European Journal of Forest Research (2023) 142:415–426 https://doi.org/10.1007/s10342-023-01531-6 ORIGINAL PAPER Forest bathing and hiking benefits for mental health during the COVID‑19 pandemic in Mediterranean regions Anna Muro1,2 · Corel Mateo1 · Eva Parrado1,3 · Montse Subirana‑Malaret4 · Montserrat Moya5 · Adrià Garriga6 · Josep Canals7 · Andrés Chamarro1,2,3 · Antoni Sanz1 Received: 18 April 2022 / Revised: 7 October 2022 / Accepted: 5 January 2023 / Published online: 3 February 2023 © The Author(s) 2023 Abstract Forest bathing (FB) has evidenced positive effects on individuals’ mental health and well-being, but its benefits have mainly been studied in Asian biomes. The present study aimed to evaluate whether its benefits are also generalisable to other forests and biomes of the world, such as the Mediterranean. Eighty-six healthy adults of the general population were assessed before and after a FB near Barcelona (Spain) during the COVID-19 pandemic. A control-hiking group of participants was also analysed to contrast the FB effects on anxiety, affect, mood states and mindfulness. Results show that the guided practice of FB in Mediterranean-Catalan forests increases mindfulness states and positive affect and reduces anxiety and negative affect, with effect sizes being large to very large. Hiking also induced significant changes in all variables tested, but FB showed higher effect sizes. An exploratory analysis also revealed a different profile of the FB participants compared to the hiking practitioners, being highly educated women living in urban areas and with lower basal levels of psychological well-being. Accordingly, it is concluded that both Mediterranean FB and hiking (to a lesser degree) might be cost-effective strategies to promote and restore psychological well-being after the COVID-19 pandemic and to promote sustainable tourism in Mediter- ranean biomes of the European forested and protected areas. Keywords Forest bathing · COVID-19 · Mediterranean forests · Well-being · Mental health Introduction Shinrin-Yoku (forest bathing; FB) is a traditional Japanese nature practice which consists in walking by the forest in Communicated by Thomas Knoke. silence and by paying attention to the one’s senses in con- * Anna Muro nection with nature (Kotera et al. 2020; Miyazaki 2018). anna.muro@uab.cat Its practice has been spread around the world during the last decade, and it is considered both a recreational and a 1 Departament of Basic, Developmental and Health therapeutic activity, guided and structured, aimed at improv- Psychology, Autonomous University of Barcelona, Office B5‑111, Campus UAB, Bellaterra, 08193 Barcelona, Spain ing health and well-being (Farkic et al. 2021; Hansen et al. 2 2017; Wen et al. 2019). It activates human senses, allow- Serra Húnter Programme, Generalitat de Catalunya, Barcelona, Spain ing multisensory, affective and kinaesthetic experiences 3 that induce relaxation and vitality. During the last decade, Sport Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain numerous studies performed in Asian biomes have consist- 4 ently reported the restorative effects of FB for mental health Faculty of Psychology, University of Barcelona, Barcelona, Spain (Hansen et al. 2017; Timko-Olson et al. 2020), showing how 5 walking by a forest in silence reduces stress, depression and Cooperativa Sèlvans, La Garrotxa, Girona, Spain anxiety levels. FB is a nature activity mainly practiced in 6 School of Nature La Muntada, Sant Llorenç Savall, Japan, a country that counts with around 60 forest medicine Barcelona, Spain centres that coordinate with the major health and primary 7 Natural Park of Sant Llorenç, Catalan Net of Natural Parks, care units of major metropolises (Li 2018; Park et al. 2010). Barcelona Provincial Council, Barcelona, Spain 13 Vol.:(0123456789) 416 European Journal of Forest Research (2023) 142:415–426 FB provides an added value to forested areas and channel the Mediterranean forests, more specifically in the protected areas demands of contact with nature by a growing urban popula- of the Catalan region, at the north-east of the Iberian penin- tion with intense levels of stress, competitiveness, screen or sula. The study also aimed to facilitate the implementation new technologies addiction and related problems such as of FB in Catalan forests during the pandemic among urban sedentarism, obesity and cardiovascular problems (Morita populations, whose mental health has been significantly hit by et al. 2007; Oh et al. 2017; Wen et al. 2019). Accordingly, the COVID-19 pandemic (Sanabria-Mazo et al., 2021; WHO FB has been also regarded as a sustainable touristic activ- 2020); finally, it also aimed to replicate a pilot study published ity that enable visitors discover forest landscapes and that during the COVID-19 pandemic exploring the benefits of FB promotes pro-environmental attitudes and well-being (Far- in a Mediterranean-Catalan forest. It reported large increases kic et al. 2021). Empirical evidence suggests that exposi- in positive affect, vigour, friendship and mindfulness and large tion to natural environments improves per se well-being, decreases in negative affect, anxiety, anger, fatigue, tension reduces stress and depressive mood (Antonelli et al. 2019; and depressive mood in sample of 17 healthy adults (Muro Park et al. 2010; White et al. 2021). Coherently, walking et al. 2022). Despite the very large effect sizes reported in by the forest in silence adds significant improvements for this pilot study, methodological issues related with the small other health outcomes given the revitalising effect of nature sample