Potential of retrofitted urban green infrastructure to reduce runoff - A model implementation with site-specific constraints at neighborhood scale

The urbanization has resulted in significant changes in the water balance. Urban Green Infrastructures (UGI) have become a promising method for reducing reoccurring floods whilst providing additional social and ecological benefits. However, there are several challenges to successfully implementing UGI in already developed areas, such as accounting for retrofitting UGI scenarios and pre-existing use of spaces. Accurate estimations of the potential of UGI in reducing flood-causing at the watershed scale are therefore important. This study investigates the influence of site-specific constraints on the effectiveness of UGI in reducing flood-causing runoff at the watershed scale. In particular, this study takes urban fabric characteristics in the development of UGI implementation strategies for different types of residential and industrial neighborhoods into account. Furthermore, it applies a hydrological simulation-based approach to estimate the runoff reduction potential of these strategies for a case study in the Metropolitan Area of San José, Costa Rica. The results indicate that UGI implementation potential depends on urban fabric characteristics and modelling different UGI implementation scenarios shows differing hydrological performance. In residential areas, either permeable pavement or infiltration trenches and street planters lead to the highest runoff reduction. In industrial areas, only permeable pavements lead to the highest runoff reduction. Overall, industrial areas enable more potential for UGI and reduce runoff generation. The findings of this study can guide the development of retrofitting UGI scenarios and upscaling strategies under heterogeneous settlement characteristics.     

A gradient analysis of urban landscape pattern: a case study from the Phoenix metropolitan region,Arizona, USA

Landscape Ecology - Urbanization is arguably the most dramatic form of land transformation that profoundly influences biological diversity and human life. Quantifying landscape pattern and its...     

A comparison of metrics predicting landscape connectivity for a highly interactive species along an urban gradient in Colorado, USA

Many organisms persist in fragmented habitat where movement between patches is essential for long-term demographic and genetic stability. In the absence of direct observation of movement, connectivity or isolation metrics are useful to characterize potential patch-level connectivity. However, multiple metrics exist at varying levels of complexity, and empirical data on species distribution are rarely used to compare performance of metrics. We compared 12 connectivity metrics of varying degrees of complexity to determine which metric best predicts the distribution of prairie dog colonies along an urban gradient of 385 isolated habitat patches in Denver, Colorado, USA. We found that a modified version of the incidence function model including area-weighting of patches and a cost-weighted distance surface best predicted occupancy, where we assumed roads were fairly impermeable to movement, and low-lying drainages provided dispersal corridors. We also found this result to be robust to a range of cost weight parameters. Our results suggest that metrics should incorporate both patch area and the composition of the surrounding matrix. These results provide guidance for improved landscape habitat modeling in fragmented landscapes and can help identify target habitat for conservation and management of prairie dogs in urban systems.     

Subjective perception of noise exposure in relation to urban green space availability

Noise pollution has been recognized as one of major threats to the health of urban residents. Increasing green space availability can create a natural buffer to the adverse effects of living in an urban environment. These positive effects of urban green space can be directly related to an objective reduction of noise levels and – indirectly – to the subjective perception of noise exposure. In our study carried out in Lodz, Poland, we explored the relationship between objective noise levels and the subjective perception of noise exposure by urban residents in relation to urban green space availability. We refer to objective noise exposure expressed as GIS modelled L_den derived from noise maps (compliant with the Environmental Noise Directive, 2002/49/EC), and subjective (self-reported) perception of noise exposure as declared in a questionnaire-based survey. We compared the percentage of green space in a buffer, the objectively measured noise level, and the perceived exposure to noise to find the most appropriate radius of the green space buffer. We decided to choose the green space coverage which is not correlated with an objective noise level to avoid potential multicollinearity in regression models. This contrasts with most studies, in which the radius of the buffer is set a priori. We thus compared the selected buffer of green space coverage – 300 m (representing green space availability) – with perceived noise exposure. We used the spatial error probit model to differentiate the impacts of objective and subjective noise indicators, at the same time including also the factor of green space availability. We found out that the direct effect of objectively measured noise levels, education, the presence of noisy neighbours, and building characteristics were the most important variables influencing the self-reported perception of noise by urban residents. The indirect effect of green space availability on noise perception was not strong, yet statistically significant. Although our study does not provide clear-cut evidence, it indicates that the indirect, psychological effects of urban green spaces can positively affect the life satisfaction of urban residents.     

