Integrating Forest Ecosystem Services into Health Strategies to Improve Human Well-Being

Abstract

As the largest terrestrial ecosystem covering extensive expanses of the Earth’s surface, forests offer crucial health benefits to humans, both directly and indirectly. Presently, health services derived from forest resources have presented significant opportunities for enhancing human well-being. Nonetheless, the absence of a comprehensive understanding regarding the mechanisms by which forests impact human health jeopardizes the potential gains in health. Regrettably, there remains a dearth of scholarly work elucidating these pathways. This paper aims to furnish a thorough examination of how forests influence human health. We initiate by formulating a conceptual framework upon which we delineate the various pathways through which forests impact human health. These encompass the provisioning of resources, preventive services, and forest therapies. Concurrently, we outline the moderating influence of social, economic, and individual characteristics as mediators within this pathway. These characteristics are classified into two overarching dimensions: accessibility and behavioral choices, which notably affect marginalized demographics such as those with lower socioeconomic status, women, the elderly, individuals with disabilities, and children in developing nations. Consequently, we build upon these foundational insights to propose six strategies aimed at perpetuating the positive impact of forests on human health in the foreseeable future. In the future, the development of forest management policies, the assessment of long-term health benefits, social practices, and international cooperation must be considered holistically to attain the dual objective of sustainable forest management and the advancement of human well-being.

1. Introduction

The World Health Organization delineates health as “a state of complete physical, mental, and social well-being, not merely the absence of disease or infirmity”. Health represents a dynamic concept influenced by a spectrum of interrelated biological, physical, economic, and environmental factors [1]. Nevertheless, the accelerating shifts in climate and ecosystem functionality pose threats to the fundamental elements of population health: adequate nutrition, safe water, and unpolluted air [2,3,4]. As access to such essentials becomes increasingly constrained, it could precipitate far-reaching health ramifications for millions of individuals [5,6].

Particularly for marginalized human demographics, forests represent a limited avenue through which they can access health benefits. Globally, for instance, approximately 1.6 billion individuals reside near forests, with more than two-thirds of them inhabiting low- and middle-income countries, heavily relying on forests for their fundamental health requisites [7,8]. Simultaneously, individuals residing further from forested areas can avail themselves of health and wellness resources or enhance their physical and mental well-being through engagement with urban forests [5]. Consequently, there is an urgent need to comprehend the interconnections between forests and human health.

Previous studies have tended to focus on single health effects [9,10,11,12]. For instance, antecedent studies have demonstrated that forests possess the capacity to ameliorate conditions such as depression, anxiety, and cardiovascular ailments to a certain extent [13,14]. Nonetheless, the contribution of forests to health is multifaceted and intricately interconnected, such that considering the human impact of forests solely in terms of a singular health outcome circumscribes the full potential of forests to enhance human well-being. Furthermore, certain vulnerable demographics are susceptible to various socioeconomic and educational determinants, rendering them more prone to discrimination and hindered access to equitable health benefits from forests [15]. Consequently, elucidating these pathways assumes paramount importance in fostering synergies between forests and public health.

This paper outlines the main pathways through which forests affect human health. We introduce a conceptual framework designed to comprehensively delineate the interconnections among forests, humanity, and health outcomes. Initially, we delineate the pathways by which forests influence human health, grounded in existing empirical evidence. This encompasses examining forest resource provision, preventative interventions, and the therapeutic effects of forest environments on human well-being. Furthermore, we elucidate the challenges encountered by vulnerable groups in accessing forest resources and services. Based on this foundation, and considering the equitable and sustainable health impacts associated with forests, we delineate priorities for the future management of forest resources, emphasizing the necessity of sustainable forest management practices while fostering the empowerment of marginalized communities to manage forests effectively. Within each section, we succinctly summarize pivotal discoveries to chart a course for future endeavors.

2. Systematic Review

This study adhered to a systematic review methodology akin to those employed in analogous studies and reviews [14,16,17]. Snyder et al. assert that the primary objective of systematic evaluation is to pinpoint empirical evidence that aligns with predetermined inclusion criteria, aiming to address a particular research inquiry or hypothesis [18]. Hence, this review concentrates on articles examining the impacts of forests on human health or well-being, with the subsequent synthesis of the insights and overarching conclusions drawn from these articles.

We conducted a keyword search using the Google Scholar database, focusing on the literature published between 2000 and 2022 (Figure 1). Articles prior to 2000 were excluded due to their early publication dates. The initial keyword combinations employed were “forests and human health”, “forests and human well-being”, and “forest ecosystem services and human health”. Inclusion criteria required studies to focus on forests and be related to human health or well-being. Studies exclusively concerning the condition of forests, with no relevance to human well-being, were excluded. Based on these criteria, an initial screening yielded 3025 potentially relevant articles. The further exclusion of duplicates and off-topic articles resulted in a final count of 1056 articles. An initial exploration of these articles identified key themes, prompting us to supplement our keywords with more detailed searches specific to each subfield. These additional search strings included “forests” paired with “infectious diseases”, “mental health”, “diet and nutrition”, “clean water”, “medicine”, “physical activity”, “natural disasters”, and “air pollution”. A subsequent screening of 4324 relevant articles, excluding duplicates and articles lacking direct relevance based on titles, abstracts, and keywords, retained 765 articles. Ultimately, only articles demonstrating a direct impact of forests on human health or well-being were included, yielding a final selection of 356 articles. These articles were read to identify the pathways and evidence of forest influence on human health.

3. Conceptual Framework Delineating the Nexus Between Forests and Human Health

We have devised a subsequent conceptual framework to delineate the pathway from forests to human health (Figure 2). The journey from forests to human well-being is segmented into three distinct processes: ecosystem services, mediating variables, and health performance. Ecosystem services encompass the array of benefits bestowed upon individuals by ecosystems [19]. Forest supply resource services typically pertain to the direct material ecosystem services that forests offer to humans, encompassing primarily food, medicinal plants, and water resources. Forest preventive services mainly aim to decrease the likelihood of extreme disasters and alleviate hazards to human health, encompassing the mitigation of air pollution, temperature extremes, and natural disasters. Forest therapy, on the other hand, involves enhancing the individuals’ physical and mental well-being through specific activities and methods conducted within forest environments, such as forest walks and forest bathing, ultimately promoting health, disease prevention, and health restoration.

