Initiatives in Urban Greening: analysis of attitudes towards a voluntary-assisted urban residential road verge-planting program

ABSTRACT

City road verges often represent existing green space and provide opportunities for ecological enhancement. Urban greenspace improvement initiatives at the residential verge scale require genuine community support and engagement for success. We examined a community-based voluntary assisted verge greening program designed to enhance greenspace connectivity using native plants in a local municipality in Perth, Western Australia. A social survey of verge-greening program participants and non-participants was conducted to understand factors associated with community involvement. Results indicated general resident support for the program, where both groups viewed the program objectives positively. However, non-participants were less convinced, than participants, of the likelihood that the verge greening program would achieve its aims and the merits of some aims. This paper provides insight into a voluntary community engagement tool for developing urban green space connectivity and enhancing natural values at the residential roadside verge level.

KEYWORDS:

• Urban greening
• residential road verges
• verge enhancement
• public perceptions
• community invovlement
• native vegetation

Introduction

Urban green space comprises a variety of vegetated areas in the urban environment including remnant vegetation, public parks, private gardens and vegetated streetscapes (Roy, Byrne, and Pickering 2012; Rupprecht and Byrne 2014; Mensah et al. 2016). The widely recognised ecological and social benefits of green space in cities has led to a worldwide social interest alongside the development of extensive scholarship on urban greening that aims to inform decision makers, contribute to community understanding, reduce ecological losses and identify challenges in urban-greening programmes (Fuller et al. 2007; Van den Berg et al. 2010; Kirkpatrick, Davison, and Daniels 2012; Beyer et al. 2014; Bratman et al. 2015; Henderson 2018; Wood et al. 2018; Parker and Zingoni de Baro 2019; Coffey et al. 2020; Cooke 2020; Mumaw and Mata 2022). Despite the acknowledged importance of urban green space, such areas face the continuing challenge of urban expansion and urban densification (Nisbet, Zelenski, and Murphy 2011; Ewing, Catterall, and Tomerini 2013; Pietilä et al. 2015; Sarkar et al. 2015; Farkas et al. 2023). Urban densification is used as a mechanism to mitigate urban sprawl while housing a growing human population (Haaland and Konijnendijk van Den Bosch 2015). In many cities urban green spaces, particularly remnant vegetation and private gardens, are being reduced, fragmented, or removed (Haaland and Konijnendijk van Den Bosch 2015). At the same time, residential road verges comprise a significant part of the global urban landscape (Rupprecht and Byrne 2014). Phillips et al. (2020a) state that road verges are ‘strips of land in the immediate vicinity of roads that separate them from the surrounding landscape’. As extensive linear areas traversing urban landscapes, vegetated road verges can function as ecological corridors that enhance green space connectivity and biodiversity values in fragmented urban areas (Douglas and Sadler 2011; Arenas et al. 2017; O’Sullivan et al. 2017; Phillips et al. 2020b, 2021).

Australian residential urban road verges are part of the public road reserve, located between the edge or kerb of a carriageway and the road reserve boundary (Main Roads 2011), In Australian city residential areas, the road verge boundary commonly abuts private residential property (Main Roads 2020), Hence the road verge generally occupies the space between the carriageway and private property boundary and may range in width from virtually non-existent to several metres wide (Main Roads 2020). Many urban road verges in Australia are common areas of lawn grass (and occasionally trees and weeds) with limited biodiversity (e.g. Figure 1).

Figure 1. Location of City of Vincent study area within the Perth Metropolitan Area, Western Australia.

Source: adapted from Google maps.

Urban verges that host locally native vegetation can potentially afford several benefits (Hunter and Hunter 2008; Goddard, Dougill, and Benton 2010; Ewing, Catterall, and Tomerini 2013; Standish, Hobbs, and Miller 2013; Haaland and Konijnendijk van Den Bosch 2015). Native vegetation is suited to the local climate and can provide optimal habitat for native wildlife (Stenhouse 2004a; Goddard, Dougill, and Benton 2010; Davis and Wilcox 2013). In being suited to the local climate native plants, because of their adaptive traits, use less water and are better able to tolerate variation in environmental conditions such as limited water and nutrient resources (Goddard, Dougill, and Benton 2010; de Carvalho et al. 2022). Accordingly, road verges comprised of native vegetation (Figure 2) contribute to biodiversity and increase available habitat while facilitating connectivity between patches of urban green space (Ramalho et al. 2014; Perkl 2016; Mumaw and Bekessy 2017). Given that up to 30% of the green space in a city occurs as road verge, its role in ecological functioning, biodiversity conservation and human well-being is highly significant in enhancing the quality of city living (Marshall, Grose, and Williams 2019a; Phillips et al. 2020a; Nieuwenhuijsen 2021). Moreover, urban greening is becoming increasingly important for mitigating urban heat island effects and in the modulation of stormwater discharge under emerging climate change scenarios (e.g. Chen and You 2020; Horne 2021; Farkas et al. 2023). Given the vital role that vegetation plays in the urban environment, it is important to understand public support for, and the perceived success, of local government initiatives regarding urban greening and especially in relation to residential roadside verge enhancement.

