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.     

Sniff the urban park: Unveiling odor features and landscape effect on smellscape in Guangzhou,China

Smellscape, as the sense of smell cross space, has a huge impact on human behavior, attitudes and health. However, so far it has rarely been addressed and measured in both landscape practice and theories. The present case study refined the quantitative smellwalk method to examine the spatial and temporal features of urban park smellscape. The effects of landscape patterns on smellscape were further unraveled combining with remote sensing techniques and field surveys. The results indicated that: (i) human activities and nature odors dominated the urban park odor environments, (ii) the temporal variation of the urban park smellscape was mainly driven by human activities, (iii) the different site types of urban park exerted a significant impact on the composition of the smellscape, and (iv) the landscape pattern characteristics of forest, shrubs, grass, water, buildings and roads had significant effects on different types of odors. This study poses a first systematic exploration of various odors in urban green environments and offers novel insights into the design of smellscape via unveiling spatial-temporal odor distribution patterns.     

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.     

Economic development and natural amenity: An econometric analysis of urban green spaces in China

Rapid urbanization and spontaneous economic development has brought about profound changes in urban landscapes throughout the world. The task of managing transforming urban landscapes, particularly urban green spaces, so as to provide sufficient natural amenity for increasing urban populations, is one of the critical challenges facing policy makers. However, little empirical evidence exists about the evolving path of urban green spaces along with economic development and urbanization. This study attempts to fill in this knowledge gap through an econometric analysis of panel data across 285 Chinese cities during a period of rapid urbanization and economic growth (2001–2010). The results point to the existence of an N-shaped environmental Kuznets curve (EKC) for an important aspect of environmental quality: urban green spaces. Urban green space coverage increases at the initial stage of economic development, and then it starts to decrease as GDP per capita exceeds RMB50,855 and then increases again at a high GDP per capita level (RMB107,558). Large elasticity (>1) is expected as GDP per capita grows to a higher level (beyond RMB128,095). By the end of 2010, 30% of Chinese cities are still located on the downward-sloping path and only four cities have attained elasticities greater than one. The findings present a challenging and pressing call for policy makers to effectively manage the tradeoffs between continuous economic development and better natural amenities.     

Amenity trees and green space structure in urban settlements of Kigali,Rwanda

According to the national policy, overall forest and agroforestry cover in Rwanda is to increase up to 30% land cover by 2020. On the other hand, demographic data reveal that Rwanda's urban areas are among the fastest-growing on the continent. Unfortunately, there is only little information of the effects of such a rapid urbanization on tree cover and green space structure, knowing that data on urban plant assemblages in the country are rather rare. The paper discusses developments in Kigali's green spaces with regard to its rapid rate of expansion. An integrated approach of research, combining results from interview sessions, desk-based investigations, walk-over and vegetation surveys, and photogrammetric analyses of remotely acquired imagery was applied. The findings suggest that the city green space network consists of plant assemblages largely dominated by alien species (75%). Tree cover fraction averaged at around 10–35%. No significant difference was observed between field-drawn and photogrammetric-based fraction of tree cover estimates; making the later a quick but cheap tool for rapid tree cover evaluation. Cultivated forests, urban woodlots and domestic garden tree stands are far the most dominant types of green spaces in terms of coverage of city surface area. Street tree communities and institutional gardens appear to be the most intensively designed green space layouts. Both distribution and species composition in domestic gardens were socioeconomic-driven. For instance, palm trees were characteristic of fortunate quarters while fruitbearing ornamental such as Psidium guajava and Persea americana were common within scattered and informal settlements. Markhamia lutea, Erythina abyssinica, Euphorbia candelabrum, Phoenix reclinata and Acacia sieberiana are among native taxa that thrive to keep a place in the city. Euphorbia tirucalli, a native tree that is widespread in home compound fences within informal settlements, is significantly declining as modern housing expands and concrete-based fences replace live enclosures.     

Protest response and contingent valuation of an urban forest park in Fuzhou City,China

Urban forest parks, such as Fuzhou National Forest Park (FNFP), provide residents with landscape amenities, recreational opportunities, and interaction with nature. Understanding the recreational quality of green spaces and visitors’ behaviors and preferences is essential for effective forest park conservation strategy. We aimed to assess the recreational use and amenities of FNFP and calculate the monetary value of provided services using a contingent valuation method (CVM). A total of 249 park visitors were interviewed face-to-face based on a questionnaire using entrance fee as the payment vehicle, in October 2015 and January 2016. A considerable number of protest responses may cause selectivity bias; consequently, we used models excluding protest zeros. Sample selection models were estimated using Heckman’s two-step and full information maximum likelihood methods The average willingness-to-pay (WTP) was estimated to be 13.79 RMB (equivalent to 2.00 USD) for the unconditional model, and the lower mean values were estimated for two selectivity bias corrected models. In this case, park visitors would be willing to pay an average 11.6 RMB (equivalent to 1.69 USD) per person according to the full information maximum likelihood estimate and an average 10.96 RMB (equivalent to 1.60 USD) per person by the two-step method. Respondents’ satisfaction of forest park facilities and service significantly influenced their WTP value for forest park improvements. Socio-demographic features could not effectively discriminate the protest bidders and the other non-protest bidders. Our results suggest that protesters may value the resource less than positive bidders. The high percentage of protest respondents may be due to the current free use of FNFP and payment vehicle of entrance fee. The CVM approach takes residents’ preferences into consideration and allows the study of heterogenous socio-demographic groups; thus, our data may help to develop effective management plans for improving urban forest parks in China.     

