Urban forest management and governance in Latin America and the Caribbean: A baseline study of stakeholder views

Cities in the Latin America and Caribbean (LAC) region and around the world are setting long-term greening goals that include planting more trees and increasing green cover. Research in LAC cities has mainly focused on biodiversity and vegetation, with little understanding of the mechanisms underlying the decisions through which stakeholders achieve urban greening. Exploring stakeholders’ views about urban forest management and governance can provide us with an opportunity to identify needs and research gaps for urban greening and urban forestry in LAC. To our knowledge, there has never been a region-wide empirical study to capture these stakeholder views. Here we explore how stakeholders working in urban forestry in LAC, including governmental, and non-governmental professionals, define urban forests, and view management and governance issues as well as educational opportunities. We used an online survey based on a combination of open- and closed-ended questions. The survey was delivered to participants at the first two regional conferences on urban forests in LAC organized by the United Nations. We collected 91 responses from stakeholders working in 50 different cities of varying population sizes across 6 LAC bioregions. Most respondents considered parks, planted green corridors, street trees, and remnant forests in urban and peri-urban areas as components of urban forests. Stakeholder views on management and governance were divided in two distinct perspectives, one dominated by public participation issues, and another one related to operational issues. Most respondents considered operational and management tools for urban forests to exist in LAC cities, but they disagreed on the existence of inventories, long-term strategies, and ways for the public to engage in urban forestry. Responses also revealed that some educational opportunities, such as arboricultural certification, are still relatively scarce and in high demand in the region. This study provides a regional baseline and first insights into a more diverse view of urban forestry which could be enriched with more empirical studies in the future.     

Biological potential in cities: An estimate from Melbourne

Despite the many benefits of vegetation in urban settings, inner-city areas often are sparsely vegetated or devoid of plants. This suggests substantial opportunity for improving provision of ecosystem services in densely populated areas, through retrofitting of urban environments with plants. This paper introduces the concept of ‘biological potential’ – the pragmatic potential for urban areas to be retrofitted with suitable green infrastructure.This paper demonstrates a method for making a quantitative, spatially explicit estimate of the biological potential of walls in the CBD of Melbourne, Australia. The results of this study represent an estimate of how much wall space could be home to green façade plants (i.e. creepers and climbers). The methodology is also spatially explicit – it estimates where the best locations in the city are for this kind of greening, recognising that not all walls have suitable physical characteristics or local microclimates. Employing a combination of GIS and microclimatic modelling techniques, this study estimates that over 16 ha of wall space has potential for greening in Melbourne's CBD, with 1.8 ha showing optimal characteristics.     

A balancing act: Biodiversity and human wellbeing considerations in the management of urban forest in a global biodiversity hotspot

Environmental and urban forest managers in cities located in highly biodiverse regions may need to balance biodiversity conservation with the provision of ecosystem services to people. However, striking this balance is not easy and many competing factors influence the decision-making process. Set in the Perth Metropolitan Area, located in the global biodiversity hotspot of the Southwestern Australia Floristic Province, this study aimed to understand: (i) the extent to which a benefits-oriented approach is used by local governments to optimise biodiversity and human wellbeing urban forest outcomes, and (ii) what other factors influence the decision-making process shaping urban forest composition. Using a social-ecological framework, we conducted semi-structured interviews with 29 local government practitioners. We found that biodiversity conservation is actively considered in the planning and management of urban forest in natural areas and parks, but rarely in streetscapes. Maximising shade and cooling, and to a lesser extent enhancing sense of place, were the key benefits actively sought in streetscapes. Parks appeared to straddle the middle ground as areas with most flexibility to accommodate multiple biodiversity and human wellbeing benefits. Yet, benefits were only some of a multitude of social-ecological factors influencing the decision-making process shaping urban forest composition. In particular, streetscapes were affected by a large number of social and political factors (e.g., perceived risk and nuisance, ad-hoc decisions by elected members), many of them leading to suboptimal urban forest outcomes. For a benefits-oriented approach to prevail in complex and contested urban spaces it is important that the decision-making process is evidence-informed and capable of handling the challenges and conflicts that are likely to arise. Reactive decision-making results in a conservative, “safe” species palette that over time defines streetscapes by what they do not do (creating disservices) rather than what they do (delivering multiple biodiversity and wellbeing benefits), which ultimately is not a desired outcome in the context of an increasingly urbanized world.     