Figure 2. Examples of residential urban road verges of varying width in the City of Vincent with non-adopted verges comprising lawn (a, b) and adopted verges with native plantings (c, d). (Photo source: authors)

Community involvement in residential road verge enhancement

Attitudes and beliefs towards urban-greening programs have been variously explored in Chinese and North American contexts (e.g. Balram and Dragićević 2005; Jim and Chen 2006; Lo and Jim 2012; Shan 2012). The urban green space literature from Australia is paying increasing attention to the environmental role, political and social aspects of residential road verges (e.g. Ligtermoet et al. 2021; Barona et al. 2022; Hunt et al. 2022). Further to this, Kirkpatrick, Davison, and Daniels (2012) and Kendal et al. (2022) posit that people are mostly positive about trees in the urban environment. Kendal et al. (2022) additionally providing a useful definition of ‘attitude’ as being ‘people’s positive or negative evaluation of things’, although previously Kirkpatrick, Davison, and Daniels (2012) considered that attitudes may not align with practices consistent with those attitudes. For all that there is an increasing need for social information pertaining to road verges that represent existing green space, and which also provide opportunities for ecological enhancement (Barona et al. 2022).

Verge enhancement may be implemented in different ways. For example, it may be a government-driven process (Henderson et al. 2001; Newsome 2021), a combined government and public partnership (van der Jagt et al. 2017; Coffey et al. 2020; Cooke 2020; Hunt et al. 2022) or a community led road verge greening/gardening initiative (Marshall, Grose, and Williams 2019a, 2019b). Marshall, Grose, and Williams (2019b) emphasise that optimal ecological and social outcomes of verge greening and enhancement programmes will depend upon effective collaboration between road authorities, residents, and local governments. Moreover, it has previously been reported that effective verge enhancement is unlikely to be achieved through governmental intervention alone (Stenhouse 2004b; Ewing, Catterall, and Tomerini 2013). Governments generally lack the resources for effective urban greening and may depend upon the intervention of local community groups (Stenhouse 2004b). Local government may have conflicting priorities which stretches funds even more, and government may rely on having community support to improve the quality and quantity of urban green spaces (Roy 2017; van der Jagt et al. 2017). Community engagement is important in the planning of urban green spaces as the local community understand how local areas function (e.g. as a park or thoroughfare), and can suggest ways to improve an area for the whole community (Faehnle et al. 2014; Marshall, Grose, and Williams 2019a, 2020). As previously acknowledged, urban-greening programs driven by government generally require community support and engagement to be effective (Coffey et al. 2020; Cooke 2020).

Research focus: Urban Perth, Western Australia

While road verges in Australia are part of the public road reserve, local government requires residents to maintain their verge in a reasonable condition that does not pose a safety risk (City of Stirling 2022a). Urban verges are commonly maintained and used by residents for a range of purposes such as car parking, a play area for children or as an extension of the private garden. Resident community support for any verge planting program is essential as it is the residents who are responsible for ensuring verges are maintained according to specified local government regulations (Ligtermoet et al. 2021). Proactive local governments thus require community support regarding their urban-greening programmes (City of Stirling 2022b). The research reported in this paper critically examines the social dimensions of a local government led but community-driven urban-greening program focussed on enhancing the ecological and social values of residential road verges. We compared attitudes and perceptions of residents who participated in the program with those who did not, regarding the program and its aims. While this study was conducted in 2017–2018, the findings are relevant owing to the paucity of research regarding community views towards verge-based greening programs and the growing recognition of road verges in terms of their potential contribution to urban greening (Ligtermoet et al. 2022). Understanding community perceptions of urban green space connectivity programs offers a valuable learning opportunity for urban/suburban settings globally.

