Classification of institutional barriers affecting the availability,accessibility and attractiveness of urban green spaces

The main goal of this article is to identify and classify institutional barriers which prevent the use of urban green spaces (UGS) at three levels: availability (whether a UGS exists), accessibility (whether it is physically and psychologically accessible, e.g., not fenced off), and attractiveness (whether it is attractive enough for potential users to visit). We reviewed the impacts on UGS provision exerted by different actors (individuals, formal and informal groups, community councils, city authorities, national governmental and non-governmental organizations), along with the relevant institutional foundations of those impacts. As a result, we identified and classified the different barriers for which these actors are responsible in the case of fifteen UGS types in our case study city, Lodz (Łódź) in Poland. The main barriers at different levels concern conflicting interests, physical barriers (private green spaces), and the lack of funds, together with legal and governmental failures (public green spaces). These barriers result from the different actors’ mandates or lack thereof. Our analysis has implications for the operationalization of UGS availability, accessibility and attractiveness, and, in particular, for mapping UGS and setting the relevant indicators and thresholds for UGS availability, accessibility and attractiveness.     

The fate of urban green spaces: Assessment of the ownership,availability and conditions of parks in Accra,Ghana

Globally, the loss of green spaces threatens the sustainability of many cities. Among other factors, complex land ownership and management regime reportedly disrupt land administration and development; but with inconclusive empirical evidence on how this influences the conditions, availability and development of parks. This study, using Accra, thus employs document analysis, 16 key informant interviews and observation of majaor parks to: (i) explore the spatial location of parks and the relationship between their ownership and conditions, (ii) examine the factors which have influenced the decline in park size and conditions, and (iii) examine the institutional response to improving upon park planning, availability and conditions. The findings show distributive injustice of parks as most of them are located in high- and middle-income neighborhoods. There is also evidence of decreasing available park land per 1000 population between 1991 and 2022. Parks managed by private institutions were found to be in very good state compared to those managed by state institutions. The existing dualistic and complex land tenure regime have largely led to the decline in park availability and conditions. Other reported factors were rapid urbanization, land litigation, low priority to park development and planning, laxity in the enforcement of regulations, and political interference. The study makes recommendations to improve upon existing practices and generally enhance park creation, availability and conditions.     

The relationship between the distribution and use patterns of parks and their spatial accessibility at the city level: A case study from Tehran,Iran

Parks are recognised as important elements of urban green infrastructure and for providing many benefits to city residents. In countries where urban growth is unplanned and sprawling, green space provision falls behind, inadequate amounts are provided or spaces are not located in the most effective places. Tehran, the capital of Iran, has experienced huge growth in population and corresponding sprawl in recent years. There has been no study of the effectiveness of parks as part of the range of green spaces in the city − their location, accessibility within the urban structure, relationship to the socio-demographic character of the population, amount per capita or quality and condition. Using a combination of existing data supplemented by new data from site surveys, this study firstly looked at the citywide scale of public open space in relation to population and socio-economic patterns. Second, a representative sample of 16 parks was examined in terms of their accessibility within the urban street structure using space syntax. The syntactical results were correlated with several different aspects of each park collected and rated on a 1–5 scale. The results showed a wide range of availability of parks with no specific pattern related to whether the district is better off or poor. The data on green space per district was often heavily biased by the presence of large areas of forest park or non-recreational land which gives a false picture.Many of the best parks are poorly integrated into the street network and found in the better off districts yet are very popular because they are “destination” parks in cooler, hilly areas. Poorly integrated parks in the inner city districts tended to show lower levels of maintenance, were often little used and had vandalism. Much more attention is needed to provide green space in an equitable way.     

