Urban Forest Research Articles

Unraveling lead sources in a tropical urban Swamp Forest: Insights and challenges

We investigate the contributions of natural (geogenic) and anthropogenic sources of lead (Pb) to the Nee Soon Swamp Forest, a relatively undisturbed catchment in Singapore. Using a Bayesian statistical source tracking approach with Pb isotopes preserved in sediment sections, our findings reveal a predominance of geogenic Pb in contemporary sediments, despite the significant presence of anthropogenic Pb in aerosols from local and distant sources. However, the geogenic Pb isotope signatures of the two main soil types in the catchment overlap with those of anthropogenic sources, introducing considerable uncertainty in using Pb isotopes as tracers within this catchment and potentially across larger areas. This uncertainty raises concerns about past interpretations of Pb contamination in both terrestrial and aquatic environments in Singapore and the broader region. To address these challenges, we emphasize the importance of accurately determining the signatures of all natural sources before using Pb isotopes as tracers in future studies. We also suggest that incorporating additional Pb isotope ratios or other stable isotope ratios (e.g., Ba, Cu, Sr, Zn) could enhance our ability to distinguish between natural and anthropogenic Pb sources. Ultimately, our study highlights the complexity of Pb sources in the environment and underscores the need for more comprehensive approaches to assessing their impacts. SynopsisThis paper highlights insights and challenges in lead (Pb) source tracing studies conducted in urban catchments. These challenges primarily stem from the inadequate identification of all Pb isotope sources. We address these challenges by employing a Bayesian statistical approach to effectively identify, discriminate, and quantify Pb sources within a wetland ecosystem in Singapore.

Terrain's steepness governs sensitivity of urban oak forests to climate variability

Terrain's steepness governs sensitivity of urban oak forests to climate variability

Meadows or asphalt road – Does momentary affective well-being vary with immediate physical environment? Results from a geographic ecological momentary assessment study in three metropolitan areas in Germany

We investigated the association between the immediate physical environment of individuals and individual fluctuations of momentary affective well-being in everyday life with a focus on medium sized metropolitan areas in Europe representing a typical living environment of a large proportion of the world’s population. The sample comprised 365 individuals (54.8 % female) with participants ranging from 14.08 to 88.27 years of age (M = 43.9, SD = 20.9). In an geographic ecological momentary assessment (GEMA), participants were prompted six times a day on at least 9 days over the course of 3 weeks, covering a total of six weekdays and three weekend days on mobile phones to report their momentary affective well-being. Urban land use categories (forest, water, urban green) were assessed with GPS-localization as environmental variables. Additionally, sunshine, rainfall, whether participants were inside or outside as well as whether they were alone or had company were included into the analyses.We used dynamic structural equation modelling to model the inter- and intraindividual differences as well as fluctuations and assess potential covariates while acknowledging the autoregressive nature of affect.The results showed that on individual level, fluctuations of momentary affective well-being were associated with sunshine, having company and travelling. No significant association emerged for urban green, forest, and water neither within individuals nor between. Methodological as well as conceptual implications are discussed and an interpretation of the present findings are provided.

Differential predation pressure on island pit vipers shape their niches and defensive behavior

Abstract Animals are naturally exposed to several predators, and, given that a single encounter with a predator may cause prey’s death, natural selection will strongly act upon its defensiveness. Therefore, defensive behavior is strongly shaped by predation pressure. Predation rate in islands tends to be relaxed due to lower abundance of predators. The aim of this study was to test the hypothesis that predation rates upon the two island pit vipers Bothrops alcatraz and B. insularis would be lower than correlated mainland B. jararaca. Additionally, we evaluated the defensive behavior of these island snakes in the field to compare with the mainland B. jararaca. Predation pressure upon the insular species was assessed utilizing plasticine replicas, and we evaluated their defensive behavior to approach. These data were compared to those previously reported for B. jararaca. We found a lower predation pressure on B. insularis (from the smaller area) than on B. alcatraz and B. jararaca from the urban mainland forest fragment (areas with intermediate size), and all of them showed lower predation pressure than B. jararaca from the continuous mainland forested area. In the field, island snakes show narrower defensive repertoire than B. jararaca, since most B. insularis fled, and B. alcatraz either fled or remained immobile on approach. Apparently, the predation pressure to which these island pit vipers are exposed shapes their defensive behavior, as well as the niches exploited by them.