Methods

Study area

The study area was within the City of Vincent, a local government area (municipality) in the Perth Metropolitan Area, the capital of Western Australia (WA) (Figure 3). Perth is a sprawling city, based on a traditional grid layout, mainly consisting of low density, detached housing and a resident population of approximately 2 million people spread over 6418 km² (Dushkova et al. 2021).

Figure 3. Verge adopter (n = 91) and non-adopter (n = 70) environmental worldview scores calculated using the New Ecological Paradigm Scale.

The Perth Metropolitan Area experiences a Mediterranean climate with hot dry summers (24.8°C annual mean maximum) and cool, wet winters (12.9°C annual mean minimum), with an annual mean rainfall of 850 mm, although rainfall is not uniform across the extensive urban area (BOM 2023). The Perth area is also located in one of only two recognised biodiversity hotspots in Australia and 34 worldwide (Dushkova et al. 2021; Ritchie et al. 2021). The Swan Coastal Plain is recognised for its diverse range of endemic species, with the area originally dominated by extensive wetlands, Banksia woodlands and Tuart Forest both of which are formally recognised as threatened. These endemic native species and ecosystems are now under significant threat due to habitat fragmentation and loss mainly resulting from urban development and associated land clearing. Approximately 25% of the original native vegetation remains as remnant patches of varying sizes across the metropolitan area (Tomlinson, Smit, and Bateman 2021) and is under threat from groundwater abstraction, altered fire regimes and disease caused by phytophthora cinnamomi (Shearer and Dillon 1996; Groom, Froend, and Mattiske 2000; Ritchie et al. 2021). About 17% of the Perth area is urban greenspace of varying types, including parklands (Dickinson et al. 2018).

The City of Vincent is a municipality situated close to the central business district of Perth. The City has approximately 36,537 residents and 18,159 private dwellings (ABS 2021) across a total area of 11.4 km², with 139 km of road (https://profile.id.com.au/vincent). The City of Vincent resident median weekly household income is AU$2,209, compared to the Australian national median of AU$1,746. A higher proportion of residents are in professional occupations (40%) and have a higher level of educational attainment (46% university degree) compared to the national population (24% and 26%, respectively). A higher proportion of residents have both parents who were born in a country other than Australia (43.3%) compared to 38% of the Australian population (ABS 2021). Thus, City of Vincent residents are more likely to have migrant parents, be relatively well educated and have higher incomes compared to the wider Australian population. Furthermore, the City of Vincent includes a range of residential housing types, from suburban areas with detached houses on private properties of several hundred square metres, with road verges of varying sizes, through to inner-city high-density residential areas with little or no road verge. The City of Vincent’s area of public green space, not including road verges, equates in total to about 9.3% of the area of the municipality (https://www.vincent.wa.gov.au/statistics.aspx).

City of Vincent adopt-a-verge program

The City of Vincent implemented an adopt-a-verge program in 2013 as part of a wider municipal urban-greening strategy. The adopt-a-verge program encouraged and facilitated residents to plant native vegetation on the verge area between their property and the road reserve carriageway, usually replacing existing verge lawn and weeds while retaining any existing trees (Figure 2). The program is promoted on the City of Vincent official website and Facebook as well as being promoted on social media channels by the City of Vincent’s elected representatives. The community-based program had six stated aims:

1. encourage planting of native vegetation,

2. increase local biodiversity,

3. contribute to urban greening,

4. create wildlife corridors,

5. enhance local beauty, and

6. contribute to community wellbeing.

To adopt a verge, residents formally applied to the City as part of a biannual application process. Applications included an indicative plan for the verge design (shape, area, special features such as, paths, boulders or logs). Once the application was accepted, The City removed grass and existing topsoil from the nominated verge, applied a layer of mulch to the verge and provided the residents with up to 20 free native plant tube stock. The resident was responsible for planting and maintenance of their adopted verge. Between 2013 and 2017, resident households in the City of Vincent adopted 332 verges. Aside from this study, there has been no formal evaluation of the adopt a verge program and achievement of its aims since its inception. The lack of evaluation is primarily owing to a lack of staff and resources available for undertaking such as task within the City of Vincent.

Social survey

Social survey sampling approach

The social survey included two sample groups: a questionnaire distributed to households participating in the adopt-a-verge program (adopters); and a questionnaire distributed to households not participating in the adopt-a-verge program (non-adopters). Adopters were identified as those recorded on the City of Vincent’s adopt-a-verge registration database. Non-adopters were those households not recorded on the adopt-a-verge program database. Non-adopter houses, with a road verge area, in the same streets as those included in the adopter sample were targeted to reduce potential confounding factors such as neighbourhood demographic characteristics and non-adopter social norms bias (Germar and Mojzisch 2019).