Spatial variations of plant species diversity in urban soil seed banks in Beijing,China: Implications for plant regeneration and succession

The near-to-nature urban forestry concept and practices are widely recognized for urban greening, urban ecosystem restoration, urban greenspace management for biodiversity conservation and ecosystem services provision. However, the regeneration and succession of urban vegetation are rarely studied due to the complex settings of the urban environment. To this end, we conducted a large-scale field investigation in the metropolitan area of Beijing, China to explore the spatial variations in plant species composition and diversity in soil seed banks, and their similarity to the aboveground vegetation to assess the potential of urban plant regeneration. Overall, 657 vegetation and soil sampling plots from 219 grids, measuring 2 km × 2 km each, were investigated within two perpendicular 10 km wide transects running across the urban center in north-south and east-west directions within the 6th Ring Road of the city. We recorded a total of 102 plant species in soil seed banks, including 13 tree species, 10 shrub species, and 79 herb species. We found that the soil seed bank species diversity and its similarity to that of the aboveground vegetation communities decreased significantly with the urbanization intensity. Higher urbanization intensity is typically associated with increased human management and a reduction in Greenspace Area (GSA). Soil seed bank species richness increased significantly when GSA exceeded 45 % and the similarity of species composition and diversity between soil seed banks and aboveground vegetation communities was the highest in forest parks. This suggests that habitats under forest park management are more conducive to plant regeneration. Soil seed bank species diversity first increased and then decreased significantly with increased distance to the city center, whereas the species similarity between the soil seed banks and the aboveground vegetation communities showed little change with the ring roads going out. The results of this study have important implications for further understanding the potential for urban vegetation regeneration and sustainability, which have significant implications for urban biodiversity conservation and restoration.     

Understanding spontaneous biodiversity in informal urban green spaces: A local-landscape filtering framework with a test on wall plants

In densely urbanized areas, small pockets of vegetated areas such as street verges, vacant lots, and walls can be rich in biodiversity. In spite of their small size, these ‘informal urban greenspaces’ can provide critical ecosystem services to urban residents. Maintaining and enhancing the provisioning of ecosystem services requires a systematic understanding of biodiversity patterns and drivers in informal urban green spaces. The ‘environmental filtering’ (a process of certain species selected by specific environmental conditions) concept in community ecology theory may serve as a useful tool for this goal. We tested a multi-scale filtering framework by examining the spontaneous plant diversity patterns (from 83 surveyed sites) on the vertical surfaces of the ancient city wall of Nanjing, China. We found that the variables representing local-habitat filtering (e.g., wall substrates and aspect) and landscape filtering (including spatial configuration of urban land cover, and nighttime light intensity surrounding the local habitats) can jointly explain substantial fractions of variations in taxonomic diversity (up to ca. 60%) and functional diversity (up to ca. 40%). The explanatory power was stronger in the repaired wall habitats than in the unrepaired counterparts, in line with the prediction that environmental filtering is more pronounced during the early stages of community assembly. While the strength of landscape filtering showed clear scale-dependency, its relative importance consistently outweighs local-habitat filtering across all study scales of 200–1600 m, suggesting that configuration of neighboring landscape context can play an important role in shaping local-scale biodiversity of informal urban green spaces. Our results have useful implications for the study, design, and management of informal urban green spaces. Well-tailored multi-scale filtering frameworks may contribute to understanding urban biodiversity patterns in a systematic way.     