The mediating variables primarily encompass various influencing factors that connect forests with human health, categorized mainly into accessibility and behavioral choices. These factors regulate the availability and utilization of health services derived from forests. The accessibility we focus on is primarily concerned with equity issues, encompassing age, gender, income, ethnicity, religious beliefs, policies, and infrastructure, among others, which hinder optimal access to forest-related well-being. Notably, in developing countries like India, Nepal, and Tanzania, deeply ingrained forest cultures can exacerbate inequities (Table S2). Health performance denotes the impacts of forests on human health and well-being, encompassing facets such as nutritional status, dietary diversity, infectious disease prevalence, and mental well-being. The subsequent sections of this study will delve into a comprehensive discussion elucidating the hierarchical structure of conceptual frameworks delineating the intricate interplay between forests and human health.

The theoretical framework underlying sustainable forest management as a crucial mechanism for facilitating the transition to forest-based health is multifaceted: (1) When utilizing forest resources to enhance well-being, it is imperative to consider the long-term ecological, economic, and social benefits of forests. (2) Maximizing the benefits of improving human well-being necessitates a holistic examination of the multifaceted ecosystem services provided by forests. (3) Maintaining ecological balance, preventing forest degradation resulting from overutilization, and enhancing stringent regulatory and protection systems are essential. (4) Ensuring the equitable management of forest resources necessitates a focus on collaborative engagement among diverse stakeholders, including governments, enterprises, communities, and non-governmental organizations.

4. Pathways Through Which Forests Affect Human Health

4.1. Supply Resources

4.1.1. Foods

Food insufficiency persists as a significant challenge for the world’s most resource-constrained and vulnerable populations, significantly impeding their ability to attain good health [20]. Recently, governmental organizations have increasingly recognized the potential of non-timber forest products (NTFPs) in enhancing nutrition and health outcomes. In 2023, the European Union (EU) officially introduced the EU Deforestation-Free Products Regulation (EUDR), a regulation that establishes stringent requirements for various NTFPs, such as soybeans, beef, palm oil, and coffee, ensuring they adhere to relevant forest protection regulations [21]. The EUDR aims to prevent NTFPs from contributing to illegal logging and forest degradation while safeguarding the rights of indigenous peoples. Improving health through NTFPs is thus complementary to the EUDR, and additional clarity is required regarding the mechanisms through which forest-derived foods enhance health outcomes (Table 1).

Primarily, as per our synthesis, forests can enhance human well-being by furnishing a cost-effective food source. Forests indirectly shield countless individuals from the perils of malnutrition by providing an economical food source [22,23,24]. They assist in sustaining food supplies crucial for households during periods of meager harvests, diminished agricultural yields, and vulnerability induced by climatic factors, thus bridging food shortages [25,26,27,28,29,30]. Evidence also underscores the contribution of forest-derived foods to dietary diversity in the rural areas of developing nations [31,32]. For instance, a study examining forest impact on children’s dietary diversity across 27 developing countries revealed that residing within 3 km of a forest augmented the children’s dietary variety by at least 25% compared to households situated more than 8 km away from forests [33]. This enhanced dietary diversity often correlates with health benefits specific to the most marginalized populations. For instance, in regions such as Madagascar and the Amazon, the depletion of wild game would potentially elevate the prevalence of anemia in children by 29% and 10%, respectively [34,35,36,37].

The evidence also indicates that an additional avenue for enhancing health entails augmenting the nutritional quality of women and children in developing regions. Forest-derived foods, including nuts, fruits, and wild game found in the forest vicinity, persist as pivotal sources for enhancing the nutritional standards of local populations [38,39]. In Tanzania, wild edibles sourced from forested farm landscapes contribute to 31% of vitamin A intake, 25% of iron consumption, and 23% of calcium intake [40]. Ghana-centric studies underscore the efficacy of essential non-timber forest products such as wild game, mushrooms, snails, foliage, honey, and fruits in elevating nutritional standards [41,42]. Forest foods account for more than 80% of women’s intake of vitamin A, calcium, iron, and zinc in forest-dependent households in Cameroon [43,44].

Table 1. Impact of supply resource services on human health.

