The intensity of Bangkok’s urban heat island during the dry season can be as high as 6–7° and in the densest areas the urban heat island’s intensity is approximately 4°C. The urban heat island thus ...is causing a city already oppressively hot to become even hotter. The urban heat island also contributes to health problems, such as heat stroke and fatigue, particularly to those with lower incomes. We historically examine the numerous causes of Bangkok’s urban heat island, such as the lack of green space, high levels of air conditioning, and high rates of vehicle exhaust fumes. For example, Bangkok has only three square metres of green space per person which is one of the lowest in all of Asia. Local governmental weaknesses, administrative fragmentation, prioritisation of economic growth and limited buy-in from the private sector have intensified Bangkok’s urban heat island, and imposed numerous barriers to actions that would reduce heat, such as establishing green space, restructuring urban transport or creating and following an effective urban plan. Ideas mooted to remedy these problems have yet to come to fruition, largely because of bureaucratic inertia, fragmentation and divisions within the relevant lead organisations. The political ecology lens also reveals how political–economic processes largely determine the vulnerability of urban inhabitants to heat, but also that thermal governance is highly unequal and unjust. Those who contribute to and profit the most from Bangkok’s urban heat island, such as real estate developers, shopping mall owners, and automobile corporations, suffer the least from its effects, whereas low-income communities hardly contribute to this problem, yet are the most vulnerable.
Indigenous health interventions have emerged in New Zealand aimed at increasing people's interactions with and exposure to macro and microbial diversity. Urban greenspaces provide opportunities for ...people to gain such exposures. However, the dynamics and pathways of microbial transfer from natural environments onto a person remain poorly understood. Here, we analysed bacterial 16S rRNA amplicons in air samples (n = 7) and pre- and post-exposure nasal samples (n = 238) from 35 participants who had 30-min exposures in an outdoor park. The participants were organised into two groups: over eight days each group had two outdoor park exposures and two indoor office exposures, with a cross-over study design and washout days between exposure days. We investigated the effects of participant group, location (outdoor park vs. indoor office), and exposures (pre vs. post) on the nasal bacterial community composition and three key suspected health-associated bacterial indicators (alpha diversity, generic diversity of Gammaproteobacteria, and read abundances of butyrate-producing bacteria). The participants had distinct nasal bacterial communities, but these communities did not display notable shifts in composition following exposures. The community composition and key health bacterial indicators were stable throughout the trial period, with no clear or consistent effects of group, location, or exposure. We conclude that 30-min exposure periods to urban greenspaces are unlikely to create notable changes in the nasal microbiome of visitors, which contrasts with previous research. Our results suggest that longer exposures or activities that involves closer interaction with microbial rich ecological components (e.g., soil) are required for greenspace exposures to result in noteworthy changes in the nasal microbiome.
•Passive interaction with nature has been highlighted as a health intervention.•Microbially rich outdoor ecological components can transfer microbiota to humans.•Short-term outdoor exposures did not create notable changes in the nasal microbiome.•Changes to nasal microbiomes may require longer and/or more direct exposures.
Cultivating a deeper understanding of the response mechanism of cultural ecosystem services to urbanization is increasingly recognized as a critical component of sustainable governance and land-use ...decision making. However, except for a range of studies exploring changes in ecosystem services during urbanization that address cultural ecosystem services as merely one service type, few investigations reveal the changing mechanism of cultural ecosystem services in rapid urbanization. To fill this knowledge gap, this study selected Changyang Township, Fangshan District, Beijing as a case to understand the influence of intense urbanization on changes in cultural ecosystem services in the context of Chinese cities. Cultural ecosystem services were classified and mapped based upon a systematic and critical review of previous literature, field surveys, and kernel density analysis. The influence of urbanization on cultural ecosystem services’ changes was examined through casual loop diagrams. Urbanization was found to contribute positively to cultural ecosystem services in general, although a reconstruction process revealed that these were initially diminished and then revamped during China’s urbanization. The primary development of the land was the key factor contributing to the process by which conventional cultural ecosystem services deteriorated during urbanization, while spatial planning and design facilitated the reconstructions of cultural ecosystem services across larger core areas. Meanwhile, cultural ecosystem services were experienced differently by residents in areas with varied urbanization intensities. This study provides an in-depth analysis and suggestions for primary land development in the Chinese context to achieve sustainable urbanization concerning cultural ecosystem services. In addition, this study enriches the cultural ecosystem services literature from a dynamic lens while highlighting the complexity of recreation as both an experience and a component of cultural ecosystem services.