玉林市城区道路绿化树种调查及配置模式研究

以玉林市城区道路绿化建设的必要性为出发点,以打造玉林市＂城在林中,路在绿中,房在园中,人在景中＂的绿化格局为目标,通过对城区道路绿化树种生活型、主要观赏特性、生长状况、配置方式等方面进行系统调查及筛选,结合玉林的发展规模和道路绿化状况,探索出对玉林市绿化树种选择及配置的合理对策,以期为广西乃至全国的城市道路绿化提供科学依据。     

Implementing urban greening aid projects – The case of St. Petersburg, Russia

Recent years have seen the introduction of the concept of urban greening, defined as embracing the planning and management of all urban vegetation to create or add values to the local community. Green-space development has become recognised by international agencies and donors as important tool in improving the quality of urban livelihoods and urban environment. This paper evaluates an example of an urban greening aid project, carried out by Danish and Russian partners in the city of St. Petersburg, Russia. The project aimed to contribute to conservation and development of the cultural–historical, social and ecological values of St. Petersburg's urban green areas by implementing a structured, socially inclusive, well-informed planning and management approach. The project had three main components: (1) the development of a GIS-based information system to assist green-space planning and management; (2) on-site improvements in selected green areas and (3) awareness raising and public involvement activities. Ex post evaluation of the project showed that in spite of the limits of time and resources, important results were achieved. A more strategic approach to urban green-space planning and management, as promoted by urban greening, was adapted by some of the Russian project partners. Achievements also included notable physical improvements to one park. But the main project impacts were improved communication and collaboration between the local park department and local academia, as well as expertise developed in running a complex urban greening project. The project failed, however, in its public involvement ambitions.Moreover, the project should have facilitated discussion on some of the current premises of urban green-space planning and management in St. Petersburg, which insufficiently consider changing values and public preferences related to green spaces.     

A GIS-based mapping methodology of urban green roof ecosystem services applied to a Central European city

Green roofs provide a number of different urban ecosystem services (UESS), e.g. regulation of microclimate, support of air quality improvement, or stormwater retention. To estimate the spatial variation of green roof UESS across an urban area, a GIS-based mapping and spatial analysis methodology was established and applied to the city of Braunschweig, Germany. Based on the analysis of available geodata, in a first step, a quantity of 14,138 rooftops in the study area (14% of all buildings) was found to be generally suitable for greening. This resulted in a green roof area of 3 km². Based on criteria such as roof slope and minimum roof size, nearly two-thirds of these buildings (8596 buildings, 8.6% of total number of buildings) were categorised ‘appropriate’ for greening and subject to green roof UESS analysis.The spatial distribution of green roof UESS was estimated based on the categories thermal urban climate, air quality, stormwater retention and biodiversity. Due to their potential benefits in the four UESS categories an overall assessment resulted in a number of 867 roofs (0.9% of total number of buildings) categorised as ‘high benefit’ from rooftop greening. Another 3550 buildings (3.5%) and 4179 buildings (4.2%) were defined as ‘moderate benefit’ and ‘low benefit’, respectively. The inner city area of Braunschweig appears as a hot-spot of green roof UESS, i.e. higher percentage of ‘high benefit’ green roofs in comparison to residential areas. The proposed method is a simple but straightforward approach to analyse urban green roof UESS and their spatial distribution across a city but it is sensitive to the quality of the available input geodata.     

城市道路坡面绿化设计及实例分析——以重庆市奉节快速通道边坡为例

坡面绿化是以保护环境和工程防护为目的,利用各种植物来保护坡面的一种立体绿化形式。由于城市道路景观在城市景观中的重要地位,坡面绿化的应用显得尤为重要。以重庆市奉节县快速通道一侧的坡面绿化为例,简单介绍目前城市道路绿化中的坡面绿化。     

A walk on the wild side: Perceptions of roadside vegetation beyond trees

Urban nature is of vital importance for human well-being in an increasingly urbanized world. Despite the wide variety of urban greenspaces, previous research has mostly focussed on parks and in particular presence of trees. Although streets are fundamental urban structures and offer an array of green elements beyond trees, the perception and valuation of other kinds of roadside vegetation by urban residents is understudied so far. This study explores the range of roadside vegetation and associated ecosystem services perceived by city dwellers in densely populated inner city districts of two German cities. Further, we explored how wild-grown roadside vegetation is valued by interviewees. Results confirmed the important role of trees but also demonstrated that city dwellers perceive a variety of cultivated and “wild” green components other than trees. Respondents attached a wide range of meanings and values to roadside greenery and showed a surprisingly high awareness of associated ecosystem services. Wild urban roadside vegetation met with high approval, although planted and maintained vegetation was preferred. Our study illustrated that trees and other elements of roadside vegetation fulfil important functions in the view of the public. For many respondents, ecological and economical functions of roadside vegetation were more important than orderliness. This indicates opportunities for enhancing the biodiversity of urban streetscapes. As public green spaces are in short supply in many cities, enhancing cultivated and wild roadside vegetation could help to deliver ecosystem services in the areas near where people move and live.     

