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Health Benefits from Forests

This module will be of interest to the general public because it provides basic and more detailed information on the ways in which forests and trees influence human health and well-being. It also gives links to tools, case studies, websites and literature to further assist users in understanding the relationships between forests, trees and human health. 

Health benefits from forests contributes to SDGs:

The dependence of a community on forests and trees for their health is likely to vary with the social, economic and cultural contexts, including whether the community is urban or rural. In urban centres, the presence of forests and trees helps citizens in adopting healthy lifestyles and improving their physical and mental health. Rural communities are more likely than urban centres to use forests and trees directly as sources of medicines, foods and nutrition.

Physical and mental health and well-being

There is increasing evidence that forests and trees contribute in many ways to people’s physical, mental and social well-being. Forests and woodlands, including those in urban areas, provide restorative environments – places where people can relax, reduce stress and screen out noise; forests and woodlands have the ability to absorb large numbers of people without seeming crowded. They also offer opportunities for a wide variety of exercise and fitness activities, and they can be inexpensive to visit, which is important for reducing health inequalities and enabling social inclusion.

Undertaking physical activities in forests and woodlands can have short-term benefits in terms of fitness, as well as longer-term health benefits in reducing obesity, cardiovascular disease, the risk of type 2 diabetes and colon disease and in promoting mental health, enhancing and protecting brain function, helping in the management of painful conditions, and improving health-related quality of life.

Government agencies are increasingly acknowledging the role of forests and woodlands in healthy lifestyles (see, for example, State of Europe’s Forests 2015). 

Health benefits through pharmaceutical products

Health benefits through pharmaceutical products

Traditional healthcare systems are based on significant local knowledge of medicinal plants. Traditional medicine is therefore often highly available and accessible to people in developing countries, and poor and marginalized people – especially those in rural areas –are often highly reliant on it.

Many pharmaceutical products are derived from tropical forest species; some of these products are now synthesized, but others are still collected in the wild. The economic value of traditional medicines derived from forest species (mainly plants) is considerable: the global value of the annual market for these products was estimated at US$60 billion in 2002.

Interest in traditional knowledge and medicine has grown in the last two decades, stimulated by the role of such knowledge in the development of new commercial products, including pharmaceuticals, herbal medicines, seeds, cosmetics, and personal care and crop protection productsTraditional knowledge is used in screening plants for medically active compounds.

The commercial users of traditional medicines (“bioprospectors”) are often companies and scientists in technologically advanced countries. Concerns have arisen in recent years about “biopiracy” – the unauthorized commercial use of genetic resources and traditional knowledge and the lack of sharing of the benefits with the countries and communities of origin, as well as the patenting of spurious “inventions” based on such knowledge and resources. In the case of traditional medicine, pharmaceutical companies have sometimes been charged with reaping unacceptably and disproportionally large benefits from the knowledge of forest peoples, many of whom live in highly impoverished conditions. Other more general threats to traditional knowledge and forest-based medicines are those posed by deforestation, forest degradation and over-exploitation, and the consequent loss of genetic diversity among therapeutic species, and the loss of traditional knowledge under fast-changing social and environmental conditions.

Exposure to natural environments, including forests

Exposure to natural environments, including forests

There is evidence that exposure to natural environments or green spaces has positive health impacts. Exposure to forests specifically has stress-reducing effects – possibly due to the recovery effect of viewing attractive or aesthetic forest landscapes, as well as the forest climate, light conditions and air composition (including essential oils).

Forest environments may also pose risks to human health. For example, people with frequent interactions with forests may be exposed to forest-related infectious diseases. Several emerging infectious diseases (EIDs), the incidence of which in humans has increased in recent decades and could increase further in the future, are associated with forests. The proximate causal factors in the emergence of EIDs include deforestation and other land-use changes, increased contact with forest pathogens among people lacking previous exposure, and pathogen adaptation. EIDs may be transmitted via non-human primate hosts or insect vectors, with a variety of intermediate hosts, including domestic animals.

The role of forests and forest management in the emergence of infectious diseases in humans appears to involve three separate but interacting dynamics:

  1. land-use change and the expansion of human populations into forest areas, resulting in the exposure of immunologically naïve human and domestic animal populations (i.e. those lacking previous experience with microparasitic fauna) to pathogens occurring naturally in wildlife;
  2. forest clearing and alteration producing an increase in the abundance or dispersal of pathogens by influencing host and vector abundance and distribution; and
  3. the alteration of ecohydrological functions such as water infiltration, peak discharge and runoff, thereby facilitating the survival and transport of water-borne pathogens in watersheds and catchment basins.

These changes are often linked to forest clearing and increased edge habitat, the fragmentation of the forest landscape, and disturbance of the vertical structure and diversity of forest stands.

The virus that causes yellow fever is maintained in a transmission cycle involving arboreal monkeys and sylvatic (jungle) mosquitoes, and a frequent cause of outbreaks is the expansion of human settlements into forests. In many areas, malaria – which causes the largest number of deaths and disabilities of any infectious disease, by far (300 million–500 million cases annually, with a death toll as high as 2.7 million) – is transmitted by forest-associated mosquitoes.

Forests have other risks for human health, such as those posed by forest fires (and associated smoke hazes) and landslides. Forests may harbour dangerous wildlife and toxic plants and fungi. The stings and bites of forest insects, snakes and other animals may cause irritation, pain and, in some cases, deaths in humans. Some forest plants produce pollen, a major cause of allergies, pointing to a clear need to identify non-allergenic or low-allergenic trees and other plants when designing parks and managing urban forests.

The diversity of forest types, wildlife, disease vectors, human populations and cultures, and interactions among these factors, all affect human health. It has been projected that the incidence of disease in forested areas and elsewhere will increase as the climate changes.