size, the lack of control group and the lack of forests’ exposure with low physical activity and silence (Chen et al. diversity, made it hard to generalise results. Accordingly, the 2018; Hansen et al. 2017; Kobayashi et al. 2018; Lyu et al. present study increased the sample size, the type of forests and 2018; Li 2018). Thus, FB has also been associated to over- included two control groups of hiking activities to contrast the all improvements in immune and cardiovascular functioning results of the FB-experimental condition. Hiking, as a nature and to increases in positive emotions and cognitive functions activity that consists in walking around green landscapes, has such as attention, as well as to reductions in pain perception also numerous benefits for health, but it is rather considered (Hansen et al. 2017; Kotera et al. 2020; Li 2018; Wen et al. a touristic- recreational and physical activity (Mitten et al. 2019; Yau and Loke (2020). Some authors suggest that the 2018). Therefore, in an exploratory way, we aimed to study inhalation of terpenes, as main volatile oils contained in for- whether there was any self-selection bias between participants est aerosols, is the mechanism that mediates the relationship who decided to carry out a guided practice of forest bathing between FB and health improvements (Cho et al. 2017). It vs. a guided practice of hiking, since the first is perceived as is also argued that the specific forest’s biome is also a factor a more therapeutic activity while the second is considered a that might mediate these restorative and healing effects for recreational-sports activity. Likewise, given the fact that the humans’ health (Bach et al. 2020a, b). study included two different sub-biomes of the Mediterranean- Given the mounting evidence of FB’s health benefits, it Catalan biome, the differential effect obtained with the practice is considered an evidence-based activity in forest medicine in both was also explored. and included as a key element in nature-outdoor therapies The hypotheses were the following: (Biedenweg et al. 2017; Bratman et al. 2019). However, although empirical studies in Asian biomes are plentiful, a H1 FB would significantly increase participants’ posi- recent review indicates that more evidence is needed to study tive affect, vigour, friendship and mindfulness and would the differential impact of FB in other biomes of the world decrease negative affect, anxiety, anger, fatigue, tension and (Kotera et al. 2020), such as the Mediterranean biome. FB depressive mood. practice has grown significantly during recent years in this area, but just a few pilot-empirical studies have been carried H2 There would be also changes in the control-hiking groups out to date exploring its specific effects for health (Hansen in the indicators measured, but changes would be expected et al. 2017; Bach et al. 2021; Muro et al. 2022; Rodríguez to have a higher impact in the FB group. 2018; Wen et al. 2019). Unlike Asian mesophytic or decidu- ous forests, Mediterranean forests are part of a temperate ter- H3 There would be no differences among the forest bath- restrial biome, characterised by hot, dry summers and rainy ing effects performed in the two different Mediterranean winters (Bach et al. 2021; Mucina 2019). Mediterranean sub-biomes. forests can be mainly found in big five ecoregions of the world: the Mediterranean Basin, California, central Chile, southwestern Australia and the Western Cape of South Materials and methods Africa. The Mediterranean biome is also called evergreen sclerophyll (scleros = hard, sharp = leaf), as it is mostly made Design and procedure up of hard-leaved perennials (Woodward et al. 2004). Therefore, the present study was designed to assess the A pre-post with control group design was used to evalu- psychological benefits of FB and other hiking activities in ate the psychological benefits of FB compared with guided 13 European Journal of Forest Research (2023) 142:415–426 417 hiking in Catalan forests. Most of the Catalan territory lies est areas by Pinus sylvestris and Pinus nigra. These pine on the north-east of the Iberian Peninsula, at the south of forests, for the most part, are the result of the human the Pyrenees Mountain range. The capital and largest city transformation of the primitive forest and in many areas is Barcelona, the second most populated city in Spain and appear mixed with holm oaks (Quercus ilex) and Medi- the fifth most populated urban area in the European Union terranean shrubs such as heather (Erica) and strawberry (Demographia 2021). (Arbutus unedo). The holm oak groves are the charac- The intervention followed the procedure employed in a teristic and most widespread vegetation of the natural pilot study carried out in May 2020 (Muro et al. 2022), but park, which above 800 masl is enriched with species the current study included some variations, including two typical of wetlands such as whitebeam (Sorbus), box- experimental conditions distributed in different locations: wood (Buxus) and oak (Quercus humilis) (Lorenzo and Fernández; 2009). The walk included 2 stops (one at the • Experimental group. It included participants that took a beginning and one at the middle of the walk) to practice FB with specialised nature guides, in two different main short mindfulness-meditations of 10 minutes each and different allocations: (1) Vallès Occidental, natural park train deep breathing and mindful attention. Participants of Sant Llorenç and (2) la Garrotxa area, volcanic zone were asked to be aware and open their senses to facilitate Natural Park. Both spaces are located at a linear distance nature