Table 1.

Table of studies that conducted primary data collection relevant to any of the five components.

Study	Publication Type	Study Design	Population	Intervention	Control	Outcome	Headline Result
Pank et al. [30]	Commissioned report, not peer-reviewed.	Survey, social return on investment analysis, and qualitative study.	Broad range of stakeholders of the Gorgie City Farm.	Engagement with (as volunteer or visitor) Gorgie City Farm.	None	Broad range of outcomes related to mental health, eating habits, education, environment, NHS interactions.	Estimated a SROI of £3.56 for social value for every £1 invested in the project.
New Economic Forum [31]	Commissioned report, not peer-reviewed.	Case reports and costing analysis.	5 selected Ecominds participants.	5 different Mind funded Ecominds projects.	None	Avoided public sector costs.	Annual public sector costs avoided of between £4151 and £12,799 per person.
MIND [32,33]	Commissioned report containing two studies, not peer-reviewed.	Survey	Unspecified members of a local Mind green exercise groups.	19 groups covering a range of gardening, conservation, and walking activities.	None	Qualitative questionnaire related to the benefits of the groups.	109 questionnaires returned showing potential benefits of nature-based activities.
		Survey	20 members of local Mind associations (age 31 to 70).	Half an hour walk in a country park.	Half an hour walk inside a shopping centre.	Questionnaire covering self-esteem, mood, and mood disturbance.	Outside walk showed increase in all aspects of self-esteem and mood.
Wildlife Trust [34,35]	Unfunded peer-reviewed publication.	Before and after study.	318 members of 6 existing nature-based wellbeing projects.	Interventions range in design but all nature-based with focus on mental and physical wellbeing.	None	WEMWBS wellbeing scale collected at the start and end of each project.	Pooled results showed large improvement in wellbeing.
Thompson et al. [36]	NIHR funded peer-reviewed publication.	Before and after controlled quasi-experimental study and cost-effectiveness analysis.	Community living near woodlands selected for improvement.	Physical improvements to woodlands and community engagement activities.	Control population selected who lived further from the selected woods.	Primary outcome was stress (using the PSS), secondary included EQ-5D, and physical activity.	2117 responses indicated intervention was associated with increases stress, with no change in EQ-5D or physical activity.
Wilson et al. [37]	Peer-reviewed publication.	Before and after study.	People referred from secondary and tertiary mental healthcare services.	12 week programme of multiple ecotherapy activities in two areas.	None	Mental (WEMWBS), physical (SPAQ) and general (SF12) health questionnaires.	Little change in mental or general health but significant increase in physical activity.