Changing Bird Migration Patterns Have Potential to Enhance Dispersal of Alien Plants From Urban Centres

ABSTRACTThere is increasing recognition that alien species may be ‘sleepers’, becoming invasive with favourable changes in conditions, yet these changes remain difficult to predict. As populations of frugivorous birds shift with urbanisation and climate change, they could provide dispersal services for introduced fruiting plants that have previously been considered benign. This is likely to be especially problematic at higher latitudes where bird migration phenologies are altering rapidly. However, any consequences for fruit dispersal have not yet been explored. Here, we use Helsinki, Finland, to investigate whether (i) streetscapes provide birds with a fruit resource that differs from urban forest fragments and (ii) the chances for dispersal of alien species (i.e., preferential consumption of native fruits). While there were both more fruits and birds in streetscapes (replicated across multiple years), fruits were not consumed preferentially according to origin. Additionally, seed analysis from faecal samples of blackbird Turdus merula L., a previously migratory but increasingly resident species, suggested that alien and native plants are equally likely to be dispersed. These results indicate that birds could be dispersing alien species more frequently than previously thought and highlight the complex effects of changing climates on potentially invasive species.

Propagule bank dynamics in subtropical urban forest remnants: edge effects, fragmentation and plant invasion

Propagule bank dynamics in subtropical urban forest remnants: edge effects, fragmentation and plant invasion

Effects of soil compaction on above- and belowground interactions during the early stage of forest development

Forested green spaces in urban and peri-urban areas are expected to serve multiple roles, including providing ecosystem services and maintaining species diversity and soil health, both of which are particularly important for human health. However, soil compaction is a major cause of soil degradation in urban areas and brownfields (abandoned, previously developed land). We examined the effects of compaction on soil physicochemical properties, tree species richness, tree basal area, and the functional diversity of microbial communities in an immature volcanic soil through a long-term (14-year) field experiment. Our experimental results showed that soil compaction reduced not only both tree species richness and biomass but also the multifunctionality of soil microbial communities. Furthermore, tree species richness was significantly positively related to soil microbial decomposition activity. These findings provide evidence of above- and belowground interactions and underscore their importance in the design of urban forests using ecosystem-based solutions.

Examining the Impacts of Urban Tree Structure and Condition on Adult Depression in the United States

Examining the Impacts of Urban Tree Structure and Condition on Adult Depression in the United States

An Analysis of Visitor Behaviors and Satisfaction in Urban Forests: Focused on Major Forests in Incheon

Background and objective: Urban forests have increasingly integrated recreational and welfare facilities to enhance the quality of life for urban residents. This study explores the behaviors, perceptions, and satisfaction of visitors to major forests in Incheon Metropolitan City, aiming to offer guidelines for the improvement of recreational facilities within these urban forests. By understanding visitor needs and preferences, the study seeks to contribute to the development of more user-friendly and sustainable forest environments that cater to the well-being of city dwellers.Methods: The study focused on five major forests in Incheon: Munhaksan Mountain, Cheongnyangsan Mountain, Manwolsan Mountain, Wonjeoksan Mountain, and Gyeyangsan Mountain. Data were collected through field surveys and analyzed using cross-tabulation, one-way ANOVA, and regression analysis. Based on the results, targeted recommendations were made for the enhancement of recreational facilities in each forest.Results: For Munhaksan Mountain, expanding recreational spaces and offering trail-specific programs are key priorities, along with developing a maintenance plan to improve visitor satisfaction. In Cheongnyangsan Mountain, expanding popular facilities like barefoot walking paths and optimizing the forest structure for air purification and noise reduction are needed. Manwolsan Mountain requires a more efficient maintenance system, focusing on security, amenities, and visitor services to address the issue of low satisfaction. Wonjeoksan Mountain should enhance trail safety with more CCTVs and improve amenities such as restrooms and trash disposal. Gyeyangsan Mountain needs more rest areas and amenities, addressing congestion in the northwest while preserving natural scenery and providing an information platform for younger visitors.Conclusion: This study contributes to optimizing the use of urban forests and improving the quality of life for residents by proposing a strategic framework for the development of recreational welfare in forests. The findings are expected to serve as a valuable resource for local governments in formulating rational forest management and usage plans.

