Page - 153 - in Biodiversity and Health in the Face of Climate Change

153 Service Cascade Model defines biodiversity as any biophysical structure or process (Potschin and Haines-Young 2011), and biodiversity can take on different roles in the cascade (Mace et  al. 2012). Biodiversity is not explicitly discussed in the Preference Matrix, SRT and ART.  In both the Preference Matrix and SRT, the term ‘complexity’ is used, which could be considered as a proxy for biodiversity; both frameworks define complexity as the number of independently different visual elements in a setting (Kaplan and Kaplan 1989; Ulrich 1983). This suggests that a biodiverse environment could be a complex environment due to having a greater number of independently different stimuli (i.e. species; Korpela et  al. 2018) and, indeed, Ulrich (1983) specifically states that biodiversity can be considered a measure of an environment’s complex- ity. ART does not discuss biodiversity. As such, one has to hypothesise how biodi- versity could be applied to the ART; for example, an environment with a greater number of different species may contain fascinating stimuli and afford the experi- ence of being away (Marselle et  al.  2016;  Korpela et  al. 2018). This hypothesis has empirical support (see Sect. 7.3.2.1). Which Theories Address Mental Well-Being? Mental well-being is discussed in the ART and SRT.  Both the ART and SRT are theories of restorative environments, which refer to the recovery of physiological or psychological resources that have been diminished through the demands of dealing with everyday life (Hartig et  al. 2011; von Lindern et  al. 2016). Over time, lack of restoration of these resources can lead to mental and physical ill health (Hartig et  al. 2011; von Lindern et  al. 2016). Health and well-being in the ART is the restoration of the ability to concentrate or direct  attention. In SRT, health and well-being is considered as the recovery from psychological and physiological stress reactions. Mental well-being is not explicitly discussed in the Preference Matrix, fractals, Biophilia Hypothesis and the Ecosystem Service Cascade Model. The first three of these frameworks are environmental preference models. Preference can signal that certain natural stimuli could possibly contribute to health or well-being (Hartig et  al. 2011), but cannot in itself be considered a health or well-being outcome (Lovell et  al. 2014). Recent studies on fractals are finding that visual fractal objects may contribute to attention restoration (Hagerhall et  al. 2015) and physiological arousal (Stevens 2018). The Ecosystem Service Cascade Model discusses human health and well- being as benefits derived from biodiversity and ecosystem services (Haines-Young and Potschin 2010; Potschin and Haines-Young 2011), but little research links eco- system services to human health and well-being (Sandifer et  al. 2015). Which Frameworks Discuss Mediating Pathways? All six frameworks detail the mediating pathways of the relationships between nature and health. These same mediating pathways could also account for biodiversity and mental well-being rela- tionships. The Preference Matrix suggests that informational needs of understand- ing and exploration mediate the relationship between informational qualities (e.g. complexity) and preference. Frameworks on fractals in nature suggest that percep- tual fluency, the ease of cognitively processing a visual stimulus, would explain 7 Theoretical Foundations of  Biodiversity and  Mental Well-being Relationships