Patterns of urban forest composition in Utah’s growing mountain communities

Urban forests provide critical ecosystem services in cities of the Western United States, including regulating thermal extremes, supporting biological diversity, and providing cultural and recreational services. However, these services may come with trade-offs such as heavy water demand in arid environments. Thus, afforestation and its effect on the water budget – as well as other ecosystem services – can be contingent on the species composition of urban forests. Choice of tree species, in turn, is influenced by historical contingencies and development context. The objective of this study was to identify differences in tree species composition between four broad classes of urban development in Heber Valley, Utah, with classes defined by establishment age, lot size, and location within the urban-suburban environment. Publicly available information was used to categorize residential and commercial areas, and standard forestry techniques were used to collect data on trees in a stratified random survey of lots in each category. Older, established housing had the highest tree basal area and species richness per hectare, and exurban (rural, dispersed housing) developments had significantly higher species diversity than new tract housing. Because it appears that exurban communities are being replaced by tract housing, there is evidence that tree diversity may be lost. Another important aspect of community structure in urban forests is the ratio of conifers to broadleaf trees because of fundamental differences in water use patterns. Conifers were twenty-five percent of the average lot basal area in exurban and thirty-five percent in established neighborhoods, as opposed to five percent in tract housing. If functional groups are used as predictors of water use in irrigated urban systems, water demand is likely to increase with the expansion of low-diversity, angiosperm dominated tract forests in the Western US in the coming decades.     

Residents’ perceptions and valuations of urban wastelands are influenced by vegetation structure

Among the different urban green spaces, wastelands are valuable spaces for conserving urban biodiversity. By hosting wild and spontaneous vegetation, wastelands can promote the contact citizens have with nature. However, lack of regular management can lead to negative perceptions. In this study we assessed perceptions, valuations and uses of wastelands by residents in two cities in the centre of France. We tested whether preferences for wastelands depended on where wastelands were located in the city, plant community characteristics or resident characteristics. The study investigated 18 wastelands, in three successional stages (initial grassland, intermediate grassland and shrubbery stages) and located in three categories of distance from the city centre (downtown, suburban, periurban). Vegetation was sampled in each wasteland and several plant community metrics were calculated. A total of 72 residents (4 per wasteland) living in the vicinity of the wastelands were interviewed about their use, valuations and perceptions of wastelands. Based on qualitative and quantitative analyses, the results highlighted that a significant proportion of residents (36%) conducted various activities in wastelands and that perceptions and valuations of wastelands were diverse, ranging from either negative (when wastelands were perceived as wild or abandoned areas) or positive (when wastelands were considered as natural and recreational). Valuations strongly depended on the successional stage, with intermediate grassland-like wastelands being preferred. We found no effect of wasteland location in the city, whereas resident characteristics (age and gender) marginally influenced valuations. This study provides new insights into the determinants of perception and valuations of urban wastelands. Particularly, we suggest that intermediate grassland-like wastelands could be easily integrated into urban planning both for recreational activities and conserving biodiversity. Alternatively, awareness of the value of initial grassland-like and shrubbery wastelands should be raised to improve their acceptability.     

Plant and microbial biodiversity in urban forests and public gardens: Insights for cities’ sustainable development

As the world’s population gets increasingly more urban, the preservation of urban green spaces becomes an important issue in the political agenda worldwide. These spaces may mitigate the negative environmental impacts of urbanisation and improve quality of life. Aiming to increase knowledge in urban biodiversity we compared the diversity of vascular plants and soil microbial communities (fungi and bacteria) in two contrasting typologies of urban green spaces (public gardens and remnant forests) in the city of Coimbra (Portugal). We found 252 taxa of vascular plants of which 58% were native and 42% exotic. Although overall diversity indices were similar in both typologies of green spaces, species richness and percentage cover of native taxa were significantly higher in forests than in gardens. Overall, plant communities in the two typologies of green spaces were distinct. We found high variability among gardens, which is consistent with vegetation in gardens being determined by man rather than by competitive or successional processes. Interestingly, the disparity between gardens and forests was also visible for both bacterial and fungal communities indicating an association between above and below-ground communities. We showed that, due to their origin, remnant forests harbour plant taxa with high conservation and ecological values. It also showed that gardens have higher percentage of exotic species, which led us to conclude that native plant species should be given more emphasis in these spaces. City planners should promote urban development by incorporating an ecological perspective into their management plans to enhance human health and global environmental quality.     