Social survey design

Both adopters and non-adopters completed similar questionnaires with slight variations to accommodate their verge adoption status (Table 1).

Table 1. Summary of adopter and non-adopter social survey questionnaire items.

Question types	Adopters	Non-adopters
Reasons for adopting verge	x
Reasons for not adopting verge		x
Perceived likelihood each of the six adopt-a-verge program aims can be achieved (0 = unlikely through to 6 = likely)	x	x
Perceived evaluation of the six adopt-a-verge aims in terms of whether they are good or bad aims to have (−3 = very bad through to +3 = very good)	x	x
Overall evaluation of adopt-a-verge program as a good or bad thing to do (−3 = very bad through to +3 = very good)	x	x
Environmental world view (New Ecological Paradigm scale)	x	x
General demographic information	x	x

Attitudes towards each of the six stated adopt-a-verge program aims were measured drawing on techniques applied by Brown, Ham, and Hughes (2010) and Hughes, Ham, and Brown (2009). Each of the six aims were rated separately using two seven-point rating scales: a unipolar likelihood rating scale (0–6) regarding the likelihood the program would achieve the respective stated aims, and a bipolar evaluation rating scale (−3 to +3) regarding whether the aims were good or bad things to achieve. This approach provided a more nuanced insight into adopter and non-adopter attitudes towards the program aims relative to a single attitudinal rating scale (Obregon et al. 2020). Environmental world view of Adopters and Non-adopters was measured using the New Ecological Paradigm scale (Dunlap et al. 2000). The intent was to identify any relationships between environmental worldview and verge adoption behaviour.

The New Ecological Paradigm (NEP) scale consists of 15 statements regarding the relationship between humans and nature, that are rated on a Likert scale from agree to disagree. The 15 statements are broadly divided into anthropocentric and ecocentric conceptualisations of the human-nature relationship. The NEP has been used to measure environmental attitudes, beliefs and worldviews of the general public as well as identifying differences between specific groups within a community. The scale has demonstrated criterion validity, meaning that the NEP is reliably predictive of environmental values and behaviours (Dunlap et al. 2000). Understanding environmental world view provides insights into why particular environmental behaviours are, or are not, carried out by a group of interest (Rossi et al. 2015).

General demographic information was collected to characterise the sample and any potential differences between verge adopters and non-adopters.

Social survey distribution

All Adopters on the adopt-a-verge registration database were sent an email, or hard copy letter if email was not available, in June 2017 informing them of the study and advising them that researchers would be knocking on doors and requesting residents to complete a questionnaire about their verge. The door-to-door survey was conducted between September and December 2017. Adopters who were at home were invited to participate and complete a questionnaire. If they agreed, researchers asked participants each question in turn and entered the responses online using a portable device. Where adopters were not able to complete the questionnaire immediately, an identical but hardcopy version of the questionnaire was provided with a reply-paid envelope for later completion and return by the resident. If residents were not home at the time of door knocking, a hardcopy questionnaire, reply-paid envelope and a brief information letter explaining the study were left in the resident’s letterbox.

Non-adopters living in the same streets as the adopters received a hand delivered hardcopy letter inviting them to participate in an online version of the social survey, with a URL and QR code link to the questionnaire. Letters were hand delivered to resident letterboxes in the study area between September and October 2017.

Data analysis

Data analysis was conducted using SPSS software (IBM SPSS v24). The analysis included descriptive statistics, Chi-square tests of association for categorical data and nonparametric tests (such as Mann–Whitney U and Kruskal Wallis tests) for ordinal data. The New Ecological Paradigm (NEP) Scale statement ratings were totalled for each respondent, with human-centric statements reverse coded to create a total score that was subsequently standardised to a fraction ranging from zero (ecocentric) to one (human centric). Mann–Whitney U tests were used to compare the NEP score between adopters and non-adopter groups. The perceived likelihood and evaluation ratings for each of the six program aims were compared within and between the adopter and non-adopter groups using nonparametric statistical tests. The product of the likelihood and evaluation ratings for each program aim was calculated for each respondent to generate attitude scores ranging from negative 18 (very likely/very bad) to positive 18 (very likely/very good). The attitudes scores for each program aim were compared within and between the adopter and non-adopter groups using nonparametric statistical tests.