Country	Resource Type	Research Focus	Health Impact	Study
Benin	Foods	Forest foods enhance the nutritional quality of women in southern Benin by improving micronutrients such as copper and iron	Nutritional quality	[45]
Malawi, Mozambique	Foods Medicinal Plant Timber	Forests provide food, medicine, and timber to improve nutrition and increase the capacity of community populations in Malawi and Mozambique to cope with AIDS	AIDS Nutritional quality	[46]
Ghana	Foods Medicinal Plant	Forest foods and medicines contribute to the nutrition and food security of the Ghanaian population and help in the treatment of various diseases	Injury or death Nutritional quality	[42]
21 African countries	Foods	Forest cover contributes to more diverse and nutritious diets for African children	Nutritional quality Diversified diet	[47]
Nepal	Foods	Wild mushrooms help improve diet and nutritional quality	Nutritional quality Diversified diet	[48]
Tanzania	Foods	Forest foods contribute to improving dietary diversity and nutritional quality	Nutritional quality Diversified diet	[23]
	Foods	Forest foods based on apples and pears, among others, have been found to have ingredients with the ability to improve health by suppressing high blood sugar, obesity, and antioxidant activity	Cardiovascular disease, Nutritional quality	[49]
	Foods Medicinal Plant	Forests provide food and medicine to help vulnerable groups fight malnutrition and undesirable diseases	Nutritional quality Injury or death Cardiovascular disease	[31]
Sub-Saharan Africa	Foods Medicinal Plant Timber	Forest foods, timber, and medicines to guarantee basic nutritional security for the most vulnerable populations and to improve AIDS prevention and treatment	Aids, Nutritional quality	[46]
Africa	Foods	Forests provide nutritious food for humans and help fight AIDS in Africa	Aids, Nutritional quality	[50]
	Foods	Wild game from forests provides most of the protein consumed by rural populations	Nutritional quality	[51]
Cameroon	Foods	Food from the forest helps improve the immune system of AIDS patients in Cameroon	Aids, Nutritional quality	[52]
Assam, India	Medicinal Plant	Collection of 80% of medicinal plants from forests to ameliorate diseases such as snakebite and malaria	Injury or death Infectious disease	[53]
Tanzania	Medicinal Plant	Traditional healers use forest medicine to treat humans for diseases such as AIDS	Aids	[54]
China	Medicinal Plant	The bioactivity of Cordyceps sinensis, a traditional herb from China, has a wide range of abilities, including antiatherosclerosis and antidepressant properties	Cardiovasculardisease, Mental disorder	[55]
Brazilian Amazon	Medicinal Plant	Medicinal plants near forests provide healthcare measures for the poor in the Brazilian Amazon for the treatment of diseases	Injury or death Non-communicable disease	[56]
Tanzania	Medicinal Plant	Local people rely on natural medicines near forests to meet their basic health needs, and 45 local forest medicines can treat 22 human diseases	Injury or death Non-communicable disease	[57]
Burkina Faso	Medicinal Plant	Use of medicinal plants in the vicinity of forests as a means of health treatment, especially for the population in rural areas in the south–central region	Injury or death Non-communicable disease	[58]
	Clean water	Forests help to maintain and enhance the quality of drinking water and have a long-term impact in protecting human health, especially among the poorest populations	Infectious disease Long term health	[59]
Malawi	Clean water	Forests and clean water are closely linked, with each 1% increase in deforestation reducing access to clean drinking water by 0.93%	Infectious disease	[60]
Saharan Africa	Clean water	Forests provide clean water to local populations in a sustainable manner	Infectious disease Long term health	[61]
Global	Clean water	Forests store, release, and purify water through the interaction of hydrological processes to provide clean drinking water for humans	Infectious disease Long term health	[62]

Table 1. Impact of supply resource services on human health.

Country	Resource Type	Research Focus	Health Impact	Study
Benin	Foods	Forest foods enhance the nutritional quality of women in southern Benin by improving micronutrients such as copper and iron	Nutritional quality	[45]
Malawi, Mozambique	Foods Medicinal Plant Timber	Forests provide food, medicine, and timber to improve nutrition and increase the capacity of community populations in Malawi and Mozambique to cope with AIDS	AIDS Nutritional quality	[46]
Ghana	Foods Medicinal Plant	Forest foods and medicines contribute to the nutrition and food security of the Ghanaian population and help in the treatment of various diseases	Injury or death Nutritional quality	[42]
21 African countries	Foods	Forest cover contributes to more diverse and nutritious diets for African children	Nutritional quality Diversified diet	[47]
Nepal	Foods	Wild mushrooms help improve diet and nutritional quality	Nutritional quality Diversified diet	[48]
Tanzania	Foods	Forest foods contribute to improving dietary diversity and nutritional quality	Nutritional quality Diversified diet	[23]
	Foods	Forest foods based on apples and pears, among others, have been found to have ingredients with the ability to improve health by suppressing high blood sugar, obesity, and antioxidant activity	Cardiovascular disease, Nutritional quality	[49]
	Foods Medicinal Plant	Forests provide food and medicine to help vulnerable groups fight malnutrition and undesirable diseases	Nutritional quality Injury or death Cardiovascular disease	[31]
Sub-Saharan Africa	Foods Medicinal Plant Timber	Forest foods, timber, and medicines to guarantee basic nutritional security for the most vulnerable populations and to improve AIDS prevention and treatment	Aids, Nutritional quality	[46]
Africa	Foods	Forests provide nutritious food for humans and help fight AIDS in Africa	Aids, Nutritional quality	[50]
	Foods	Wild game from forests provides most of the protein consumed by rural populations	Nutritional quality	[51]
Cameroon	Foods	Food from the forest helps improve the immune system of AIDS patients in Cameroon	Aids, Nutritional quality	[52]
Assam, India	Medicinal Plant	Collection of 80% of medicinal plants from forests to ameliorate diseases such as snakebite and malaria	Injury or death Infectious disease	[53]
Tanzania	Medicinal Plant	Traditional healers use forest medicine to treat humans for diseases such as AIDS	Aids	[54]
China	Medicinal Plant	The bioactivity of Cordyceps sinensis, a traditional herb from China, has a wide range of abilities, including antiatherosclerosis and antidepressant properties	Cardiovasculardisease, Mental disorder	[55]
Brazilian Amazon	Medicinal Plant	Medicinal plants near forests provide healthcare measures for the poor in the Brazilian Amazon for the treatment of diseases	Injury or death Non-communicable disease	[56]
Tanzania	Medicinal Plant	Local people rely on natural medicines near forests to meet their basic health needs, and 45 local forest medicines can treat 22 human diseases	Injury or death Non-communicable disease	[57]
Burkina Faso	Medicinal Plant	Use of medicinal plants in the vicinity of forests as a means of health treatment, especially for the population in rural areas in the south–central region	Injury or death Non-communicable disease	[58]
	Clean water	Forests help to maintain and enhance the quality of drinking water and have a long-term impact in protecting human health, especially among the poorest populations	Infectious disease Long term health	[59]
Malawi	Clean water	Forests and clean water are closely linked, with each 1% increase in deforestation reducing access to clean drinking water by 0.93%	Infectious disease	[60]
Saharan Africa	Clean water	Forests provide clean water to local populations in a sustainable manner	Infectious disease Long term health	[61]
Global	Clean water	Forests store, release, and purify water through the interaction of hydrological processes to provide clean drinking water for humans	Infectious disease Long term health	[62]

4.1.2. Forest Medicine

Forests serve not only as a source of food for humans but also as a vital reservoir of medicinal plants. Approximately 4 billion individuals in developing countries rely on medicinal plants for healthcare, as estimated [63]. In numerous developing nations, medicinal plants sourced from forests assist the most vulnerable populations in accessing basic healthcare [64,65]. Given their widespread accessibility across diverse populations, medicinal plants remain a viable alternative even in areas where modern medicine is accessible [66,67]. For instance, in Ghana, 56% of the population depends on forests for medicinal plants, with 30% of this population utilizing these plants to treat various illnesses, including malaria, typhoid, and fever [42]. By 2011, the number of individuals reliant on herbal products in China, India, and Africa alone had reached 2.8 billion [68,69]. In India, rural locals obtain medicinal plants from forests, enabling them to treat issues such as snake bites, asthma, jaundice, edema, and gynecological problems [70]. Forest resources offer affordable medicinal plants to families affected by AIDS, alleviating the suffering of infected members. For example, 60% of households in Malawi with adult-onset diseases within 12 months resorted to medicinal plants as a coping strategy [46,52].

