BackgroundThere is increasing interest in the potential role of the natural environment in human health and well-being. However, the evidence-base for specific and direct health or well-being benefits of activity within natural compared to more synthetic environments has not been systematically assessed.MethodsWe conducted a systematic review to collate and synthesise the findings of studies that compare measurements of health or well-being in natural and synthetic environments. Effect sizes of the differences between environments were calculated and meta-analysis used to synthesise data from studies measuring similar outcomes.ResultsTwenty-five studies met the review inclusion criteria. Most of these studies were crossover or controlled trials that investigated the effects of short-term exposure to each environment during a walk or run. This included 'natural' environments, such as public parks and green university campuses, and synthetic environments, such as indoor and outdoor built environments. The most common outcome measures were scores of different self-reported emotions. Based on these data, a meta-analysis provided some evidence of a positive benefit of a walk or run in a natural environment in comparison to a synthetic environment. There was also some support for greater attention after exposure to a natural environment but not after adjusting effect sizes for pretest differences. Meta-analysis of data on blood pressure and cortisol concentrations found less evidence of a consistent difference between environments across studies.ConclusionsOverall, the studies are suggestive that natural environments may have direct and positive impacts on well-being, but support the need for investment in further research on this question to understand the general significance for public health.

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Global financial donors have invested billions of dollars in “Sustainable Forest Management” to conserve forests and the ecosystem services they provide. A major contributing mechanism, community forest management (CFM), aims to provide global environmental benefits (reduce deforestation, maintain biodiversity), while also improving local human welfare (alleviate poverty). We have systematically reviewed available evidence of CFM effectiveness and consider the implications of our findings for future investment in CFM programs. There is evidence of CFM being associated with greater tree density and basal area but not with other indicators of global environmental benefits. We found no data on local human welfare amenable to meta‐analysis. Poor study design, variable reporting of study methodology or context, and lack of common indicators make evidence synthesis difficult. Given the policy interest in and the planned donor expenditure on CFM, evaluation must be improved so that informed decisions can be made about appropriate investment in this approach.

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