Results

Respondent profile

Of the 198 verge adopters invited to participate in the social survey, 91 completed a questionnaire either in person or self-completed and returned in their own time (46% response rate). Out of 3000 letters delivered to non-adopter households, 109 attempted the questionnaire (3.4% response rate). Of the responses received, 71 (65%) were usable. A total of 38 responses were deemed unusable because the questionnaire was mostly incomplete, or the respondents indicated they had adopted, or planned to adopt their verge but were not registered on the City’s database.

A significant relationship was evident between verge status and proportion of home ownership (X² = 5.542, df = 1, p = 0.020), the number of household occupants (Mann–Whitney U = 3783.5, p = 0.02), and the number of adult children living at home (X² = 4.742, df = 1, p = 0.030). Verge adopter respondents tended to have a lower proportion of renters, fewer household occupants and fewer adult children living at home, relative to the non-adopter sample.

Comparison of the New Ecological Paradigm scale scores indicated that the environmental worldview of verge adopters (n = 91) and non-adopters (n = 70) was not significantly different (Mann–Whitney U = 2400.5, z = −1.484, p = 0.138) (Figure 3). Non-adopters had a broader spread of environmental world view scores.

Reasons for adopting or not adopting verge

The most indicated reasons for adopting a verge were: aesthetic appeal (77% of respondents); reducing water use (53% of respondents) and because it is seen as good for the environment (50% of respondents). A small proportion of respondents indicated they participated in the adopt-a-verge program because their family, friends or neighbours were participating (Table 2).

Table 2. Reasons indicated by respondents for adopting a verge (n = 91) and not adopting a verge (n = 69).

Reasons for adopting a verge	Frequency	Per cent of adopters
For aesthetic reasons	70	76.9%
Reduce water use	48	52.7%
Good for the environment	46	50.5%
Increase birds or other wildlife in the garden	39	42.9%
Family/friends or neighbours were doing it	14	15.4%
Other	32	35.2%
Reasons for not adopting a verge		Precent of non-adopters
Not aware of the program	23	33.3%
Verge needed for other uses	16	23.2%
Not enough personal time	15	21.7%
Financial constraints	7	10.1%
Don’t know how	7	10.1%
Just not Interested	5	7.2%
Don’t like native plants	5	7.2%
Other	22	31.9%

Commonly indicated reasons for not adopting the verge were a lack of awareness of the program (33% of respondents); needing the verge for other uses (e.g. car parking) (23% of respondents); and/or not having enough time to be involved in the program (22% of respondents). A small proportion of non-adopter respondents were aware but not interested in the program (7.2%) or indicated that they did not like native plants (7.2%). There was no significant statistical relationship between reasons indicated for not adopting the verge, NEP score, or the rating of the program aims.

Adopt-a-verge program aims ratings

All adopter likelihood and evaluation ratings of the verge adoption program aims were significantly more positive than the non-adopter ratings (Table 3, Figure 4). This result indicates adopters considered that the aims were more likely to be achieved when compared with the ratings of non-adopters. Similarly, while both adopters and non-adopters rate all aims as good things to do, non-adopters tended to rate the aims less positively compared to the adopter ratings.

Figure 4. Adopter and non-adopter mean likelihood (a) and evaluation (b) ratings of the adopt-a-verge program aims (error bars = standard error of the mean).

Table 3. Mann–Whitney U test results for pairwise comparisons between adopters (n = 91) and non-adopters (n = 70) regarding adopt-a-verge program aims likelihood and evaluation ratings.

Attribute	Program aim	Mann–Whitney U	Z	P value
Likelihood (likely–unlikely)	Encourage native planting	2129.500	−3.843	0.000
	Enhance local beauty	2047.500	−4.284	0.000
	Contribute to urban greening	2313.500	−3.049	0.002
	Increase local biodiversity	2260.500	−3.087	0.002
	Create wildlife corridors	2137.500	−3.544	0.000
	Improve community wellbeing	2046.000	−3.781	0.000
Evaluation (good–bad)	Encourage native planting	1949.000	−5.401	0.000
	Enhance local beauty	2296.500	−3.901	0.000
	Contribute to urban greening	2217.000	−4.152	0.000
	Increase local biodiversity	1935.000	−5.015	0.000
	Create wildlife corridors	1887.500	−5.017	0.000
	Improve community wellbeing	2397.500	−3.181	0.001

Within group analysis indicated that non-adopters rated the likelihood (X² = 49.660, df = 5, p ≤ 0.001) and evaluation (X² = 13.085, df = 5, p < 0.001) of the six respective program aims significantly differently, as did adopters (likelihood X² = 53.945, df = 5, p < 0.001; evaluation X² = 25.954, df = 5, p < 0.001). These differences indicate that respondents within each group rated some program aims as less positive or less likely than other aims.