People with the least positive attitudes to green exercise derive most anxiolytic benefit from walking in green space

Green exercise elicits greater psychological benefits than urban exercise. We assessed the role of expectations, attitudes to green exercise, and trait anxiety on the anxiolytic effect of green exercise. Participants were randomly assigned to one of two groups to reduce order effects. One group completed a bout of green exercise followed by a bout of urban exercise and the second group vice-versa. Participants ( N = 22) completed 30-minutes of walking in both green and urban environments, with state anxiety assessed pre-, during- and post-activity. Measures of expectations, attitudes to green exercise, and trait anxiety were recorded at baseline. The findings suggest that green exercise does not elicit greater reductions in anxiety than urban exercise. However, a 30-minute walk in green space elicited greater improvements in state anxiety for participants with a lower positive attitude to green exercise(b = 5.14, 95% CI 0.48–9.80, p = 0.032). Attitudes to green exercise play a role in the anxiolytic effects of green exercise and should be considered when delivering green exercise interventions for mental health outcomes.     

Street trees as cultural elements in the city: Understanding how perception affects ecosystem services management in Porto,Portugal

Processes shaping urban ecosystems reflect and influence the cultural context in which they emerge, bearing implications for ecosystem services (ES) planning and management. Investigating the perception of benefits and losses / costs delivered by a specific service providing unit (SPU) can generate objective orientations suitable for urban planning and management deeply embedded in the social-ecological systems where they occur, because the realization of ES into benefits and losses / costs is mediated by specific beneficiaries and reflects their characteristics, information and use of ecosystems. Street trees are a particularly relevant SPU in many densely built Southern-European cities due to the difficulty in implementing new sizeable green areas. In this study, a questionnaire was developed and applied in Porto to investigate how benefits (cultural, regulating and economic) and losses / costs caused by street trees are perceived by citizens and influenced by a set of socioeconomic variables (N = 819 people aged 18 years or older), and parametric statistical tests were used to analyze the effect of gender, age and school level. Results evidenced that people in Porto valued more environmental benefits (particularly air quality improvement) than cultural ones. School level was the variable accounting for more differences, underlining a tendency in people with lower level of academic education to value less the benefits provided by street trees in Porto and attribute more importance to losses and damages, compared to people who attended university or had higher academic degree. Age also held considerable differences in mean responses, with older people showing more concern towards losses and costs, while gender influenced perception of cultural benefits, which were more important for women than for men. The findings of the research are discussed concerning implications for environmental justice, planning and management of urban ecosystems.     

Evaluating the quality of street trees in Washington,D.C.: Implications for environmental justice

Urban street trees are part of the bundle of environmental amenities that support healthy social, economic, and environmental functions. In this study, we systematically evaluate the quality of 196,825 street trees at the US. Census tract level in Washington D.C., as well as related impacts from socioeconomic, landscape patterns and environmental factors using Ordinary least-squares (OLS) regression, geographically weighted regression (GWR) and structural equation modeling (SEM). Our results reveal that environmental and socioeconomic factors can explain most of the spatial variation of street tree quality in Washington, D.C. There is a substantial statistical negative relationship between median household income and the percent of street trees under stress, which provided the evidence of the inequities of street tree quality in Washington D.C. Higher-income neighborhoods exhibited a lower proportion of street trees under stress. In addition, the extreme summer temperature is positively associated with the proportion of street trees under stress. The quality of street trees is directly impacted by environmental and landscape pattern factors. There is also an indirect impact from socioeconomic factor toward quality of street trees. Our findings suggest that multiple variables, related to income, age, education, landscape pattern, and environment contribute to the quality of street trees in D.C. Based upon our findings, we identify strategies and insights for urban street tree management in DC to not only address environmental inequity and injustice, but also promote a more inclusive and resilient urban greenery system.     