Green and calm: Modeling the relationships between noise pollution propagation and spatial patterns of urban structures and green covers

The mechanism of noise pollution propagation is considerably affected by 1) the type and configuration of its receiving environment and 2) the distance that sound waves pass to reach that environment. This study adopts a spatio-statistical approach to quantify and model associations between noise pollution levels and landscape metrics of land categories (built-up structures and urban green covers). Accordingly, noise levels were measured employing a sound pressure meter to quantify equivalent levels (Leq in dB A), in addition to their corresponding percentiles (L₁₀ and L₉₀). A collection of 30 sampling points were selected to measure noise data within the fall season and between 4 p.m. and 8 p.m. hours of the day. A hierarchical distance-sampling framework based on buffer areas with different radius (300 m, 600 m and 1 km) around each sampling point was compiled to measure composition and configuration metrics of land categories within each buffer area. The results derived from Pearson correlation analysis and multiple-linear regression models indicated that there is a distance-dependent relationship between the metrics of green areas and noise levels. We didn’t find remarkable distance-dependency between built-up structures and noise levels. Based on our new spatio-statistical approach, we conclude that more connected and compacted pattern of green areas closer to pollution centers can significantly alleviate the effects of noise propagation mechanism and appropriate pattern of built-up areas follows a low density distribution with coming green areas in between. Findings of this study highlight the potential of landscape ecology approach as an effective planning paradigm for designing greener and calmer cities.     

A satellite image-based analysis of factors contributing to the green-space cool island intensity on a city scale

Urban green spaces provide cooler microclimates and create localized urban cool islands and, as part of an adaptation strategy to cope with future urban climate change, have been proposed as a means to mitigate the urban heat island effect. Numerous previous research papers have discussed green-space size, type, and vegetation density, as well as many other factors that might influence green-space cooling effects. However, little has been done with regard to exploring and quantifying the characteristics of the green-space cool island (UCI). It is also largely unknown whether or how the patterns of green space and land use, as well as the adjacent urban thermal environment, affect UCIs. In this paper, the land surface temperature (LST) was retrieved from satellite imagery. The UCI was identified, and one of the UCI characteristics, the UCI intensity, was defined. Multiple linear regression models were then used to explore and quantify the combined effects of factors related to the UCI intensity. The results show that the intensity differed between UCIs, and correlated significantly with the extent of and mean temperature reduction associated with an UCI. Multiple linear regression analysis found that UCI intensity was affected by areas of forest vegetation and its spatial arrangements, as well as by the composition of the cool island and its neighboring thermal environment. The study validated the suitability of using intensity as an indicator of the UCI. Identifying the UCI as a result of the green-space cooling effect, will help in the management and planning of the spatial arrangement of green spaces in cities to reduce the effects of the urban thermal environment and help cities adapt to climate change.     

A decision-making framework for promoting the optimum design and planning of Nature-based Solutions at local scale

Urbanization is a key driver of land use/land cover changes climate change. It produces a reduction in natural capital with alteration to the energy budget of land, air ventilation and land surface temperature. The urban morphology derived from the combination of natural capital and human-derived capital is important in urban ecosystem services (UESs) provisioning to mitigate the Urban Heat Island (UHI) effect. Here we report a decision-making framework starting from an applicative case study to assess UESs and promote the best design and planning of Nature-based Solutions (NbS) at local scale. The human thermal comfort has been chosen here as a surrogate to estimate climate regulation as a priority UES in mitigating UHI. The analysis of human thermal comfort in different urban neighbourhood planning scenarios of a city located in Southern Italy has been carried out using the microclimate model ENVI-met. The analysis has been developed to highlight the variation in human thermal comfort in terms of Physiological Equivalent Temperature index (PET) between past agricultural scenarios (no longer more present), current state and several proposed urban scenarios. Such new scenarios have been developed by considering different building arrangements according to municipal planning rules of the city and choosing different types of NbS composition and structure. The analysis has allowed to identify the best scenario characterized by the presence of a community garden with olive groves and estimate the capacity of NbS to reduce the human thermal comfort by about 3.5ºC and improve the PET in selected locations within the current state. In accordance with the aim and topics of the Special Issue, this study shows how such a framework can be useful to support decision-making processes in choosing the best strategy in terms of urban plans and thus making the urban transformation process more sustainable, contributing to assessing the global targets of the 2030 Agenda at local scale.     