4.1.3. Timber

Another pivotal manner in which forests influence human health is through the provision of wood. According to the Food and Agriculture Organization (FAO), approximately 2.4 billion individuals globally still rely on wood fuels for cooking purposes, with 764 million of them (representing 11% of the world’s population) utilizing wood to sterilize and boil water, thereby significantly decreasing the occurrence of waterborne diseases [71]. When employed as the primary construction material for house walls, roofs, floors, and other components, wood offers shelter to approximately 18% of the global population [72]. However, the utilization of these forest products for enhancing health in resource-constrained countries necessitates attention in two critical areas. Firstly, the escalating demand for commodities linked to deforestation not only heightens the risk of disease acquisition but also necessitates the avoidance of deforestation stemming from sustained forest product consumption [73,74]. Secondly, safer methods of utilizing wood fuels are required, particularly in resource-limited countries, where the integration of improved cookstoves can mitigate health hazards associated with indoor air pollution [75,76].

4.1.4. Clean Water

Forest ecosystems wield a significant influence on global water production, particularly in their indispensable role concerning both water quantity and quality [77]. Globally, forest and mountain ecosystems contribute over 75% of renewable water for human use and purify water for 61% of the global population, serving as a paramount aspect of our water security [78,79]. Evidence indicates that alterations in the global forest cover profoundly impact global precipitation patterns. For instance, modifications in the forest cover within the Amazon region may affect precipitation in distant regions like Canada, Northern Europe, and even East Asia [80]. Moreover, research demonstrates that global forest restoration efforts alter water availability, potentially augmenting water resources for local communities [81]. Furthermore, forests serve as natural water filters and provide timber for water sterilization, significantly diminishing waterborne diseases (see Figure 3). Take, for instance, waterborne diarrheal diseases, which claim approximately 2 million lives annually, with a majority of fatalities occurring among children under 5 years of age [82,83]. Hence, forests harbor immense potential in regulating the nexus between water resources and health. Moving forward, stakeholders ought to explicitly recognize the value of forests in delivering clean water to further bolster human health [84].

4.2. Preventive Services

4.2.1. Air Pollution

Forests constitute an efficacious means of mitigating air pollution issues and can substantially enhance human health [86]. Estimates suggest that augmenting urban forest cover at an annual expenditure of $3.2 billion could decrease air pollution-related mortality by a minimum of 2.7% to 8.7%, thereby saving approximately 11,000 to 36,000 lives globally [87]. In this study, we integrated global data on forest cover and air pollution-related deaths, revealing that in most developed countries and some developing nations, higher forest cover is associated with lower individual air pollution-related fatalities (Figure 4). For instance, forests in the United States mitigate approximately 17.4 million tons (t) of air pollutants and prevent 670,000 cases of acute respiratory infections [86]. Incorporating forests into various management strategies could yield even greater benefits [88]. Specifically, carbon farming, a novel agricultural production model that integrates forests, can enhance carbon sequestration rates in soils and plants, thereby swiftly reducing atmospheric carbon emissions, augmenting crop yields, and mitigating air pollution [89]. Additionally, we emphasize that carbon reduction policies and pollution reduction policies exhibit significant effects and synergies in the integrated management of diverse industries and air pollutants. For example, combining forests with carbon credit systems as a long-term primary strategy not only aids in mitigating air pollution but also generates economic benefits [90]. Consequently, exploring the potential for air pollution mitigation in forest management remains a focal area of current research.

4.2.2. Temperature

Global forests represent nature-based solutions with the potential to ameliorate planetary warming and enhance human well-being in the years ahead [91]. Among these, urban forests have garnered considerable attention as a strategy for mitigating heat [92]. Evidence indicates that urban forests constitute the most efficient and economically viable means of alleviating and adapting to heat waves [93,94]. They enhance thermal comfort in outdoor environments and mitigate the hazards associated with heat-induced illnesses, such as heat stroke resulting from elevated temperatures [95,96]. In the forthcoming years, a blend of urban forest management techniques will effectively reduce temperatures and diminish the prevalence of heat-related ailments. For instance, thermal management initiatives aimed at augmenting forest cover in the United States could potentially mitigate 40–99% of heat-related fatalities by 2050 [97]. Furthermore, if urban forests are strategically planted at optimal densities, they could yield maximal reductions in temperature, thereby benefiting the health of approximately 220 million individuals to some extent [87]. Nevertheless, these statistics represent conservative estimates, as there remains a substantial amount of underutilized space suitable for expanding forest coverage. For instance, augmenting forest cover in urban areas at an annual investment of USD 3.2 billion could potentially reduce heat-related fatalities by 2.4% to 5.6% [87].

4.2.3. Natural Disasters

In addition to ameliorating air pollution and regulating temperature, forests serve as bulwarks for human well-being by mitigating natural disasters [98]. Evidence indicates that forests safeguard human health primarily by averting floods, storms, landslides, mudslides, and avalanches (

Table 2. Natural disaster prevention in forests.