connectedness (by listening the sounds of the for- of 70 km, in the Mediterranean biome of the Mediter- est, the smell of plants and flowers, etc.) during the walk. ranean basin, included in the north-eastern Spain and • The second experimental group took a FB in different for- Southern France Mediterranean forests (Olson and Din- ests of La Garrotxa area: Les Olletes (geographical coor- erstein 1998). The groups were conducted by different dinates: N 42° 9.886; E 2° 31.831) Serra d'Heures (geo- guides and sub-biomes but both walked by paths near graphical coordinates: N 41° 53.968; E 2° 31.683) and old trees, big stones and little rivers that enriched the Can Fornaca (geographical coordinates: N 41° 48.200; participants’ sensory stimulation. E 2° 38.979). This group of participants was recruited in • The first group (Sant Llorenç) was recruited in collabo- collaboration with Sèlvans Association (https://​selva​ns.​ ration with the Diputació de Barcelona, a public admin- ong/). Sèlvans Association is a non-profit organisation istration that promotes the progress and well-being of that was born in 2007 with the main aim of conserv- the citizens and local governments of its territorial area, ing and adding value to the Catalan forests. It organises and the Network of Natural Parks of Catalonia (https://​ activities related to environmental education and nature parcs.​diba.​cat), announcing the activity for the general conservation, such as FB. This group also did mindful population during the first waves of the pandemic: one walking in silence (without stops) being aware and open- for October 2020 (https://​parcs.​diba.​cat/​web/​agend​a/-/​ ing their senses to facilitate nature connectedness (by sant-​lloren%​C3%​A7-​obac-​banya-t-​al-​bosc-​experi%​C3%​ listening the sounds of the forest, the smell of plants and A8ncia-​immer​siva-a-​la-m%​C3%​A0gia-​de-​les-​arenes) flowers, etc.) around 2 h through the mentioned forests and the other for May 2021 (https://​parcs.​diba.​cat/​web/​ of La Garrotxa. It is located at the eastern end of the agend​a/-/​sant-​lloren%​C3%​A7-​obac-​banya-t-​al-​bosc-​ Catalan Pre-Pyrenees and is known as the volcanic area experi%​C3%​A8ncia-​immer​siva-a-​la-m%​C3%​A0gia-​de-​ of Catalonia. Its geographical location makes it attrac- les-a​ renes-1). The activity was framed within the Ginesta tive for its proximity to the sea and to the mountainous project of environmental education, included in projects regions of the country. This whole area is part of the of the European Charter for Sustainable Tourism for Natura 2000 Network, an European initiative to protect 2021, which is a set of good environmental practices for the most unique, diverse, rare, well conserved, repre- the management of tourism in protected natural areas, sentative or vulnerable natural spaces. The climate of La promoted by the Europarc Federation (Canals 2014; Garrotxa is medium mountain Mediterranean. Rainfall Europarc Federation 2010). is abundant throughout the year, and the winter is the • The forested area chosen for the FB was in Les Arenes driest season. The frequent showers keep summers cool, de Sant Llorenç del Munt (geographical coordinates: N while the influence of the Pyrenees makes the winters 41° 38.799 N, E 2° 3.457): it is an area of a mountain very cold. The vegetation reflects the climate. While in Mediterranean forest in Sant Llorenç del Munt i Serra de the Alta Garrotxa and the east of the county there is an l’Obac Natural Park (Catalonia, north-east of the Iberian area of typically Mediterranean vegetation, the rest of the Peninsula), a massif included in the central pre-coastal county is covered with sub-mediterranean vegetation that Mediterranean climate, close to urban centres. The base becomes Atlantic in the most humid parts. Holm oaks are of the massif is occupied by white pine groves (Pinus typical on the sunny hillsides of the eastern sector, with halepensis), very resistant to water scarcity and up to relatively dry and hot summers, the oak tree predomi- 600 masl, often being replaced in the darkest and/or tall- nates in other parts, and the beech is found in the most 13 418 European Journal of Forest Research (2023) 142:415–426 humid sectors. On the Olot plain, the most characteristic la Garrotxa n = 23), and 29 in the control group of hiking natural species is the common oak, although nowadays practice (with inclination n = 18; plain n = 11). The final its presence is limited to small woods found around the sample analysed recorded an average age of 49.6 years city. (ranging from 19 to 78). Most of participants were resi- • Control group It included two hiking groups that did dents in urban areas (75.6%), were women (69.8%) and not take a FB but practiced a group-guided activity such had higher education (76,7%) (see Table 1). as hiking. Hiking is a walk, usually on trails or foot- paths in the countryside. The activities were organised in collaboration with the Network of Natural Parks of Instruments Catalonia and the School of Nature La Muntada (https://​ www.​lamun​tada.​cat/​ca), located in the Vall d’Horta of Both FB and hiking participants responded 4 standardised Sant LLorenç Savall (geographical coordinates: N 41º tests before and after the FB session. These questionnaires 40.638; E 2º 1.864). One grup hiked around 8 km. from are widely used in the study of the psychological effects la Vall d’Horta to a small-mountain called els Emprius- of FB and are cross-culturally validated for both the gen- la Roca Foradada with an unevenness/inclination of eral and clinical populations (Hansen et al. 2017; Oh et al. 250 m (https://​parcs.