The bene ﬁ ts of nature-based therapy for the individual and the environment: an integrative review

Purpose – This review aims to identify the commonly used nature-based therapies, the cohorts that bene ﬁ t from these interventions, and the potential environmental impact of nature-based therapies. Design/methodology/approach – An integrative review methodology was taken. The literature was analysed and synthesised through thematic analysis. Findings – Three themes emerged from the analysis: categories of nature-based therapies; bene ﬁ ts of nature-based therapies; and the gains from nature-based therapies are not universal. Evidence of physiological, psychological, social, vocational and quality of life bene ﬁ ts from participation in nature-based therapies was evident in the literature. However, there was insuf ﬁ cient empirical evidence of the bene ﬁ ts for the environment. Practical implications – Occupational therapists assist populations across the life course. Consequentially, they can be found working in a diverse range of clinical contexts. This review asserts that nature-based therapies could be a positive addition in many of these contexts. Further, while engagement in activities in natural environments is frequently used by occupational therapists practicing within institution environments, there is evidence to support its use in community service models and potentially in public health strategies. Originality/value – This integrative review brings together evidence on a diverse range of nature-based therapies, cohorts, associated bene ﬁ ts and factors that in ﬂ uence these. The lack of empirical evidence on the bene ﬁ ts of nature-based therapies for the environment is acknowledged as a gap in the literature


Introduction
Nature-based therapy is an approach to interventions that use the natural environment as a facilitator during the therapeutic process (Corazon et al., 2010). Nature-based therapy, which can also be referred to as green care, nature-assisted therapy, nature therapy or animal-assisted therapy (Annerstedt and Währborg, 2011;Fieldhouse and Sempik, 2014;Lee et al., 2012), incorporates horticulture-based activities, being in natural environments and engaging in nature-related crafts or green exercise.
Previous occupational therapy literature elucidated the following meaning and benefits behind nature-based occupationsenhanced well-being, social connectedness or belongingness, identity, connection to nature and a sense of challenge and achievement (Feighan and Roberts, 2017;Jeffery and Wilson, 2017;Wensley and Slade, 2012). Occupational therapy and nature-based therapy share some theoretical underpinnings such as therapeutic use of occupation, or being occupation-based, and the therapeutic use of environment (Jeffery and Wilson, 2017). This synergy provides occupational therapists the opportunity to integrate nature-based activities into their practice (Jeffery and Wilson, 2017).
Nature-based therapies have been shown to benefit the psychological, physical and social well-being of different patient cohorts (Annerstedt and Währborg, 2011). The diversity of the populations amongst the reviewed studies indicates the potential of nature-based therapies as a resource for public health (Annerstedt and Währborg, 2011). With this supporting research, occupational therapists can advocate for the provision of opportunities for the public to have access to engage in purposeful occupation within a variety of natural environments (Genter et al., 2015;Wensley and Slade, 2012).
However, it must be acknowledged that human occupation is also at the root of the current environmental crisis. On the other hand, it is also the way towards sustainability (Ung et al., 2020). An occupational lens offers insight into how some occupational behaviours negatively impact the environment, which, in turn, poses a threat to global health (Dieterle, 2020). The impact of the environment on health is widely recognised and forms part of many health-enhancing policies, such as Healthy Ireland (Department of Health, 2013) and Ireland 2040 (Department of Health, 2013;Government of Ireland, 2020). The World Federation of Occupational Therapists (2012, 2018) emphasises the role of occupational therapy in promoting sustainability within practice through a list of guiding principles for the profession and a position statement on global climate change (World Federation of Occupational Therapists, 2012, 2018. Past literature reviews, such as that conducted by Chavaly and Naachimuthu (2020), state that there is scope to use nature-based therapies to benefit the general population and their mental health. However, it remains unclear whether nature-based therapies could potentially benefit both the individual and the natural environment. When conducting preliminary searches, we identified a gap in the knowledge surrounding nature-based therapies and their application to occupational therapy practice. Rather, previous reviews focused on specific areas or cohorts for nature-based therapies, such as outdoor pursuits or older adults (Gagliardi and Piccinini, 2019;Feighan and Roberts, 2017). The purpose of this review is to bring together research and knowledge on the commonly used nature-based therapies, evidence on the benefits reported from these interventions with various cohorts and the potential impact of nature-based therapies on the natural environment. We used an occupational performance lens when conducting this review to identify the practical implications of nature-based therapies for clinical practice within occupational therapy.