Trends in Tree Species Selection for Urban Street Planting: A Thematic Review

In major cities, street tree failures pose ongoing challenges related to user safety, tree management, and maintenance. This study evaluates trends in urban street tree selection by analysing 45 articles from 2019 to 2024 using keywords such as “street,” “tree species,” and “selection.” The thematic analysis identifies five key themes: species diversity, ecosystem services, climate adaptability, public perception, and management challenges. Findings highlight the need for a multifaceted approach, recommending criteria to reduce conflicts and ensure proper tree placement. The proposed framework aims to enhance urban tree resilience and coexistence with humans by emphasising genetic diversity and ecological benefits. Keywords: Street tree, species selection, urban forestry, thematic review

Biomass-Based Gas Turbine Systems for Power Generation: Sustainable Feedstocks and Environmental Benefits

This paper explores the significance and operational mechanisms of biomass-based gas turbine systems, which present a renewable and sustainable substitute for conventional fossil fuel-based electricity production methods. These systems utilize biomass as a source of fuel to produce heat, which is then converted into power through a gas turbine. The process involves the combustion of biomass fuel to heat a working fluid, such as air, which subsequently drives the turbine to produce electricity. Biomass can be derived from various organic materials, encompassing urban solid trash, forest residues, and agricultural residues, making it a versatile and sustainable fuel option. The paper also includes a practical case study, highlighting the system's advantages and disadvantages. Additionally, it identifies future trends, emphasizing the importance of efficiency enhancement. To achieve this, scientists are increasingly proposing hybrid systems that combine biomass-based gas turbines with other technologies. This approach aims to optimize performance, reduce emissions, and contribute to guaranteeing a future with more sustainable energy. The study underscores the potential of biomass-based gas turbine systems to play a crucial part in the shift to renewable energy sources.

Identification of Forest City Multi-Policy Using the MULTIPOL: A Study In The New Indonesian Capital, East Kalimantan

The policy-planned development in the new Indonesia Capital City (IKN) area must be accompanied by good planning to ensure the continued availability of forestry ecosystem services, especially forestry areas. These ecosystem services are strongly influenced by their ecological functions. Humans depend on essential ecosystem services to satisfy their inherent needs and enhance or preserve their quality of life. Natural resources are being overused to satisfy these demands, endangering biodiversity and putting more strain on ecosystems. Therefore, a multi-policy approach describes and visualizes the relationships between multi-aspect policies that provide and benefit from forestry ecosystem services. The method used in compiling this paper is multi-policy, part of the prospective analysis method. This method will map and create a model, the best policy scenario that can be applied to achieve the goal of a forest city in the new nation's capital. The results show that the presidential regulation implementation scenario is the best policy choice for the forest city model in the new state capital.

New species and records of the treehopper genus Cyphonia (Hemiptera: Membracidae) from the northern Amazonia lowlands of Ecuador

Summary. We describe two new species of Cyphonia Laporte, 1832 from the Amazonia lowlands of Ecuador: Cyphonia dayuma Montalvo-Salazar & Karbaum n. sp. (♀) and C. kellyswingi Montalvo-Salazar & Torres n. sp. (♀). We also add two new records for Ecuador from an urban forest remnant in the Amazonia: Cyphonia clavigera (Fabricius, 1803) and C. longistyla Sakakibara, 1972. With this contribution, the number of known species of Cyphonia inhabiting Ecuador is elevated to seven. We lastly provide a key to the known Cyphonia species of Ecuador.

Knowledge Distillation for Urban Tree Image Classification Based on the Diffusion Model

As urban areas continue to emerge as significant contributors to global carbon emissions, the classification of urban street trees has gained increasing importance in carbon sequestration research. By precisely identifying and categorizing different tree species, the carbon absorption capabilities of urban vegetation can be evaluated more accurately. This understanding is essential for addressing the growing environmental challenges posed by carbon emissions, as urban trees play a crucial role in absorbing carbon dioxide and mitigating the effects of climate change. In this study, a Feature Distillation Based on Diffusion Model (FDBD) framework was proposed, utilizing state-of-the-art image classification technology to enhance the accuracy of urban tree species identification. The framework utilized knowledge distillation, a process where a smaller, more efficient “student” model is trained to mimic the performance of a larger, more complex “teacher” model, significantly reducing computational demands while maintaining high accuracy. The model’s effectiveness has been validated through combination experiments with a selected backbone model, achieving promising results. This approach not only enhances the understanding of urban trees’ carbon sequestration potential but also provides crucial insights for policymakers. By facilitating precise tree classification, it empowers urban planners to implement more informed and targeted strategies for carbon reduction, ultimately promoting more sustainable urban environments.