​diba.​cat/​web/​agend​a/-/​sant-​lloren%​ 2017; Timko-Olson et al. 2020; Wen et al. 2019): C3%​A7-​obac-​els-​empri​us-​el-​queix​al-​corcat-​i-​el-​cau-​ dels-​embos​cats). A second control group hiked around 3 km. without inclination, along a plain and flat route in State‑trait anxiety inventory la Vall d’Horta https://​parcs.​diba.​cat/​web/​agend​a/-/​sant-​ lloren%C​ 3%A ​ 7-o​ bac-p​ assej​ ada-t​ eatra​ litza​ da-j​ oan-o​ liver-​ (STAI; Guillén-Riquelme and Buela-Casal (2011); Spiel- al-​marqu​et-​de-​les-​roques-1. The two groups of activity berger et al. 1982): This test measures the levels of state that are reported as control condition were selected from (situational) and trait (global personality) anxiety with a among the cathalog of recreational and sports activities total of 20 items in each scale and format of Likert-type offered in the catalogue of activities of the institutions answers. In the present study, only state-anxiety was meas- that have promoted the forest bathing experiences ana- ured. High scores warn of altered states related to anxi- lysed in this study. For the selection of these activities, ety, low scores indicate emotional stability and absence the researchers set the following inclusion criteria a of stress. In the original Spanish validation, STAI-state priori: (1) Being a guided activity, (2) practiced in the showed an internal consistency of Cronbach’s α = .90. In same geographical spaces, (3) qualitatively different from the study sample, STAI-state showed an internal consist- forest bathing, (4) with the same duration (2 h) and (5) ency of Cronbach’s α = .88. intensity. Of the two selected groups, second one met the 5 criteria and the first one 4 of them (all except low intensity). This gave rise to a statistical control of this possible confounding variable that is explained later. Table 1  Descriptive statistics of the study participants Study sample (n = 86)* A call for participation was made through the website of the corresponding organisers. Prior registration was Age M ± SD (Range) 49.02 ± 11.91 (19–78) requested to participate in all the activities. All participants Gender, n women (%) 60 (69.8) consented to collaborate voluntarily and provided informed Education, n (%) consent before participating in the study. The same pre- Secondary 19 (22.4) post surveys were administered immediately before and Tertiary 66 (77.6) after all the activities online via Google Forms©, but also Origin area, n (%) using paper–pencil questionnaires in the cases in which no Urban 65 (76.5) internet-connection was available. The ethics committee of Rural 20 (23.5) the Autonomous University of Barcelona (CEEAH-UAB) Location and Activity, n (%) approved the study protocol (reference code UAB5339). FB Sant Llorenç 34 (39.5) FB Garrotxa FB 23 (26.7) Participants HI Sant Llorenç 18 (20.9) HP Sant Llorenç 11 (12.8) Ninety-five people signed up for the events. A final sam- FB forest bathing, HI hiking with inclination, HP hiking plain ple of 86 volunteers participated in the study, including * Education and origin (n = 85); secondary (16 years), tertiary (around 57 participants in the FB session (Sant Llorenç n = 34; 25 years) 13 European Journal of Forest Research (2023) 142:415–426 419 Positive affect and negative affect scale gathering procedure (less than 0.5%) explains the slight dif- ferences in the degrees of freedom indicated in the hypoth- (PANAS; Watson et al. 1988; López-Gómez et al. 2015): esis tests. Prior to the analyses, an evaluation of the quality It includes two subscales of 10 items each that assess the of the raw data obtained was carried out in two steps. In experience of positive emotions related to psychological the first step, a principal components analysis (PCA) was well-being and experiencing negative emotions related to carried out with a VARIMAX rotation, an extraction of the psychological distress and mental health problems. In the theoretical factors reported in the respective psychometric original Spanish validation, positive affect subscale showed validations, and a selection of factor loadings greater than an optimal internal consistency of Cronbach’s α = .88, and 0.40. In all cases, a satisfactory factorial structure (match- negative affect subscale showed an internal consistency of ing the theoretical one) was obtained. In the second step, a Cronbach’s α =. 87. In the study sample, positive affect sub- reliability analysis was performed using Cronbach's alpha scale showed an optimal internal consistency of Cronbach’s internal consistency index for all scales and subscales. As α = .91, and negative affect subscale showed an internal reported in the instruments section, internal consistency consistency of Cronbach’s α =. 910. indices obtained were in the range of Cronbach’ α = 0.77 and Cronbach’ α = 0.96, thus very satisfactory and compa- Profile of mood states rable to those of the original validations of the respective instruments. The empirical structure of all the measurement (POMS; McNair et al. 1971; Andrade et al. 2010). This test scales was identical to the theoretical, except for the friend- measures 6 moods from 30 items: Anger, fatigue, vigour, ship subscale of the POMS, from which one of the items friendship, tension, and depressive mood; each item can be was eliminated due to a significant reduction in reliability; scored in a scale ranging from 0 to 4. In the original Spanish this subscale values have been rescaled to the original range validation, the subscales showed an internal consistency of [0–20] for a better interpretation of the results. Cronbach’s ranging from α = .77 to Cronbach’s