Seite - 144 - in Biodiversity and Health in the Face of Climate Change

144 cognitive appraisal is positive, which results in positive emotional responses, and a reduction in negative emotions. These emotions may result in a change in physio- logical arousal, which could foster feelings of relaxation. Behavioural responses are to approach, explore or continue with one’s activities in this environment. 7.3.1.1 Connection to  Biodiversity in  the  SRT According to SRT, there are visual qualities of the natural environment that facili- tate these restorative responses. These visual qualities are: moderate to high com- plexity (i.e. number of independently perceived elements in a setting); a focal point in the setting to attract or direct attention; moderate to high level of depth (or open- ness); a smooth and even ground surface that is conducive for movement; a lack of threat; and presence of a deflected vista (e.g. path bending away) and water (Ulrich 1983). Biodiversity can be considered as a measure of an environment’s complexity (Ulrich 1983 p.  96). Based on Berlyne’s aesthetic model (see Sect. 7.2.1), Ulrich (1983, p.  97) speculated that high (e.g. ‘a  thicket’) and low levels (e.g. ‘a  flat, fea- tureless open field’) of complexity would not be preferred and generate an immedi- ate emotional reaction of dislike and low interest. From this, it is reasonable to assume that environments with moderate levels of complexity would be restorative as they would be preferred, have an immediate emotional reaction of like and inter- est, and behavioural responses to stay or explore in the environment. Researchers have investigated whether biodiverse environments could facilitate restorative outcomes associated with SRT.  Inconsistent results have been found. Fractal dimensions of habitats with varying levels of species richness were nega- tively correlated with physiological arousal, suggesting that physiological arousal is related to the fractal dimension of a natural landscape (Stevens 2018) (see Sect. 7.2.3). Greater perceived species richness of animals/plants was associated with more positive mood and arousal, suggesting that higher perceived levels of biodi- versity are associated with higher restorative outcomes related to SRT (White et  al. 2017). In an experimental study, participants’ positive affect, vitality and anxiety were assessed after viewing pictures of trees and birds with either low or high bio- diversity (Wolf et  al. 2017). Participants reported higher levels of positive affect, as well as lower levels of anxiety, in the high species-richness conditions of trees and birds, compared to low species-richness conditions; no effect was found for vitality between the high and low species-richness conditions of birds and trees. The level of biodiversity of fish and crustaceans in an aquarium had no effect on participants’ heart rate, blood pressure and mood (Cracknell et  al. 2016). In a separate study, pictures of fish and crustaceans with low or high species richness had no effect on happiness, when abundance of fish and crustaceans was held constant (Cracknell et  al. 2017). Ensinger and von Lindern (2018) found that wilderness environments facilitated greater positive arousal, but no change in negative arousal, compared to other landscape types (see Box 7.4). See Korpela et  al. (2018) for a deeper examina- tion of studies investigating biodiversity and SRT outcomes. M. R. Marselle