A Review of Residents’ Perceptions of Urban Street Trees: Addressing Ambivalence to Promote Climate Resilience

Abstract

Street trees are a unique component of the urban forest. They provide multiple ecosystem services but can damage property and infrastructure, so they are frequently perceived with residents’ ambivalence. Global attempts to expand urban tree canopy cover to improve climate resilience are increasingly reliant on residents to establish and maintain street trees. Success depends on community support, which requires an understanding of how residents perceive trees located outside their homes. A review of the literature revealed 21 eligible studies on residents’ perceptions of street trees. Most of these studies were more than 10 years old and were restricted to single geographic regions but contained a wealth of information on factors including residents, sites, and trees. Few studies investigated the potential of these factors to influence residents’ perceptions; those that did had variable results. Inclusion of residents’ perceptions in street tree management requires careful consideration to account for the complexity of responses. Residents’ ambivalence can be addressed through increased awareness of the significant environmental, social, and economic values of street trees through public engagement programs and visual AI. Enforcement of tree protection policies and incentives for tree establishment and maintenance will also aid in the expansion of urban tree cover for improved climate resilience.

1. Introduction

Urban trees and forests are critical for the development of sustainable cities [1]. They provide numerous benefits across all three pillars of sustainability: environment, society, and economy [2]. Environmental benefits include pollution absorption [3], storm water mitigation [4], provision of habitat [5], atmospheric cooling [6], and amelioration of urban heat [7,8]. Social benefits of urban trees provided to people living within the built environment include aiding in recovery from stress and illness [9], reduced risk of heat wave mortality [10], reduced mental fatigue [11], and lowered rates of lung cancer [12]. The opportunity to interact with urban forest has been described by some as a human right [13]. Urban trees also promote a sense of community and place attachment [14]. The economic benefits derived from urban trees include reduced costs associated with heating and cooling of living spaces, water regulation [15], and increased land values [16].

Recognising the many benefits of urban trees, numerous cities around the world have implemented programs to expand urban tree canopy cover [17]. The targets are often ambitious, and include efforts to maintain and nurture existing trees as well as establish new trees through local, regional, and global initiatives [18]. Urban forests include trees growing on both private and public land; however, government initiatives to expand tree canopy cover predominately target public land. Street trees have been identified as a priority nature-based solution for many cities facing the overlapping challenges of managing urbanisation, climate change, health, and social inequalities [19].

Street or roadside easements often represent a significant portion of urban green space available for tree planting [20], although information is biased towards cities in Europe, North America, and Asia [21]. In Seattle, United States, road verges comprised almost 5% of land area [22], and approximately 7% in 10 census districts in New York State, United States [23]. In Melbourne, Australia, roadsides account for over 36% of public greenspace [24]. Tree canopy associated with such easements is a variable but often significant part of the urban forest, accounting for almost 12% in Melbourne [25] and 35% in Brisbane, Australia [26], and between 4 and 46% in Davis, California, United States [27]. In Wuhan, China, urban forest cover accounts for between 15 and 22% of the surface area, a considerable proportion of which is occupied by street trees [28]. Governments are increasingly turning to regulatory mechanisms such as local bylaws and policies including state and federal legislation to help preserve urban forests [29]. The adoption of tree protection is usually driven by appreciation of urban forests, but non-compliance may be driven by socioeconomic pressures and other factors [30].

Expansion of street tree networks is a prominent component of many urban tree planting initiatives [31,32]. In a nationwide survey in the United States, over half the trees included in recent planting initiatives were along public streets [33]. Planting of new street trees is especially relevant in new residential developments where urban green infrastructure is often restricted to streets [34].

In contemporary urban forest governance, residents are increasingly being asked to participate in tree management [35]. This includes efforts to increase canopy cover through the care and maintenance of existing trees and establishment of new trees [36]. Obviously, the success of such an agenda depends on public engagement and support [37]. This places inordinate importance on human perceptions and behaviour in relation to urban green resources [38], and has led to calls to increase understanding of public opinions about urban trees [39]. Knowledge about residents’ perceptions of positive and negative impacts of urban trees is therefore fundamental in designing and planning green infrastructure for sustainable cities [40].

Street trees have not always been part of the urban landscape. The streets of early cities were often void of trees [41,42], and the concept of an urban tree is sometimes considered somewhat paradoxical (Schulze, 1881 in [41]). Street trees, in particular, are positioned both physically and conceptually in an ‘ambiguous space between built and natural environments’ [43] (p. 46). When planted along a street, trees are seen as part of a streetscape along with other elements such as flooring, lighting, and street furniture [34]. They are expected to perform as pieces of built infrastructure [44], despite the fact that they are living organisms. Street trees provide many of the benefits (services) described for other elements of green infrastructure [45]; however, they can also cause problems (disservices) (Figure 1). For example, roots and branches can damage surrounding infrastructure including drains and footpaths, while leaves, flowers, fruit, and seeds create debris that has to be managed and incurs an economic cost [46]. Negative impacts on humans can lead to physical (e.g., allergies [47]), social (e.g., reduced mobility [48]), and psychological harm (e.g., fear [49]).

People often have ambivalent responses to the presence of street trees, with opinions being many and varied [37], but often strongly polarised and highly emotive [50]. Differences in perceptions have been noted among stakeholder groups including local and state government departments, urban forestry professionals, visitors, pedestrians, cyclists, city workers, street vendors, urban developers, and homeowners [20,33,51,52]. Differences in perceptions have also been attributed to demographic factors including those relating to the person (e.g., age [53], income and housing type [54], race and ethnicity [55], gender [56], and socio-demographic background [57]), the tree itself (e.g., species [57,58], size [57], shape or form [59], and location of the tree [39,60,61], including how visible it is from within the house [62]), and seasonal changes [53].

Despite the complex nature of human perceptions, most studies report that the services (benefits or advantages) of street trees outweigh disservices (annoyances or disadvantages) [46,53,63], and therefore, residents can be relied upon to support tree canopy growth targets. While this broad generalisation may be true across the general population, there is evidence to suggest that results may be quite different under more specific situations. Most notably, residents’ perceptions of street trees directly outside their homes may be very different from their view of urban trees more generally. Schroeder et al. [64] documented the ‘I love trees, but not in front of my house’ phenomena, highlighting that many people approve of the idea of urban trees but are not always happy with the reality of them [65]. In Pennsylvania, for example, residents with a street tree in front of their house had significantly poorer attitudes towards street trees than residents that did not [61]. A tree directly in front of a person’s home has tactile, auditory, and olfactory qualities that impact householder attitudes [66]. Further, street trees are linked to people’s experiences of place attachment [14], which vary with spatial scale—from an individual’s home to a neighbourhood or city [67]. The inconclusive nature of reported views demonstrates that our understanding of people’s perceptions and preferences regarding street trees is still limited [58], and knowledge about the motivations and drivers of both perceptions and behaviours is even less comprehensive [40].

