Nature connectedness connects the visibility of trees through windows and mental wellbeing: a study on the “3 visible trees” component of the 3-30-300 rule

To examine the mediatory role of nature connectedness between tree visibility through windows and mental wellbeing, we conducted a questionnaire survey and examined the mediation effect using both cross-sectional and semi-longitudinal mediation models. We evaluated nature connectedness using the Inclusion of Nature in Self (INS) scale and the Connectedness to Nature Scale (CNS) and measured mental wellbeing using the WHO-5 wellbeing index. Our results showed that participants who could see at least three trees through their windows reported higher levels of both nature connectedness and mental wellbeing compared to those without such visibility. Nature connectedness significantly mediated the relationship between the visibility of trees through windows and mental wellbeing, albeit with a somewhat limited effect. More broadly, this study provides additional evidence in support of the "3" component of the 3-30-300 "rule" for equitable access to greenspace in cities.