Country	Natural Disasters	The Role of Forests	Study
Trinidad	Flood	There is a non-linear relationship between forest cover and flooding, with deforestation leading to a significant increase in flood risk	[103]
China	Flood	Rainfall thresholds for extreme floods increase significantly when local forest cover reaches 70% or more	[104]
India	Flood	Forest cover helps reduce flood damage and has the capacity to protect human life and property	[105]
China	Flood	Increased forest area mitigates flooding, and broadleaf and mixed forests have a flood-mitigating effect	[106]
UK, New Zealand, USA, Chile	Flood	Forest cover combined with additional forestry interventions, such as road networks and drainage canals, can be effective in mitigating flood damage	[107]
India	Flood	Increased forest cover reduces runoff to limit flood damage and protects human life	[99]
China	Storm	50 years of sustained afforestation, effectively reducing the number of days of dust storms, the power, and the number of days of storms in the Chinese region	[108]
China	Landslides	Different types of forests play different roles in landslide control, providing a reference for landslide susceptibility control	[101]
Switzerland	Landslides	Forest roots immobilize slopes and have a significant effect on landslide susceptibility	[109]
Japan	Avalanche	Forests have a braking effect on avalanches, and without forests, avalanches would travel even 600 m further in Makunosawa Valley	[110]
USA	Mudslide	Coarse woody debris from underneath forests can act as a brake on mudslides, thus reducing their damage	[111]

). Initially, forests diminish precipitation runoff by enhancing water infiltration into the soil and retention by the tree canopy, thereby effectively curbing flooding [99]. Furthermore, by adjusting the structure, composition, and density of forests, it is feasible to effectively counteract hurricane disturbances and prevent the formation of larger hurricanes that pose a threat to human health [100]. Forests forestall and alleviate landslides, mudslides, and avalanches by capturing solid materials and ultimately restricting their movement [101]. Specifically, forests exhibit remarkable efficacy in mitigating erosion and conserving soil and water resources via the synergistic effects of three distinct layers: the canopy and understory vegetation, the litter layer, and the rooted soil layer [102]. The forests’ role in mitigating natural disasters is widely acknowledged as cost-effective and dependable. Indeed, the successful realization of the forests’ potential to avert natural disasters hinges, to some extent, on the efficacy of their management. It is important to underscore that the ability of forests to prevent natural disasters focuses on reducing the likelihood of their occurrence rather than combating them during large-scale destructive events. Consequently, in the future, policymakers and stakeholders will need to formulate and implement plans for reducing health risks and managing disasters related to forests, natural hazards, and human health to mitigate vulnerability and exposure to risks.

4.3. Forest Therapy

The merits and potential of arboreal treatments have been officially acknowledged by the United Nations within the COVID-19 pandemic’s green recovery framework [112]. Evidence indicates that certain Asian nations have commenced integrating forest therapy into their policies; for instance, Japan, the Republic of Korea, and China have included forests in their medical strategies as an integrative therapeutic resource for enhancing human health (Table 3) [113]. Our findings reveal that research on forest therapy is still in a relatively nascent stage of development. While past studies have demonstrated the beneficial effects of short-term exposure to forests on human health, the sustainability of these impacts remains inadequately substantiated. Thus, future research efforts should be directed towards elucidating this aspect more comprehensively. Consequently, we will delineate the contributions of forest therapy to human health, drawing upon evidence from both physical and mental health domains.

4.3.1. Mental Health

Evidence indicates that forests play a pivotal role in assisting individuals in alleviating mental disorders and enhancing human mental well-being (Table 3) [114]. Short strolls in wooded settings alleviate fatigue and aid in diminishing negative emotions such as anxiety, anger, and confusion [115,116]. Beyond mitigating negative feelings, exposure to forested environments can elevate women’s sense of well-being and exert a more positive influence on mood and vitality [117,118]. Forests also alleviate mental burdens on vulnerable individuals, fostering improvements in their health (Table 3). For instance, forest therapy can enhance sleep quality in patients grappling with heart failure and cancer, thereby facilitating recovery from illness [119,120]. Furthermore, forest environments contribute to enhanced cognitive function and attentional restoration, promoting better mental health [121,122]. Moreover, increased urban forest coverage fosters social cohesion and diminishes stress [123]. Particularly amid the recent COVID-19 pandemic, individuals residing near forests exhibited superior mental well-being [124]. Nonetheless, we observed that most studies have overlooked the correlation between the frequency and duration of exposure to forested environments and the mental health benefits. Consequently, research aimed at quantifying the relationship between forest exposure and its corresponding mental health outcomes remains a focal point for future investigations [125].

4.3.2. Physical Health

Much of the scientific and gray literature reveals that forests have the potential to enhance various physiological parameters in humans (Table 3). Current mainstream research highlights that forest therapy interventions aimed at human physiological well-being primarily target three key areas: cardiovascular health, the immune system, and cancer (Table 3). Specifically, brief exposure to forest environments has shown to ameliorate several physiological markers associated with cardiovascular disease in humans, as validated by studies focusing on salivary cortisol, blood pressure, pulse rate, heart rate variability, parasympathetic and sympathetic nervous system indicators, systolic and diastolic blood pressure, and heart rate recovery. For instance, forests have been associated with reduced blood glucose levels and sympathetic nerve activity in diabetic patients, along with increased parasympathetic activity to mitigate [126,127]. Moreover, forest therapy contributes to enhancing the human immune system’s functionality, with a focus on augmenting natural killer cell activity, atopic dermatitis score index, oxidative stress, thymus function, and activation-regulated chemokine expression [128,129]. Strengthening the immune system can notably alleviate inflammation and bolster the body’s ability to combat cancer. Additionally, forests emit immune-modulating volatile organic compounds that fortify the human immune system, mitigate the transmission of viral diseases, and directly contribute to reducing mortality from new cases of pneumonia [130,131]. Nevertheless, a few studies have evaluated the sustained effects of forest treatments on human physiological well-being, warranting further investigation into the enduring efficacy of forest treatments in enhancing immunity.

Table 3. Impact of forest therapy on human health.