Methods
The four key features of an integrative review, which are regarded asto generate/refine a theory; combine empirical and theoretical research; examine research on a health phenomenon; and inform health-care policy and practice-most closely aligned with our ambition for the review (www.guides. library,duq.edu; accessed 1st November 2021; Coughlan et al., 2013;Whittemore and Knafl, 2005). Ethical approval was not sought for this study as no additional data was being collected. The information used is already in the public domain and therefore available for inclusion. Using the review methodology, we systematically gathered published research on this topic, selected the relevant works and summarised what we determined through our analysis. This is the essence of a good review (Grant and Booth, 2009 . These databases were selected based on accessibility, relevance to the topic and the allied healthcare literature. The following search terms were used: "green" or "sustainab Ã " or "environment Ã " or "eco friendly" or "ecofriendly" or "environmentally friendly" in the title or abstract and "horticulture therap Ã " or "horticultural therap Ã " or "nature based therap Ã " or "nature-based therap Ã " or "nature therap Ã " or "ecotherap Ã " or "eco-therap Ã " or "forest therap Ã " in the title or abstract. Additional search strategies included reviewing reference lists of included papers and relevant literature reviews identified during the search.

Inclusion/exclusion criteria
To determine relevant primary sources, qualitative, quantitative and mixed-method research; theoretical and opinion pieces; and programme descriptions or evaluations were reviewed. Studies published between 2011 and 2021 in full, in English and in peer-reviewed journals were included. The primary focus of the search was on nature-based therapies and their benefits for the individual and the environment. Studies that met the inclusion criteria were included regardless of evidence level or study design as this provided a holistic review of the concept. The search was not limited to papers pertinent to occupational therapy because of the paucity of such specific literature. Literature reviews were excluded from the search as they may be re-iterating findings from papers that were already included.

Analysis
As presented in Figure 1, the search provided 158 records and a further 46 were discovered through hand searches. Duplicates (n = 54) were removed, resulting in 150 articles being processed with an initial screen. A further 91 articles were excluded following this, primarily because of a lack of relevance to the research question. Full texts of 59 articles were reviewed by the second and third authors which resulted in 25 papers progressing to full review by all authors.
The third and fourth authors critically appraised each of the identified studies. Thematic analysis, as outlined by Braun and Clarke (2014), was then used to enable the authors to analyse a wide range of literature and to synthesise a variety of study methods (Braun and Clarke, 2014). The selected articles were read by the authors in dyads, and emergent themes were given initial codes.
These codes emerged based on patterns in reported findings which appeared relevant or specifically addressed the aims of this review. Earlier themes were refined as the process of reviewing and discussing papers continued. Codes were developed manually, and included, for example, "physiological effects of nature-based therapy". Throughout the coding process, a difficulty emerged in addressing the research question concerned with the impact of nature-based therapy on the environment. There was a notable paucity of data in the identified studies concerning this topic, and thus there was insufficient detail with which codes and themes could be developed. The codes were subsequently refined as themes. These were further reviewed in collaboration with all authors, before being finally defined as follows: categories of nature-based therapies; benefits of nature-based therapies; and the gains from nature-based therapies are not universal.

Results
As previously stated, the initial search of the databases yielded 204 papers, with a total of 25 papers included for the final review. Table 1 summarises the details of these studies. These 25 papers consisted of eight quantitative studies, six qualitative studies, five mixed-method studies and seven theoretical and opinion papers (Figure 1).
The thematic analysis yielded three themes: 1 categories of nature-based therapies; 2 benefits of nature-based therapies; and 3 the gains from nature-based therapies are not universal.
We have organised the results by these themes and the previously mentioned four key features of an integrative review.

