The public consultation is open: Insights from urban green infrastructure planning in Romania

Due to its potential to help mitigate current societal challenges and provide ecological, social, and economic benefits, urban green infrastructure (UGI) is an important investment for cities. However, its planning and implementation may be challenging due to the limited application of the conceptual foundations and the often-unknown character of the ways how the results of public consultations were integrated into the implemented UGI design. Using five Romanian urban areas as model system, we developed an evaluation protocol to assess 177 written comments submitted during the public consultation processes for 13 public UGI planning documents, along with the formal responses to these comments. Our results show critical comments towards the planning proposals (86.2 % of the comments) and a discussion of the shortcomings of the planning process (60.8 % of the comments). The analysis revealed that the UGI as it is developed and implemented currently in Romania has little public support as in 52.2 % of the comments none of UGI planning principles could be identified. Furthermore, we found a relatively low level of public comment consideration into the approved version of the planning documents as only 7.6 % of the comments were included, most of them being delegitimized by the responses of public officials/municipal administration. Thus, our results highlight that UGI consultation process is characterized by a lack of both genuine conceptual aspects and public participation substance.     

Evaluating naturalness and functioning of urban green infrastructure

Evaluating the state of urban green infrastructure (UGI) is a basic step to reach urban sustainability. Two indicators were used to evaluate 89 UGI sites in Zaragoza, a medium-sized city in NE Spain: Naturalness (Nat), related to the area covered by natural components; Functioning (Fun), related to the area showing natural hydro-geomorphological features. Complementarily, 15 biophysical and social variables were used to characterize these sites. A principal component analysis (PCA) was performed to group variables and types of UGI, while linear regressions and ANOVAs were applied to identify relationships between UGI characteristics, Nat and Fun.The Zaragoza UGI was dominated by artificial regular sites. Most sites (73%) have low-medium values of Nat and Fun. They were mostly flat urban parks with very regular forms located in the most densely urbanized zones, and 20% of the sites have high values of Nat and Fun, corresponding to well-conserved natural areas, either unchanged or slightly transformed. Only 3 sites displayed high Nat values and low Fun values. No sites had high Fun values and low Nat values. These groups of UGI sites were mostly distributed along the first axis of the PCA which represented the natural and heterogeneous forms versus regularity and flatness features. The UGI sites scattered throughout the second axis represented a gradient from paved to vegetated sites. Both Nat and Fun were positively correlated with area, natural subsoil and the area covered by vegetation but negatively with artificial soil, regularity and flatness after the linear regressions and ANOVAs.These results show that Nat and Fun are effective indicators to assess UGI sites. Minimizing regularity of design, preserving the natural topological relief, and restricting the area covered by artificial components are suggested to achieve a balanced representation of ecosystem processes, functions, and services within the UGI network of a city.     

The effect of street trees and amenity grass on urban surface water runoff in Manchester,UK

It is well known that the process of urbanization alters the hydrological performance of an area, reducing the ability of urban areas to cope with heavy rainfall events. Previous investigations into the role that trees can play in reducing surface runoff have suggested they have low impact at a city wide scale, though these studies have often only considered the interception value of trees.This study assessed the impact of trees upon urban surface water runoff by measuring the runoff from 9 m² plots covered by grass, asphalt, and asphalt with a tree planted in the centre. It was found that, while grass almost totally eliminated surface runoff, trees and their associated tree pits, reduced runoff from asphalt by as much as 62%. The reduction was more than interception alone could have produced, and relative to the canopy area was much more than estimated by many previous studies. This was probably because of infiltration into the tree pit, which would considerably increase the value of urban trees in reducing surface water runoff.     