Fragmentation of China’s landscape by roads and urban areas

China’s major paved road-ways (national roads, provincial roads, and county roads), railways and urban development are rapidly expanding. A likely consequence of this fast-paced growth is landscape fragmentation and disruption of ecological flows. In order to provide ecological information to infrastructure planners and environmental managers for use in landscape conservation, land-division from development must be measured. We used the effective-mesh-size (M_eff) method to provide the first evaluation of the degree of landscape division in China, caused by paved roads, railways, and urban areas. Using M_eff, we found that fragmentation by major transportation systems and urban areas in China varied widely, from the least-impacted west to the most impacted south and east of China. Almost all eastern provinces and counties, especially areas near big cities, have high levels of fragmentation. Several eastern-Chinese provinces and biogeographic regions have among the most severe landscape fragmentation in the world, while others are comparable to the least-developed areas of Europe and California. Threatened plant hotspots and areas with high mammal species diversity occurred in both highly fragmented and less fragmented areas, though future road development threatens already moderately divided landscapes. To conserve threatened biodiversity and landscapes, we recommend that national and regional planners in China consider existing land division before making decisions about further road development and improvement.     

Temporal variation of characteristic scales in urban landscapes: an insight into the evolving internal structures of China’s two largest cities

Urbanization has induced profound landscape changes. While the spatiotemporal patterns of urban landscapes have been extensively studied, the manner by which the internal structures of already urbanized areas change remains little understood. Characteristic scales are an important measure of landscape structure, and they represent the typical spatial extents of landscape elements in hierarchies. In this study, we quantified temporal variations of the characteristic scales in the central urban landscapes of Beijing and Shanghai over an 18?year period. Using transect data from Landsat images, characteristic scales were identified through wavelet analysis and then classified into several discrete domains using the k-means clustering method. These characteristic scale domains appeared to correspond with the typical extents of the blocks and block clusters in the study areas. Results showed that the number of the characteristic scale domains changed within a small range of 3?C5 while the mean values of the characteristic scales within the domains showed substantial temporal variation. Larger characteristic scales were more variable than smaller ones in both cities. Distinguishing relative change rates of building forms, land use and street layout of urban landscapes allowed us to interpret these differences. The street layout of urban landscapes usually reacts slowly to the force of change, acting as the skeleton of the urban landscape. As a result, block sizes can remain relatively stable and corresponding characteristic scales present inheritance features. Land use and building forms are more susceptible to changes. Block clusters with flexible extents could result in significant variation of characteristic scales.     

A review of the concept ‘management’ in relation to urban landscapes and green spaces: Toward a holistic understanding

The management of urban landscapes concerns existing urban open spaces such as public parks, playgrounds and residential green spaces. It involves many different actors and organizations and its practice is of importance for the sustainable development of cities. As a research field, it needs further theoretical development and common definitions. For example, the central term ‘management’ is seldom defined in the relevant literature regarding an urban landscape context, and public participation in management processes is unusual. This paper introduces urban landscape management as an overarching concept that brings together knowledge about management of urban landscapes from fields such as urban forestry, park management and landscape planning. Based on a literature review, a common understanding of management in an urban landscape context is proposed, including organizational and strategic aspects of managerial activities. Our approach is that urban landscapes are ultimately managed to provide user benefits. Urban landscape management can be viewed as a complex process that includes a number of different actors, elements and relationships, mutually affecting each other. This view supports future studies of urban landscape management and its role in sustainable urban development.     

Can pruning help maintain vitality of ash trees affected by ash dieback in urban landscapes?

Hymenoscyphus fraxineus causes a destructive invasive tree disease known as ash dieback threatening the survival of common ash not only in the forests, but also in urban and landscape settings. Pruning is a potential management practice that could help maintain tree vitality and aesthetics in parks, gardens, alleys and recreation areas, as well as maintaining veteran trees having high heritage or cultural value, or trees with high genetic importance (e.g. located in clonal seed orchards). In this study we investigated the maximum distance proximal to the lesion margin at which H. fraxineus can be detected on individual branches infected by the fungus in order to provide recommendations for pruning. Pruning of branches was carried out on 38 trees in southern Sweden. Tissue samples including bark and wood were collected from the margin of the lesion and at 5 cm intervals proximal to the lesion. Molecular analysis revealed presence of H. fraxineus in 91.3% of the investigated lesions. The proportion of lesions at which H. fraxineus could be detected declined with increasing distance from the lesion margin, with a significant reduction in the number of positive samples at 10 cm proximal to the margin. At 30 cm from the lesion edge the pathogen was never detected. Our results suggest that routine pruning may help maintain the vitality of younger trees. Pruning branches at least 35 cm from visible, active lesions in the bark should exclude the fungus and therefore reduce the probability of stem infection by H. fraxineus, however this cultural control tactic may only be economically feasible for high value amenity trees.     