Local variation of outdoor thermal comfort in different urban green spaces in Guangzhou,a subtropical city in South China

To understand the influence of different urban green spaces on outdoor thermal comfort, researchers have focused on developing a thermal comfort range and estimating neutral and preferred temperatures through questionnaire surveys and microclimatic measurements. The simultaneity of investigation among different sites is often neglected, which decreases the accuracy and reliability of the outcomes. To fill this gap and to better address the local variation of outdoor thermal comfort in different urban green spaces, both surveys and measurements were performed simultaneously at three sites, “central grassland,” “pond-side garden” and “grove” in a subtropical urban local area in warm and cool periods. Remarkable differences in microclimatic conditions, thermal sensations, thermal comfort, and both neutral temperatures and preferred temperatures were observed among the three sites and in the two periods. Preferred temperatures were lower than neutral temperatures among different sites in each period or both periods combined, indicating the instinctive preference of people from relatively hot regions for a cooler thermal state. The grove yielded the best cooling capability but was perceived as the hottest and most uncomfortable site in the warm period. The central grassland with the highest air temperature, conversely, was perceived as the most comfortable site. The subjective perceptions were also reflected by lower neutral and preferred temperatures in the grove than those in the central grassland in the warm period. In particular, for preferred temperatures, up to 8.8 °C operative temperature (T_op) and 4.3 °C physiological equivalent temperature (PET) differences between these two sites were observed. Hence, a high density of trees does not necessarily result in better outdoor thermal comfort. Future urban planning and management, therefore, should emphasize the types and structures of different urban green spaces. To further comprehensively explore the roles of different urban green spaces in outdoor thermal comfort, high synchronicity among sites during investigation is important.     

Casual evaluation of the effects of a large-scale greenway intervention on physical and mental health: A natural experimental study in China

Many cross-sectional studies have supported the health benefits of urban greenways. However, the causal relationship between urban greenway intervention and residents’ physical and mental health remains unclear. Furthermore, the potential dose-response effect by distance to a greenway intervention remains unknown. This study explored the impact of a large-scale urban greenway intervention (construction of a 102-km-long East Lake Greenway in Wuhan, China) on the health outcomes of residents by using a natural experimental research design. We collected data before and after the intervention (in 2016 and 2019, respectively) from 1,020 participants living within a 5-km street-network distance from the entrances of this greenway. The average age of the participants was approximately 50, and most of them were married. More than half of the participants were female, currently employed, and had received a college education or above. Mixed-effects difference-in-difference (DID) models were used while controlling for individual and neighbourhood covariates. The results showed that the East Lake Greenway had a positive effect on the self-reported mental health of residents who lived within 2 km, and these benefits decreased with distance. The physical health benefit was insignificant. To increase the health benefits of urban greenways, more effort should be made to improve the accessibility of greenways and the surrounding environment. We also advocate that future natural experiments should explore the distance-varying dose-response effect of green space interventions on health outcomes.     

Similar spaces,different usage : A comparative study on how residents in the capitals of Finland and Denmark use cemeteries as recreational landscapes

Several studies from the Nordic countries show that cemeteries not only fulfil an important societal function as places for the disposal of bodily remains; they are also recreational landscapes that people visit to reflect, experience nature or perhaps go for a walk with the dog. In this comparative study, based on PPGIS data collected between 2018 and 2020 from residents in Copenhagen (Denmark) and Helsinki (Finland), we explored the extent to which residents use urban cemeteries as everyday recreational landscapes. We also assessed users’ characteristics and the values they attached to the cemeteries. The results show that several of Copenhagen’s cemeteries were actively used for recreation, while those in Helsinki were used much less frequently for this purpose. Of the total 7276 mapped visiting points in Copenhagen, 16.5% were located within cemeteries, compared with 1.9% of the 4298 mapped visiting points in Helsinki, hence conclusions from Helsinki should be drawn with caution. Physical activity and experiencing nature were the most common values attached to cemeteries in Copenhagen, whereas social interaction, spirituality and tranquillity were most common for Helsinki cemeteries. The results also revealed that younger Danes were particularly inclined to use cemeteries for social interactions, physical activity and spirituality and tranquillity. In the discussion, we elaborate on spatial differences between the cases, such as the availability of other green spaces, the size of cemeteries or people living in proximity to a cemetery, as well as on differences in policies and practices, including how Copenhagen stands out in actively promoting municipal cemeteries as recreational landscapes.     

Wealth and land use drive the distribution of urban green space in the tropical coastal city of Haikou,China

Urban green spaces (UGSs) provide a plethora of ecosystem services that benefit humans and wildlife within cities. UGS both promotes and is affected by overall urban ecological health, which can be measured by a wide range of indices. In this study, we investigated the distribution patterns and drivers of UGS within the tropical coastal city of Haikou, Hainan, China over the past decade using a combination of remote sensing data and field work. We interpreted Google earth images from 2010 and 2020 to determine the land cover of UGS within Urban Functional Units (UFUs). We collected socioeconomic variables to test if wealth, site age, and land use determine the proportion of UGS in the city. We found that the proportion of UGS in parks was the highest among all UFUs in 2010 and 2020. In general, UGS increased with maintenance frequency and housing price, which are proxies for the luxury effect. However, land use also played a role in UGS distribution across UFUs, especially in transportation areas, recreation and leisure districts, and residential districts. Haikou is similar to other cities in showing a positive luxury effect on the distribution of UGS. Our results highlight the key roles that parks, colleges and universities, and research institute areas have played in maintaining stable green space within Haikou over the past decade. We suggest that relatively recently implemented governmental programs to increase green space elsewhere in the city may not yet have achieved success within the time span that we analyzed.