Rationale for This Review

The effects of street trees on environmental variables (e.g., microclimate) have been extensively reported [68]. Similarly, perceived services and disservices, preferences, and measures of satisfaction associated with urban trees and green infrastructure among different stakeholders have all been recently reviewed [20,35,69,70]. However, none of these works provide adequate information to help inform current efforts to increase urban tree canopy cover through programs that rely on residents to care for street trees outside their homes.

The aim of this study was to closely examine the peer-reviewed published literature relating specifically to residents’ perceptions of urban street trees. We firstly assessed the general characteristics of the body of research, including spatial and temporal variation, research methods, metrics, and data granularity. We then compiled a list of demographic and descriptive data collected in each study, which included information about the study participants (resident(s)), location (site), and the street tree(s) in question. Finally, we recorded residents’ perceived services and disservices of street trees. Our findings are discussed in relation to addressing residents’ ambivalence toward the increasing need to utilise urban trees in the development of climate resilient cities. We provide insights to help direct future initiatives, investments, and policies in urban forest management, particularly considering rapid urban development and climate resilience.

2. Materials and Methods

2.1. Review Design and Implementation

To follow good practice, we conducted a literature review based on the PSALSAR (Protocol, Screening, Appraisal, Synthesizing, Analysis and Reporting) framework that provides an explicit, transferable, and reproducible way to conduct systematic review work that helps to assess both quantitative and qualitative content that is applicable within the environmental sciences [71] with reference to the PRISMA 2020 statement [72]. The study scope included global peer-reviewed literature in indexed journals, available online and written in English. We searched two multidisciplinary databases: Web of Science (Clarivate) and Scopus (Elsevier), which are the two main bibliographic databases [73] generally accepted as the most comprehensive data sources for scientific purposes [74]. The initial search was conducted on 9 May 2024, and a follow-up search was conducted on 21 May 2024.

Search terms were designed to firstly identify studies relating to perceptions of street trees expressed by urban residents. For Web of Science, we used a strict search: ALL-FIELDS (“street tree*” OR “sidewalk tree*” OR “road verge tree*” OR “nature strip tree*” OR “tree lawn tree*” OR “boulevard tree*”) AND (perception* OR attitude* OR preference* OR feeling* OR service* OR large* OR small* OR resident* OR homeowner* OR householder*); for Scopus, we used ARTICLE TITLE, ABSTRACT, KEYWORDS (“street tree*” OR “sidewalk tree*” OR “road verge tree*” OR “nature strip tree*” OR “tree lawn tree*” OR “boulevard tree*”) AND (perception* OR attitude* OR preference* OR feeling* OR service* OR large* OR small* OR resident* OR homeowner* OR householder*).

From the initial results, we identified review articles (n = 58), which were checked to make sure the topic had not been reviewed elsewhere. No similar reviews were found, so the search was repeated excluding review articles. To be considered for inclusion, articles had to report original research with qualitative and/or quantitative data.

Search results (Web of Science, n = 691; Scopus, n = 648) were imported to Covidence (Veritas Health Innovation Ltd., Melbourne, Australia), where duplicate entries were identified and repetitions were removed (n = 437). Citation searches, including the review articles identified in the initial search, identified an additional 48 references. Studies were screened for their title and abstract and were excluded if (i) they did not specify where the trees being studied were located (i.e., the study was not demonstrated to be specifically about street trees), (ii) street trees were considered together as part of the urban forest or general urban green infrastructure such as vegetation in public parks or private gardens, (iii) responses of residents could not be separated from other stakeholders, or (iv) responses were related to perceptions of factors other than street trees (e.g., general environment, climate or microclimate, thermal comfort, safety/fear). All studies not excluded were able to be retrieved (n = 208) and were eligible according to these criteria, so full texts were screened. The result was 21 articles eligible for inclusion in this review. An overview of the article selection process is presented in the PRISMA flowchart in Figure 2.

2.2. General Study Characteristics

The year of each publication was collected to determine a basic publication pattern including journal titles, authors, and affiliations for included works. Information describing general study characteristics included geographical spread (the country in which a study was conducted was recorded as the geographic location/continent, following work by Cheng et al. [75]). We determined the Koppen climate classification (see [76]) for each city in which a study was conducted, together with details about the types of street trees studied (genera and species) where they were specifically mentioned.

2.3. Assessment of Study Components and Metrics

To understand how the eligible studies had been conducted, at what scale they had been performed, and the types of measurements that were recorded, we collated information related to three key study components. These were described as the method(s) of investigation (i.e., mailed or online survey, interview, or presentation), the scale (i.e., whether the information collected related to a single tree outside a residential building, multiple trees on a single residential street, street trees within a neighbourhood, or street trees in the more general sense, giving an indication of data granularity), and metrics (or response type, i.e., Likert scale, open-ended questions, or binary responses).

2.4. Assessment of Study Quality

Study methods were assessed using a modified form of the mixed methods appraisal tool (MMAT, 2018 version; [77]) to help analyse the diversity of methods and gather insights into the robustness of techniques and quality of studies. The MMAT is a systematic procedure for critical appraisal of methods of social and psychological studies [78] that combine qualitative and quantitative evidence [79] using binary assessments (yes/no responses) for a series of questions relating to qualitative, quantitative, and mixed methods studies. Here, all studies reviewed were assessed using the criteria relating to the qualitative, quantitative–descriptive, and mixed methods categories of study design (

Table A5. Screening questions and quality criteria used for mixed methods appraisal tool (MMAT, based on [77]).