α = .92 for Once the data quality tests had been carried out, the the six subscales. In the study sample, the subscales showed scales’ scores were calculated, as an identification of a pos- an internal consistency of Cronbach’s ranging from α = .92 sible confounding variable, the homogeneity of the two to Cronbach’s α = .96 for the six subscales. control groups was checked regarding the level of inten- sity of the hiking carried out. An analysis with a general State mindfulness scale linear model of mixed design revealed the absence of dif- ferences between both groups in the pre-post evolution for (M-E; Tanay and Bernstein (2013)): It is composed of 21 state-anxiety, positive affect, negative affect, the six POMS items with a Likert-type response scale to indicate whether subscales and body mindfulness. Significant differences the sentences describe well their experiences in the last 15 were found between both groups in mindfulness of mind minutes. It assesses two dimensions: (1) mindfulness state of (Wilk' λ(1,27) = 4.55; p = 0.04; η2 = 0.14) and in the general mind (e.g. "I realized thoughts coming and going") and (2) mindfulness scale (Wilk' λ(1,27) = 4.73; p = 0.04; η2 = 0.15), mindfulness state of the body (e.g. "I realized physical sen- so that the activity intensity variable was generated, which sations coming and going"). In the original Spanish valida- was included as a covariate in the following statistical analy- tion, mind mindfulness subscale showed an optimal internal ses of these two variables. consistency of Cronbach’s α = .95, and body mindfulness subscale showed an internal consistency of Cronbach’s α = .90. General score of mindfulness also showed an optimal Results internal consistency of Cronbach’s α = .95. In the study sam- ple, mind mindfulness subscale showed an optimal internal Cognitive and affective effects of the practice consistency of Cronbach’s α = .94, and body mindfulness of forest baths vs. hiking subscale showed an internal consistency of Cronbach’s α = .90. General score of mindfulness also showed an optimal Socio-demographics and descriptives of the study partici- internal consistency of Cronbach’s α = .96. pants can be seen in Table 1. A general linear model of analysis of variance (mixed design) was carried out with a Data preparation and statistical analyses within-subject factor (pre- vs. post-phase) and a between- groups factor (experimental vs. control group) on all the Statistical analyses were conducted using the IBM-SPSS variables evaluated (see Table 2 and Fig. 1). A statistically 26.0 statistical package. No participants had to be discarded significant pre-post change was observed for all the vari- due to significant data loss. The omission of answers in some ables in the sample as a whole: an increase in mindfulness of of the participants in the little group of paper-and-pencil data mind, body and global, positive affect vigour and friendship, 13 420 European Journal of Forest Research (2023) 142:415–426 as well as a reduction in state-anxiety, negative affect, anger, Mforestbath = 10.82; F(1,84) = 3.88; p = 0.05), POMS-friendship fatigue, tension and depression were observed. (Mhiking = 16.07 vs. Mforestbath = 14.21; F(1,84) = 4.35; p = 0.04) All statistical significances were equal or less than and POMS-tension (Mhiking = 1.64 vs. M forestbath = 4.80; p = 0.003, and effect sizes ranged from ηp2 = . 10 (POMS- F(1,84) = 9.24; p = 0.003), so they were included as covari- anger) to ηp2 = 0.56 (STAI-state-anxiety). Group x phase ates of the respective hypothesis tests as statistical control. interactions revealed a greater pre-post increase in the No statistically significant differences were found in the rest experimental condition for mindfulness of mind (Wilks' of the variables evaluated. With regard to the sociodemo- λ(1,80) = 5.13; p = 0.03; ηp2 = 0.06, controlling for intensity), graphic variables, it was found that there are differences in for mindfulness of body (Wilks' λ(1,81) = 15.27; p < 0.001; gender (women 77% of the forest bathers vs. 55% of the hik- η p 2 = 0.16), total mindfulness (Wilks' λ (1,80) = 7.84; ing practitioners; χ2 = 4.41; p = 0.03) and in the level of stud- p = 0.006; ηp2 = 0.09, controlling for intensity), positive ies (university students 84% of the forest bathing practition- affect (Wilks' λ (1,84) = 4.90; p = 0.03; ηp2 = 0.06), friend- ers vs. 66% of the hiking practitioners; χ2 = 3.73; p = 0.05). ship (Wilks' λ (1,83) = 16.36; p < 0.001; ηp2 = 0.17), as well No differences were found in age, origin (urban vs. rural) or as a greater reduction in state-anxiety (Wilks' λ (1.84) = 3.62; in previous pathologies. p = 0.06; ηp2 = 0.04), anger (Wilks' λ (1.81) = 4.51; p = 0.04; ηp2 = . 05) and tension (Wilks' λ (1.83) = 6.31; p = 0.014; ηp2 = 0.07). Discussion and conclusions Differences in cognitive and affective effects The present study aimed to explore whether FB in Mediter- depending on the FB’s sub‑biome ranean forests would significantly increase psychological well-being in a sample of healthy adults and to contrast its Given that the groups that practised guided forest bath- effects with a control-hiking group. It was also aimed to test ing were carried out in two different biomes, a specific if there was a differential effect among the FB performed in sub-analysis of the experimental group was carried out to two different Mediterranean sub-biomes of the Catalan ter- identify the possible differences in the effects observed in ritory during the COVID-19 pandemic. The main results of both (see Table 3). Given that the very nature of the study this study are in line with those reported