Page - 255 - in Biodiversity and Health in the Face of Climate Change

255 11.2 Overview of  Associations Between  Public Health and  Biodiversity Some ecosystem benefits in Fig.  11.1 rely on explicit exploitation of biodiversity (e.g. for food, medicine). There is abundant evidence that biodiversity is required for the basic needs of life (e.g.  food, clean water). However, for ‘nature experience’, biodiversity could have an  impact on human health  via multiple pathways, and these could operate differently depending on whether the nature experience is ‘passive’ or ‘active’. A more biodiverse environment may offer greater opportunities for active participation, whereby the pathways to health outcomes could include physical activity and a  reduction in social isolation. There are a number of theories proposed by which passive exposure to nature improves well-being, including Wilson’s (1984) Biophilia hypothesis, Ulrich et  al.’s (1991) Stress Recovery Theory, and Kaplan and Kaplan’s (1989) Attention Restoration Theory (see Marselle Chap. 7, this volume, for further discussion of these theories). Specifically, greater biodiver- sity may offer greater scope for ‘soft fascination’ (passive interaction, entered into almost involuntarily, catching and holding one’s attention), a feature of Attention Restoration Theory. Greater biodiversity would also be more likely to trigger the innate response predicted by the Biophilia Hypothesis. A given habitat can simultaneously provide multiple ecosystem (and therefore health) benefits. For example, tree canopies and open water provide shade and cooling in urban areas, providing physical benefits to human physiological systems, and can elicit aesthetic and spiritual benefits, thereby reducing stress, mental fatigue and exhaustion. Exposure to greenspace has been linked to a range of health benefits (Maas et  al. 2006; Nieuwenhuijsen et  al. 2017), and more naturalistic (and therefore possibly more biodiverse) environments have been postulated as being best suited to promoting such benefits (e.g. Tyrvainen et  al. 2014). There is little empirical evidence that biodiversity specifically (rather than natural environments in general) contributes directly to human health and well-being. Lovell et  al.’s (2014) systematic review iden- tified only 17 studies that included an explicit consideration of biodiversity and a health outcome, ten of which suggested an association. In the wider literature, there is some expectation that habitats found to provide health and well- being benefits may also be biodiverse; for example, Park et  al. (2011) reported mood changes, including in depression, when comparing forest to urban settings. One major work that does explicitly link human health with biodiversity in an urban context is Fuller et  al. (2007), who found an increase in psychological well-being with exposure to sites of high biodiversity (species richness). Luck et  al. (2011) also described associations between well-being and biodiversity (especially of vegetation). Much other research in this area provides evidence of (mainly positive) links between people’s perception of biodiversity and health and well-being benefits. From the wider literature, we can postulate some specific components of biodiversity that link to aspects of public health. Figure  11.2 presents a summary of our review of the links between levels of biodiversity (rows) and domains of public health (columns). The body of the table gives our assessment of the state of the evidence for links between the domains and levels of biodiversity. In general, the evidence for a direct link between biodiversity 11 Biodiversity and  Health in  the  Face of  Climate Change: Implications for  Public…