Aligning fragmented planning structures through a green infrastructure approach to urban development in the UK and USA

Globally green infrastructure (GI) planning has developed with alternative conceptual and implementation viewpoints. In the UK and USA this has led to the establishment of a dual narrative; one identifies a set of conceptual principles within the wider global GI debate, whilst the second focusses on localised interpretations of these principles within divergent delivery approaches. Such plurality adds a level of complexity to the development of GI policy and subsequent investments, which can be understood if both narratives are debated simultaneously. A number of factors have influenced this process; the most prominent being the dislocation between GI policies, practice and funding. This paper addresses this fragmentation proposing that a ‘policy-implementation’ gap exists within national and sub-national planning practice which limits the transferability of global principles into delivery. Therefore although the conceptual understanding of GI is grounded in the global literature, greater variability is evident in the application of these principles within localised (i.e. national, regional and sub-regional) planning. The paper extends this debate through a discussion of whether a consensus for the conceptual advancement and implementation of GI is a necessary aim of its development. It concludes that such plurality of understanding is both a positive and negative attributes of GI planning, highlighting the complexity of attempts to align global and local development narratives for GI.     

园林绿化在城镇扩容中的发展与提高

发展与提高园林绿化建设,发挥其景观功能与生态性,保护与改善城市生态环境,防止城市扩容对环境的不利影响,有效改善日益严重的城市环境污染问题是现代城市建设的一个重要内容.当今,人们对人居环境提出更高的要求.在城镇扩容中,其园林规划要更加人性化、标准化,景观工程更加艺术化.     

The multifunctionality concept in urban green infrastructure planning: A systematic literature review

Urban green infrastructure is critical for providing a wide range of ecosystem goods and services that benefit the urban population. Past studies have suggested that multifunctionality concerning urban infrastructure services and functions is a prerequisite for targeting effective and impactful urban green infrastructure. Moreover, urban green infrastructure with multiple functions can offer socio-economic and environmental benefits. However, there has been a knowledge gap in the planning literature to elaborate multiple ecosystem functions in urban green infrastructure. In particular, existing methods and approaches are lacking for quantifying and monitoring such ecological services and biodiversity in urban green infrastructures at different spatial scales. Therefore, this research aims to review studies focusing on the multifunctionality concept in urban green infrastructure planning. The study highlights the current status and knowledge gaps through a systematic review. Our analysis revealed that current studies on green infrastructure multifunctionality have focused on five main themes: 1) planning methods for urban green infrastructure, 2) assessment approaches of urban green infrastructure, 3) ecosystem services and their benefits, 4) sustainability and climate adaptation, and 5) urban agriculture. The study found that the five themes are somewhat connected to each other. The study has revealed a knowledge gap regarding incorporating multifunctional green infrastructure in the planning principle. The results suggest at least five critical elements to ensure multiple functions in urban infrastructure. The elements are spatial distribution, optimal distance, integrated network, accessibility, and public participation and engagement. The study further recommends research directions for future analysis on green infrastructure multifunctionality that are critical for urban planning.     

Enhancing plant diversity and mitigating BVOC emissions of urban green spaces through the introduction of ornamental tree species

Promoting the plant diversity of urban green spaces is crucial to increase ecosystem services in urban areas. While introducing ornamental plants can enhance the biodiversity of green spaces it risks environmental impacts such as increasing emissions of biogenic volatile organic compounds (BVOCs) that are harmful to air quality and human health. The present study, taking Qingdao City as a case study, evaluated the plant diversity and BVOC emissions of urban green spaces and tried to find out a solution to increase biodiversity while reducing BVOC emissions. Results showed that: (1) the species diversity and phylogenetic diversity of trees in urban green spaces were 22% and 16% lower than rural forest of this region; (2) urban areas had higher BVOC emission intensity (2.6 g C m⁻² yr⁻¹) than their rural surroundings (2.1 g C m⁻² yr⁻¹); (3) introducing the selected 11 tree species will increase 15% and 11% of species diversity and phylogenetic diversity, respectively; and (4) the BVOC emissions from green spaces will more than triple by 2050, but a moderate introduction of the selected low-emitting trees species could reduce 34% of these emissions. The scheme of introducing low-emitting ornamental species leads to a win–win situation and also has implications for the sustainable green space management of other cities.     