Category of Study Design	Methodological Quality Criteria
Screening questions	S1. Are there clear research questions?
	S2. Do the collected data allow to address the research questions?
Qualitative	1.1. Is the qualitative approach appropriate to answer the research question?
	1.2. Are the qualitative data collection methods adequate to address the research question?
	1.3. Are the findings adequately derived from the data?
	1.4. Is the interpretation of results sufficiently substantiated by data?
	1.5. Is there coherence between qualitative data sources, collection, analysis and interpretation?
Quantitative–descriptive	4.1. Is the sampling strategy relevant to address the research question?
	4.2. Is the sample representative of the target population?
	4.3. Are the measurements appropriate?
	4.4. Is the risk of nonresponse bias low?
	4.5. Is the statistical analysis appropriate to answer the research question?
Mixed methods	5.1. Is there an adequate rationale for using a mixed methods design to address the research question?
	5.2. Are the different components of the study effectively integrated to answer the research question?
	5.3. Are the outputs of the integration of qualitative and quantitative components adequately interpreted?
	5.4. Are divergences and inconsistencies between quantitative and qualitative results adequately addressed?
	5.5. Do the different components of the study adhere to the quality criteria of each tradition of the methods involved?

). To provide greater differentiation of quality assessments, we modified the responses from ‘yes = 1’, ‘no = 0’, or ‘cannot tell’ to ‘yes-fully = 1’, ‘yes-partially = 0.5’ or ‘no = 0’.

2.5. List of Services and Disservices

A complete list of perceived benefits and advantages (hereafter referred to as services) and disadvantages (hereafter referred to as disservices) of street trees was also generated. Where a service or disservice was described by very similar wording in different studies, it was listed only once using the most common or appropriate description. For example, a service described as being ‘pleasing to the eye’ was considered to be equivalent to ‘aesthetically pleasing’ and was therefore recorded as ‘aesthetically pleasing’ and counted as having been used in multiple studies. We also identified where a feature was considered a service in some cases but a disservice in others (e.g., ‘screens unwanted views’ was considered to represent the same sentiment as ‘blocks views’ where the former is a service, and the latter is a disservice).

To enable identification of the type of tree traits most highly valued as well as those viewed as most problematic, perceptions were noted as relating to social, environmental, and/or economic aspects (adapted from [40]). All aspects of each service and disservice were noted, with some perceptions pertaining to multiple aspects. For example, the service of ‘provide food’ was considered to have both social and economic aspects. Where the intention behind the statement was unclear, a service or disservice was recorded as pertaining to all aspects that could reasonably be applied.

2.6. Identification of Factors Related to Residents’ Perceptions

A list of factors that were linked to residents’ perceptions of street trees was compiled. To provide an understanding of the distribution of types of information collected, factors were categorised as relating to the (i) participant (resident) demographics, (ii) location (site) characteristics, or (iii) individual tree characteristics. For example, participant demographics included resident age, gender, and income, while site characteristics included type of residence, affluence level of the suburb, and aggregated data such as tree density, average tree height, and diameter. Characteristics of individual street trees included genus, species, age, health, and qualitative information about tree size and shape. We also recorded whether or not the factor was noted or tested to have had an impact on residents’ perceptions.

3. Results

3.1. General Study Characteristics

Surprisingly, the literature search identified a total of only 21 articles (full details of the articles are provided in Appendix A,

Table A1. Details of the publications included in the literature review.

No.	Author (s)	Year	Title	Journal	doi
1	Anujan, K.; Velho, N.; Kuriakose, G.; Ebin, P.J.; Pandi, V.; Nagendra, H.	2024	Beyond the metropolis: street tree communities and resident perceptions on ecosystem services in small urban centres in India	Journal of Urban Ecology	10.1093/jue/juae004
2	Booth J.A.	2006	Developing a sustainable community strategy for street trees II. Research for strategic development	Arboricultural Journal	10.1080/03071375.2006.9747458
3	Breuste, J.H.	2013	Investigations of the urban street tree forest of Mendoza, Argentina	Urban Ecosystems	10.1007/s11252-012-0255-2
4	Carmichael, C.E.; McDonough, M.H.	2018	The trouble with trees? Social and political dynamics of street tree-planting efforts in Detroit, Michigan, USA	Urban Forestry and Urban Greening	10.1016/j.ufug.2018.03.009
5	Coleman, A.F.; Eisenman, T.S.; Locke, D.H.; Harper, R.W.	2023	Exploring links between resident satisfaction and participation in an urban tree planting initiative	CITIES	10.1016/j.cities.2023.104195
6	Coles, R.; Millman, Z.; Flannigan, J.	2013	Urban landscapes—everyday environmental encounters, their meaning and importance for the individual	Urban Ecosystems	10.1007/s11252-013-0327-y
7	Flannigan, J.	2005	An evaluation of residents’ attitudes to street trees in southwest England	Arboricultural Journal	10.1080/03071375.2005.9747428
8	Gorman, J.	2004	Residents’ opinions on the value of street trees depending on tree location	Journal of Arboriculture	10.48044/jauf.2004.005
9	Gwedla, N.; Shackleton, C.M.	2019	Perceptions and preferences for urban trees across multiple socio-economic contexts in the Eastern Cape, South Africa	Landscape and Urban Planning	10.1016/j.landurbplan.2019.05.001
10	Heimlich, J.; Sydnor, T.D.; Bumgardner, M.; O’Brien, P.	2008	Attitudes of residents toward street trees on four streets in Toledo, Ohio, U.S. before removal of ash trees (Fraxinus spp.) from Emerald ash borer (Agrilus planipennis)	Arboriculture and Urban Forestry	10.48044/jauf.2008.007
11	Hunter, M.R.	2011	Impact of ecological disturbance on awareness of urban nature and sense of environmental stewardship in residential neighborhoods	Landscape and Urban Planning	10.1016/j.landurbplan.2011.02.005
12	Jeong, N.-R.; Han, S.-W.; Ko, B.	2023	Understanding urban residents’ perceptions of street trees to develop sustainable maintenance guidelines in the Seoul Metropolitan Area, Korea	Forests	10.3390/f14040837
13	Pistón, N.; Silva Filho, D.S.E.; Dias, A.T.C.	2022	Social inequality deeply affects people’s perception of ecosystem services and disservices provided by street trees	Ecosystem Services	10.1016/j.ecoser.2022.101480
14	Richardson, E.; Shackleton, C.M.	2014	The extent and perceptions of vandalism as a cause of street tree damage in small towns in the Eastern Cape, South Africa	Urban Forestry and Urban Greening	10.1016/j.ufug.2014.04.003
15	Schroeder, H.W.; Ruffolo, S.R.	1996	Householder evaluations of street trees in a Chicago suburb	Journal of Arboriculture	10.1016/j.ufug.2014.04.003
16	Sommer, R; Barker, P.A.; Guenther, H.; Kurani, K.	1989	Householder evaluation of two street trees species	Journal of Arboriculture	10.48044/jauf.1989.023
17	Sommer, R; Sommer, B.A.	1989	The factor structure of street tree attributes	Journal of Arboriculture	10.48044/jauf.1989.053
18	Sommer, R; Guenther, H.; Barker, P.A.	1990	Surveying householder response to street trees	Landscape Journal	10.3368/lj.9.2.79
19	Sommer, R.; Guenther, H.; Cecchettini, C.L.	1992	A user-based method for rating street trees	Landscape Research	10.1080/01426399208706372
20	Sommer, R.; Guenther, H.; Barker, P.A.; Swenson, J.P.	1993	Comparison of four methods of street tree assessment	Journal of Arboriculture	10.48044/jauf.1993.005
21	Williams, K.	2002	Exploring resident preferences for street trees in Melbourne, Australia	Journal of Arboriculture	10.48044/jauf.2002.024