The role of green spaces and their management in a child-friendly urban village

Environmental child-friendliness is affected by how built environments and green spaces are planned and designed, but also by their ongoing management, including both development and maintenance. This study examined children’s perspectives on their local environments with focus on green spaces and their management in an urban village. Five groups totalling 16 children aged 10–11 were interviewed through child-led walks. Both the qualities of the village as a whole and of specific places within it added to the child-friendliness of the local environment. The children showed planned and managed spaces including playgrounds and parks, and unmanaged places such as abandoned gardens. They found many qualities in multifunctional planned places with a varied, rich content. In unmanaged areas the lack of management was seen as positive for exploration, play possibilities and for the place to be children’s own. The findings suggest that children’s perspectives can play an important role not only in planning and design, but also in the ongoing process of landscape management, including the provision of more variation in local green spaces.     

Gradual or abrupt? An algorithm to monitor urban vegetation dynamics in support of greening policies

While greening becomes a more and more popular strategy to address multiple urban challenges and to enhance wellbeing and human-nature connectedness, there is an increasing need for usable methods and indicators to monitor its implementation. Earth observations produce a wealth of data on vegetation dynamics, but their use for monitoring urban greening policies is still limited. In this article, we develop and test an algorithm for the analysis of urban vegetation dynamics based on NDVI time series. Specifically, we focus on yearly greenest pixel composites that illustrate the maximum value of NDVI during the year (“greenness”): a key structural attribute to monitor urban ecosystems in the European Union. The algorithm is inspired by earlier examples of segmentation algorithms but fits the specific requirements of the targeted use in urban areas. It takes the series of NDVI values associated to each pixel, detects existing (multiple) break points, and quantifies related abrupt changes, as well as significant gradual changes that occurred during a selected period. We tested the algorithm on a 30-year Landsat series in Berlin and partially validated the output through a comparison with infrared ortophotos. The results reveal a net increase in NDVI between 1988 and 2017 in 84% of the pixels, with an average change over the whole city of + 0.096. Around 20% of the pixels show at least one abrupt change. Most abrupt changes (71.5%) were positive, but the negative ones had on average a greater absolute value (−0.170 vs +0.085). However, considering the cumulative impacts during the whole period, 97% of the total change is attributable to gradual changes. The validation proves that abrupt changes successfully capture variations in the extent of vegetation due to land cover changes (e.g., vegetation removal or new greening interventions), while gradual changes can be associated to vegetation growth or decline. We discuss the strengths and limitations of the proposed algorithm, and how the spatially- and temporally-explicit results can be a step forward in the interpretation of urban vegetation dynamics towards an effective monitoring of the impacts of local greening policies.     

Vegetation establishment on ‘Green Walls’: Integrating shotcrete walls from road construction into the landscape

The establishment of a sustainable vegetation layer on shotcrete walls subjected to road environment represents enormous challenges. High inclination of almost 90°, the exposed position of the walls near streets as well as lack of soil and water supply pose major limiting conditions. The objective of this study was to evaluate the performance of an innovative greening technology for vertical structures in terms of vegetation development on varying plant substrates and geotextiles.The field experiment included testing three plant substrates on basis of nearby rocky excavation material (‘Innsbrucker Quarzphyllit’, ‘Bündnerschiefer’ and ‘Zentralgneis’) combined with compost. Additionally, five geotextiles (geogrid (3x4 mm), geogrid (9x10 mm), coir net, coir mat, geo mat) were applied for assessment. All test combinations were evaluated regarding vegetation cover, species composition, and biomass production from 2015 to 2016. Analyses of chemical properties were conducted for all plant substrates.Results showed highest vegetation cover ratio on ‘Bündnerschiefer’ and ‘Innsbrucker Quarzphyllit’, which can be explained by the favorable mineral composition (nutrient storage capacity) and chemical properties of compost (lower values of electrical conductivity and C/N ratio).In conclusion, the use of ‘Green Walls’ filled with ‘Bündnerschiefer’ or ‘Innsbrucker Quarzphyllit’ plant substrate in combination with netlike geotextiles like geogrid or coir net proved best. They are promising in terms of establishing an optimal vegetation cover on vertical structures and are well suited for integrating shotcrete walls into the landscape. The use of local excavation material for greening purposes thus can be confirmed. Though, the use of high-quality compost is crucial.     