Enhancing pollination ecosystem service in urban green areas: An opportunity for the conservation of pollinators

The rapid growing urbanization is one of the main threats to urban biodiversity and the ecosystem services (ES) that they provide. Pollination is one of the most affected ES in urban areas mainly due to the decline in urban green areas (UGAs) and other factors derived from urbanization itself. Considering this and the already existing global pollinator crisis, the aim of this work is the evaluation of urban green infrastructure as an opportunity for pollinator conservation. For that purpose, the ornamental vegetation of a medium-sized Mediterranean city (Granada, south-eastern Spain) was determined. The floral origin, phenology and floral traits of the conforming species and the pollinator species that they attract were analysed. Additionally, NMDS analysis were performed in order to determine if the “Pollination Syndromes” are a useful tool to actually predict the pollinator group attracted to a certain plant species. It was found that UGAs have huge potential for pollinator conservation as the major part of its ornamental species have an entomophilic pollination strategy. However, there is an imbalance in the availability of flower resources throughout the year. Hence, the addition of species flowering out of the main flowering season would be advisable in order to get a continuous supply of floral resources for pollinators. A current disproportion in the potentially attracted pollinator groups was also found out, being bees the predominantly attracted ones. However, results showed that the “Pollination Syndromes” are a tool with limitations at the moment and needs to be used with considerations. Thus, the specific plant-pollinator relationship should be determined through field work in each case-study. Further studies considering key factors such as urban connectivity and fragmentation would be desirable to ensure a comprehensive management for urban pollinators.     

Challenges of urban green space management in the face of using inadequate data

Effective urban planning, and urban green space management in particular, require proper data on urban green spaces. The potential of urban green spaces to provide benefits to urban inhabitants (ecosystem services) depends on whether they are managed as a comprehensive system of urban green infrastructure, or as isolated islands falling under the responsibility of different stakeholders. Meanwhile, different urban green space datasets are based on different definitions, data sources, sampling techniques, time periods and scales, which poses important challenges to urban green infrastructure planning, management and research. Using the case study of Lodz, the third largest city in Poland, and an additional analysis of 17 other Polish cities, we compare data from five publicly available sources: 1) public statistics, 2) the national land surveying agency, 3) satellite imagery (Landsat data), 4) the Urban Atlas, 5) the Open Street Map. The results reveal large differences in the total amount of urban green spaces in the cities as depicted in different datasets. In Lodz, the narrowly interpreted public statistics data, which are aspatial, suggest that green spaces account for only 12.8% of city area, while the most comprehensive dataset from the national land surveying agency reveals the figure of 61.2%. The former dataset, which excludes many types of green spaces (such as arable land, private and informal green spaces), is still the most commonly used. The analysis of the 17 other cities confirms the same pattern. This results in broader institutional failures related to urban green infrastructure planning, management, and research, including a lack of awareness of green space quality (e.g. connectivity) and benefits (ecosystem services), and the related political disregard for urban green spaces. Our comparison suggests that a better understanding of green space data sources is necessary in urban planning, and especially when planning urban green infrastructure.     

The utilisation potential of urban greening waste: Tartu case study

In light of climate change and the increasingly limited availability of energy resources, any form of renewable raw materials that can be used for energy production should be accounted for. One of the most promising renewable sources is considered to be that of lignocellulosic feedstock. In urban forestry and greening, millions of tons of lignocellulosic waste is produced every year but that biomass mostly goes unused. The aim of this research project was to investigate the utilisation potential of this very form of waste biomass using a medium-sized town as a sample for the work (Tartu in Estonia, with a population circa 100,000). Woody and non-woody vegetation representing greening waste from different seasons was investigated: spring and autumn leaves, and mixed waste from urban greening which contained grass, twigs, and leaves. BMP assays were conducted to estimate the biogas production potential and the three step bio-ethanol production process was used to estimate the bio-ethanol production potential. In the bio-ethanol production process, an N₂ explosion pre-treatment was used, followed by enzymatic hydrolysis and fermentation. Map analysis was used to assess the area that was manageable by urban forestry and greening in the city of Tartu in order to estimate the amount of greening and forestry waste that was available for bioconversion and the volumes of biofuel that could be produced.     