). The biggest reduction in potential publications was at the full text screening stage, with the majority of studies deemed to be ineligible because they incorporated perceptions of street trees into the wider context of urban greenspace, forests, woodlands, or parklands. Unfortunately, these studies were unable to be used in subsequent analyses since they could not be interpreted for views specifically about street trees. The lack of clear distinction among terms has been noted as causing a challenge for reviews in urban forest research [80]. Another important point of exclusion was studies not reporting specifically on interactions between residents and trees in close vicinity of their properties. Such studies did not allow separation of perceptions of the subset of residents from other stakeholders. Our search criteria are not exceptional as the earliest year of publication for the sample set reviewed was 1989 and the most recent was published in 2024. For the years between, there has been a single study published around every 2–3 years, with two papers published in 2013 and 2023. This is clearly a topic that has been investigated for some time but not frequently or extensively.

The perception of street trees has been studied in a total of 37 different cities (

Table A2. Details of cities (state, country, and geographical region/continent) included in the studies reviewed. (Note: Ref. no. refers to publications in Table A1. UK, United Kingdom; US, United States; MI, Michigan; MA, Massachusetts; PA, Pennsylvania; OH, Ohio; IL, Illinois; CA, California; VIC, Victoria).

No.	City, State	Country	Geographical Region/Continent	Koppen Climate Classification
1	Kochi	India	Asia	Tropical monsoon (Am)
	Panjim	India	Asia	Tropical monsoon (Am)
2	Derby	UK	Europe	Humid temperate oceanic (Cfb)
3	Mendoza	Argentina	South America	Arid desert (BWk)
4	Detroit, MI	US	North America	Humid continental (Dfa)
5	Greenfield, MA	US	North America	Humid continental (Dfb)
6	Birmingham	UK	Europe	Temperate oceanic (Cfb)
7	Torbay	UK	Europe	Temperate oceanic (Cfb)
	North Somerset	UK	Europe	Temperate oceanic (Cfb)
8	State College, PA	US	North America	Humid continental (Dfa)
9	Libode	South Africa	Africa	Temperate oceanic (Cfb)
	Peddie	South Africa	Africa	Temperate oceanic (Cfb)
	Tsolo	South Africa	Africa	Temperate oceanic (Cfb)
	Port St John’s	South Africa	Africa	Temperate oceanic (Cfb)
	Cradock	South Africa	Africa	Temperate oceanic (Cfb)
	Matatiele	South Africa	Africa	Temperate oceanic (Cfb)
	Queenstown	South Africa	Africa	Temperate oceanic (Cfb)
	Willowmore	South Africa	Africa	Temperate oceanic (Cfb)
	Burgersdorp	South Africa	Africa	Temperate oceanic (Cfb)
	Graaff-Reinert	South Africa	Africa	Temperate oceanic (Cfb)
10	Toledo, OH	US	North America	Humid continental (Dfa)
11	Ann Arbor, MI	US	North America	Humid continental (Dfa)
12	Seoul	South Korea	Asia	Humid continental (Dwa)
13	Rio de Janeiro	Brazil	South America	Tropical savanna (Aw)
14	Grahamstown	South Africa	Africa	Humid subtropical (Cfa)
	Adelaide	South Africa	Africa	Cold semi-arid (steppe) (BSk)
15	Downers Grove, IL	US	North America	Humid continental (Dfa)
16	Sacramento, CA	US	North America	Hot Mediterranean (Csa)
17	Albany CA	US	North America	Cool Mediterranean (Csc)
	Berkeley, CA	US	North America	Warm Mediterranean (Csb)
	Davis CA	US	North America	Hot Mediterranean (Csa)
	Fairfield, CA	US	North America	Hot Mediterranean (Csa)
	Napa, CA	US	North America	Warm Mediterranean (Csb)
	Sacramento, CA	US	North America	Hot Mediterranean (Csa)
	Stockton, CA	US	North America	Hot Mediterranean (Csa)
	Vacaville, CA	US	North America	Hot Mediterranean (Csa)
18	Davis, CA	US	North America	Hot Mediterranean (Csa)
	Stockton. CA	US	North America	Hot Mediterranean (Csa)
	Sacramento, CA	US	North America	Hot Mediterranean (Csa)
	Berkeley, CA	US	North America	Warm Mediterranean (Csb)
	Napa, CA	US	North America	Warm Mediterranean (Csb)
	Albany, CA	US	North America	Cool Mediterranean (Csc)
	Fairfield, CA	US	North America	Hot Mediterranean (Csa)
	Vacaville, CA	US	North America	Hot Mediterranean (Csa)
19	Sunnyvale, CA	US	North America	Warm Mediterranean (Csb)
	Redwood City, CA	US	North America	Warm Mediterranean (Csb)
20	Sunnyvale, CA	US	North America	Warm Mediterranean (Csb)
	Redwood City, CA	US	North America	Warm Mediterranean (Csb)
21	Melbourne, VIC	Australia	Oceania	Temperate oceanic (Cfb)

), the highest proportion (52%) having been conducted in North America. This was largely due to the two multiple-city studies in CA, both by Sommer et al. [81,82]. Several studies included multiple cities: five studies included two cities; two studies included eight cities; and one study included ten cities. Most studies have been conducted in coastal cities with Mediterranean climates (Koppen classifications Csa and Csb) where there are hot or warm summers.

More than 121 tree species within 60 genera were mentioned in the studies reviewed (

Table A3. Street tree genus and number of species in each genus, with the number of studies in which they are mentioned.

