Urban trees support urban sustainability by contributing to the environmental, economic and social health of urban communities through the provision of important ecosystem services3,41,2. Therefore, enhancing and protecting urban trees is necessary to make cities inclusive, safe and resilient (https://sdgs.un.org/goals/goal11). This has been recognized from UN-led initiatives (https://habitat3.org) to numerous local initiatives to plant more trees in urban areas3. The success of such initiatives depends not only on technical knowledge about care, protection and planting, but also on the development and implementation of policies that respond to the needs and desires of the public, while taking into account people’s different perspectives and experiences with urban trees.
Despite efforts to increase urban tree stands, these populations are declining worldwide5 due to pressures from urban (re)development6 and climate change, which can exacerbate existing environmental stressors such as heat stress, drought, and pests and diseases7. In addition, the current distribution of urban trees is often uneven, leading to inequalities in experiences with them and the services they provide. For example, historical racial housing discrimination in the US today is linked to the disparity of urban trees across different neighborhoods8, which can result in lower well-being and other health indicators due to lower exposure to urban trees9.
While greater exposure to urban trees could be beneficial for health and well-being, tree propagation without considering how the community experiences and perceives it can produce incoherent and potentially harmful outcomes. Urban trees provide important regulating and providing ecosystem services, such as B. Air pollution regulation, noise reduction and heat reduction4,10, regardless of what people think or think about them, but they may not provide other services that are also desired by the community, such as aesthetic and cultural value, or for mitigation of disadvantages, such as allergies or windthrow11. In fact, urban trees that do not live up to people’s expectations can result in reduced community support for tree planting initiatives12.
To support successful improvement efforts and address existing inequalities, it is necessary to understand how specific responses to community perceptions are related to specific ecological structures around a person’s living environment. Perception is the way people mentally process information from their environment. Perception can be influenced by various biological (e.g., how we perceive), physical (ie, what we perceive, including specific objects or visual fields), and sociocultural factors (ie, how we interpret the inputs of what we perceive). How these factors can be taken into account when researching how people perceive urban nature depends on the specific perceptual responses (ie specific cognitive constructs such as values, beliefs, attitudes and preferences; see Methods section) and the specific ecological structures. Numerous studies have been conducted on people’s universal preferences for the urban environment and the role of images of nature in these preferences, with the aim of broadly integrating nature into these environments13,14. However, fewer studies have been conducted on people’s perceptual responses to specific ecological structures (e.g., values, beliefs, attitudes, and preferences related to the abundance, variety, arrangement, visibility, or state of urban trees)15.
An important perceptual response is contentment, that is, the discrepancy between expectation and experience, and an important ecological structure of the urban environment are urban trees. Satisfaction with urban trees is a useful perceptual response as it helps to understand whether people’s experiences of existing trees and management initiatives are consistent with their expectations16,17. While the assumption that more trees may lead to greater happiness is intuitive, this has not been explicitly explored at multiple spatial levels at which people experience these urban trees. Previous work has shown only a weak association between the presence of trees and satisfaction with them, based on the correlation between mean satisfaction and mean urban canopy at the city level18. However, it remains unclear whether tree abundance at relatively finer spatial scales (eg, neighborhood scale) translates into different levels of community satisfaction with trees.
Although perceptual response measures specific to urban trees are appreciated by practitioners, they are not typically considered in urban tree management19. Traditional measures focus on technical aspects or biophysical conditions, such as B. the maintenance, health, diversity, arrangement and distribution of urban trees20, or the consequences of these conditions, such as e.g. B. Ecosystem services and damage21. Social measures of economic (e.g. property values22) and sociological conditions (e.g. crime rates23) have been extensively studied in relation to the characteristics of urban trees8, but these measures typically do not capture community perceptual responses to urban trees, including happiness. Few studies have paired specific community perceptual responses with the characteristics of urban trees (e.g. frequency, variety, arrangement, condition)15,18. Recent research suggests that people’s preferences for biodiverse landscapes can be influenced by how diverse those landscapes are24,25 and that people’s preferences for places with or without trees can be influenced by the absence or presence of trees26. There are also numerous studies examining how people perceive the benefits/benefits or costs/disadvantages of urban trees in general27,28,29. However, there is no evidence that greater numbers and more visible urban trees could result in greater satisfaction with urban trees.