Refining the accessibility evaluation of urban green spaces with multiple sources of mobility data: A case study in Shenzhen,China

Urban green space (UGS) is an important component of urban resources which contributes to human physical and mental health. Studies on the accessibility of UGS under the two-step floating catchment (2SFCA) framework have recently received much attention. However, the effects of people’s actual mobility patterns have not been fully considered in current studies. Proposed in this study is an improved accessibility model called AM-Ga2SFCA, which refines the traditional Gaussian 2SFCA method with the actual mobility information extracted from mobile phone big data and online map. A new attractiveness index of UGS is implemented by combining the popularity evaluated by the PageRank algorithm and the actual utilisation based on buffer analysis. In addition, realistic travel time between each demand point and UGS is retrieved from the online map, which is further introduced into AM-Ga2SFCA as the travel cost. A case study is conducted in Shenzhen, China to validate the proposed model. Results show that the accessibility of UGS is strongly correlated with regional urbanization level, for example, higher accessibility generally occurred in the region with developed transportation and rich green resources. From the perspective of age groups and travel modes, we found that the environmental justice issue had already occurred in Shenzhen especially for the non-elderly: under the walk mode, nearly 80% of the non-elderly only shared 20% of UGS whilst approximately 80% of the elderly shared 30% of UGS. However, taxi or private vehicles can effectively alleviate the aforementioned phenomenon by reducing the Gini index to less than 0.5. The proposed model is expected to advance the understanding of UGS accessibility and facilitate effective planning to reduce environmental justice.     

Valuing urban trees: A hedonic investigation into tree canopy influence on property values across environmental and social contexts in Baltimore,Maryland

Urban tree canopy yields numerous environmental and social benefits. This study investigates whether the marginal contribution of tree canopy cover to home values depends on certain characteristics of a property and its location. We address this using a hedonic property analysis with data from Baltimore, Maryland. Both Ordinary Least Square and Spatial Lag models were conducted, all including interaction terms between tree canopy cover and various site factors. Our results indicated that, on average, the amount of tree canopy in the 100–400 zone around a single-family property is positively associated with home price. We also find that the marginal impact of canopy on property price increases for properties that are larger in lot size and closer to downtown Baltimore. Model results were mixed in terms of the interactive effects of crime and proximity to major roadway with tree canopy. We suggest that the benefits that tree canopy provides in the form of added privacy, reduced urban heat, noise and pollution may influence these price increases. These findings may signal concerns about the potential for urban greening to contribute to gentrification. In a competitive housing market, those with the capacity to afford to pay more for urban tree canopy and the benefits it provides such as a cooler downtown environment, privacy on larger lots, or reduced noise and pollution from a major roadway may price out those who are unable to pay this urban tree canopy premium. There is, therefore, the potential for unequal increases in home equity across neighborhoods following tree planting and urban greening in Baltimore.     

Twelve-year change in tree diversity and spatial segregation in the Mediterranean city of Santiago,Chile

Tree diversity is one of the most important components of urban ecosystems, because it provides multiple ecological benefits and contributes to human well-being. However, the distribution of urban trees may be spatially segregated and change over time. To provide insights for a better distribution of tree diversity in a socially segregated city, we evaluated spatial segregation in the abundance and diversity of trees by socioeconomic group and their change over a 12-year period in Santiago, Chile. Two hundred vegetation plots were sampled across Santiago in 2002 and 2014. We found that overall abundance and diversity of urban trees for the entire city were stable over 12 years, whereas species richness and abundance of native tree species increased. There was segregation in tree species richness and abundance by socioeconomic group, with wealthier areas having more species and greater abundance of trees (for all tree species and native species) than poorer ones. Tree community composition and structure varied with socioeconomic group, but we found no evidence of increased homogenization of the urban forest in that 12 years. Our findings revealed that although tree diversity and abundance for the entire city did not change in our 12-year period, there were important inequities in abundance and diversity of urban trees by socioeconomic group. Given that 43% of homes in Santiago are in the lower socioeconomic areas, our study highlights the importance of targeting tree planting, maintenance and educational programs in these areas to reduce inequalities in the distribution of trees.     