Genus	No. of Species	No. of Studies
Acacia	3	5
Acer	5	5
Agonis	1	1
Ailanthus	1	1
Albizia	1	1
Allocasuarina	1	1
Angophora	1	1
Bombax	1	1
Callitris	1	1
Callistemon	2	1
Carpinus	1	2
Cassia	1	1
Celtis	4	4
Cocos	1	1
Corymbia	1	1
Cupressus	1	2
Delonix	1	1
Ekebergia	1	1
Eucalyptus	2	2
Fraxinus	11	11
Geijera	2	2
Gleditsia	3	3
Gliricidia	1	1
Gymnocladus	1	1
Jacaranda	1	1
Lagerstroemia	1	1
Lannea	1	1
Lophostemon	1	1
Ligustrum	1	1
Liquidamber	4	4
Liriodendron	5	5
Magnolia	2	2
Malus	1	1
Mangifera	1	1
Melaleuca	1	1
Melia	2	2
Monoon	1	1
Morus	1	1
Peltophorum	1	1
Pinus	2	2
Pistacia	1	2
Platinus	13	13
Podocarpus	1	2
Populus	2	2
Prosopis	1	1
Pyrus	2	4
Quercus	3	3
Robinia	2	2
Salix	1	1
Schinus	1	1
Sophora	2	2
Sorbus	2	2
Terminalia	1	1
Thespesia	1	1
Tilia	3	4
Tipuana	1	1
Tristania	1	2
Ulmus	6	6
Wodyetia	1	1
Zelkova	2	2

), with 27 genera (45%) mentioned in multiple studies, the 3 most frequent genera being Platanus, Fraxinus, and Ulmus (

Table 1. Names of street tree genera mentioned in reviewed studies with number (and %) of studies in which they appear.

Genus	No. of Studies	% of Studies
Platanus	9	21
Fraxinus	8	19
Ulmus	6	14
Liriodendron	5	12
Liquidamber	4	10
Tilia	4	10
Acer	3	7
Gleditsia	3	7

). The two most popular species were Liriodendron tulipefera and Platanus acerifolia (five studies each).

3.2. Study Components and Metrics

Residents’ perceptions of urban street trees were investigated via one of three main methods: surveys (posted or online), face-to-face interviews, or slide presentations (

Table 2. Number and proportion of studies using specific metrics relating to each study component: method, scale, and measures (data provided for genera noted in more than two studies).

Study Component	Metric	No. of Studies	% of Studies
Method	Survey—posted	12	52
	Interview	8	35
	Survey—online	2	9
	Slide presentation	1	4
Measures	Likert scale	17	77
	Open-ended questions	3	14
	Binary responses	2	9
Scale	Outside home	8	38
	In neighbourhood	7	33
	On home street	5	24
	In general	1	5

). For the slide presentations, a set of photographs displayed on slides were presented to respondents who used a 5-point scale to rate trees for various attributes such as visual aesthetics and ‘overall suitability’. Two studies used multiple methods. Two studies included the use of photographs to depict various tree characteristics in addition to verbal or written descriptors. The scale of the studies and the resultant level data granularity were determined by the material presented to study participants (Table 2), and were considered as the following: single or specific target tree outside the home (38%), multiple trees on a single residential street where the respondent lives (24%), street trees within the neighbourhood or general residential area where the respondent lives (33%), or street trees in a more general sense (5%).

Quantitative and qualitative data were collected via responses to predetermined multiple-choice questions or open-ended questions (Table 2). The majority of studies (77%) used Likert scales (4-, 5-, or 7-point scales). Fewer studies used open-ended questions (14%) or binary responses (9%). Studies collected responses regarding ‘satisfaction with perceived attributes’, ‘rating of suitability of tree species’, ‘overall rating of tree outside home’, ‘perceived importance of street tree’, or ‘preferences for tree attributes (e.g., size, form, foliage texture)’.

3.3. Study Quality

Use of the mixed methods appraisal tool (MMAT) showed that most reviewed studies had a clear research question and that the data collected were appropriate to address the research question(s) asked (Criteria S1 and S2, Figure A1a). Qualitative, quantitative–descriptive, and mixed methods studies all showed similar results. Data collection was generally appropriate but of moderate quality (Figure A1b–d), indicated by mean values generally between 0.7 and 0.8 (means closer to 1 indicating higher value for that criterion). Criterion 5.1 received the highest score (0.98), indicating that there was good evidence that the use of a mixed methods study design was appropriate to address the questions being asked in the street tree investigations reviewed. The risk of non-responsive bias (Quantitative 4.4) scored the lowest of all criteria (mean value of 0.6), primarily because many studies reported low response rates to surveys.

3.4. Services and Disservices

The studies identified that street trees provided more perceived services (n = 46) than disservices (n = 37) (

Table A4. A description of services and disservices of street trees perceived by residents, the aspects they relate to (S, social; Env, environmental; Eco, economic), and the number of studies in which they occurred.

	Description	Aspect(s)	No. of Studies
Services	Aesthetically pleasing	S	15
	Provides autumn colour	S	8
	Flowers are attractive	S	7
	Enhances look of yard and home	S	2
	Make city look better and brighter	S	2
	Add colour and green to the street	S	1
	Make neighbourhood feel safer	S	1
	Exercise from raking leaves	S	1
	Reduces noise	S, Env	8
	Cools home in summer	S, Env, Eco	9
	Sense of wellbeing	S	1
	Symbolises life and nature	S	1
	Provides nice smell on street	S	1
	Leaves make interesting sounds	S	1
	Improves psychology/happiness/calming	S	2
	Stress relief	S	1
	Brings nature closer/’countryside’ in the city	S	4
	Increases privacy	S	9
	Screens unwanted views	S	2
	Make city better place to live	S	2
	Increases sense of home, family, community	S	10
	Provides spiritual values (place for shrines)	S	4
	Improve city’s image	S	1
	Offers historical/heritage context to street	S	2
	Provides cultural values	S	1
	Provide place for children/people to play	S	3
	Help define property boundary	S	1
	Makes neighbourhood more livable	S	1
	Marks change in season	S	5
	Gives shade (in home/garden)	S	13
	Slows wind speed (act as windbreak)	S, Env	9
	Filters pollutants from air	S, Env	6
	Takes up carbon dioxide	Env	2
	Provides oxygen	Env	2
	Improved (important for) environment	Env	4
	Maintain urban ecosystems	Env	1
	Intercepts rain/flood mitigation	Env	3
	Roots cleanse the soil	Env	1
	Attracts birds/wildlife	Env	3
	Provides habitat for wildlife/birds	Env	5
	Increases property values	Eco	1
	Makes area look more affluent/established	Eco	1
	Lowers utility bills	Eco	2
	Attracts business	Eco	1
	Provide food	S, Eco	1
	Provide firewood/timber/medicine	S, Eco	1
Disservices	Aesthetically displeasing/unattractive	S	1
	Makes street dark/blocks streetlight	S	7
	Blocks views	S	5
	Fear of root damage	S	1
	Host bad spirits	S	1
	Fear of falling limbs	S	8
	Causes allergies	S	9
	Reduces personal safety	S	5
	Slip on fruit	S	1
	Obscure traffic signs	S	2
	Reduces mobility	S	1
	Criminals hide behind trees	S	3
	Increases maintenance of lawn (under tree)	S	1
	Use up too much space	S	1
	Fallen leaves in autumn	S	10
	Sap drips	S	6
	Leaves fall continuously in summer	S	8
	Roots too close to surface	S	6
	Branches and suckers at base	S	6
	Fruit or seed pods fall	S	7
	Roots send up suckers	S	4
	Flower parts fall	S	6
	Dropping debris	S	2
	General debris (messy)	S	2
	Seeds and seedlings from tree	S	1
	Make unwanted shade and cooling	S, Eco	3
	Insects in tree	S, Env	9
	Diseases on tree	S, Env	5
	Mistletoe	S, Env	3
	Attracts animal/wildlife problems	S, Env	3
	Sidewalk damaged by roots	S, Eco	8
	Roots clog sewers	S, Eco	5
	Branches damage power lines/streetlights	S, Eco	2
	Actual damage by roots	S, Eco	1
	Road damage by roots	S, Eco	1
	Leaf litter clogs drains	S, Eco	2
	Cost of maintenance	S, Eco	2