Categories of nature-based therapies
Refining the theory of nature-based therapy Categories of nature-based therapies ranged from forest therapy to maintaining and cultivating a garden bowl in the home environment. The most common forms of nature-based therapies were identified as horticulture therapy and forest therapy, appearing in 12 of the 25 studies reviewed (Christie et al., 2016;Kusumawaty and Yunike, 2020;Lee et al., 2021;Lee et al., 2014;Lim et al., 2020;Masel et al., 2018;Oh et al., 2020;Seifert, 2014;Song et al.,      . These included horticultural-based activities, forest therapy, yoga, meditation and mindfulness, creating a garden bowl in the home environment and the use of support groups. The remaining studies included a wilderness camp (Warber et al., 2015), naturebased crafts (Masel et al., 2018), and incorporating natural environments indoors, such as a living wall within the university setting (Windhorst and Williams, 2016).

Empirical and theorical research
The reviewed studies demonstrated that nature-based therapy interventions were used with a wide variety of cohorts. These

Benefits of nature-based therapies
Examining research on a health phenomenon In spite of the heterogeneity of the studied cohorts, the benefits of nature-based therapies for the participating individuals To investigate the effects of bamboo FT on physiological responses, namely, blood pressure, heart rate and peripheral oxygen saturation Quantitative; RCT; physiological measurements and semantic differential method questionnaire Following the FT, blood pressure and heart rate decreased, and peripheral oxygen saturation increased. The viewing activities had a more pronounced effect on decreased heart rate remained relatively consistent across the reviewed studies. In terms of physiological benefits, a decrease in heart rate, blood pressure and salivary cortisol level was reported by five studies (Lee et al., 2014;Song et al., 2013;Sung et al., 2012;Zeng et al., 2020;Wang et al., 2019). The findings from these studies are in accordance with the finding of Lee and colleagues that forest walking significantly decreased the mean value of sympathetic nervous system activity (p < 0.01) and correspondingly significantly increased the mean value of parasympathetic nervous system activity (p < 0.01) (Lee et al., 2014). Zeng et al. (2020) also reported that bamboo forest therapy increases peripheral oxygen saturation. The study by Nakau et al. (2013) reported that an integrated nature-based therapy approach increased natural killer cell activity. Two studies found a change in physical well-being and fitness (Christie et al., 2016;Oh et al., 2020). However, several papers did not find any significant changes in physical well-being (Nakau et al., 2013), physical activity or physiological change (Warber et al., 2015), or cardiac health (Lee et al., 2014;Sung et al., 2012;Lim et al., 2020). Notably, decreased stress and increased relaxation, both physiologically and psychologically, were reported in nine studies (Christie et al., 2016;Kucher et al., 2020;Lim et al., 2020;Masel et al., 2018;Pretty et al., 2017;Seifert, 2014;Vujcic et al., 2017;Wang et al., 2019;Warber et al., 2015). In terms of improvements in mental health for the individual, a decrease in depression, anxiety, tension, pain and fatigue was reported by a significant number of studies (Kucher et al., 2020;Lee et al., 2021;Nakau et al., 2013;Wang et al., 2019). Furthermore, engagement in nature-based therapies resulted in psychological benefits, such as enhanced self-concept, selfesteem, positive identity, confidence, emotional stability, motivation, self-reflection, and a sense of achievement and responsibility for the participants (Christie et al., 2016;Kusumawaty and Yunike, 2020;Lee et al., 2021;Masel et al., 2018;Oh et al., 2020;Phelps et al., 2015;Sahlin et al., 2012;Seifert, 2014;Warber et al., 2015;Corazon et al., 2011). Other improvements reported within cohorts include decreases in negative feelings and dysfunctional thinking patterns, increases in positive feelings and mood, the attainment of a general sense of happiness and joy and positive changes in behaviour towards self and others (Christie et al., 2016;Lee et al., 2021;Lee et al., 2014;Lim et al., 2020;Masel et al., 2018;Oh et al., 2020;Phelps et al., 2015;Sahlin et al., 2012;Sidenius et al., 2020;Wang et al., 2019;Warber et al., 2015). Participants referred to experiencing feelings of empowerment, transcendence, hope, trust, courage, the will to live, rejuvenation and mindfulness (Christie et al., 2016;Lim et al., 2020;Oh et al., 2020;Phelps et al., 2015;Sahlin et al., 2012;Warber et al., 2015).