In terms of the likelihood that the program aims would be achieved, adopters rated ‘Enhance local beauty’ and ‘Encourage native planting’ as significantly more likely than the remaining aims (Table 4). Non-adopters rated all aims as equally likely, except ‘improve community wellbeing’ and ‘create wildlife corridors’, which were rated significantly less likely to be achieved relative to the other program aims. In terms of the program aims as good things to do, adopters rated ‘create wildlife corridors’ and ‘improve community wellbeing’ less positively than the remaining aims.

Table 4. Adopter pairwise comparisons of adopt-a-verge program aim ratings for likelihood and evaluation (n = 91).

Program aims		Evaluation (good–bad)
		Enhance local beauty	Encourage native planting	Contribute to urban greening	Increase local biodiversity	Improve community wellbeing	Create wildlife corridors
Likelihood (likely–unlikely)	Enhance local beauty		z = −1.155 p = 0.248	z = −0.302 p = 0.763	z = −0.711 p = 0.477	z = −3.103 p = 0.002	z = −1.922 p = 0.055
	Encourage native planting	z = −1.751 p = 0.08		z = −1.387 p = 0.166	z = −1.933 p = 0.053	z = −3.027 p = 0.002	z = −2.800 p = 0.005
	Contribute to urban greening	z = −2.259 p = 0.011	z = −0.303 p = 0.762		z = −0.535 p = 0.593	z = −3.205 p < 0.001	z = −1.704 p = 0.088
	Increase local biodiversity	z = −3.814 p < 0.001	z = −2.299 p = 0.022	z = −2.177 p = 0.029		z = −2.914 p = 0.004	z = −1.809 p = 0.070
	Improve community wellbeing	z = −5.246 p < 0.001	z = −3.689 p < 0.001	z = −4.401 p < 0.001	z = −2.407 p = 0.007		z = −1.379 p = 0.168
	Create wildlife corridors	z = −5.225 p < 0.001	z = −4.120 p < 0.001	z = −4.113 p < 0.001	z = −2.971 p = 0.003	z = −0.108 p = 0.914

Bolded text = significant difference based on Mann–Whitney pairwise comparisons.

In terms of program aim evaluation, non-adopters rated ‘Create wildlife corridors’ significantly less positively than the remaining aims, except ‘Encourage native planting’ (Table 5).

Table 5. Non-adopter pairwise comparisons of adopt-a-verge program aim ratings for likelihood and evaluation (n = 70).

Program aims		Evaluation (good–bad)
		Enhance local beauty	Encourage native planting	Contribute to urban greening	Increase local biodiversity	Improve community wellbeing	Create wildlife corridors
Likelihood (likely–unlikely)	Enhance local beauty		z = −1.646 p = 0.100	z = −0.137 p = 0.891	z = −1.634 p = 0.102	z = −0.936 p = 0.349	z = −3.286 p < 0.001
	Encourage native planting	z = −1.424 p = 0.155		z = −1.988 p = 0.047	z = −0.044 p = 0.965	z = −0.448 p = 0.654	z = −1.277 p = 0.202
	Contribute to urban greening	z = −0.633 p = 0.527	z = −0.645 p = 0.519		z = −2.054 p = 0.040	z = −1.098 p = 0.272	z = −3.148 p = 0.002
	Increase local biodiversity	z = −0.508 p = 0.611	z = −1.926 p = 0.054	z = −1.448 p = 0.148		z = −0.287 p = 0.774	z = −2.421 p = 0.015
	Improve community wellbeing	z = −4.023 p < 0.001	z = −4.191 p < 0.001	z = −4.035 p < 0.001	z = −3.159 p = 0.002		z = −2.293 p = 0.022
	Create wildlife corridors	z = −3.301 p < 0.001	z = −4.038 p < 0.001	z = −3.580 p < 0.001	z = −3.336 p < 0.001	z = −0.461 p = 0.644

Bolded text = significant difference using Mann-Whitney pairwise comparisons.