Envisioning the future—Creating sustainable,healthy and resilient BioCities

Numerous challenges – from population increase to climate change – threaten the sustainable development of cities and call for a fundamental change of urban development and green-blue resource management. Urban forests are vital in this transition, as they provide various ecosystem services and allow to re-shape and re-think cities. Based on a Europe-wide community effort with diverse experts centered around urban forests and urban greening, we propose five key research fields to generate the knowledge required to unlock fundamental changes in urban development and green-blue resource management: circular bioeconomy, climate resilience, governance, social and human environment, and biodiversity. To support the design of greener, cooler, more inclusive and resilient cities, all these research fields require inter- and transdisciplinary collaboration, engaging stakeholders in transforming urban engagement and functioning. We summarise main inter-, trans- und multi-disciplinary research paths for each field and the cross-cutting knowledge areas that can help to address the challenges many cities face (e.g., modelling and assessment of the urban microclimate). For transforming cities further knowledge is needed on e.g., urban innovation, transition, participation, and more. Finally, we address how the identified research gaps can be implemented (e.g., international coordinated research effort, interdisciplinary networks).     

Soundscapes of urban parks: An innovative approach for ecosystem monitoring and adaptive management

Urban foresters are addressing the challenge of urban biodiversity loss through management plans in the context of rapid urbanization. Protecting the integrity of the urban ecosystem requires long-term monitoring and planning for resilience as well as effective management. The soundscape assessment has attracted attention in this field, but applying the soundscape assessment in urban ecological monitoring requires a protocol that links soundscapes to the impact of resource management on biodiversity over time. The effective processing and visualization of large-scale data also remains an important challenge. The aim of this study was to better understand the relationship between soundscape and physical environment, and examine the feasibility of this innovative soundscape approach in highly urbanized areas. Soundscape recordings were collected for 20 urban parks twice on 4 consecutive days in Spring. A total of 691,200 min of sound material were automatically obtained. In order to track the spatio-temporal patterns of a soundscape and determine its potential suitability for ecosystem monitoring, our study characterized soundscape information by adopting 4 widely used acoustic indices: acoustic diversity index (ADI), bioacoustic index (BIO), normalized difference vegetation index (NDSI), and power spectral density (PSD). Daily patterns of PSD have provided a potential connection between soundscapes and bird songs, and 1–2 kHz presented a similar pattern that was linked to human activity. Through further modeling, we tested the relationship of soundscapes to physical environment characteristics. The results showed the importance of habitat vegetation structure for acoustic diversity. More vertical heterogeneity, with an uneven canopy height or multilayered vegetation, was associated with more acoustic diversity. This suggests that clearing ground cover may have a significant negative impact on wildlife. Our results suggest that soundscape approaches provide a way to quickly synthesize large-scale recording data into meaningful patterns that can track changes in bird songs and ecosystem conditions. The proposed approach would enable regular assessment of urban parks and forests to inform adaptive planning and management strategies that can maintain or enhance biodiversity.     