Engagement in nature-based therapies promoted social wellbeing and relationship development between participants, as well as between patients and staff (Christie et al., 2016;Kusumawaty and Yunike, 2020;Masel et al., 2018;Warber et al., 2015). For those suffering from alcohol addiction, participation in nature-based therapy acted as a preventative factor against adverse peer groups and participants reported a sense of belonging and connectedness to the group or wider community during nature-based therapy (Sahlin et al., 2012;Seifert, 2014). However, Nakau et al. (2013) did not find any significant changes in emotional or social well-being and research by Vujcic et al. (2017) found no significant difference in anxiety and depression subscales.
Participants in several studies reported an increase in their skills and knowledge following nature-based therapy (Christie et al., 2016;Seifert, 2014;Warber et al., 2015) and enhanced employability and productivity were also noted among some cohorts (Christie et al., 2016;Sahlin et al., 2012;Seifert, 2014). Two studies highlight participants developing new interests and hobbies as a result of their taking part in nature-based therapy (Phelps et al., 2015;Sahlin et al., 2012).
Increased quality of life, life satisfaction, well-being and spirituality were consistently reported across the cohorts (Christie et al., 2016;Kusumawaty and Yunike, 2020;Lee et al., 2021;Nakau et al., 2013;Pretty et al., 2017;Sahlin et al., 2012;Sung et al., 2012;Vujcic et al., 2017;Warber et al., 2015). Among palliative care patients, it was reported that improved quality of daily routine and relief of symptom burden was attained (Masel et al., 2018). Participants in many studies reported that increased connectedness with nature and engagement in "green" activities were perceived as beneficial, enjoyable and meaningful, and as an outcome and reward in themselves (Christie et al., 2016;Lim et al., 2020;Warber et al., 2015;Corazon et al., 2011). Participation in nature-based therapy was reported to facilitate immersive attention and positive stimulation for healing and change (Oh et al., 2020;Pretty et al., 2017), a feeling of being safe and hidden (Sidenius et al., 2015), or an escape (Christie et al., 2016;Seifert, 2014) and a distraction from worries and ruminations (Masel et al., 2018;Oh et al., 2020;Sahlin et al., 2012).
Gains from nature-based therapies are not universal Relevance to health-care policy and practice The benefits of nature-based therapies for the natural environment were not largely considered or measured in the reviewed papers. A theoretical paper discussed the use of person-centred approaches to facilitate a realisation of one's embeddedness in their ecosystems and a subsequent increase in one's awareness of the environment and sustainability (Chatalos, 2013). Supporting empirical research is scarce; however, participants in the study of Sidenius et al. (2020) reported an increased awareness of self and environment following nature-based therapy.
In spite of the previously discussed research, some studies indicate that not all nature environments support health and well-being (Stigsdotter, 2015). This view is supported by research, which highlighted that although more natural environments were more effective at relieving stress, the most natural environment is not always the most beneficial (Wang et al., 2019). Natural environments with some structure or artificial components can significantly reduce diastolic blood pressure (p < 0.01; p < 0.05 -depending on the environment), systolic blood pressure (p < 0.01; p < 0.05) and heart rate (p < 0.05) (Wang et al., 2019). Similarly, natural environments with features that facilitate the use of that environment can be preferred by participants (Sidenius et al., 2015). Notably, a dynamic water landscape or feature had a significant effect on decreasing systolic blood pressure (p < 0.01) and diastolic pressure (p < 0.05) (Wang et al., 2019), and facilitating a feeling of relaxation (Sidenius et al., 2015). Participants generally showed preference for nature-like environments, that are somewhat enclosed, with the possibility to sense expanses while still feeling safe to relax or interact with the environment, for example, through scent, sounds and sights (Sidenius et al., 2015). Seasonal factors did not affect the use of nature-like environments, while weather influenced the choice of naturebased activities (Sidenius et al., 2015).