•Urbanization is found to play both negative and positive roles in changing CESs.•There was a destruction and reconstruction process of CESs during urbanization.•Land preparation was the key factor in CESs destruction, and park design represented CESs reconstruction.•Recreation was found to be both a way of experiencing CESs and a component of CESs.
The impacts of urbanization on aboveground biodiversity are well studied, and its impact on soil microorganisms are also receiving increased attention. However, the impact of urbanization on the soil ...protists are hardly investigated. Here, we studied how urbanization and distinct urban greenspaces affect protist communities. We used amplicon sequencing of the18 S rRNA gene of samples from five types of urban greenspaces (parks, greenbelts, industrial areas, residential areas and hospital lawns), neighboring natural forests and agricultural ecosystems in Ningbo, China. We found that urban greenspaces harbored higher protist α-diversity than forests, while protist β-diversity increased from agricultural systems to urban greenspaces to forests. Among the studied driving factors, soil bacterial α- and β-diversity best predicted phagotrophic protist α- and β-diversity in urban greenspaces, while differences in α- and β-diversity of phototrophic protists were best explained by soil carbon-to-nitrogen ratio and fungal β-diversity, respectively. Abiotic factors i.e., total phosphorus and carbon-to-nitrogen ratio, best predicted the α- and β-diversity of protist parasites in urban greenspaces, respectively. The results revealed that the composition and drivers of protist communities vary between functional groups and urban ecosystems. Overall, our findings contribute to a better understanding of drivers of soil protist communities and indicate that soil protist communities and associated soil functions could be managed in predictable ways in urban greenspaces.
Climate change (higher frequency and intensity of precipitation events) and land use change (urbanization reducing soil drainage capacity) are increasingly causing stormwater problems globally, ...especially in cities. Nature-based solutions such as urban greenspace rehabilitation programs are gaining considerable attention for restoring soil retention capacity and protecting cities against increasing flood risk. However, a better understanding of how effective such measures are in practice is needed to enable and promote their adoption across urban settings.
To this end, in this study, we assess the effect of soil rehabilitation measures in terms of soil compaction, vegetation cover and unsaturated hydraulic conductivity by analysing the results of an infiltration measurement campaign conducted across a wide range of real-world greenspaces (from recently rehabilitated, to poorly maintained, down to highly degraded) in the Italian city of Milan, one of the most urbanized areas in Europe.
Our results show that the unsaturated hydraulic conductivity varies significantly across the examined greenspaces, due to differences in time from rehabilitation, soil compaction and vegetation cover. Specifically, we find that the highest unsaturated hydraulic conductivity is obtained after approximately 5 years since implementation of soil rehabilitation measures, which can be explained by the time needed (i) by the introduced vegetation to develop root systems, and (ii) by the soil matrix to develop a coherent structure that allows stable connections between pores and thus the strengthening of preferential water pathways. Finally, our study shows that, in absence of soil and vegetation maintenance, unsaturated hydraulic conductivity may decrease rapidly after about 9–12 years.
These findings provide useful information for supporting the planning of nature-based solutions in practice, which will become increasingly important to protect our cities from climate change impacts and widespread urbanization going forwards.
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•Soil rehabilitation increases the unsaturated hydraulic conductivity of urban greenspaces•The highest unsaturated hydraulic conductivity is obtained after 5 years after soil rehabilitation•In absence of soil and vegetation maintenance, unsaturated hydraulic conductivity may decrease after 9-12 years•Vegetation cover increases unsaturated hydraulic conductivity due to preferential flow and improved soil structure
•Short text topic modeling identifies Twitter opinions related to urban parks.•Urban parks continue to be valued for physical activity during the pandemic.•A decrease in conversations about general ...activities in urban parks during the pandemic.•Concerns about social distancing in urban parks have been a trending topic on Twitter.•The potential for monitoring attitudes and values about parks through Twitter data.