Urban parks,value uplift and green gentrification: An application of the spatial hedonic model in the city of Brisbane

This paper explores the impact of urban parks on real estate prices making use of a hedonic price approach. Focusing on Brisbane, Australia, as a case study site, we use spatial hedonic models to analyse housing sales data across 15,000 sales transactions to investigate the effects of parks on nearby housing prices, paying attention to park typology and classification. Our findings indicate that recreational and sport parks are differently associated with price variations. The study also examines a specific and significant inner-city park currently undergoing a major redevelopment—namely Victoria Park. Our analysis of the Victoria Park site seeks to quantify the value uplift, that is, the future increase in property prices as a result of the transformation of the current private golf course in this location into a new publicly accessible parkland. This study’s property economics modelling analysis indicates the conversion of Victoria Park from a golf course to public parkland will increase property prices by an average of 3 % for properties located within 750 m of the park. The article concludes with a discussion of value capture opportunities that these findings present as well as challenges of green gentrification for this and similar urban renewal projects and possible policy responses.     

Crisis mediated new discoveries,claims and encounters: Changing use and perception of residential greenery in multistory housing in Berlin,Germany

With the stay at home orders during the pandemic, the often semi-public green spaces of the residential environment, usually created during the building of the houses, became our literal spheres of experience. In our study, we explored use and perceptions of local greenery by residents after sixteen months of the COVID-19 crisis, using face to face questionnaires in eight socially disadvantaged neighborhoods of Berlin, all exposed to high loads of environmental stressors and belonging to four relevant building types of Central European cities. Residential greenery was highly appreciated by residents during COVID-19, and fostered a more active appropriation such as meeting neighbors to reduce the sense of loneliness, doing sports and co-creating refugia in challenging times (e.g. greened balconies). Having children or doing home office/schooling encouraged people to use the green in front of the door in more active ways, such as gardening or even during winter. A minor proportion of respondents reduced contacts mainly due to fear of infections, underlining the need to overcome those distances and to re-connect neighbors and living inside and outside the houses in a post-pandemic city. Our data prove the functionality of residential greenery as ‘social tissue’ or ‘social hubs’ of neighborhoods by fostering attachment to place and people and, at the same time, as healthy environment for practices such as enjoying nature and physical activity in fresh air.     

The inequity of distribution of urban forest and ecosystem services in Cali,Colombia

Little is known about urban forest planning, management and its benefits in emerging countries. The uneven distribution of tree canopy cover and parks in urban area is related to environmental justice, especially with disadvantaged socio-economic and marginated communities. However, the inequity of urban forest in many cities of emerging countries where often found irregular and unregulated land use patterns and social and socio-economic inequities, is hardly highlighted. This study explores the inequity of distribution of tree canopy cover and public park in Cali, Colombia. Utilizing the traditional socio-economic indices, the stratification, linear regression analysis is conducted to describe relationship between total tree canopy cover, tree canopy cover of various land use types, number of parks and park area per capita. The result demonstrates that lower income communities have lower tree canopy cover, fewer parks and smaller park area than higher income communities. This paper discusses importance of accounting for urban forests and ecosystem service in city planning efforts and better strategies of reducing inequity in emerging countries. Addressing the inequity of urban forest could be a better strategy to create resilient, sustainable, safe and livable cities in emerging countries.     

Selecting trees for urban paved sites in Scandinavia – A review of information on stress tolerance and its relation to the requirements of tree planners

Urban paved sites are complex stress environments and when selecting trees for such sites, tree planners must prioritise stress tolerance above aesthetic appeal and functional aspects. This requires detailed information about the tolerance of tree species to environmental stresses, so as to support urban tree planners in selecting a wide range of trees. In Scandinavia there is currently no overview of the extent to which the character of information about stress tolerance and its dissemination in books and papers support urban tree planners in selecting a wide range of species for paved sites. Books on dendrology, literature on plant use in cities, tree nursery catalogues and scientific papers were therefore reviewed. For the review, eight tree species were selected along a gradient representing their intensity of use in Northern Europe. We examined the character of information and assessed it relative to tree planners’ requirements for information to be; contextual, local to Scandinavia, referring to existing plantings in paved sites and recommendations for use of the species in paved sites. The results showed that existing information is piecemeal and that most is either too general (dendrology literature) or too specific or contradictory (scientific literature) to meet the requirements of urban tree planners, while books intended for plant use in cities do not sufficiently integrate the local perspective. Moreover, contextual information local to the Scandinavian region is mainly provided for already much used species. These findings led to suggestions on how future urban forestry and arboriculture research and dissemination efforts in Scandinavia can encourage tree planners to use a greater variety of tree species in urban paved sites.     