Responses of four hornet species to levels of urban greenness in Nagoya city,Japan: Implications for ecosystem disservices of urban green spaces

Although there is a common trend towards increasing green space in modern cities, urban green spaces provide not only ecosystem services but also disservices for urban dwellers. However, the relationship between urban greenness and ecosystem disservices has been poorly examined. We aimed to understand the effect of greenness level on the abundance and species composition of hornets – critical pests in Japan and to identify the best spatial scale for estimating their abundance with reference to greenness levels. We used a dataset that contained eight years of abundance data for four hornet species at 11 sites in Nagoya city. The levels of greenness around the hornet sampling points were measured using averages from the Normalized Difference Vegetation Index (NDVI) with radiuses of 0.1–10.0 km. We analysed the relationship between abundance and species composition of hornets and NDVI at different spatial scales using generalized linear mixed models. Higher NDVI values positively affected the abundance of all the hornet species except Vespa analis. The abundances were estimated most effectively using the NDVI average with a 1–2 km radius for all species. The species composition of hornets drastically changed along the gradient of NDVI values; V. mandarinia was dominant in greener areas (over 0.2–0.3 NDVI average with a 2 km radius) and V. analis in less green areas (below 0.2–0.3 NDVI average). Our study showed that the abundance and species composition of hornets were both strongly associated with the level of urban greenness. This suggests that increases in the greenness of urban areas can increase hornet abundance and alter the species composition of hornets; a more aggressive species, V. mandarinia, may also increase in urban areas, although V. analis is currently the most critical species according to regional consultants. Balancing ecosystem services and disservices has become crucial for the planning and management of green spaces, particularly when urban green space increases. We also demonstrate how human tolerance towards wildlife may have to be improved in order to live in greener environment where wildlife can be expected.     

Thermal Comfort Maps to estimate the impact of urban greening on the outdoor human comfort

Outdoor human comfort is an important factor in the evaluation of the liveability of a city as well as for promoting people’s health and well-being. In hot arid climates in particular, urban planning and design can considerably impact the day-to-day thermal comfort of the pedestrians, for better or for worse. Strategies to reduce thermal discomfort include shading structures, water bodies, and the promotion of natural ventilation – and most significantly, green areas. Trees have a major impact on the pedestrians in the built environment as they not only provide shading but also improve the microclimate in urban areas, thereby reducing the time during which discomfort is felt. The objective of this paper is to present a new methodology for dynamically quantifying the impact of different plants in urban areas on outdoor human comfort, through 3D urban energy modelling. The proposed methodology makes use of an urban energy modelling tool, providing a comprehensive view of the city energy fluxes, with a focus on the impact of trees on the human thermal comfort. Outdoor human comfort is assessed using the Index of Thermal Stress for the campus of the Swiss International Scientific School of Dubai (UAE), where “Thermal Comfort Maps” are designed to quantify the pedestrian thermal sensation and its variation in time and space. Additionally, the energy fluxes impinging on the urban pedestrians are quantified, dynamically, in hourly time step, providing an important instrument to understand their thermal stress, and the environmental factors affecting it. Based on the simulations, thanks to native greening, a significant improvement in outdoor comfort conditions was achieved in the campus, reducing the “warm/hot” and “very hot” thermal sensations from 1,291 h (on average over the entire campus) to less than 300 h by planting Ghaf and Acacia trees.     

Green infrastructure inequality in the context of COVID-19: Taking parks and trails as examples

Urban green infrastructures play a critical role in enhancing the well-being of residents, yet their equitable access remains a concern, particularly during the COVID-19 outbreak. There is a lack of knowledge on how people respond to the pandemic regarding the usage of green infrastructure in cities. This paper explores the shifts in visitation to parks and trails, two popular types of green infrastructures in Salt Lake County, Utah, by analyzing the results of a survey conducted during the pandemic. Our conceptualization considers personal and neighborhood level factors, including personal socioeconomic status, existing inequalities of green infrastructures, urban form, and neighborhood conditions. People who reside close to the city center tend to go to parks more often, while those living in urban edges use trails more. Visiting green infrastructures less often is more likely in areas with higher COVID-19 infection rates. The regression results confirm the importance of neighborhood level factors and illustrate the intricate elements influencing people's decisions to visit different green infrastructures during the pandemic, which shows non-linear relationships. Wealthier, white, and younger people seem to enjoy green infrastructures more often, leading to the concern of amplified inequality. Higher COVID-19 cases result in higher demands for green infrastructures, which are not fulfilled during the pandemic, especially for vulnerable communities, leading to spatial exclusion. The findings highlight the importance of smart growth, including compact development, public transit, and pocket parks, in promoting the urban resilience of park and trail visits, as they may provide more opportunities for access and alternatives to green infrastructures even in the context of the pandemic.     