Users’ recreation choices and setting preferences for trails in urban forests in Nanjing,China

With increased demand for outdoor recreational spaces, it is imperative to understand the experience of recreational hikers. This study explored users’ recreation choices and behavior-based setting preferences for certain trails in one forest park. Using on-site intercept surveys, a total of 1019 samples were collected from users of hiking trails and greenways in Purple Mountain Forest Park, Nanjing, China. The results from multiple regressions revealed that visitors’ recreation choices for trail settings, companions, and activities were associated with personal attributes, usage patterns, visitor motivations, and their preferences for the trail’s landscape attributes. The findings provide insights for the design and maintenance of trail settings in forest parks to satisfy the needs of various recreational hikers.     

Residents’ place attachment to urban green spaces in Greater Tokyo region: An empirical assessment of dimensionality and influencing socio-demographic factors

Although many researchers highlight the benefits of Urban Green Spaces (UGS) to city dwellers, understanding of residents’ emotional association with UGS remains an incomplete and exciting area of place research. In this study, we conducted an empirical assessment of residents’ Place Attachment (PA) towards UGS in the Greater Tokyo region. For this, we tested a widely used PA model consisting of four dimensions, namely, place identity, place dependence, social, and nature bonding. Data were collected from an online questionnaire survey (n = 2093) and subjected to an Exploratory Factor Analysis (EFA) to examine the underlying place dimensions. To examine the association of PA with socio-demographic variables, we performed a multiple regression analysis with the factor scores and key socio-economic variables (e.g. age, gender, income, marital and parental status, etc.). Additionally, we compared the PA constructs among three different groups, namely (1) men and women, (2) married and unmarried, and (3) people with and without children. Results indicated a three-dimensional PA model, consisting of ‘place identity’, ‘place and nature dependence’, and ‘social bonding’. In particular, variables originally used for nature bonding co-loaded with the variables for place dependence. The other tested dimensions, nonetheless, remained identical with conventional PA models. The finding indicates that personal connections to nature - as hypothesized in the nature-bonding dimension - may not be truly replicable for UGS. As such, the influence of demographic variables on the overall place-construct remains minimal, although a significant but relatively weak positive influence was observed for age and frequency of green space visits. In the comparative analysis, women reported a significantly higher-level place and nature dependence. Besides, a significant difference of mean was observed among married and unmarried respondents, as well as the persons with/without children for all three-place dimensions. Overall, the findings are imperative to better understand the human-green space relationship in large cities and call for further directed research on creating ‘green places’ and not just ‘green spaces’.     

Visitors’ and residents’ perceptions of urban forests for leisure in Washington D.C

While there is an increasing number of studies on the experience of urban forests, few have examined the similarities and differences between first time visitors, repeat visitors, and local residents in their perceptions of urban forests for leisure. This study fills this research gap using Analysis of Covariance (ANCOVA) and Structural Equation Modeling (SEM), based on data collected on-site from a year-long survey of 1090 participants in Washington D.C. Results indicate that participants are generally positive on urban forests’ value for leisure and are highly satisfied with their leisure experience in the city, with “beliefs in parks and gardens” and “beliefs in street trees” being assessed the highest and lowest, respectively. The study also finds that interaction effects do exist between gender, season, location, and past experience, suggesting respondents’ visiting experience with urban forests is multidimensional, contextual, and situational. Specifically, the older the respondents are, the more positive their responses would be. A location with diverse and dense urban forests is more likely to stimulate positive perceptions, particularly for first timers. In addition, residents tend to focus on recreational aspects of urban forests as opposed to visitors, especially repeaters who are more likely to value the visual and aesthetic aspects of urban forests. This is not only evidenced by the ANCOVA results whereas fall and summer, the best seasons for pursuing outdoor activities, are highly positively perceived by residents, but also by the SEM analyses which show that street trees significantly contribute to repeaters’ satisfaction via their perceptions of “leisure value of urban forests” while no such relationship exists for first timers and residents. Urban parks and gardens are found to significantly and positively contribute to respondents’ visiting experience, which, in turn, leads to satisfaction for each respondent group. Finally, research limitations and theoretical, methodological, and managerial implications are discussed.     