Factors that influence effectiveness of NBT
The benefits of nature-based therapy depend on individual characteristics, gender and needs (Stigsdotter, 2015;Song et al., 2013). Positive effects of nature-based therapy were subject to participants being at the appropriate phase of their recovery (Sahlin et al., 2012). Male participants experienced a larger change in their anxiety levels as a result of nature-based therapy compared to females; however, a bigger sample is required to verify the significance of this finding (Vujcic et al., 2017). Meanwhile, female participants experienced lower systolic blood pressure and slower heart rate than males in the bamboo forest environment (Zeng et al., 2020). Interestingly, Vujcic et al. (2017) found that gender and education did not change the benefits of horticultural therapy. Type A and B behavioural patterns, as proposed by Friedman and Rosenman (1974), affected the benefits of nature-based therapy (Song et al., 2013). The beneficial physiological effect, namely, significantly decreased heart rate (p < 0.01), of forest therapy was only present in participants with Type B behavioural pattern, with significantly lower pulse rate (p < 0.01) and blood pressure (p < 0.05) in low-scoring Type B participants (Song et al., 2013). However, this study was limited to male participants. Decreased mental capacity made participants more susceptible to having their participation influenced by weather conditions (Sidenius et al., 2015). Tolerant and permissive environments, the flexibility of level of engagement with nature-based therapy and continuous admissions of new participants to the programme facilitated participation (Phelps et al., 2015;Sahlin et al., 2012). Conversely, a prison setting restricted engagement in nature-based therapy (Lee et al., 2021). Whether forest walks were guided or unguided did not affect nature immersion and associated benefits (Lim et al., 2020). More frequent trips to local "green" environments were more effective than occasional trips to remote nature environments, such as mountains (Oh et al., 2020). Limited access to phones and the internet in the wilderness camp facilitated the benefits of the natural environment (Warber et al., 2015).

Discussion
The three themes in the current study explored the forms of nature-based therapies, benefits across various cohorts and whether gains from nature-based therapies pertained to the natural environment. The reviewed literature generally aimed to elucidate the physiological and psychological effects of nature-based therapies on individuals (Lee et al., 2021;Zeng et al., 2020). The number of participants in the reviewed papers ranged from n = 5 (Kusumawaty and Yunike, 2020) to n = 485 (Song et al., 2013). Factors that influenced the effectiveness nature-based therapies have been explored (Lim et al., 2020;Song et al., 2013). Fewer papers attempted to develop a theoretical model (Oh et al., 2020) or approaches (Chatalos, 2013) for nature-based therapies. According to Fieldhouse and Sempik (2014), the theories, frameworks and principles behind nature-based therapies were derived in some way from occupational therapy.
Nature-based therapies could be a pathway for incorporating sustainability into occupational therapy practice. The earlier mentioned World Federation of Occupational Therapists (2012, 2018) Guidelines set clear ambitions for occupational therapists' role in sustainability and acting against the current environmental crisis. An occupational stewardship perspective within nature-based therapies, where individuals are encouraged to recognise the interconnectedness of their occupational choices and their environment, would be a positive addition in future practice (Rushford and Thomas, 2016). There is a call for occupational therapists to be the agents of change by practicing "environmentally informed occupational therapy", proposing eco-occupations and educating service users on the benefits and meaning behind those occupations to both the individual and the natural environment (Dieterle, 2020;Ung et al., 2020). However, this review found low levels of empirical evidence to support the view that nature-based therapies benefit the environment and contribute to sustainability. Only one paper (Sidenius et al., 2020) investigated participants' nature consumption one year following the nature-based intervention. Papers mainly focused on the benefits of various green environments to the individual and how human needs inform the design of green spaces. To explore the effects of human occupation on the natural environment, a different perspective is needed.
The use of community gardens and allotments has the potential to benefit public health and bring the benefits of nature-based therapies beyond clinical cohorts (Genter et al., 2015). The Environmental Protection Agency (EPA) (2020) acknowledges the association between green and blues spaces and public health and well-being (Environmental Protection Agency, 2020). This view is echoed in the Institute for European Environmental Policies Report (ten Brink et al., 2016). The report discusses the effect of nature-based solutions on public health and social well-being, while highlighting how these solutions are a sustainable and affordable option to benefit health and well-being (ten Brink et al., 2016). The Healthy Ireland Strategic Action Plan 2021-2025 identifies 13 priority focus areas for 2021-2023 (Government of Ireland, 2021). Within these areas, there are several that could be linked to nature-based therapies, such as "Keeping active", "Staying connected" and 'Eating well'. However, the document does not specifically discuss the use of green and blue spaces to benefit public health and work towards a more sustainable and healthfocused Ireland. Stigsdotter (2015) suggests a model for evidence-based health design when creating natural environments for the benefits of public health. Occupational therapists are well-positioned to provide their expertise in and advocate for these developments (Ung et al., 2020).