Future climate risk and urban tree inventories in Australian cities: Pitfalls,possibilities and practical considerations

Urban tree inventories are useful tools to assess the environmental and socio-economic services provided by urban forests. These inventories enable the evaluation of the climate change risk to urban forests, and governments rely on such inventories for urban planning and management. Here, we assessed the future climate risk of Australia and the state of urban tree inventories across 116 local government areas (LGAs), representing 21 % of the country’s LGAs and encompassing 55 % of the national human population. We evaluated projected changes in temperature and precipitation by 2050 for each LGA and conducted a survey to obtain information on the extent and types of data available in existing urban tree inventories. Additionally, we compiled demographic, socio-economic, and geographical data for all LGAs to explore correlates with tree inventory status. Temperature increases in 2050 were predicted in all LGAs, with higher latitude and smaller LGAs identified to undergo greater increases in temperature compared to larger and lower latitude LGAs. Decreases in seasonal precipitation were predicted for 97 LGAs. Seventy-six (66 %) of surveyed LGAs had urban tree inventories, which most commonly included trees along streets and in parks. Sixty-one LGAs record information on tree mortality, while 31 LGAs dynamically update their inventories. The presence of an inventory and the area it covered were positively associated with human population density. More than 30 years ago, in 1988, John Gray wrote that “insufficient statistics were available in Australia to provide an accurate picture of the urban forest estate”. Our research shows there has not been a significant advance in the adoption and use of urban forest inventories over the past three decades. Long-term, dynamically updated inventories are crucial for urban forest management to inform planting choices to support sustainable and resilient cities.     

Exploring public preferences and preference heterogeneity for green and blue infrastructure in urban green spaces

Green and blue urban infrastructure (GBI) has many positive functions often not recognised by residents (e.g., microclimate regulation, water retention, etc.). The question for urban planners who are aware of these functions when planning new GBI elements or revitalising existing GBI is how much they need to account for the preference heterogeneity of locals, who typically consider only aesthetic and recreational value. This study uses data from a discrete choice experiment among residents of the medium-sized Czech city of Liberec to reveal which combinations of nature-based or semi-natural GBI and recreational facilities respondents prefer and how strong their preferences are in terms of their willingness to pay. Overall, study respondents preferred nature-based GBI to semi-natural ones. A mixed-latent class model identified two groups of respondents who differ in preferences, trade-offs, and socio-demographic characteristics: (i) mostly older educated women who prefer nature-based elements and enjoy park infrastructure; (ii) mostly less educated men who dislike urban gardens and semi-natural streams and do not value park infrastructure. Based on the results, we recommend that spatial planners and green space managers design and implement more nature-based elements in Liberec, which are in line with the respondents’ preferences.     

Promoting and preserving biodiversity in the urban forest

Efforts at mitigating global biodiversity loss have often focused on preserving large, intact natural habitats. However, preserving biodiversity should also be an important goal in the urban environment, especially in highly urbanized areas where little natural habitat remains. Increasingly, research at the city/county scale as well as at the landscape scale reveals that urban areas can contain relatively high levels of biodiversity. Important percentages of species found in the surrounding natural habitat, including endangered species, have been found in the urban forest.

This contribution concisely highlights some examples of urban biodiversity research from various areas of the world. Key issues involved in understanding the patterns and processes that affect urban biodiversity, such as the urban–rural gradient and biotic homogenization, are addressed. The potential for urban areas to harbor considerable amounts of biodiversity needs to be recognized by city planners and urban foresters so that management practices that preserve and promote that diversity can be pursued. Management options should focus on increasing biodiversity in all aspects of the urban forest, from street trees to urban parks and woodlots.     