Synergy of urban green space planning and ecosystem services provision: A longitudinal exploration of China’s development

Ecosystem services (ES) concepts and approaches have become more appealing to practice, such as municipal/urban planning, environmental policies and governance to address sustainable development. Inclusion of this concept in the planning or policy discourses is the first step for further implementation on the ground. Using China’s capital, Beijing, as the case study, this article analyzes how ES (or similar concepts) have permeated China’s urban development history since 1949 when the New China was established and how this has to be with China’s urban green space development. The results show: (1) There were no explicit references to “ecosystem services” per se, but overlapping concepts such as “functions”, “values” and “benefits” can be found in planning documents and, importantly, the lack of the concept per se has not affected the detailed services that emerged in all plans. (2) Among the three ES sections, only cultural services run from the beginning to end although the included services kept changing. Other sections show considerable variation and less continuity – the focal services of each stage changed over time. (3) Through the ES lens, some general patterns regarding China’s urban development can be found such as regulation services gradually become valued for their own sake. The patterns found in Chinese planning documents are then compared with some western regions. This study reveals limitations of the past and opportunities for the future to inform urban development decision-making. Adaptation of old and incorporating new ES concepts can improve the quality of plans and foster cities’ ability to learn from past patterns for future sustainability.     

Greening residential quarters in China: What are the roles of urban form,socioeconomic factors,and biophysical context?

Residential greenspace has great intracity variations. Its driving factors have been widely investigated in Western countries (e.g., in Europe and North America), where residential areas are mostly privately owned, but few studies have examined the determinants of residential greenspace in China, where land is owned by the government. Taking the subtropical city of Changsha, China, as an example, this study mapped the percent green cover (PGC) in residential quarters with a fine-resolution satellite image. We also investigated its driving factors measured from multisource geospatial data. The results show that (1) the PGC in the residential quarters showed great spatial variation, with an average of 36.6% (0–85.7%) and a standard deviation of 18.3%. (2) Urban form, biophysical context, and socioeconomic factors together explained 49.18% of the variation in the PGC, and they independently explained 22.87%, 11.17%, and 2.31% of the variation, respectively. (3) Residential quarter size, PGC in the surrounding buffer zone, residential quarter age, housing value, and population density significantly and positively impact the PGC, while percent building cover, floor area ratio, and distance to city center had significant negative impacts. The strongest positive and negative impacts came from PGC in the surrounding buffer zone and percent building cover, respectively. Socioeconomic factors, the dominant driving factors in Western countries, show little impact on residential PGC. These findings expand our understanding of the intracity variation in greenspace coverage and the driving factors, which sheds light on the effective planning and management of urban greenspaces in China.     

Impact of urban park’s tree,grass and waterbody on microclimate in hot summer days: A case study of Olympic Park in Beijing,China

Urban heat island (UHI) often cause negative impact and has been linked to heart stroke rate, morality, human comfort, energy consumption and air pollution. Fortunately, urban green spaces have been considered as an effective element to mitigate UHI through their cooling effect. However, further empirical research is necessary in order to efficiently guide the design and planning of urban green space. We observed the impacts of urban park's tree, grass and waterbody on microclimate inside the Olympic park of Beijing during summer days. The results indicated that, on average, the park was 0.48–1.12 °C cooler during the day, as well as increased air humidity 2.39–3.74% and reduced human comfort index 1.02–2.43 to generate more comfortable thermal environment. Urban park's cluster trees with short ground vegetation generated higher cooling effect than single trees, grass and waterbodies; proper irrigation regime enhanced the cooling effect of grasses, even the irrigated grass have similar cooling effect with small waterbody on sunny, windless summer days. Therefore, we advise to increase undergrowth coverage and grass irrigation management in order to take advantage of cooling effect of urban parks.     

Relation between visitors’ behaviour and characteristics of green spaces in the city of Granada,south-eastern Spain

This paper examines the relation between visitor behaviour and certain features of a number of major green spaces in the city of Granada, south-eastern Spain, focussing on key urban, ecological and landscape-related issues. Information on user profiles and numbers, the various uses made of these areas, their design, plant species richness and local urban and sociological background, was collected by means of in situ observation in a total of ten urban green spaces with surface areas of over 5000 m². Findings indicated that these spaces were used largely for purposes directly related to well-being: recreational and sporting activities, socialising, or simply relaxing. Interestingly, the most common activities in each space were governed by features intrinsic to the space itself: accessibility, design, maintenance and plant richness and distribution, all of which affected the health-related attributes and aesthetic value of the space. The study also highlighted a number of serious deficiencies in certain green spaces, which will need to be addressed in future action plans and replanning projects as an essential step in ensuring that they meet the real needs and expectations of the target population. The information provided by this research may prove particularly valuable for improving the systemic functions of green spaces in Mediterranean cities sharing similar bioclimatic and sociological features, and for ensuring that they fulfil the role assigned to green spaces in sustainable cities.     