A challenge is that there are different methods for measuring the abundance and visibility of urban trees, as well as different spatial analysis scales. These different measurements and scales may not tally with how people perceive trees. For example, many studies have measured tree abundance using the Normalized Difference Vegetation Index (NDVI) derived from satellite imagery, which reflects the abundance of trees and all other vegetation, while others account for canopy cover. These approaches capture actions from a bird’s eye view9,30. Such measures are positively correlated with city-wide indicators of well-being and physical health1,2,31, but it is unclear whether these top-down measures are related to tree satisfaction.
Recently emerging urban green policies that may more accurately reflect people’s experiences of urban trees based on what is visible at eye level32,33. These “eye-level” green scores include the Green View Index, which uses street view data34, and the Viewshed Greenness Visibility Index (VGVI), which uses digital elevation data33. While these measurements also indicate positive associations with mental illness34 and subjective well-being35, the associations between measures of eye-level tree visibility and satisfaction with trees have not yet been explored.
This research examined whether people’s satisfaction with trees and their management is related to different types of greening measures at the neighborhood level. We addressed three research questions: (1) Is there a relationship between residents’ satisfaction with urban trees and green policies? (2) Is there a relationship between residents’ satisfaction with urban tree management and green policies? and (3) does the size or strength of the associations change when the neighborhood size changes?
By assessing both satisfaction with urban trees and satisfaction with the management of those trees (questions 1 and 2), we wanted to address different aspects of community satisfaction. On the one hand, people can be satisfied with the characteristics of the ecological structures around their living environment, such as their abundance, diversity, and distribution. On the other hand, people may be content with how they make decisions about these ecological structures, such as B. investments, responsiveness and maintenance, with such decisions directly impacting the abundance, diversity and distribution of urban trees. By asking about these two aspects, we can complementarily assess the different dimensions of community satisfaction with urban trees.
To answer these questions, we collected data on people’s perceptual responses through an online panel survey in the city of Toronto, Canada. The survey included questions about people’s satisfaction with urban trees and people’s satisfaction with urban tree management18. To account for the cognitive, socio-ecological context, and demographic influence on these perceptions, we also collected data on the level of nature connectedness36, level of tree knowledge37, and various socio-ecological context and demographic variables including age, education, and year of life in the neighborhood and cultural identity (see Methods).
Based on the postcodes of the survey participants, we calculated three green dimensions at district level. We focused on NDVI, percent canopy cover, and VGVI for trees only. Each measure was calculated based on three buffer sizes around the zip code: 100m, 300m and 500m. We then analyzed this data using regression-based approaches. In our analysis, we chose to control for these cognitive, socio-ecological, contextual, and demographic factors so that we can focus on the relationship between people’s subjective satisfaction and objective neighborhood-level greenery measures (see Methods).
We hypothesized that there would be a comparatively stronger positive association (i.e., higher correlation and coefficient values) between occupant satisfaction and the VGVI than for the NDVI and canopy, since the VGVI improves the visibility of urban trees at people’s eye level reflected than the other two top-down measures. We also hypothesized that there would be a comparatively stronger positive association between these measures at larger neighborhood scales, since tree greenness measures cover a larger spatial extent and include areas with larger tree counts, so at larger spatial scales of analysis the statistics may be due of the spatial aggregation effect indicate comparatively stronger correlations30,38 These hypotheses also have a psychosocial basis, considering the standard walking distance used in urban greenery and physical health studies31.
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https://www.nature.com/articles/s42949-023-00119-8