The differences in likelihood and evaluation ratings within and between the adopter and non-adopter groups resulted in differences in the attitudes towards each of the program aims (Figure 5). The largest difference between the two groups was the attitude (Kendal et al. 2022) towards ‘Encouraging native planting’ (Mann–Whitney U = 1791.0, z = −4.883, p < 0.001), where non-adopter attitudes (mean attitude score = 9.36) were significantly less positive compared to the adopter attitudes (mean attitude score = 15.36). The results suggest that the less positive non-adopter attitude towards encouraging native planting is mainly associated with the greater difference, between the adopter and non-adopter groups, in the evaluation rating of this aim (good or bad thing to do). That is, while non-adopters tended to indicate the aim was very likely to be achieved, non-adopters were less positive about whether the aim was a good thing to do.

Figure 5. Adopter (n = 91) and non-adopter (n = 70) attitude scores for the respective adopt-a-verge program aims.

Discussion

This paper has quantified some key social aspects of a community led, local municipality facilitated voluntary urban-greening program, known as adopt-a-verge. Results revealed program participants (adopters) and non-participants (non-adopters) were similar in their environmental world view, based on the NEP, and both viewed the adopt-a-verge program in a positive light in terms of its aims and the likelihood those aims would be achieved. However, program adopters were significantly more positive than non-adopters in terms of the likelihood the aims could be achieved and how ‘good’ they were. This formed the foundation for a more positive attitude towards the program aims by the adopters. Adopter reasons for participation mainly included aesthetic appeal while reduced water use and environmental benefits were indicated to a lesser extent. Non-adopter reasons for not participating in the program were mostly associated with a lack of awareness of the program and verges being required for other uses not compatible with verge plantings. Adopters tended to have fewer people living in their household and less older children, than the non-adopters. These results provide insights into the facilitators and perceived barriers to community involvement in an urban-greening initiative.

While community support is vital for successful local urban-greening initiatives (Roy 2017; van der Jagt et al. 2017), understanding why community members may or may not participate enables program managers to adjust or focus the program to maximise involvement. At the same time, various authors emphasise that much remains to be done in relation to understanding community values and beliefs when it comes to various urban-greening programmes (Barona et al. 2022; Kendal et al. 2022). The results of this study suggest that environmental world view was not a significant factor determining involvement in the program. Both adopter and non-adopter groups had similar worldviews, generally tending towards the ecocentric end of the spectrum. Moreover, effectively encouraging environmentally responsible behaviour, such as planting native vegetation on the residential verge, may be best approached through targeting the significant differences between participants and non-participants associated with performing the behaviour (Hughes, Ham, and Brown 2009; Hughes, Weiler, and Curtis 2012; Obregon et al. 2020). The lack of difference in environmental world view could mean that attempting to encourage greater involvement in planting native vegetation on verges in urban areas by emphasising the general environmental imperative may not be effective. However, Ligtermoet et al. (2021) have proposed that the provision of incentives, education and evidence of benefits has the potential to foster increasing public interest in such programmes. Hunt et al. (2022) have explored public motivations for verge gardens comprising native vegetation in the City of Bayswater LGA in Perth. In this case environmental imperatives such as wildlife corridors, reducing urban heat, re-wildling, water conservation and aesthetics were identified as motivating factors with those people that had a verge garden comprising native vegetation.

While about half of adopter respondents in the City of Vincent (this study) indicated environmental reasons for participation, the vast majority indicated aesthetic appeal of native plantings on their verge as the reason for participation. This suggests that the environmental imperative, while present, is not a primary reason for involvement in the program. Non-adopters stated several main reasons for not being involved including not being aware of the program, as well as requiring the verge for other purposes (such as car parking). It seems that environmental concerns in relation to promoting urban greenspace were not a top-of-mind factor regarding involvement in the adopt-a-verge program. Rather, practical considerations regarding established views on verge value and function (Muratet et al. 2015; Marshall, Grose, and Williams 2019a) and the extent of awareness of the program appeared to dominate. While identifying enabling factors, such as evidence-based approaches, for verge-greening programmes Ligtermoet et al. (2021) also specified that stakeholders were interested in a variety of preferences (natives, exotics, car parking) some which may act as barriers to participation.