Can you really see ‘green’? Assessing physical and self-reported measurements of urban greenery

Urban vegetation provides a wide array of services; yet, there is still a knowledge gap regarding the mechanistic processes behind urban vegetation–human well-being relationships. Two main approaches have been used to assess urban greenery associated with human well-being: physical and self-reported. We here assessed the associations between physical (green view index–GVI, green cover–GC) and self-reported measures (perceived visible greenery–PVG) of the streetscape greenery of two southeastern Mexican settlements (Xalapa, Coatepec). Our results show that both sites have considerable GC (Xalapa = 37.2%, Coatepec = 47.4%). We found a clear association between GVI and GC in Xalapa, but none in Coatepec. The latter was due to an important proportion of the vegetation of Coatepec being mainly constrained at block interiors, obstructed by walls. Regarding the self-reported measure, our results show an important discrepancy in relation to one of the physical measures (GVI), assessed through PVG/GVI ratios. In general, respondents tended to overestimate greenery, with greater overestimations related to GVI values <10%. Among the assessed respondent traits (gender, education level, live and/or work in neighborhood, time living and/or working in neighborhood), we found none to explain variations of PVG/GVI ratios in Coatepec, but respondent age did relate, non-linearly, with PVG/GVI ratios in Xalapa. In a nutshell, our findings indicate that the assessed physical and self-reported measures capture different aspects of urban greenery that differ in their potential uses, with GVI representing a helpful tool to quantify visible greenery at eye-level; GC being a highly informative physical measure to assess the amount of public and/or private urban greenery; and PVG as a quick and inexpensive measure of people’s perception of visible urban greenery. Depending on the monitoring, managing, and/or planning goals, the use of the three assessed measures can provide an integral evaluation of urban greenery.     

Assessment and optimization of green space for urban transformation in resources-based city – A case study of Lengshuijiang city,China

Urbanization in China has changed gradually from production-oriented to consumption-oriented in recent years. Comfort and accessibility of green infrastructures effect the rate of urbanization and transformation. A well designed urban green space system is an essential part of the urbanization process. In this paper, the urban green space of Lengshuijiang city was assessed both qualitatively and quantitatively using data of field survey and high resolution remote sensing. In the study area, green space coverage was 37.14%, green space percentage was 33.45% and per capita park green space was 16.25 m². The high green space coverage suggested that there were ample potentials for further urban transformation. Within a 30 min service radius of existing green space, total service area was 204.49 ha, which accounted for 16.26% of the study area. A high proportion of the green space was made up of urban parks which were unevenly distributed across the study area. A green space optimization strategy, aimed at improving green space quality and accessibility, was proposed. After optimization, total service areas within the 30 min service radius will increase to 492 ha (39.12%), an increase of 22.86%. Our study demonstrated that combining qualitative and quantitative methods is an effective and reliable way for green space assessment and reliable and can be used for urban green space planning and management for small resource-based cities like Lengshuijiang in its process of urban transformation.     

Why don’t we go outside? – Perceived constraints for users of urban greenspace in Sweden

Urban greenspace (UGS) is important for human wellbeing, particularly physical and mental health, and is claimed to support social cohesion. However, the expansion and densification of urban centres in recent decades has occurred largely at the expense of UGS. This risks its attractiveness for users. Although recent research has identified various factors that influence the use of UGS in different contexts, few studies have taken an explicit, bottom-up approach to understand which factors constrain willingness to use it. This study analyses responses from an online survey in Sweden (N = 2806) to identify the main constraints to UGS usage, and for whom these are constraints. Respondents could select from 22 different types of constraints – relating to incivilities, management, accessibility and availability, safety, and personal issues. Respondents could also provide comments to identify additional constraints. Incivilities were the most perceived problem. For example, litter was selected by 53% of respondents, while vandalism was selected by 24%. At the same time, many respondents perceived few or no constraints – 59% stated that nothing prevented them from using UGS, while 35% stated that they saw no problems. Safety-related and accessibility/availability constraints were not strongly identified although many respondents commented that UGS in Sweden is inadequate given the large number of users, and that the UGS that people want to use the most is often inaccessible without a car. Multiple binary logistic regression was used to investigate relationships between perceptions of constraints and fourteen predictor variables. Odds ratios were used to determine whether significant (p < 0.05) relationships were meaningful. Our findings show that different groups have starkly divergent perceptions of constraints relating to UGS. Several key factors – including age, self-reported nature-connectedness, distance to UGS, and frequency of use – were associated with a heightened likelihood of perceiving different groups of constraints. However, relationships between constraints and factors relating to environmental justice were not straightforward. These findings indicate the complexity of UGS planning challenges relating to densification, the New Urban Agenda and promotion of societal benefits, and a need to further integrate multiple user perspectives, especially of younger adults and infrequent users.