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.     

Perception and preference of trees: A psychological contribution to tree species selection in urban areas

Trees can enhance human mental and physical well-being in urban environments. However, the tree benefits in urban planning are insufficiently recognised, and there is little knowledge on the tree characteristics that are relevant to humans and how they are evaluated. This paper presents perceptual tree parameters and their relation to human preferences. In study 1, participants sorted 24 tree images by perceived similarity. Hierarchical cluster analysis and multidimensional scaling (MDS) revealed the distinction between conifers and deciduous trees, crown shape, the two-dimensional crown size to trunk height ratio and the crown density as important to humans. In study 2, participants rated the trees based on their preferences. Multiple linear regression analyses showed that a high two-dimensional crown size to trunk height ratio and a high crown density predicted deciduous tree preferences. These findings are discussed in light of the savannah hypothesis and the Gestalt grouping principle of closure. In the task of tree selection and placement for urban areas, the identified perceptual tree parameters may allow for achieving a coherent overall picture with a simultaneous increase of tree species richness. Thus, urban landscape planning can apply the presented findings for increasing ecosystem health and residential satisfaction.     

A method for the use of landscape metrics in freshwater research and management

Freshwater research and management efforts could be greatly enhanced by a better understanding of the relationship between landscape-scale factors and water quality indicators. This is particularly true in urban areas, where land transformation impacts stream systems at a variety of scales. Despite advances in landscape quantification methods, several studies attempting to elucidate the relationship between land use/land cover (LULC) and water quality have resulted in mixed conclusions. However, these studies have largely relied on compositional landscape metrics. For urban and urbanizing watersheds in particular, the use of metrics that capture spatial pattern may further aid in distinguishing the effects of various urban growth patterns, as well as exploring the interplay between environmental and socioeconomic variables. However, to be truly useful for freshwater applications, pattern metrics must be optimized based on characteristic watershed properties and common water quality point sampling methods. Using a freely available LULC data set for the Santa Clara Basin, California, USA, we quantified landscape composition and configuration for subwatershed areas upstream of individual sampling sites, reducing the number of metrics based on: (1) sensitivity to changes in extent and (2) redundancy, as determined by a multivariate factor analysis. The first two factors, interpreted as (1) patch density and distribution and (2) patch shape and landscape subdivision, explained approximately 85% of the variation in the data set, and are highly reflective of the heterogeneous urban development pattern found in the study area. Although offering slightly less explanatory power, compositional metrics can provide important contextual information.     

Statistical models of landscape pattern metrics,with applications to regional scale dynamic forest simulations

Forest managers in Canada need to model landscape pattern or spatial configurationoverlarge (100,000 km²) regions. This presents a scalingproblem, as landscape configuration is measured at a high spatial resolution,but a low spatial resolution is indicated for regional simulation. We present astatistical solution to this scaling problem by showing how a wide range oflandscape pattern metrics can be modelled from low resolution data. Our studyarea comprises about 75,000 km² of boreal mixedwoodforest in northeast Alberta, Canada. Within this area we gridded a sample of 84digital forest cover maps, each about 9500 ha in size, to aresolution of 1 ha and used FRAGSTATS to compute a suite oflandscape pattern metrics for each map. We then used multivariate dimensionreduction techniques and canonical correlation analysis to model therelationship between landscape pattern metrics and simpler stand table metricsthat are easily obtained from non-spatial forest inventories. These analyseswere performed on four habitat types common in boreal mixedwood forests: youngdeciduous, old deciduous, white spruce, and mixedwood types. Using only threelandscape variables obtained directly from stand attribute tables (totalhabitatarea, and the mean and standard deviation of habitat patch size), ourstatistical models explained more than 73% of the joint variation in fivelandscape pattern metrics (representing patch shape, forest interior habitat,and patch isolation). By PCA, these five indices captured much of the totalvariability in the rich set of landscape pattern metrics that FRAGSTATS cangenerate. The predictor variables and strengths of association were highlyconsistent across habitat classes. We illustrate the potential use of suchstatistical relationships by simulating the regional, cumulative effects ofwildfire and forest management on the spatial arrangement of forest patches,using non-spatial stand attribute tables.This revised version was published online in May 2005 with corrections to the Cover Date.     