Country	Type of Indicators	Key Findings	Health Impact	Study
Japan	Salivary cortisol, blood pressure, pulse rate, heart rate variability	Forest environments promote lower cortisol concentrations, lower pulse rates, lower blood pressure, higher parasympathetic activity, and lower sympathetic activity	Cardiovascular disease, mental disorders	[132]
Finland	Blood pressure, heart rate, heart rate variability	Visiting green environments such as urban forests is associated with beneficial short-term changes in cardiovascular risk factors	Cardiovascular disease	[133]
Taiwan, China	Natural killer cells	The number of natural killer cells in the forest group (19.5 ± 9.1%) was higher than that in the urban group (16.4 ± 8.4%). Exposure to the forest environment may enhance the immune response of human natural killer cells	Immune system	[116]
Japan	Heart rate variability, heart rate, psychological questionnaire	Brief exposure to the forest has physiological and mental relaxation effects in middle-aged hypertensive individuals and can also reduce anxiety, anger, and confusion	Cardiovascular disease, mental disorders	[134,135]
Japan	Heart rate variability, parasympathetic and sympathetic indicators	Walking in a forest environment benefits autonomic nervous activity	Cardiovascular disease	[126]
Korea	Sleep apnea, subjective sleep quality, sleepiness, Anxiety, and depression	Forest therapy may help improve sleep quality in patients with gastrointestinal cancer	Cardiovascular disease	[126]
Korea	Atopic Dermatitis Score Index, thymus, and activation-regulated chemokines	Short-term exposure to forest environments may have clinical and immunological effects on children with allergic diseases living in urban communities	Immune system	[136]
Japan	Levels of hydrogen peroxide (H2O2) and 8-hydroxy2′deoxyguanosine (8-OHdG) in urine	Exposure to forests may reduce oxidative stress in the body	Cardiovascular disease, immune system	[137]
Japan	Natural killer cell activity, granulin, perforin, granzyme expression lymphocyte number, and urinary epinephrine concentration.	Forest exposure increases natural killer cell activity, improves the immune system, and fights cancer	Immune system, cancer	[138]
Japan	Number of natural killer cells, expression of perforin, granzyme, and granulin in peripheral blood lymphocytes (PBLs)	Exposure to forests can increase the activity of natural killer cells to improve the human immune system and ability to fight cancer	Immune system, cancer	[129,139]
Sweden	Perceptual recovery, mood, attention capacity, heart rate, systolic and diastolic blood pressure, and heart rate recovery	The forest environment is more rejuvenating, enhances mood and concentration, and is beneficial to the recovery of patients with fatigue	Cardiovascular disease, mental disorders	[125]
South Korea, China	Mental questionnaire	Urban and rural forests help mental recovery and reduce anxiety and stress among local middle-aged women and teenagers	Mental disorders	[140,141]
Japan	Diastolic blood pressure, parasympathetic activity, sympathetic activity, heart rate	Forest landscapes are good for lowering blood pressure and alleviating negative emotions	Cardiovascular disease, mental disorders	[142]
Japan	Blood pressure, urinary norepinephrine, dopamine	Habitual walking in forest environments may lower blood pressure by reducing sympathetic activity	Cardiovascular disease	[143]
Japan	Blood pressure, salivary amylase, emotional state	Forest walking significantly reduced mean arterial pressure and alleviated mental stress in both groups of patients	Cardiovascular disease, mental disorders	[144]
UK	Longitudinal data on 3569 adolescents aged 9 to 15 years	Regular exposure to woodlands improves cognition and reduces emotional and behavioral problems in adolescents	mental disorders	[9]

Table 3. Impact of forest therapy on human health.

Country	Type of Indicators	Key Findings	Health Impact	Study
Japan	Salivary cortisol, blood pressure, pulse rate, heart rate variability	Forest environments promote lower cortisol concentrations, lower pulse rates, lower blood pressure, higher parasympathetic activity, and lower sympathetic activity	Cardiovascular disease, mental disorders	[132]
Finland	Blood pressure, heart rate, heart rate variability	Visiting green environments such as urban forests is associated with beneficial short-term changes in cardiovascular risk factors	Cardiovascular disease	[133]
Taiwan, China	Natural killer cells	The number of natural killer cells in the forest group (19.5 ± 9.1%) was higher than that in the urban group (16.4 ± 8.4%). Exposure to the forest environment may enhance the immune response of human natural killer cells	Immune system	[116]
Japan	Heart rate variability, heart rate, psychological questionnaire	Brief exposure to the forest has physiological and mental relaxation effects in middle-aged hypertensive individuals and can also reduce anxiety, anger, and confusion	Cardiovascular disease, mental disorders	[134,135]
Japan	Heart rate variability, parasympathetic and sympathetic indicators	Walking in a forest environment benefits autonomic nervous activity	Cardiovascular disease	[126]
Korea	Sleep apnea, subjective sleep quality, sleepiness, Anxiety, and depression	Forest therapy may help improve sleep quality in patients with gastrointestinal cancer	Cardiovascular disease	[126]
Korea	Atopic Dermatitis Score Index, thymus, and activation-regulated chemokines	Short-term exposure to forest environments may have clinical and immunological effects on children with allergic diseases living in urban communities	Immune system	[136]
Japan	Levels of hydrogen peroxide (H2O2) and 8-hydroxy2′deoxyguanosine (8-OHdG) in urine	Exposure to forests may reduce oxidative stress in the body	Cardiovascular disease, immune system	[137]
Japan	Natural killer cell activity, granulin, perforin, granzyme expression lymphocyte number, and urinary epinephrine concentration.	Forest exposure increases natural killer cell activity, improves the immune system, and fights cancer	Immune system, cancer	[138]
Japan	Number of natural killer cells, expression of perforin, granzyme, and granulin in peripheral blood lymphocytes (PBLs)	Exposure to forests can increase the activity of natural killer cells to improve the human immune system and ability to fight cancer	Immune system, cancer	[129,139]
Sweden	Perceptual recovery, mood, attention capacity, heart rate, systolic and diastolic blood pressure, and heart rate recovery	The forest environment is more rejuvenating, enhances mood and concentration, and is beneficial to the recovery of patients with fatigue	Cardiovascular disease, mental disorders	[125]
South Korea, China	Mental questionnaire	Urban and rural forests help mental recovery and reduce anxiety and stress among local middle-aged women and teenagers	Mental disorders	[140,141]
Japan	Diastolic blood pressure, parasympathetic activity, sympathetic activity, heart rate	Forest landscapes are good for lowering blood pressure and alleviating negative emotions	Cardiovascular disease, mental disorders	[142]
Japan	Blood pressure, urinary norepinephrine, dopamine	Habitual walking in forest environments may lower blood pressure by reducing sympathetic activity	Cardiovascular disease	[143]
Japan	Blood pressure, salivary amylase, emotional state	Forest walking significantly reduced mean arterial pressure and alleviated mental stress in both groups of patients	Cardiovascular disease, mental disorders	[144]
UK	Longitudinal data on 3569 adolescents aged 9 to 15 years	Regular exposure to woodlands improves cognition and reduces emotional and behavioral problems in adolescents	mental disorders	[9]