robustly in Asian prevented the random assignment of the participants, a prior biomes (Hansen et al. 2017; Li 2018; Timko-Olson et al. comparison of the baseline values was made, in case it was 2020; Wen et al. 2019) and show how FB in Mediterranean necessary to declare the confounding variables and carry regions also enhance mood states by decreasing anxiety, out a statistical control through analysis of covariance. Sig- negative affect, tension, colera, fatigue and depression indi- nificant differences were found in the baseline values of the cators, and by increasing mindfulness, positive affect, vigour Sant Llorenç (pre-coastal Mediterranean) and La Garrotxa and friendship outcomes, a result which is also in line with (mountain Mediterrean) groups in state-anxiety (F = 7.33; a pilot study in Mediterranean biomes (Muro et al. 2022). p = 0.009), anger (F = 5.58; p = 0.022), tension (F = 9.96; An improvement was obtained in all the affective and cogni- p = 0.003), depression (F = 10.31; p = 0.002) and negative tive processes evaluated within subjects participating in the affect (F = 4.69; p = 0.035), with consistently higher values FB, with effect sizes ranging from moderate to very large, in baseline values in these variables in the Sant Llorenç the latter being the predominant ones. Therefore, results are group. The variance analysis showed a better evolution after consistent with hypothesis 1 and add more evidence to uni- the nature activities of this group for all these variables. versal benefits of FB for mental health in different biomes of However, once the pre value was introduced as a covari- the world and thus for the therapeutic effects of this nature ate, the differences in the pre-post evolution between both activity (Kotera et al. 2020). It is worth noting that signifi- groups disappeared for all the variables, except in state- cant changes have been observed in all the psychological anxiety, (F(1,54) = 15.02; p < 0.001; ηp2 = 0.21) and tension indicators measured in the present study, with large effect (F(1,54) = 9.56; p = 0.003; ηp2 = 0.15) which showed higher sizes after one single FB session. The highest impact has effects for the group that carried out the FB in Sant Llorenç. been shown in anxiety and tension decreases, as well as increases in vigour, a result that is also in line with physi- Profiles of people practising forest bathing vs hiking ological studies reporting lower salivary cortisol levels in FB participants, a solid marker of relaxation and stress reduc- A univariate analysis of variance was carried out to compare tion (Antonelli et al. 2019; Bach et al. 2020a, b; Chen et al. the baseline values of the variables evaluated between the 2018; Park et al. 2010). It is also remarkable that although experimental group. Differences were found in the baseline participants were walking around 4 km., fatigue decreased values of POMS-cholera (Mhiking = 0.34 vs. Mforestbath = 2.33; and vigour increased, suggesting that walking in plain ter- F(1,84) = 6.17; p = 0.01), POMS-vigour (Mhiking = 12.34 vs. ritory is a physical activity with revitalising properties that 13 Table 2  General linear models for cognitive and affective effects of experimental intervention group (guided forest bathing) versus control group (guided hiking) Group Phase Interaction group*Phase FB (n = 57)* M ± SD Hiking (n = 29)** M ± SD F p ɳp2 F p ɳp2 F p ɳp2 STAI-S State-anxiety Pre 19.23 ± 12.02 14.76 ± 7.6 2.43 .123 .03 107.71 < .001 .56 3.62 .06 .04 Post 8.68 ± 7.09 7.48 ± 4.45 PANAS Negative affect Pre 18.84 ± 8.15 15.69 ± 5.73 3.06 .084 .04 27.53 < .001 .25 1.91 .171 .02 Post 13.63 ± 4.53 12.65 ± 2.24 Positive affect Pre 32.93 ± 8.62 34.52 ± 6.26 .06 .802 .001 11.68 .001 .12 4.90 .03 .06 Post 37.93 ± 8.34 35.59 ± 5.03 European Journal of Forest Research (2023) 142:415–426 POMS Anger Pre 2.33 ± 4.24 .35 ± 1.05 6.83 .011 .09 9.11 .003 .10 4.51 .04 .05 Post .35 ± 1.26 .00 ± 0 Fatigue Pre 4.39 ± 5.48 2.48 ± 3.99 4.42 .039 .05 17.48 < .001 .17 .58 .45 .01 Post 1.8 ± 2.51 .72 ± 1.28 Vigour Pre 10.82 ± 4.65 12.83 ± 4.05 .49 .49 .01 23.70 < .001 .22 3.12 .082 .04 Post 15.32 ± 7.74 14.93 ± 5.30 Friendship Pre 14.21 ± 4.31 16.07 ± 2.74 .02 .877 0 18.08 < .001 .18 16.36 < .001 .17 Post 17.79 ± 3.40 16.16 ± 4.34 Tension Pre 4.81 ± 5.21 1.64 ± 2.50 11.02 .001 .12 31.86 < .001 .28 6.31 .014 .07 Post .81 ± 1.42 .11 ± .31 Depression Pre 3.60 ± 4.97 1.93 ± 2.89 2.95 .09 .03 21.51 < .001 .20 1.55 .217 .02 Post 1.09 ± 2.14 .48 ± .91 SMS Mindfulness of the Mind Pre 44.26 ± 14.42 39.59 ± 11.96 8.82 .004 .10 26.92 < .001 .25 5.13 .03 .06 Post 64.19 ± 9.07 53.66 ± 8.74 Mindfulness of the Body Pre 16.56 ± 5.90 15.48 ± 5.78 18.60 < .001 .19 56.74 < .001 .41 15.27 < .001 .16 Post 25.26 ± 4.67 18.24 ± 4.32 Mindfulness General Pre 60.82 ± 19.67 55.07 ± 17.23 9.72 .003 .11 25.40 < .001 .24 7.84 .006 .09 Post 89.44 ± 13.21 71.90 ± 12.29 FB forest bathing, PANAS positive affect and negative affect scale, POMS profile of mood states, SMS state mindfulness scale, STAI-S state-trait anxiety inventory (state subscale) * Mindfulness of the mind, mindfulness of the body and mindfulness general (n = 54); ** friendship and tension (n = 28) 13 421 422 European Journal of Forest Research (2023) 142:415–426 13 European Journal of Forest Research (2023) 142:415–426 423 ◂Fig. 1  Marginal estimated means and CI 95% for pre-post assessment more powerful effect of the FB activity, as well as the dif- of cognitive and affective variables. Comparing between experimen- ferential participants’ profile: FB practitioners, compared to tal group (red line) and control group (blue line). Marginal estimated means for