Making use of the ecosystem services concept in regional planning—trade-offs from reducing water erosion

In this article we demonstrate how to integrate the ecosystem services concept into regional planning using the example of a case study in Saxony, Germany. We analysed how the reduction of water erosion as a regulating service impacts six other ecosystem services. Ecological integrity, provisioning services (provision of food and fibre, provision of biomass), regulating services (soil erosion protection, drought-risk regulation, flood regulation), and the cultural service landscape aesthetics are taken into account. Using a decision support software, we found that the greening of preferential discharge paths can reduce water erosion by 2–7 %. The introduction of hedgerows and the change in the soil management system from tillage to no-till practices revealed a reduction in the total soil loss by 33 and 89 %, respectively. A combination of the three erosion control measures—greening, hedgerows, and no-till management—reduced the soil loss most efficiently by 92 %. We found synergies between the measures for reducing erosion and the provision of ecological integrity, of regulating and cultural ecosystem services. In contrast, the impact on provisioning services was slightly negative. For the land use planning in the case study region we recommend therefore a combination of greening, hedges, and management change. We found that the applied integrated ecosystem services assessment approach, in combination with stakeholder involvement in the scenario development, helped communicating cross-sectoral effects of different management strategies in a comprehensive way and therefore supports regional planning.     

Why don’t people plant trees? Uncovering barriers to participation in urban tree planting initiatives

Urban tree cover is inequitable in many American cities, with low-income and non-white neighborhoods typically having the least coverage. Some municipal and non-profit tree planting programs aim to address this inequity by targeting low-income neighborhoods; however, many programs face lack of participation or resistance from local residents. In this study, we aimed to uncover the economic, social, cultural, and physical barriers that community leaders face in planting trees and fostering engagement in a neighborhood with low tree canopy. In collaboration with an urban greening nonprofit in Philadelphia, Pennsylvania (US), twenty in-depth interviews were conducted with community leaders in a low canopy neighborhood, North Philadelphia. Half of these leaders were already involved with local tree planting programs, while the other half were not. Findings reveal that despite broad appreciation for trees and greenspaces, there are concerns about the risks and costs residents assume over the course of a tree’s life cycle, the threat of neighborhood development and gentrification associated with trees, limited plantable space, and limited time and capacity for community organizations. Additionally, these barriers to participation may be amplified among low-income and communities of color who face the legacies of historical tree disservices and municipal structural disinvestment. Addressing community concerns regarding the long-term care of trees beyond the initial tree planting would likely require further programmatic support. Overall, this research highlights the complexity of addressing inequities in tree canopy and the importance of integrating resident and community leader perspectives about disservices and management costs into tree planting initiatives.     

“A living street and not just green”: Exploring public preferences and concerns regarding nature-based solution implementation in urban streetscapes

Leveraging the benefits offered by nature-based solutions (NBS) will be vital in addressing present and future environmental and social challenges as urban densification continues to exert pressure on cities. The greening of urban streets, in particular, provides many benefits in terms of livability, health, and biodiversity. While many studies have explored the suitability of NBS in a particular context considering the benefits they provide in relation to local environmental challenges (e.g. filtering the air in areas with high pollution, absorbing water in areas prone to flooding), this study focuses on residents’ perspectives on and their demand for NBS. This is particularly relevant given the importance of public acceptance of NBS measures for their success. The research presented in this paper is based on a mixed-methods study, combining an online survey and eight focus group interviews, which aimed to better understand which types of NBS people prefer, how much and what types of street space they are willing to exchange for street greening, and the opportunities and concerns they have regarding varying degrees of street greening. Findings suggest that respondents are overwhelmingly in favor of greening their street with NBS, yet preferred NBS and opinions on where to implement them vary among participants. Further, street greening was thought to come up against other understandings of how streets should be used and for what purpose. These considerations should be taken up by planners to improve the uptake of NBS.     

Drivers of diversity and tree cover in gardens,parks and streetscapes in an Australian city

While we know that urban vegetation is often distributed unequally, most studies have been undertaken in cities with relatively high levels of income inequality, using a single measure of distribution (usually tree cover) and in a single land use. This study explores predictors of both tree cover and species richness in gardens, streetscapes and parks in Ballarat, Australia. Spatial regression models found that education level was a more important predictor of tree cover than household income across all land uses in Ballarat which can be explained by some people with high incomes relative to education level choosing to live in new residential developments with disproportionately low levels of tree cover. Inequality in tree cover was greater in streetscapes than in residential gardens, suggesting that ‘top down’ political factors are more important than individual behaviours in determining tree cover in Ballarat. In contrast, physical rather than socioeconomic factors were better predictors of species richness across all land uses, highlighting that different measures of vegetation distribution are not necessarily correlated.