In the City of Vincent, the six stated aims of the adopt-a-verge program relate to enhancing connectivity of urban green space, to enhance biodiversity and provide some key social benefits at the local municipal scale. The benefits and challenges of establishing wildlife corridors, including the use of road verges, to connect fragmented urban greenspace are well recognised (Arenas et al. 2017; Phillips et al. 2020b, 2021). While both adopters and non-adopters were positive about the program aims, non-adopters had a significantly less positive attitude compared to the adopter respondents. This less positive attitude was composed of non-adopter beliefs that some program aims were less likely to be achieved, while also being less positive about the aims as good things to do, relative to adopter beliefs. For example, while non-adopters and adopters both rated the aim, ‘encourage native planting’ as likely to be achieved, non-adopters were less positive about this aim as being achievable and considerably less positive about this aim as a good thing to do. Community support for urban-greening programs requires understanding and support of the program aims (Marshall, Grose, and Williams 2020). Encouraging the involvement of non-adopters in the program may not only require raising effective public awareness about the program but may also require different messaging emphasising the achievability and merit of the specific program aims (Ligtermoet et al. 2021; Hunt et al. 2022).

The mainly aesthetic reasons for adopting a verge indicated by adopters aligns with the adopters’ significantly higher likelihood and evaluation rating of ‘Enhance local beauty’ compared to the other program aims (c.f. Muratet et al. 2015; Marshall, Grose, and Williams 2019a). Coupled with this, adopters rated the ‘create corridors’ aim lower than the other aims. This suggests that the connectivity and biodiversity aspects, as central components of the program from an urban greening and biodiversity perspective, are generally less important to the respondents than the aesthetic appeal of planting native vegetation on their road verges. This has ramifications for community engagement in urban-greening programs such as adopt-a-verge. Considerations that warrant inclusion and topics of further research include elements of social geography such as demographic profiles including component immigrant populations and trends towards gentrification. Spatial geographic aspects worthy of consideration are housing density and proximity to existing green space. Place attachment and environmental values are significantly influenced by the before mentioned considerations. For example, Hunt et al. (2022) suggest that households located next to existing green space are more likely to be interested in nature which in turn is likely to lead to greater native garden densities. Hunt et al. (2022) also reported that the southern area of the City of Bayswater in Perth, which had a higher density of verge gardens, was also typified by retirees, smaller household sizes and higher than average incomes. Further to understanding public opinion would be appreciation of the role of networks such as local government authorities, advocacy groups and environmental consultants (Ligtermoet et al. 2021). This is especially so regarding their role in community engagement such as in providing incentives and educational opportunities in support of urban-greening initiatives.

Conclusion

The on-going geographical research on urban greening ranges from climate science, urban forestry, ecology, remote sensing, various applications of geographic information systems such as spatial analysis, as well as the broad area of human geography. From the human geographical perspective urban green space research also includes sustainability science, political analysis, psychology, demography, town planning and the framing of policy. This paper contributes additional knowledge in the Australian human geographical context by providing some insights into the social dimensions of a community-based urban-greening program aimed at increasing urban green space connectivity by facilitating residents to plant locally native vegetation on residential road verges. The findings highlight differences between adopters (program participants) and non-adopters (those not participating) in terms of their reasons, beliefs and attitudes towards the program aims. Adopters were primarily focussed on the aesthetic value they associate with planting native vegetation on their road verge. Non-adopters tended to indicate they were not aware of the program or required the verge for other uses not compatible with planting native vegetation. Non-adopters tended to have fewer positive attitudes than adopters towards the program aims, particularly planting native vegetation, mainly determined by less positive beliefs about that being a good thing to do.

Community engagement and support is vital for effective implementation of urban-greening programs. Understanding the reasons, beliefs and attitudes relating to engagement or lack of engagement can help to inform managers about how to better engage with local communities to ensure the effectiveness of urban-greening initiatives such as the adopt-a-verge program. In the context of this study, emphasising the importance of creating corridors to enhance greenspace connectivity (a central aim of the program) is less likely to encourage involvement compared with promoting the aesthetic and practical attributes of planting native vegetation. This paper thus provides some further understanding into the socio-political context regarding resident’s perceptions of the role and importance of residential roadside verges in the broader picture of urban greening. In recent years the geographical scope of urban green space studies has changed from being focused on China and the USA. Australian studies are now more prominent and provide important perspectives on the fostering and management of urban green space in rapidly warming and drying Mediterranean type climates. In acknowledging that urban sprawl often includes a vast network of residential verges then community support is vital in the push to convert to native vegetation and in the promotion of native habitat. The lesson learnt from this study is that community support is not necessarily associated with pro-environmental attitudes, and this has implications for policy development and the application of educational strategies. Perth is a sprawling city that is adopting densification resulting in a reduction of greenspace. Understanding the role of residential road verges in planning for urban green space thus remains an important topic of research.

Acknowledgements

Joe Fontaine with project supervision and assistance in the field.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by City of Vincent, Perth ($5000).