5. Pathways Moderation of Forests and Health Through Mediating Factors

We acknowledge that certain segments of society, including individuals with lower incomes, women, the elderly, people with disabilities, and children, face a heightened susceptibility to health risks. These vulnerable groups often encounter barriers in accessing health resources and services provided by forests [145]. However, while endeavoring to access these health opportunities, they frequently contend with a myriad of inequities that render accessing healthcare challenging. For instance, research indicates that vulnerable groups bear a disproportionate burden of physical and mental health challenges stemming from natural disasters compared to the general populace [146]. It is imperative, therefore, to identify the mediating factors influencing the transition from forests to human health, as these factors often govern the accessibility of health resources or services available from forests. We have categorized these mediating variables into two broad groups: accessibility and behavioral choices.

Accessibility encompasses various factors such as proximity, age, gender, socioeconomic status, ethnicity, transportation, religious beliefs, education, policy, and infrastructure. Particularly in low-income nations, disparities in gender, age, economic status, religious beliefs, and educational attainment significantly impact the access of marginalized communities to health-related resources and services provided by forests [147,148,149]. Moreover, amid the battle against the COVID-19 pandemic, individuals with higher education and income levels tended to frequent urban forests more frequently, and engagement in such activities contributed to their overall well-being [150]. Similarly, the proximity to forested areas strongly influences accessibility. For instance, in major Chinese cities like Beijing, Shanghai, and Shenzhen, housing prices are closely linked to the accessibility of urban forest parks [151]. Additionally, racial disparities in accessibility to urban forests exist. Research involving white, black, and Hispanic populations revealed that white individuals had superior access to urban forests for health benefits compared to their black and Hispanic counterparts [152]. Furthermore, vulnerable groups are disproportionately affected by natural disasters, as inadequate infrastructure hampers access to forest shelters [153,154].

Behavioral choices encompass the individuals’ inclinations towards utilizing services or products provided by forest ecosystems, largely influenced by personal characteristics, economic factors, and environmental conditions. These choices primarily entail sensory perceptions, interaction patterns, experiences, personal attributes, and subjective tendencies such as responses (frequency) and habits (acquisition dosage). For instance, the quality of human sensory experiences in forests—sight, hearing, touch, and smell—is pivotal in determining their engagement with forests and the health advantages gained from such encounters [155,156]. Furthermore, the manner in which individuals engage with and experience forests dictates the health benefits they derive. For instance, the health outcomes from engaging in physical activities in the forest differ from merely observing it [143,157]. Alongside sensory and interactive dimensions, habits and preferences also shape the correlation between forests and human well-being. Varying concerns, perceptions, and preferences among individuals regarding forests influence the frequency and consistency with which they opt to access and immerse themselves in forest environments, consequently impacting the health benefits derived [131,158,159].

6. Strategies for Sustaining the Health Impacts of Forests

In an era of escalating global health risks and inequalities, sustaining the health benefits of forests poses a formidable challenge. Primarily, to foster a sustainable supply of forest resources, the incorporation of sustainable forest management practices is imperative. Furthermore, to ensure the regularization of forest resources and services, the assessment of forest-related health resources and services must be significantly enhanced. To guarantee equitable access to forest resources and services for all individuals, particularly marginalized groups, adequate empowerment for management is necessary, particularly to promote equality in access to these resources. Ultimately, to mitigate trade-offs among forest ecosystem services, the co-management of forest resources by diverse stakeholder sectors represents the most viable approach. Herein, we propose six measures aimed at sustaining the positive health impacts of forests (Figure 5).

6.1. Sustainable Forest Management

The delivery of vital resources from forests to local inhabitants hinges on the adoption of exemplary practices in sustainable forest management, ensuring a continuous provision of forest products encompassing both sustenance and medicinal herbs [41]. We posit that the pivotal role of small-scale producers, local communities, and indigenous peoples deserves rightful acknowledgment and is fundamental to achieving the sustainable delivery of essential forest resources. Presently, the global count of rangers in terrestrial protected areas stands at approximately 286,000, with a mere one ranger per 72 square kilometers, significantly below the minimum density mandated by the Convention on Biological Diversity. This inadequacy constitutes one of the principal factors contributing to the severe lack of management efficacy [160]. Empowering small-scale producers, local communities, and indigenous peoples to oversee their forests can effectively alleviate this predicament. It is imperative, moreover, to heed the voices of local stakeholders, with small-scale producers, local communities, and indigenous peoples assuming empowered roles in determining how and where forests are cultivated as health-supporting resources. Concurrently, the health requisites and values of forest communities must be duly considered for enduring success. Consequently, forest communities must collaborate with governmental and non-local entities to foster synergies and mitigate trade-offs.

6.2. Empowering Vulnerable Groups

In Section 5, we elucidate how the unequal access of vulnerable groups to forest environments hinders their equitable access to health benefits from forests. Indeed, there is a tendency to overlook the disparities among social groups and to homogenize various actors in forest management and local governance institutions. This poses a challenge, as significant disparities within and between groups can severely impede fair access to forests [161]. Particularly for marginalized groups facing discrimination, their ability to derive health benefits from forests is likely diminished, thus jeopardizing their long-term well-being [162]. It is imperative, therefore, to address the mediating factors that influence accessibility and behavioral choices, especially through regulations and policies aimed at eradicating discriminatory practices. Valuable insights on how to promote empowerment within local communities and improve health outcomes can be gleaned from both the scientific and gray literature (Table S1). For instance, enhancing local-level monitoring can empower vulnerable groups to voice their genuine interests and needs in forest resource management decision-making processes [163]. Moreover, the effective implementation of community-based forest resource management initiatives will contribute to elevating the status of vulnerable groups in accessing forest resources [164]. Equally essential is the empowerment of social groups to access forests, acknowledging and addressing their inter- and intra-group differences.