The influence of sampling scheme and interpolation method on the power to detect spatial effects of forest birds in Ontario (Canada)

Spatial ecology is becoming an increasingly important component of resource management, and the general monitoring of how human activities affect the distribution and abundance of wildlife. Yet most work on the reliability of sampling strategies is based on a non-spatial analysis of variance paradigm, and little work has been done assessing the power of alternative spatial methods for creating reliable maps of animal abundance. Such a map forms a critical response variable for multiple scale studies relating landscape structure to biotic function. The power to reconstruct patterns of distribution and abundance is influenced by sample placement strategy and density, the nature of spatial auto-correlation among points, and by the technique used to extrapolate points into an animal abundance map. Faced with uncertainty concerning the influence of these factors, we chose to first synthesize a model reference system of known properties and then evaluate the relative performance of alternative sampling and mapping procedures using it. We used published habitat associations of tree nesting boreal neo-tropical birds, a classified habitat map from the Manitou Lakes area of northwestern Ontario, and point count means and variances determined from field studies in boreal Canada to create 4 simulated models of avian abundance to function as reference maps. Four point sampling strategies were evaluated by 4 spatial mapping methods. We found mixed-cluster sampling to be an effective point sampling strategy, particularly when high habitat fragmentation was avoided by restricting samples to habitat patches >10 ha in size. We also found that of the 4 mapping methods, only stratified ordinary point kriging (OPK) was able to generate maps that reproduced an embedded landscape-scale spatial effect that reduced nesting bird abundance in areas of higher forest age-class fragmentation. Global OPK was effective only for detecting broader, regional-scale differences. This revised version was published online in July 2006 with corrections to the Cover Date.     

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.     

Barriers to the effective planning and management of residential encroachment within urban forest edges: A Southern Ontario,Canada case study

Studies document degradation and loss of publicly owned urban woodland area following adjacent residential development due to residential encroachment. Residential encroachment is the negative impacts of housing land uses within both rural and urban green infrastructure networks. Prevailing planning, design and management approaches in Southern Ontario municipalities in Canada indicate planning and management tools have been developed to remove and impede encroachment impacts; however, many are infrequently implemented. This lack of implementation contributes to a high prevalence and spatial area of encroachment within Southern Ontario municipal woodland edges with adjacent housing. Long interviews were conducted with the planners, landscape architects, woodland managers and bylaw enforcement staff of six Southern Ontario municipalities to determine the barriers to implementation of municipal encroachment tools. Results indicate key barriers to policy implementation that reflect a lack of awareness of, and priority placed on addressing, residential encroachment impacts, and impacts following the point of development in general. Barriers include: (1) insufficient community and municipal access to information regarding residential encroachment and their significance relative to other development impacts; (2) lack of clarity of goals by municipalities and between departments; (3) insufficient municipal leadership and commitment to limiting encroachment; (4) lack of sufficient means within municipal departments to prevent and address encroachment; and (5) ineffectual dynamics of enforcement. Recommendations for overcoming barriers to the development and implementation of effective approaches for addressing encroachment are provided.     

Stemflow chemistry in relation to tree size: A preliminary investigation of eleven urban park trees in British Columbia,Canada

Given increased atmospheric loads in cities, quantification of stemflow chemistry is necessary for a holistic understanding of elemental cycling in urban ecosystems. Accordingly, the stemflow volume and associated solute fluxes (K⁺, Ca²⁺, Na⁺, Mg²⁺) were measured for eleven deciduous trees in a manicured park setting in Kamloops, British Columbia, Canada. Over nine rainfall events from late June to early September 2013, larger trees [diameter at breast height (DBH) > 30 cm] were found to generally produce higher event stemflow volumes but lower funneling ratios than the smaller trees (DBH < 30 cm). The median flux-based enrichment ratio, which compares the solute input of stemflow to that of rainfall on a per unit trunk basal area, also tended to be greater for smaller trees than larger ones. Under all-tree and single-leader tree conditions, significant negative non-linear relationships between tree DBH and mean flux-based enrichment ratios were found for Ca²⁺, Na⁺, and Mg²⁺, but not for K⁺. These preliminary results indicate that urban trees can considerably enrich rainfall that is partitioned into stemflow, and that ion concentrations and enrichment ratios exhibit notably high interspecific variability. In this study, tree size and presence of single versus multiple leaders explained some of this heterogeneity; however, further study into those physical tree characteristics that affect stemflow volume and stemflow chemistry must be carried out if the impact and challenges of urban greening, nutrient cycling, and stormwater management initiatives are to be more fully understood.     