mindfulness of mind and mindfulness total were obtained hiking ones are mainly women living in urban areas, with including intensity as a covariate to control baseline differences higher basal values of tension/anxiety and anger, and lower values of friendship and vigour. In this way, hypothesis 2 has been partially verified since higher effect sizes have also facilitates physical well-being and vitality. Furthermore, been reported after the FB. Considering all constructs of the large increases in mindfulness indicators have been found spectrum, the negative valence (anxiety, tension, depression, (both for mindfulness of the body and the mind) after the fatigue, anger) as a whole and the distances in the benefit FB, pointing out how mindfulness states and its sensory and obtained between both activities tend to be smaller in the cognitive process are highly enhanced through this silent hiking group. This result might highlight the fact that FB walk by the forest. Thus, FB could be regarded as an out- attracts individuals (women) living in urban areas that show door-mindfulness practice that could be included in psycho- less psychological well-being, and thus can benefit the most logical interventions (Sadowski et al. 2020; Timko-Olson of nature immersion through guided activities. Therefore, in et al. 2020; van Gordon et al. 2018). It is also remarkable the line with previous studies (Buckley and Westaway; 2020), changes observed in friendship feelings, highlighting how our results show that nature activities could be cost-effec- guided forest activities increase social connectedness, even tive solutions to accelerate women’s psychological recovery if they are performed in silence, without allowing partici- after the COVID-19. It is worth noting that women’s mental pants talk while they are walking through the forest. Thus, health has been more hit by the pandemic than men’s (Muro results observed in this study confirm that Mediterranean et al. 2021; Sanabria-Mazo et al. 2021) and the virus has FB is not only a touristic and nature-guided activity that also impacted less those populations living in forested areas allows visitors discover the landscape under a sustainable (Roviello and Roviello, 2020). Therefore, FB could be con- approach (Farkic et al. 2021), but it can also be regarded sidered a gender-focused approach targeted at vulnerable as a powerful nature activity that increases positive mental groups for decreasing mental health after the pandemic, such health and well-being indicators at the short therm. Accord- as women and youngest populations. ingly, it is concluded that Mediterranean FB might also be Finally, regarding the second exploratory objective of this a cost-effective intervention for promoting emotional well- study, no differences were found in the practice of forest being and sustainable tourism (Farkic et al. 2021; Ohe et al. bathing in the different allocations of this study, character- 2017). FB promotion could contribute to facilitate actions ised by two different sub-biomes of the Mediterranean-Cat- and agreements of the European Charter for Sustainable alan area. Although in a first analysis some differences were Tourism (ECST) the protected areas of Mediterranean- found suggesting a higher impact of the Sant Llorenç FB, Catalan regions (Canals 2014; Europarc Federation 2010). a control of confounding variables neutralised these differ- It is worth noting that both basal levels of stress indicators ences. It should be noted that the higher impact observed in and effect sizes were higher in the Sant Llorenç group of FB of Sant Llorenç could be better explained, as commented FB, a result that was somehow expected, since Sant Llorenç above, by the participants profile, rather than forests’ sub- forests are closer to Barcelona metropolitan area, and its biomes: participants of Sant Llorenç were living closer to participants were mostly living in this area, while partici- metropolitan areas of Barcelona surroundings and showed pants of La Garrotxa were mostly living in rural areas. This worse baseline levels in the different mental health indica- result is also consistent with previous studies reporting how tors, so they probably benefited from the restorative effects urban populations show higher levels of stress and decreased of FB to a greater extent. well-being, and thus, FB might have a more powerful impact in urban populations (Antonelli et al. 2019; Morita et al. Limitations and future directions 2007; Oh et al. 2017; Roviello and Roviello 2020; Wen et al. 2019). Nevertheless, several limitations of the present study should Regarding the second hypothesis, the comparison with be acknowledged. Firstly, it is necessary to highlight the fact the hiking group indicates that this guided nature activity that this study has only evidenced short-term psychological also produces positive changes for psychological well-being effects of one single FB, a limitation that is widely repeated (Mitten et al. 2018), but the effect sizes are lower than in on FB research. Thus, larger FB programmes should be FB, probably because the latter is rather designed with well- tested to explore long-term impacts on mental health out- being goals and might appeal specific populations who are comes, including follow-up assessments. More research looking for more therapeutic nature activities. Accordingly, should also be carried not just using larger FB programmes, it is suggested that the additive effect of silence and the but also analysing clinical samples at higher risk for stress- easiness of the plain route might explain the differential and related or anxiety disorders. 