Since school and business closures due to the evolving COVID-19 outbreak, urban parks have been a popular destination, offering spaces for daily fitness activities and an escape from the home environment. There is a need for evidence for parks and recreation departments and agencies to base decisions when adapting policies in response to the rapid change in demand and preferences during the pandemic. The application of social media data analytic techniques permits a qualitative and quantitative big-data approach to gain unobtrusive and prompt insights on how parks are valued. This study investigates how public values associated with NYC parks has shifted between pre- COVID (i.e., from March 2019 to February 2020) and post- COVID (i.e., from March 2020 to February 2021) through a social media microblogging platform –Twitter. A topic modeling technique for short text identified common traits of the changes in Twitter topics regarding impressions and values associated with the parks over two years. While the NYC lockdown resulted in much fewer social activities in parks, some parks continued to be valued for physical activity and nature contact during the pandemic. Concerns about people not keeping physical distance arose in parks where frequent human interactions and crowding seemed to cause a higher probability of the coronavirus transmission. This study demonstrates social media data could be used to capture park values and be specific per park. Results could inform park management during disruptions when use is altered and the needs of the public may be changing.
Retaining river channels and constructing waterfront greenspaces are the primary tasks of urban waterfront development in China. However, the natural characteristics of the water network are not ...fully considered in some urban greenspaces system planning and subsequent construction. We proposed a simple evaluation system to assess the morphological suitability between greenspaces and rivers in both the existing and planning stages. The evaluation indicators consist of two-level factors, in which the types of greenspace defined by the distance to the nearest river are the primary factors, including urban greenspace, waterfront greenspace and near-water greenspace, and the spatial forms of each type of greenspace are the secondary factors. The evaluation system can reflect the characteristics of each city and provide an overall comparison to cities of the same scale in similar regions. This study also investigated the impact of greenspace system planning on the current greenspace form. The results showed that near-water greenspace is a key factor that affects the matching degree among all primary factors, and the layout of greenspaces has a substantial impact on morphological suitability. Significant correlations between matching degree and evaluation factors were also found. This paper provides an in-depth understanding of urban greenspace form with urban rivers.
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•The current study investigated the effects of land cover in reducing heat loads.•The effect of surface cover is important for human thermal comfort after shade.•Grass surface cools ...more in the sun when there is sufficient moisture in the soil.•Grass surfaces shadowed by tree canopies can be effective even during soil droughts.
Urban greenspaces showed the potential to lessen the urban heat island effect. However, a detailed understanding on the mechanisms of different components of greenspaces such as grass surfaces, trees or a combination of grey and green infrastructure on reducing heat loads at local and city scale and different weather conditions is still limited. We designed a small-scale experiment within the sub-urban area Freising, close to Munich in Germany during hot summer days of the year 2020 including wet and dry spells. We investigated surface energy balance and the human thermal comfort measured in terms of physiological equivalent temperature (PET). Six sites including grass lawns and paved surfaces, with or without the shade of trees and buildings were selected. Significant positive relationships between surface (ST) and air temperature (AT) were detected both for grass and paved surfaces; however, the relationships were stronger during the wet spells compared to dry spells and for grass surfaces compared to paved surfaces. Moreover, PET was more strongly related to ST compared to AT. Overall, shade reduced 15 °C, 2 °C and 13 °C of ST, AT and PET respectively compared to sunny sites. The differences between sun and shade were steeper over the grass surfaces and during the wet spells when the grass surfaces lost more than 1.5 L m−2 d−1 of water. In contrast, sensible heat fluxes between grass and paved surfaces were not different during the dry spells. Moreover, compared to the building shade, tree shade further reduced AT by 0.6 °C and 0.4 °C during wet and dry spells, but PET by 1 °C and 1.6 °C during wet and dry spells respectively. Our results underline the importance of both shade and grass surfaces in reducing the urban heat loads, in particular, the added benefits of tree shade during the summer droughts.
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