vegetation allows the body and mind to relax, benefiting from the healing effects of nature [9]. Restoration and vitality are two measures inseparable from recreation. Many previous works [24,33,47,66,72,73] have suggested that recreation in forested areas has restorative properties and that it leads to greater vitality, strength, energy [24,37,73]. Outdoor recreation is generally associated with improved mood and well-being. Also, previous studies [31,73] confirmed that in a forest environment, values of indicators of tension, depression, anger, confusion, and fatigue decrease. Also, the authors’ previous study [43] argued that contact with the forest provides restorative properties, demonstrating that not every type of space has equally high restorative properties.

This research confirms that mature forest stands and open forestless areas such as water bodies have such properties, but open dunes no longer exist. It may be that abraded sandbanks are treated as a certain anomaly in the forest, places which are poor in terms of species diversity. Dulias [74] points out that the inland dune landscape is under heavy human pressure. Most dunes have been destroyed over the past century due to sand mining and industrial and residential construction. The area where we conducted the research was used as a military training ground in the past. With traces of this disturbance still present, albeit few, the area appears less visually appealing. In addition, people tend to prefer forested settings, where there are a large number of trees of various ages and species, and the ground consists of low, sparse ground vegetation [75]. The factor that undisputedly positively and unequivocally influences the assessment of the landscape being the subject of the largest number of studies in the field of landscape components, is, next to the water, vegetation. Its role in the evaluation of a view has been highlighted by many researchers, including Kaplan and S. Kaplan [76], Ulrich [77], and Raskovic and Decker [78]. A dune devoid of vegetation can be considered as a factor that depreciates the landscape and thus reduces the level of health benefits received.

6. Conclusions

The study compared the effects of a mature pine stand and two types of mid-forest open spaces—a swamp with water and a mid-forest sand dune—to measure the effects of these environments on human psychological relaxation during exposure in a randomized experiment. The analyses showed that both exposure to a body of water and a mature forest stand had a positive effect on participants’ psychological relaxation. The mid-forest dune, which was home to a smaller number of species, had a significantly weaker regenerative effect. Therefore, it can be said with certainty that environmental diversity is positively related to human well-being. Maintaining mid-forest water bodies, wetlands, marshes, moors, glades and similar open areas in a near-natural state or, if possible, restoring them, is important for preserving biodiversity and scenic values. This activity is also important, as seen in our study, because of the high restorative value of these areas, supporting the maintenance of people’s mental and physical health. The results we obtained can help create supportive interventions and enhance the benefits of forest therapy when people interact with the broader forest landscape. They show how diverse the forest is and how certain forest features support human well-being.

The research we conducted also led to some reflections on limitations and further research directions. The study has three important limitations. First, once again, the authors could not fully eliminate the potential error caused by the cumulative effect of renewal/fatigue at the last stage of the walk. By changing the walking route, the authors ensured that the tests were conducted at as comparable intervals as possible (walking time and exposure time). We tried to minimize this error, but we are aware of this limitation. During the experiment, participants had to answer the same questions on the psychological test questionnaires several times. This may have been tedious for some of them, but we were primarily concerned that the entire study be conducted on the same day, with full control of parameters such as noise, light, cloud cover and wind speed. The exposure time was short; this is not a disadvantage, as many other studies have also taken into account short periods of activity in nature. However, we are aware that increasing the exposure time could affect the values of the various subscales included in the psychological tests. In future studies, looking more deeply into the importance of forest water bodies for relaxation benefits would be worthwhile. Two aspects could be of interest: the naturalness of the reservoirs (artificial versus natural reservoirs) and the degree of recreational investment.