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.     

Relationships of dead wood patterns with biophysical characteristics and ownership according to scale in Coastal Oregon,USA

Dead wood patterns and dynamics vary with biophysical factors, disturbance history, ownership, and management practices; the relative importance of these factors is poorly understood, especially at landscape to regional scales. This study examined current dead wood amounts in the Coastal Province of Oregon, USA, at multiple spatial scales. Objectives were to: (1) describe current regional amounts of several characteristics of dead wood; (2) compare dead wood amounts across ownerships; (3) determine the relative importance, according to spatial scale, of biophysical and ownership characteristics, to regional dead wood abundance. Dead wood plot data were evaluated with respect to explanatory variables at four spatial scales of resolution: plots, subwatersheds, watersheds and subbasins. The relationships of dead wood characteristics with biophysical attributes and ownership were diverse and scale-specific. Region-wide dead wood abundance and types varied among ownerships, with public lands typically having higher amounts of dead wood and more large dead wood than private lands. Regression analysis of total dead wood volume indicated that ownership was important at the subbasin scale. Growing season moisture stress was important at plot, subwatershed, and watershed scales. Topography was important at the two coarser scales. Multivariate analysis of dead wood gradients showed that ownership was important at all scales, topography at the subbasin scale, historical vegetation at watershed and subbasin scales, and current vegetation at plot and subwatershed scales. Management for dead wood and related biodiversity at watershed to landscape scales should consider the distinct dynamics of snags and logs, the importance of historical effects, and the relevance of ownership patterns.     

Evaluating the accessibility of urban parks and waterfronts through online map services: A case study of Shaoxing,China

Regular access to natural environment has many physical and mental health benefits for urban residents. This study was to evaluate the accessibility of urban parks and waterfronts in a Chinese canal city at the household level. Shaoxing, a typical canal town in the Yangtze River Delta region of China, was selected as the case study because of its abundant but underused natural resources. The study had measured the shortest travel routes from individual households to parks and waterfronts using data from the online map service and intensive fieldwork. The results showed that only 22% of Shaoxing residents live within a 500 m walking distance to parks, but scenario analysis showed if the canals were well used, almost all the residents would have access to natural environment within 15 min’ walk. Thus, the route-based accessibility evaluation method developed in this research offers a fine-grained understanding of household inequality in access to natural environments. It not only provides specific recommendations for planning intervention to improve the accessibility of natural resources in Shaoxing, but also contributes to the advancement of accessibility measures for planning practice. This route-based measure makes it possible to combine other accessibility measures of the travel routes such as sidewalk qualities in future research. The simplicity of this method means that it can be used to evaluate accessibility to other public facilities at the household level to develop walkable neighborhoods in cities.     

Patterns of human behaviour in public urban green spaces: On the influence of users' profiles,surrounding environment,and space design

Public urban green spaces (PUGS) play a vital role in the dense urban fabric as places of Nature-Society contact and socialization. Despite some advances in the field, the relationship between the PUGS surroundings and their users' behaviours remains unclear. This study examined the patterns of human behaviour in four PUGS of the city of Porto, on the north Portuguese coast, where the behavioural mapping method was applied. Observational data regarding 979 PUGS users' socio-demographics and behaviours were recorded on a base map and a grid between August and November 2020. The use patterns during different times of the day were disaggregated across behaviours and users' profiles, and their relationship with the surroundings and design elements was assessed with ANOVA, Chi-Square test, and Pearson correlation. The findings presented may pave the way for future studies and inform the urban planning and design of the effectiveness of new interventions, namely providing more accurate aligning between the greenspace design language with users' needs. Furthermore, this study highlights the importance of considering the sociodemographic background of PUGS users and the surroundings to guide designers and planners.