The Relationship between Perceptions and Objective Measures of Greenness

Abstract

Exposure to greenness has been studied through objective measures of remote visualization of greenspace; however, the link to how individuals interpret spaces as green is missing. We examined the associations between three objective greenspace measures with perceptions of greenness. We used a subsample (n = 175; 2018–2019) from an environmental cardiovascular risk cohort to investigate perceptions of residential greenness. Participants completed a 17-item survey electronically. Objective measurements of greenness within 300 m buffer around participants home included normalized difference vegetation index (NDVI), tree canopy and leaf area index. Principal component analysis reduced the perceived greenspaces to three dimensions reflecting natural vegetation, tree cover and built greenspace such as parks. Our results suggest significant positive associations between NDVI, tree canopy and leaf area and perceived greenness reflecting playgrounds; also, associations between tree canopy and perceived greenness reflecting tree cover. These findings indicate that the most used objective greenness measure, NDVI, as well as tree canopy and leaf area may most align with perceptions of parks, whereas tree canopy alone captures individuals’ perceptions of tree cover. This highlights the need for research to understand the complexity of green metrics and careful interpretation of data based on the use of subjective or objective measures of greenness.

Greenspaces And Cardiovascular Health

“…Our work suggests that objective measures of greenness, in particular NDVI, may not be highly correlated with perceptions of neighborhood greenspaces. 191 While NDVI was positively correlated with tree canopy, leaf area, and perceived greenness reflecting playgrounds, it shows no associations between tree canopy and perceived greenness reflecting tree cover. 191 In some studies, researchers defined greenness based on their perception of the areas within their communities, not the communities’ or participants’ perceptions, or as defined by a quantitative metric.…”

“…191 While NDVI was positively correlated with tree canopy, leaf area, and perceived greenness reflecting playgrounds, it shows no associations between tree canopy and perceived greenness reflecting tree cover. 191 In some studies, researchers defined greenness based on their perception of the areas within their communities, not the communities’ or participants’ perceptions, or as defined by a quantitative metric. Consequently, health conclusions were drawn without relying on objective or standardized greenness variables or areas where those being studied had recognized the space as greened.…”