Does perceived restorativeness mediate the effects of perceived biodiversity and perceived naturalness on emotional well-being following group walks in nature?

• Examined restorativeness as mediator of biodiversity and naturalness on well-being.
• Perceived biodiversity and naturalness had no direct effect on emotional well-being.
• Perceived restorativeness mediated effect of perceived bird biodiversity on emotional well-being.
• Perceived restorativeness mediated effect of perceived naturalness on emotional well-being.

Natural environments are associated with positive health and well-being. However, little is known about the influence of environmental qualities on well-being and the mechanisms underlying this association. This study explored whether perceived restorativeness and it subscales would mediate the effects of perceived biodiversity, perceived naturalness, walk duration and perceived intensity on emotional well-being.Participants (n = 127) of a national walking program in England completed pre- and post-walk questionnaires (n = 1009) for each group walk attended within a 13-week period. Multilevel mediation examined the hypothesised indirect effects.Perceived restorativeness mediated the effects of perceived bird biodiversity, perceived naturalness, and perceived walk intensity on positive affect, happiness and negative affect. The effect of walk duration on happiness was also mediated by perceived restorativeness. Perceived walk intensity had a direct effect on positive affect and happiness.Findings have implications for theory development, future biodiversity-health research and practitioners interested in designing restorative environments.