206
literature. The synthesis presented here indicates that different metrics of biodiversity (e.g. species richness; abundance) could play a role and should, therefore, have
their relationships with mental health and well-being assessed separately. Functional
aspects of biodiversity, such as phenotypic diversity (colour of fish, height of trees)
(Botzat et al. 2016) and charismatic species (Dallimer et al. 2012) could also be
usefully explored. Further, studies should also measure the biodiversity that is experienced by people, as opposed to the objectively measured diversity in an environment. The bird hiding in a bush, or the nocturnal mammal, that is not seen nor heard,
is unlikely to be experienced by humans, and unlikely to influence mental health or
well-being (Bell et al. 2014; Cox et al. 2017). Assessments of the biodiversity that
people perceive or experience can be captured with Global Positioning System
(GPS) trackers, eye-tracking technology and mobile electroencephalography (EEG)
devices. We also recognise that one’s perception of biodiversity is important for
health and well-being. The synthesis presented here demonstrated that perceived
species richness is associated with mental well-being. Future studies could investigate perceived species richness-mental health relationships. Further, whilst not
investigated in any of the studies reviewed here, perceived biodiversity could also be
investigated to assess whether it mediates the effect of objectively measured biodiversity on mental health and/or well-being. See de Vries and Snep Chap. 8, this
volume, for further discussion on biodiversity measurement considerations.
Mental Health and Well-being Assessment
To facilitate cross study comparison, we encourage future research to use validated
scales of mental health and well-being that have been used previously in psychology and health.
2
As such, researchers may wish to consider the reliability of using a
mental health or well-being measure for understanding the biodiversity-health relationship. When developing new measures, theoretically grounded outcome measures are essential.
Theory
Future studies should articulate the theoretical framework(s) they are using to
hypothesise about biodiversity-health relationships (see also Marselle Chap. 7, this
volume). Researchers should use theory to drive the selection of outcome measures
and identify mediators, moderators and confounders. To our knowledge, no study
has investigated the effect of biodiversity on attention restoration, and more studies
could investigate stress as an outcome measure; both of which explicitly test theories of restorative environments. Additionally, theories on the relationship of natural
environments on health, such as Attention Restoration Theory could be developed
further, e.g. by differentiating general effects of natural environments, and specific
aspects of biodiversity, on health aspects.
Mechanisms
Future studies should continue to investigate the mediators of biodiversity and mental health and well-being using the pathways identified in nature-health frameworks
(Hartig et al. 2014; Markevych et al. 2017).
2 Researchers may wish to see Linton et al. (2016) for a list of such measures.
M. R. Marselle et al.
literature. The synthesis presented here indicates that different metrics of biodiversity (e.g. species richness; abundance) could play a role and should, therefore, have
their relationships with mental health and well-being assessed separately. Functional
aspects of biodiversity, such as phenotypic diversity (colour of fish, height of trees)
(Botzat et al. 2016) and charismatic species (Dallimer et al. 2012) could also be
usefully explored. Further, studies should also measure the biodiversity that is experienced by people, as opposed to the objectively measured diversity in an environment. The bird hiding in a bush, or the nocturnal mammal, that is not seen nor heard,
is unlikely to be experienced by humans, and unlikely to influence mental health or
well-being (Bell et al. 2014; Cox et al. 2017). Assessments of the biodiversity that
people perceive or experience can be captured with Global Positioning System
(GPS) trackers, eye-tracking technology and mobile electroencephalography (EEG)
devices. We also recognise that one’s perception of biodiversity is important for
health and well-being. The synthesis presented here demonstrated that perceived
species richness is associated with mental well-being. Future studies could investigate perceived species richness-mental health relationships. Further, whilst not
investigated in any of the studies reviewed here, perceived biodiversity could also be
investigated to assess whether it mediates the effect of objectively measured biodiversity on mental health and/or well-being. See de Vries and Snep Chap. 8, this
volume, for further discussion on biodiversity measurement considerations.
Mental Health and Well-being Assessment
To facilitate cross study comparison, we encourage future research to use validated
scales of mental health and well-being that have been used previously in psychology and health.
2
As such, researchers may wish to consider the reliability of using a
mental health or well-being measure for understanding the biodiversity-health relationship. When developing new measures, theoretically grounded outcome measures are essential.
Theory
Future studies should articulate the theoretical framework(s) they are using to
hypothesise about biodiversity-health relationships (see also Marselle Chap. 7, this
volume). Researchers should use theory to drive the selection of outcome measures
and identify mediators, moderators and confounders. To our knowledge, no study
has investigated the effect of biodiversity on attention restoration, and more studies
could investigate stress as an outcome measure; both of which explicitly test theories of restorative environments. Additionally, theories on the relationship of natural
environments on health, such as Attention Restoration Theory could be developed
further, e.g. by differentiating general effects of natural environments, and specific
aspects of biodiversity, on health aspects.
Mechanisms
Future studies should continue to investigate the mediators of biodiversity and mental health and well-being using the pathways identified in nature-health frameworks
(Hartig et al. 2014; Markevych et al. 2017).
2 Researchers may wish to see Linton et al. (2016) for a list of such measures.
M. R. Marselle et al.