Establishing a "dynamic two-step floating catchment area method" to assess the accessibility of urban green space in Shenyang based on dynamic population data and multiple modes of transportation

As an integral part of the urban environment, urban green space (UGS) is of great significance in maintaining urban ecosystem balance and biodiversity. Spatial accessibility is an important indicator of UGS distribution and can be calculated by the two-step floating catchment area method (2SFCA). However, problems exist in previous studies using 2SFCA: (1) the dynamics in population distributions are ignored when measuring UGS demand; and (2) travel costs are calculated for only a single mode of transportation. To address these problems, this study proposes a dynamic two-step floating catchment area method (D2SFCA) based on the Baidu heatmap and direction application programming interface and compares it with the traditional 2SFCA to investigate the characteristics of and differences in UGS accessibility in the first-ring built-up area of Shenyang, China. The results show the following: (1) the dynamic population distribution data calculated by the heatmap yielded the highest population density raster (581.0–1342.0 p/hm²) in areas with dense road networks and the lowest population density raster (2.0–91.0 p/hm²) in areas with railways and rivers, thereby more accurately reflecting reality and better quantifying the UGS demand than the static population distribution data; (2) the D2SFCA and 2SFCA findings had a slightly different distribution, and the D2SFCA assessment results more accurately reflected actual patterns, especially when the road data were inaccurate. In summary, the D2SFCA is more suitable for assessing accessibility and can identify specific areas that lack UGS. This study provides a scientific basis and methodological support for improving the services level and equity of UGS.     

Effect of pre- and postharvest salicylic acid treatment on physio-chemical attributes in relation to the vase life of cut rose flowers

With the aim of extending the vase life of cut rose flowers, we investigated whether the application of salicylic acid (SA), pre- and postharvest, could improve this. For this purpose, two individual trials were conducted, using a completely randomised design, with three replications. In the first trial, aqueous solutions of 0, 0.5, 1.0 and 1.5 mM SA were sprayed on roses grown in a controlled greenhouse once the flower buds had appeared, and the second stage was performed two weeks before harvest. The preharvest SA application at 1.5 mM concentration prolonged the vase life of cut roses by improving membrane stability, and decreasing the lipid peroxidation properties. In the second trial, continuous exposure to (0, 0.5, 1.0 and 1.5 mM), and pulses of (0, 5, 10 and 15 mM), SA significantly extended the vase life. Flowers treated with 1.5 (continuous exposure) and 15 mM (pulse) SA showed a significant decrease in weight loss, and antioxidant activity increased, compared to the control solution, but the flowers in the control solution indicated an increase in weight loss. The results show that pre- and postharvest SA application prolonged the vase life of cut roses through improving CAT and POD activity, and decreasing lipid peroxidation.     

Comparison of avian diversity between urban parks adjacent to mountain and river in the largest megacity Guangzhou,South China

Urban parks can provide a resource for maintaining and increasing bird biodiversity. However, little research has been conducted to show the differences in bird community diversity between parks adjacent to mountains and rivers in the city center of highly urbanized areas. This study analysed whether the bird composition and species diversity differed between parks adjacent to Baiyun Mountain (hillside parks) and Pearl River (riverside parks) in Guangzhou, South China. From January 2018 to December 2020, 137927 birds representing 206 species were recorded. The results indicated that the number of species and individuals of birds were higher in hillside parks than in riverside parks in each season. The number of species and individuals was also higher in hillside parks than in riverside parks in different functional groups according to bird food type, residential type, and ecological type. The number of species shared by the two types of parks was 120. The unique birds' species number in hillside and riverside parks were 67 and 19, respectively. Bird diversity in terms of richness and Shannon index was higher significantly in hillside parks than in riverside parks in summer. Principal component analysis of environmental traits of 18 parks showed that plant traits in parks have relatively high and positive contribution. Correlation analysis indicated that bird diversity was positively affected by water area, the highest altitude, habitats diversity and tree evenness in park, while negatively regulated by building coverage around each park. The top 20 most abundant bird species accounted for 87.5% of the total birds in the study period. Nycticorax nycticorax, Urocissa erythroryncha and Podiceps ruficollis were observed more frequently in hillside parks, while Pycnonotus aurigaster, Passer montanus, Acridotheres cristatellus were observed more frequently in riverside parks. Principal coordinates analysis also indicated that bird communities significantly differed between hillside parks and riverside parks. In conclusion, our findings highlight the importance of conserving mountains and rivers as buffer zones for serious anthropogenic disturbance in the city center. We propose that the conservation of hillside parks is a priority strategy for enhancing urban birds biodiversity.     