). Categorisation of the different aspects of services and disservices (i.e., social, environmental, and economic) was straight-forward in most cases but, in several instances, proved more difficult. This was always due to an inability to discern the intention behind a description. For example, was ‘leaf litter clogs drains’ considered a disservice because litter is costly to remove (i.e., economic aspect), causes annoyance because it must be cleaned out (i.e., social aspect), or problematic because it causes flooding after rain (i.e., environmental aspect)? Difficulties in categorisation were more common for disservices than services.

The number of services and disservices of street trees in each aspect varied considerably (

Table 3. Number of services and disservices perceived by residents to be associated with street trees according to aspect (social, environmental, economic) of each perception.

	Social	Environmental	Economic
Services	34	12	7
Disservices	33	4	8

and Table A4). The social aspect was the greatest for both services and disservices (34 services, 33 disservices); and the economic aspect was smallest (7 services, 8 disservices). The environmental aspect was the most variable, with 12 services but only 4 disservices identified.

3.5. Factors Related to Residents’ Perceptions

A large amount of information and data pertinent to street tree studies has been collected and reported in the studies reviewed. A total of 31 different factors were tested in relation to residents’ perceptions of street trees (

Table 4. Categories and factors identified as potentially influencing residents’ perspectives of street trees. ‘Impact’ is the number of studies in which the factor was identified as having impacted perceptions, and ‘no impact’ is the number of studies in which the factor was identified has having no impact on perceptions.

Category	Factor	Number of Studies	Impact	No Impact
Tree characteristics	Species	9	4	0
	Health status	3	1	0
	Size	3	2	1
	Shape	2	2	0
	Pollarding *	1	1	0
	Age	1	0	0
	Height	1	1	0
	Growth rate	1	0	1
Site characteristics	City	6	5	2
	Level of tree management	3	1	2
	House or flat	3	0	0
	Area affluence	2	1	2
	Tree density	2	0	2
	Mean basal area or diameter	2	0	2
	Mean tree height (of area)	2	0	2
	Tree species richness	2	0	1
	Simpson diversity	1	0	0
Participant demographics	Age	10	4	0
	Gender	9	1	0
	Level of education	6	1	0
	Length of residency	6	1	0
	Own/rent	5	0	0
	Income level bracket	5	0	0
	Race/ethnicity	3	0	0
	Main language spoken at home	1	0	0
	Employment status	1	0	0
	Type of income sources	1	0	0
	Health/physical ability	1	0	0
	Does own gardening	1	1	0
	Trees in own garden	1	1	0
	Has tree in front of home	1	1	0

* Pollarding is a specific type of pruning system that involves regular removal of the upper branches of a tree, promoting the growth of a dense head of foliage.

). These were put into one of three categories that related to either the study participant demographics (14 factors), characteristics of the site or location (9 factors), or characteristics of the tree (8 factors). The factors most commonly investigated were participant age (10 studies), followed by participant gender and tree species (9 studies each).

In some studies, factors were tested to see if they impacted residents’ perceptions of street trees, whereas in other studies, they were mentioned but potential impact was not investigated. Five factors were found to have an impact on residents’ perceptions in multiple studies: city (five studies), tree species and participant age (four studies each), and tree size and tree shape (two studies each). Three factors (participant age, participant gender, and tree size) were found to impact perspectives in some studies but not in others (Table 4).

4. Discussion

4.1. Overview

This review demonstrates the small number of studies that are available to provide a basis for our understanding of residents’ perceptions of street trees around the world. Much of the literature is quite dated, and publication rates are low with no evidence that they are increasing. This pattern is inconsistent with that reported in recent reviews on street tree structure, function, and value [68] and public perceptions of urban forests and urban trees [70], where the number of publications has been growing markedly since around 2014. While the critical importance in understanding people’s perceptions of urban trees is increasingly recognised [83,84], this acknowledgement has not yet translated to an increase in research publications for residents’ perceptions of street trees. This is potentially problematic given the large number of tree planting initiatives that have been implemented in cities globally since the early 2000s (e.g., the Million Tree nitiative [85]), many of which rely on community participation for the establishment and care of urban trees. Similarly, limited knowledge around public views on tree ordinances may limit the protection of mature street trees in cities undergoing significant redevelopment and densification [86]. It is likely that many local councils and other organisations have conducted studies to examine perceptions of local residents of street tree planting and management schemes. However, such work has not undergone rigorous examination intended by the peer-review process within the research community, and is not published in the scientific literature. This the first significant research gap we identified that remains to be filled but which would provide significant benefits to growth of the urban forest and climate resilience efforts in cities.