Spatial statistical analysis of the relationship between self-reported mental health during the COVID-19 lockdown and closeness to green infrastructure

The COVID-19 pandemic has produced alterations in the behaviour and psychological health of people, who have had to learn living under uncertain circumstances escaping their control. This situation has been aggravated in those countries applying strict home confinement rules to try bending their epidemic curve. This is the case of Spain, where the stringent lockdown period was extended over three months. This study aimed at proving a research hypothesis whereby living close to Green Infrastructure (GI) during the confinement period was beneficial for mental health. To this end, La Palma (Canary Islands) and Zaragoza (Peninsular Spain) were taken as case studies, since both locations distributed a questionnaire to address citizenry’s self-reported mental health under strict lockdown conditions. A spatial statistical analysis of the responses collected by these questionnaires revealed that variables such as stress, anger, medication use, alcohol consumption or visits to the doctor significantly decreased if citizens were close to GI, whereas people having very high expectations of enjoying the city after the confinement were positively correlated to proximity of green areas. Although these outcomes are limited by the inferential capacity of correlation analysis, they point out to a sense of relief derived from having visual contact with vegetated landscapes and feeling stimulated about using them for recreation, aesthetical or sporting purposes. The joint consideration of these psychological gains with the social and environmental benefits provided by GI emphasizes the importance of approaching urban regeneration through the design and implementation of interconnected green spaces.     

Public perceptions and attitudes toward green infrastructure on buildings: The case of the metropolitan area of Athens,Greece

As the impact of green space shrinkage in urban centers becomes obvious, local and regional authorities must adopt environmental planning policies that can help create new green areas to ensure a good quality of life for citizens, along with the rehabilitation of the natural environment. One approach is the promotion of green infrastructure on buildings, including multi-dwelling apartment buildings. In order to effectively promote green infrastructure on buildings, it is essential to comprehend public attitudes toward green infrastructure, so that suitable and effective strategies can be implemented by policy makers. In this study, eight hundred respondents were asked to provide their views on green infrastructure on buildings, on construction that should take place on blocks of apartments in order to accommodate green infrastructure and on the related benefits that may arise from creating green spaces on buildings. A structured questionnaire and stratified sampling were used for the interviews, which were conducted with apartment owners in two regional units of Athens. The results showed that most citizens are willing to proceed with the installation of a green roof, trellis or vertical garden, in order to improve the aesthetics and functionality of the building they live in. Most of the respondents are not familiar with the energy savings that may occur from the installation of a green roof, vertical trellis or garden and wish for a subsidy from the state in order to implement green building solutions. To conclude, the participants in our study are not environmentally aware, since they are not interested in energy conservation but only about the aesthetics of their building; furthermore, they expect to receive financial support from the state in order to make any changes to their home.     

The influence of small green space type and structure at the street level on urban heat island mitigation

The purpose of this study was to determine the types and structures of small green spaces (SGs) that effectively reduce air temperature in urban blocks. Six highly developed blocks in Seoul, South Korea served as the research sites for this study. Air temperature was measured at the street level with mobile loggers on clear summer days from August to September in 2012. The measurements were repeated three times a day for three days. By analyzing the spatial characteristics, SGs within the six blocks were categorized into the four major types: polygonal, linear, single, and mixed. The result revealed that the polygonal and mixed types of SGs showed simple linear regression at a significant level (p < 0.01). It indicated that the blocks’ urban heat island (UHI) mitigation (ΔT_Rmn) increased in a linear fashion when the area and volume of these two types of green spaces increased. The area and volume of a polygonal SG with mixed vegetation, over 300 m² and 2300 m³, respectively, lowered the ΔT_Rmn by 1 °C; SG with an area and volume of larger than 650 m² and 5000 m³, respectively, lowered the ΔT_Rmn by 2 °C. The results of this study will be useful to urban planners and designers for determine the types and structures of urban green spaces to optimize the cooling effect, as well as how such green spaces should be designed and distributed.