13 424 European Journal of Forest Research (2023) 142:415–426 Table 3  General linear models for cognitive and affective effects comparing experimental groups (Garrotxa vs. Sant Llorenç) Group Phase Interaction Group*Phase FB Sant Llorenç FB Garrotxa F P ɳp2 F p ɳp2 F p ɳp2 (n = 34) M ± SD (n = 23) M ± SD STAI-S State-anxiety Pre 22.58 ± 12.52 14.26 ± 9.43 3.82 .056 .06 108.34 < .001 .66 15.02 < .001 .21 Post 9.08 ± 7.22 8.08 ± 7.01 PANAS Negative affect Pre 20.70 ± 8.66 16.08 ± 6.57 5.66 .021 .09 28.43 < .001 .34 1.54 .220 .03 Post 14.56 ± 4.61 12.26 ± 4.11 Positive affect Pre 32.97 ± 7.78 32.86 ± 9.91 .24 .628 .004 18.04 < .001 .25 .59 .44 .01 Post 38.67 ± 6.47 36.82 ± 10.59 POMS Anger Pre 3.38 ± 4.76 .78 ± 2.75 5.21 .026 .87 10.89 .002 .16 5.00 .03 .08 Post .44 ± 1.39 .21 ± 1.04 Fatigue Pre 5.44 ± 5.96 2.82 ± 4.32 3.75 .058 .06 12.46 .001 .18 1.61 .21 .03 Post 2.20 ± 2.72 1.30 ± 2.07 Vigour Pre 10.26 ± 4.26 11.65 ± 4.90 .004 .95 .00 22.68 < .001 .29 .004 .94 .00 Post 14.70 ± 4.69 16.21 ± 10.86 Friendship Pre 14.55 ± 4.02 15.47 ± 10.30 .004 .94 .00 9.36 .003 .14 .925 .34 .02 Post 18.05 ± 2.22 17.30 ± 4.58 Tension Pre 6.47 ± 5.47 2.34 ± 3.67 8.99 .004 .14 35.18 < .001 .39 9.56 .003 .15 Post .94 ± 1.27 .60 ± 1.61 Depression Pre 5.20 ± 5.60 1.21 ± 2.39 11.55 .001 .17 16.77 < .001 .23 4.58 .037 .07 Post 1.73 ± 3.12 .13 ± .34 SMS Mindfulness of the mind Pre 45.38 ± 15.59 42.35 ± 12.32 .637 .428 .12 63.58 < .001 .55 .22 .63 .00 Post 64.41 ± 9.97 63.80 ± 7.51 Mindfulness of the body Pre 17.29 ± 5.87 15.30 ± 5.88 1.89 .175 .03 81.24 < .001 .61 .20 .66 .00 Post 25.67 ± 4.57 24.55 ± 4.86 Mindfulness general Pre 62.67 ± 20.82 57.65 ± 17.58 1.08 .304 .02 71.31 < .001 .58 .23 .63 .00 Post 90.08 ± 14.06 88.35 ± 11.89 FB forest bathing, PANAS positive affect and negative affect scale, POMS profile of mood states, SMS state mindfulness scale, STAI-S state-trait anxiety inventory (state subscale) An important strength of this study is that, on the intra- covariates of the developed statistical models. Further- subject analysis carried out on the participants in the forest more, despite having a control group, the fact that it was baths, it has been possible to incorporate the parallel evalu- implemented on the frame of nature experiences promoted ation of a hiking-control group, since hiking is considered a by various public and private institutions (with different nature activity with numerous health benefits (Mitten et al. recruitment and advertising processes) and being essen- 2018). This control group fully met 4 of 5 criteria set by tially a community service, it was not possible to carry out the researchers to reduce bias in the interpretation of those any type of randomisation. Nevertheless, this weakness was results that imply a comparison between both conditions: an opportunity to explore the possible bias in relation to being a guided activity, practiced in the same geographi- the characteristics of the population that chose FB instead cal spaces, qualitatively different from forest bathing and of other options for practicing sports in nature. Finally, we with the same duration. It was not possible to fully meet the should also remark that all measures included in this pilot fifth criterion, which consisted in the physical load being study assessed cognitive and emotional states (i.e. right now) of a low intensity, comparable to that exerted in FB. That that are highly variable. Thus, further works should assess was because one of the hiking groups did a higher intensity programmes with various sessions of FB and include objec- activity. However, this fact was recorded and conveniently tive indicators of anxiety or stress such as cortisol (Bach neutralised through the physical load intensity variable as et al. 2021), variables with larger evaluation timeframes (e.g. 13 European Journal of Forest Research (2023) 142:415–426 425 last week), which are normally preferred as main outcomes Declarations in psychotherapy research to assess long-term benefits. Thus, it would be better to reach more robust and consistent Competing interests The authors declare no competing interests. conclusions on the benefits of FB for overall psychological functioning and mental health (Kotera et al. 2020). In this Conflict of interest No potential competing interest was reported by the authors. regard, future studies comparing larger FB programmes and nature activities with “standard” psychological interventions Open Access This article is licensed under a Creative Commons Attri- are particularly welcome. bution 4.0 International License, which permits use, sharing, adapta- tion, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are Conclusions included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not The present study adds more empirical evidence to both FB permitted by statutory regulation or exceeds the permitted use, you will practice and thus to nature-medicine health model (Brat- need to obtain permission directly from the copyright holder. To view a man et al. 2019; Hansen et al. 2017; Twohig-Bennett and copy of this licence, visit http://​creat​iveco​mmons.​org/​licen​ses/​by/4.​0/. Jones 2018). It aligns with previous studies in other forested areas of the world showing that FB is a powerful outdoor activity that facilitates psychological well-being, and fol- References lowed by hiking, can be considered as sustainable touris- tic activities that could add an a relevant additive value to Andrade E, Arce C, Torrado J, Garrido J, De Francisco C, Arce I Mediterranean-European forested and protected areas. 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