4.2. Knowledge and Data Gaps Revealed

Few of the studies reviewed were conducted across multiple cities, and none included longitudinal data assessing possible changes at an individual site over time. These variables would be a valuable inclusion to the knowledge base because the age of street trees strongly influences people’s response to them [43], and a person’s age influences their perceptions of street trees [54,87]. Perceptions of urban trees more generally, as well as green spaces [88], and ecosystem services [89,90] are also known to be strongly influenced by spatial and temporal characteristics. For example, climate is a strong driver of allergic rhinitis caused by tree pollen in many areas (e.g., Belgium, the Netherlands, Luxembourg, and Johannesburg [91], South Africa [92]), and people who perceived the presence of pollen in a greenspace had lower perceptions of that space [93]. A similar assumption could be made for street trees, although supporting data are lacking. Disparities in perceptions of trade-offs between urban forest ecosystem services and disservices among key stakeholders in Canberra, Australia, were attributed mainly to the different scales at which the urban forest was perceived [94], highlighting the need for targeted and specific engagement.

Numerous research methods are available to study people’s perceptions of the environment, but according to our results, published studies are limited almost entirely to surveys and semi-structured, face-to-face interviews. Both methods generally used Likert scales to record responses based on predetermined statements, but this method can strongly influence outcomes and results [95]. Controversy surrounds the ideal number of items to be included in a Likert scale, the effect of using specific words (particularly to describe the mid-point), and whether parametric or non-parametric analyses should be used in statistical treatments, and these are all debated [96]. In response, alternatives such as the New Ecological Paradigm (NEP) scale have been proposed [97]. More recently, methods such as participatory mapping, social media-based research, and modelling methods have been used in addition to traditional questionnaires and interviews for investigating cultural ecosystem services [98]. Visual presentation methods such as those used in studies of public perceptions in forest management could also be a useful tool in assessing support for street tree planting schemes [99]. Multiple studies demonstrate the need for interdisciplinary and integrated approaches to explore complex and diverse perceptions of urban green spaces [100,101], especially in light of their impacts on climate change adaptation and mitigation [102]. Street tree studies could similarly benefit greatly from the application of new approaches to data collection.

Cities in which residential street trees studies were conducted were almost all coastal with hot or warm summer Mediterranean climates (Koppen classifications Csa and Csb), indicating that information from continental and tropical climates is scant. No studies investigated a possible link between climate and residents’ perceptions, although associations have been reported for ecosystem services provided by urban green infrastructure [103]. Differences are expected to be exacerbated by environmental injustices caused by climate change [69], so warrant close attention in future work.

Data granularity (i.e., the level of detail available in the data) varied among studies, with most work focussing on a specific tree outside the residential home or the row of trees along the street where the study participant lived. This level of granularity is critically important because overall opinions about urban trees may be strongly positive whereas opinions about local trees may be more neutral [37]. Resident’s perceptions are different from other stakeholders primarily because they have an ‘intimate relationship’ with an individual tree outside their homes [70], and are more affected by both services and disservices [64]. Guo et al. [104] noted that people often have different attitudes about trees in general compared to specific trees. This observation—often described as the ‘I love trees, but not in front of my house’ phenomenon—was first described in arboricultural texts in the United Kingdom [64]. It has subsequently been noted across multiple locations [105] as well as in response to different scenarios including extreme weather events [37], where individual urban trees can contribute disproportionately towards someone’s experiences and perceptions of trees [106]. The studies reviewed here provide a sound, albeit small, base for further studies investigating the influence of individual trees outside people’s homes on their perceptions of street trees. Such work will enable research to move beyond the more usual investigations that consider urban environments as binary combinations of green and non-green spaces [106].

Street tree studies were not designed to capture the variation within or among the categories and factors potentially impacting residents’ perspectives (but see [107] for an exception). Similar findings have been reported for urban forests and urban trees, where work rarely investigates factors driving perspectives [70]. Socio-demographic and environmental–cultural factors have been shown to affect perceptions of urban forests [51] and ecosystem services [90]. Attributes of different tree species can also drive perceptions. For example, Populus nigra (Black Poplar) is commonly perceived as giving rise to allergies and is perceived negatively [57]. The characteristics of trees, streets (sites), and respondents can all influence perceptions of street trees [57], highlighting a serious gap in research design that should be addressed in future investigations.

4.3. Perceived Services and Disservices

Street tree studies reported more perceived services than disservices. This observation has been previously reported, with several explanations being proposed: First, people generally view street trees as having a net benefit, with services outweighing the disservices [46]. Second, people’s perceptions of the negative impacts of street trees on quality of life are limited [53] and are therefore of less concern. Third, studies generally aim to measure awareness of services and put a decreased emphasis on disservices [108], and hence perceptions of the positive aspects of urban trees are more commonly studied than negative aspects [70]. Our review provides evidence to support the third explanation, with many studies using the same (or similar) lists of perceived services and disservices, which compounded a potential bias in favour of perceived services. It will be important to rectify this research design flaw to compile a more complete and nuanced list of residents’ perceptions of street trees.

The studies reviewed revealed that although some perceptions are supported by sound scientific evidence (e.g., cooling effects, reduces energy bills, and increases property values), others have been scientifically disproven (e.g., increases criminal activity and produces allergies). This highlights one of the difficulties in differentiating between actual and perceived benefits [102]. No studies compensated for this differentiation, and only a few attempts to reconcile potential differences exist in the broader literature on perceptions of urban trees or green infrastructure (e.g., [109]). Addressing this knowledge gap will be critical in gaining more widespread support from residents for street tree planting programs to build climate resilience.

Multiple attributes of street trees were perceived as services and disservices (Figure 1a). For example, shade was sometimes perceived as a service (‘provision of shade’) and sometimes as a disservice (‘unwanted shade’ or ‘makes street dark/blocks streetlight’). Similarly, perceptions of flowers were seen as a service (‘flowers on tree’) and a disservice (‘flower parts fall’) (Figure 1b), and fallen leaves were noted as a service (‘exercise from raking leaves’) and as a disservice (‘fallen leaves in autumn’ and ‘leaves fall continuously in summer’). Part of the problem seems to derive from an articulation of the reasons why particular attributes were perceived as a service or disservice. Future work should attempt to provide greater clarity around this problem and remove ambiguity in residents’ responses.