Practical implications
Occupational therapy is well placed to support the Healthy Ireland Strategic Action Plan 2021-2025 (Government of Ireland, 2021), given the priority focus areas, including "minding your mood", "minding your body" and "switching off and being creative". Furthermore, lower socioeconomic status impacts health and well-being in part because of difficulty accessing health services and green spaces (Environmental Protection Agency, 2020). This social inequity can be viewed as a form of occupational injustice (Ung et al., 2020). Given our remit to tackle this, whenever possible, we have an onus to address this injustice using an eco-socialsustainable approach which takes into account environmental, social, health and economic issues in relation to human occupations (Ung et al., 2020;Sim o Algado and Ann Townsend, 2015). Occupational therapists can promote ecooccupations and the creation, use and preservation of green spaces through education, advocacy and community initiatives (Dieterle, 2020;Pollard et al., 2020). Furthermore, the link between ecological devastation and occupational injustices calls for occupational therapy expertise for the populations at risk (Sim o Algado and Ann Townsend, 2015). That way, occupational therapists can play a role in public health, specifically through projects like those in Clonakilty, Co Cork (Murphy, 2018), where a community garden was set up for the Direct Provision Ccentre and the Hardwicke Community Garden (Sheridon, 2017), a Dublin inner city project that provides much needed green space for its residents. Ecooccupations, such as growing one's own food and using active transportation (i.e. cycling or walking), have individual, social, economic and ecological benefits (Ung et al., 2020). On a meso level, when providing nature-based interventions, occupational therapists can explore ecological meaning and value of various occupations as meaning is known to impact participation (Wensley and Slade, 2012).
Occupational therapists assist populations across the life course. Furthermore, they are used in a diverse range of clinical contexts. The findings of this review highlight that naturebased therapies could be put to positive use in many of these contexts and can benefit people of all ages. Engaging in activity in a natural environment was frequently used by occupational therapists practicing within institution environments. This review has presented the evidence to support the use of naturebased therapy in community service models. This has already begun in Ireland, particularly in mental health settings. Furthermore, research has commenced on the efficacy of a gardening and woodwork group on facilitating the achievement of individual recovery goals in a community mental health setting based in County Wexford (Sinnott, 2021). And, two nature-based therapy projects received the Ann Beckett Award in 2010 and 2013 (Association of Occupation Therapists of Ireland).

Limitations
As this review took an integrative approach to ensure a holistic view various methodologies were included. This diversity posed challenges when analysing, synthesising, and summarising data extracted from the individual findings. Only papers published in full and in English were included. The review was limited to a 10-year period; thus, relevant studies may have been missed. PRISMA guidelines were not strictly adhered to which authors recognise, in hindsight, would have strengthened the paper. Even though measures were taken to prevent bias such as using thematic analysis, critical appraisal of the data, and the assistance of a librarian, this type of review may be open to favourable inclusion of data, interpretation of results, or subjectivity of authors' world views because of a preferred hypothesis (Grant and Booth, 2009). Finally, this type of review may lack the potential to broaden the scope of the topic reviewed (Grant and Booth, 2009). There was a scarcity of literature on the environmental impact of nature-based therapies, leading to an inability to draw any firm conclusions on this issue.

Conclusion
This review identified a wide variety of interventions under the board category of nature-based therapies, the most common being horticultural and forest therapies. It unearthed themes on the benefits of these for individuals but not the government. However, careful consideration is required when planning and implementing nature-based interventions, as benefits were found not to be universal. While nature-based therapies potentially benefits the individual, public health, and the environment, the latter remains understudied. Such work, when undertaken, will inform future policies and provide a rationale for more environmentally conscious occupational therapy practice.