Indigenous and spontaneous vegetation: their relationship to urban development in the city of Leeds, UK

The concepts of indigenous and spontaneous vegetation are considered as subsets of the broader category, semi-natural vegetation. Indigenous vegetation is conceptualised as that which has originated in a rural landscape and developed over a time period of several centuries or more, either naturally or as a result of traditional management methods, together with the environmental conditions supporting it. In contrast, spontaneous vegetation is that which has naturally colonised derelict urban sites, mainly within the last century. An investigation, using map and aerial photographic data, examined the relative proportions of potentially indigenous and spontaneous vegetation on proposed development sites in Leeds, a large industrial city in the UK. Results suggested that spontaneous vegetation occupied approximately 13% by area of the development sites while possible indigenous vegetation occupied as little as 5%. However, further analysis suggested that approximately 25% of the proposed development sites were within 0.5 km of a designated site containing indigenous vegetation. It is argued that both types of semi-natural vegetation can make positive contributions to the urban environment but that public perception of spontaneous vegetation and, in particular, the locations where it occurs, are often negative. Further research into public perceptions of semi-natural vegetation and ways of incorporating it into urban development are required.     

Trees stocks in domestic gardens and willingness to participate in tree planting initiatives in low-cost housing areas of the Eastern Cape,South Africa

Increasing human populations and rapid urbanization in sub-Saharan Africa have prompted the development and maintenance of urban green infrastructure, including urban trees for sustainability, human wellbeing, liveability and climate resilience. However, there are still insufficient amounts and large inequities in the distribution of trees between and within towns and cities of the Global North and South. In South Africa, urban green space planning and planting are encoded in several policies at national level. However, these policies are rarely translated into specific guides, standards or actions, and consequently disparities in urban trees and green space distribution persist. This study assessed the prevalence of urban trees in domestic gardens in low-cost housing areas (LCHAs) of eight small to medium-sized towns in the Eastern Cape province of South Africa and examined residents’ perceptions in this regard. This was done via surveys with 800 households in old and recently developed LCHAs. The results revealed that most households (52 %) had at least one tree in their yard, with more households in the older neighbourhoods (60 %) reporting having trees than in the newer ones (44 %). Most of the trees (66 %) had been deliberately planted as opposed to natural regeneration. Experience of formal urban tree planting programs was low, but 75 % of residents expressed willingness to participate in the future, preferably in tree planting and maintenance. Urban green spaces and trees cannot be an afterthought in the development of sustainable human settlements, and municipal plans should reflect tangible commitments in this regard. Meeting goals for greener LCHAs requires the involvement of local residents, and for municipal authorities to be receptive to the wishes of residents and willingness to green their residential areas.     

Rhizogenesis of GF677, Early Crest,May Crest and Arm King stem cuttings during the year in relation to carbohydrate and natural hormone content

The rhizogenesis of GF677, Early Crest, May Crest and Arm King stem cuttings during the year was investigated. The results showed significant differences in the rooting percentage between different dates of cutting collection and also between the four cultivars. Among these, GF677 generally had the highest rooting percentage. Rooting of cuttings was high in October, November and February and relatively low in the periods March–September and December–January. Interactions among cultivars were also found.