4.4. Factors Related to Residents’ Perceptions

Factors that influenced residents’ perceptions—and, in many cases, ambivalence—were similar to those found in studies on peoples’ perceptions of street trees in Japan [53] and urban trees in the United States [51]. When tested, tree species, tree shape, and participant age always impacted perceptions, whereas tree size influenced perceptions only in some cases. This suggests the need for a highly specific study design to capture nuances in perceptions driven by these factors. Characteristics that affect perceptions will also be subject to change over time, necessitating the need for a longitudinal aspect to studies [102] that untangle the effects of factors most commonly shown to drive perceptions such as the age of residents and age of trees. Ideally, these studies should also include perceptions of children because childhood experiences are critical in determining ecological identity in adulthood [110]. Although it is not possible to confidently extrapolate our findings, it is clear that both environmental and socioeconomic contexts are very important [111].

4.5. Implications

Studies on perceptions about natural and built environments are driven by the belief that understanding people’s motivation leads to increased participation and pro-environmental action [70,112] and, therefore, an increase in provision of ecosystem services. However, not all stakeholders are focussed on ecosystem services [52], and views on the main functions of street trees vary both between [20] and within stakeholder groups [113]. Further, the roles and relative importance of various stakeholder groups is changing: some authors now consider residents to be the most important stakeholder group in urban planning [109].

The diversity of people’s perceptions and general ambivalence presents a unique challenge for researchers and practitioners in urban forestry who may seek a ‘best’ or ‘most preferred’ tree species or plant for a given situation [70]. Indeed, the primary purpose of street trees has changed over the past 40 years from their aesthetic role to a functional one that includes the provision of ecosystem services [114].

Targeted information is also important in the establishment of new street trees in cities where old trees have died or been removed, where additional trees are needed to increase canopy cover. This may occur in the vicinity of major urban redevelopments that incur the loss of street trees [115] or in new developments [112] where small properties combined with houses with large footprints preclude the growth of trees within property boundaries such that street trees are the only trees present (Figure 1c). These circumstances give rise to questions around land tenure and ownership that are rarely included in the literature about street trees. Globally, street trees are managed by multiple stakeholders at different spatial scales. Trees on public streetscapes may be managed by local governments [22,116], private organisations and land developers [37], local communities, or individuals [117]. In Detroit, United States, non-profit organisations are responsible for planting street trees on city-owned property [118], but in Portland, United States, homeowners are responsible for street trees outside their properties [119]. However, the support necessary to ensure tree survival during the establishment period is often lacking or non-existent [120], and relying on residents to manage trees outside their properties can compromise the density of street trees [119]. Tree protection legislation such as bylaws may provide part of the answer needed to protect existing mature street trees, although the socio-legal aspects of tree protection legislation are not always well understood and also require further exploration [29]. Greater onus to establish and protect street trees could be placed on land developers if they are provided with sufficient financial incentives [86]. In Florida, United States, developers showed a willingness to work with regulators and find solutions that were beneficial for both parties [86], providing a promising outlook for future urban tree establishment and retention.

Management of publicly-owned street trees is exceptionally challenging because they have such a significant physical, social, economic, and psychological impact on people’s private lives (Figure 1d). This review adds to evidence of the extreme complexity of the situation facing urban planners tasked to include residents’ ambivalence towards street trees in plans to establish and manage street trees or the urban forest tree canopy more broadly.

4.6. Future Directions

Plans to increase canopy cover of urban trees to promote climate resilience need to address the issue of residents’ ambivalence towards trees and will require ongoing location-, people-, and method-specific information. We have demonstrated the range of empirical and descriptive data already captured by the small number of studies reviewed, which, together with additional derived data (e.g., Koppen climate classifications), can begin to fill the current research gaps. Information from cities not previously studied, and especially in climates not previously included such as tropical monsoon, dry arid deserts and semi-arid steppes would be particularly novel. Systematic and targeted searches of the grey literature regarding community consultations and involvement in street tree planting and management could add further valuable insights. Reports produced by local government bodies, councils, community groups, and consultants may prove particularly useful in this regard. Multidisciplinary approaches will be essential in addressing issues such as residents’ ambivalence towards street trees within the increasing complexity of climate change amidst other contemporary global challenges [121].

New discoveries in perceptions of environmental phenomenal are being made through engagement with tools including virtual 3D landscapes, which enable crowdsourcing of preferences and knowledge [122], and visual AI, which may provide novel insights into the effects of geographical conditions on perceptions of nature [123]. The growing application of advanced deep learning-based sentiment analysis (i.e., the use of machine learning, statistics, and natural language processing to investigate how people think and feel about a subject) hold great promise for improving knowledge around human emotions in relation to their environment. This point can be illustrated with recent studies investigating the effects of urban temperature and landscapes using a microblogging platform in China [124] and machine learning analysis in an investigation on complaint emotions related to green spaces using machine learning models and hotspot analysis methods [125]. In Melbourne, Australia, a unique email-a-tree initiative revealed how designing public engagement programs can be used to promote active participation in urban tree governance [126]. Using existing technology platforms, programs such as these can be implemented at a city-wide scale without the expense of methods such as surveys or interviewing [126], so could potentially be more easily incorporated into current urban forestry and public engagement expenditure. Novel methods and technologies such as these will provide a greater understanding of residents’ perceptions of street trees in the future.

Until the knowledge gaps we have highlighted are adequately filled and new understandings can reliably inform decision-making processes, it may be prudent to reconsider the level of involvement being asked of residents in street tree establishment and care. Where willing and able participants are available, contributions would be welcomed, but where they are absent, placing the onus of care on residents puts street tree survival at risk. Elements such as physical and emotional interactions could be seen as ‘co-benefits’ [127] since to do otherwise may put urban tree canopy targets in jeopardy, and ultimately expose communities to increased climate-related health risks [128]. New and ongoing programs of community education and engagement (Figure 1d) will be crucial in fostering greater acceptance and understanding of the unique role of street trees in sustainable cities around the world. Policies and other instruments such as bylaws that protect existing mature street trees and require establishment of plants in new and existing urban developments will be necessary to avoid unintentional conflict with other climate goals [129] and provide effective protection and growth of street trees. It has been shown that such measures are beneficial as they can promote healthy and community-friendly urban environments [130].

5. Conclusions

Street trees make a unique and irreplaceable contribution to climate mitigation in the built environment. They are a key part of the urban forest canopy that can deliver solutions to urban heat and human health issues in areas where it is most needed—on the streets where people live. Our review highlights residents’ ambivalence towards street trees outside their homes. Perceptions were highly variable, and were frequently influenced by demographics, location, and tree characteristics in ways that are not well understood and that may change over time. Residential support for street trees can only be utilised when it is understood in a local context. Policies and tree preservation laws will also be required to realise the potential of street trees to improve liveability and support the development of cities for the future.