6.3. Strengthening Forest Resources Assessment

In the future, there is a pressing need to enhance the capacity of institutions across all sectors to monitor the assessments of the forests’ impacts on human health and to act accordingly based on those evaluations. For instance, given the substantial global consumption of medications derived from forests and trees, it is crucial to identify the associated risks, particularly as cases of poisoning linked to herbal medicines have surged in many regions worldwide in recent years. It is imperative to ensure that forest-derived medicinal products undergo comprehensive toxicity assessments, accompanied by active pharmacovigilance, to promote their safe usage and safeguard public health globally [165].

Emerging evidence suggests that non-timber forest products (NTFPs) constitute a significant yet underestimated sector [166]. Therefore, we propose collaborating with China’s “Belt and Road” Initiative to promote and market NTFPs. This initiative presents novel opportunities for cooperation and trade in NTFP markets along the route, enhancing the capacity of participating countries to manage forest resources sustainably [167]. The dissemination of traditional forest cultures and spiritual values is pivotal in establishing a positive correlation between forests and health. It is crucial to acknowledge the unique social, cultural, and spiritual values that indigenous peoples and local communities hold for forests.

6.4. Developing Potential of Urban Forests

Fostering the manifold functions of urban forests can yield significant positive impacts on human health, particularly for those residing in densely populated urban areas. We propose directing special attention toward the vast untapped potential of global forest expansion. Harnessing the full potential of an additional 900 million hectares of forest cover in the future could lead to a more optimal density of urban forests, benefiting the health of at least 220 million individuals [87,168].

Furthermore, although we acknowledge the capacity of urban forests to mitigate air pollution, it is evident that their potential remains largely untapped. Hence, it is imperative to secure increased funding and formulate policies for the effective management of urban forests, thereby maximizing their impact on human health. However, the realization of these endeavors hinges upon substantial policy reforms, particularly in urban planning and budget allocation. The scarcity of urban green spaces, particularly in recent years, may further exacerbate health risks for populations in low and middle-income countries worldwide, warranting profound contemplation [20]. Hence, it is urgent to dismantle barriers to access and affordability, promote the utilization of urban woodlands by city dwellers, and advocate for their preservation.

6.5. Promoting Gender Equality

The Food and Agriculture Organization of the United Nations (FAO) acknowledges the necessity of incorporating gender considerations in addressing the interrelationships among forests, health, and nutrition [169]. In many developing nations, women predominantly oversee and utilize forest resources, undertaking tasks such as gathering fuel, purifying drinking water, and providing sustenance and remedies for their families. There is a growing body of evidence highlighting the unique role of women in harmonizing the forest–health nexus. For instance, women serve as the custodians of traditional knowledge concerning the utilization of forest resources for sustenance and medicinal purposes [41]. Additionally, research on community-based conservation indicates that increased female participation in local management correlates with enhanced forest protection and adherence to regulations [170,171].

However, efforts to address gender disparities in conservation and natural resource management have progressed slowly, including initiatives aimed at promoting women’s engagement in these domains [172]. Therefore, in an endeavor to enhance the health of communities residing near forests, it is imperative to acknowledge and empower women in forest resource management. Furthermore, future endeavors should prioritize enhancing communication between women and non-governmental organizations to facilitate access to information and ensure equitable participation in forest governance, thus fostering a sustainable relationship between forests and health.

6.6. One Health

The emerging One Health movement acknowledges the inseparable connection between human, animal, and environmental health, as evidenced in previous studies [173,174,175]. We advocate for the adoption of the core concept of “One Planet, One Health”, which underscores the significant potential of forests in combating infectious diseases. Populations in developing countries, particularly, have increased interactions with forests. Consequently, addressing current and future infectious disease threats necessitates situating health issues within the ecological context of global forests, adopting the “One World, One Health” perspective. The interconnectedness among human, animal, and environmental health fosters the One Health approach, necessitating cross-sectoral and multidisciplinary collaboration in healthcare to address these threats. Building upon the foundation of One Health, we propose cross-sectoral co-development (Figure 6). For future advancements in disease prevention and management, we suggest integrating cross-sectoral collaborative frameworks with forest action measures.

7. Conclusions

Building upon the conceptual framework linking forests to human health, this study examines the impact of forests on human health in terms of their provisioning, preventive, and curative services. Existing research primarily focuses on the influence of forest provisioning resources on human health in developing countries, particularly in sub-Saharan Africa, where populations are more reliant on forests, often serving as a safety net for vulnerable groups. Current research has affirmed the physiological and mental health benefits of forests on human health, yet there remains a lack of clear understanding regarding the quantification of the relationship between exposure and response. Investigating the long-term health benefits of forests on human health remains a priority for future research. However, due to constraints related to urban management and legal policies, there is still a disparity between the ideal incorporation of forests into public health frameworks and current practices. In this context, it is crucial to emphasize that access to forest resources and services is heavily dependent on local government management and the enforcement of legal policies. Therefore, future efforts must further strengthen the management and coordination roles of government departments, while also considering the health needs and values of local populations to minimize trade-offs among different forest ecosystem services. This is essential for ensuring that vulnerable groups have access to forest resources.

We have gathered an extensive body of literature to comprehensively encompass the pathways through which forests influence human health. However, due to constraints such as our knowledge base, searching capabilities, and linguistic limitations, it is conceivable that we may have overlooked certain significant literature or research findings. Furthermore, the evaluation of the actual efficacy of the forests’ impacts on human health may lack the necessary depth, particularly regarding the influence of social or policy factors on both forests and human health, which warrants future field survey analysis. Inevitably, in striving for a more comprehensive assessment of the impact of forest ecosystem services on human health, certain typical areas, especially in resource-poor countries that are more reliant on forests for their livelihoods, have been neglected.