National Forest City Policy and Urban Ecological Resilience: Evidence from 292 Cities in China

The process of sustainable urban development faces complex and severe environmental problems. Therefore, enhancing urban ecological resilience (UER) has become an urgent and critical goal. In this study, the establishment of national forest cities (NFCs) in China is regarded as an exogenous shock event, and the impact of NFCs on UER and its mechanisms are investigated based on data from 292 cities spanning 2003 to 2021 using a difference-in-difference method. It is found that NFCs can significantly enhance UER, and this conclusion holds after a series of robustness tests. Mechanism analysis shows that NFCs can effectively strengthen environmental regulations, upgrade industrial structures, promote green innovation, and thus enhance UER. Heterogeneity analysis indicates that the effect of NFC on UER is more significant in low-carbon non-pilot cities, cities with higher levels of industrial development, and cities in central and western China. Spatial spillover analysis shows that NFCs can effectively improve the ecological resilience of neighboring cities. Therefore, NFCs should be continuously implemented and optimized to establish a long-term mechanism for urban forests to enhance ecological resilience.

Greening the mind: exploring the link between vertical gardens, urban forests, and mental health

Abstract Background Mental disorders impose a significant global burden, affecting millions of individuals, contributing to disability, reduced quality of life, and economic costs worldwide. Between 1990 and 2019, the global number of disability-adjusted life-years due to mental disorders increased from 80.8 million to 125.3 million. The economic costs are projected to rise to 6,000 billion euros by 2030. Urbanization has been associated with a worsening of mental disorders over the years due to various factors, such as increased stress, social isolation, reduced access to green spaces, and higher levels of pollution. Decades of research have instead shown that exposure to green space may promote psychological well-being, regulate stress, and endorse social health across the lifespan. In this systematic review, we aim to investigate how proximity to vertical gardens or urban forests, specifically, may affect mental health. Methods The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) were followed. The study protocol was registered in PROSPERO (CRD42024517969) with the following PECOS question: Is there an association between vertical gardens or urban forests and mental health? Results After performing searches on PubMed, Scopus, and Web of Science, and duplicate removal, we retrieved 556 articles. The main reasons for exclusion after title/abstract screening were mainly wrong outcome (not mental health) and wrong study type (not observational/intervention/cross-sectional studies). The selection of full texts is expected to end shortly and results will be available for November 2024. Preliminary findings support the role of green environmental assets in facilitating physical activity, social contact, and stress reduction. Conclusions In summary, mental disorders are exacerbated by urbanization’s stressors. Our review will further elucidate the potential benefits of urban green spaces like vertical gardens and urban forests on mental health. Key messages • Urbanization exacerbates the issue of mental disorders global burden. • Exposure to urban forests and vertical gardens may promote physiological well-being and mental health.

Health-Related Parameterization Evaluating Thermal Comfort in Urban Green Spaces: Data Sourced from a Global Database and Mapping at National Scale

Outdoor thermal comfort (OTC) is one of the most important issues for people exposed to urban green space (UGS). It is mainly evaluated by assessing equivalent meteorological factors that may combine and result in human responses of perceptions about comfortable vs. uncomfortable environments. The assessment of these responses is challenged by limits in a database that is powerful enough to support big-data analysis and an essential parameter that can evaluate health-related responses to OTC in urban forests. In this study, a meta-analysis was conducted by synthesizing studies of physiological and psychological health responses of green space (GS) visitors to meteorological factors in host cities on a global scale. A total of 15,000 numerical records about the psychological and physiological responses of UGS visitors were obtained from 105 papers across 68 global cities in 21 countries. A novel parameterization was developed to evaluate OTC by normalizing changes in health-related parameters and detecting their regressions against multiple meteorological factors. It was revealed that OTC resulted in more benefits in psychological health parameters than in physiological ones for UGS visitors worldwide. Globally, health-promoting OTC environments were more found in temperate countries than in countries subjected to other climates. People in Asian countries were indicated to live in environments with higher comfort that benefitted health states in cities at low latitudes. Thermal environments tended to be harsher and more challenging, mostly too chilling, in northern cities than in the south globally. A deep learning model using the ResNet algorithm was found to perform to an expected level with R2 as high as >70% and errors controlled generally lower than 0.01. Taking mainland China for instance, it was predicted that thermal environments in eastern cities of China highly challenged the psychological health of local UGS visitors across all seasons of the year. Northern cities of China were predicted to have satisfied thermal environments that benefited psychological and psychological health responses in spring. In summer, cities in West China were predicted to have comfortable thermal environments, and in winter, environments in the southwestern cities were more comfortable.

Effects of urban green space habitats and tree species on ectomycorrhizal fungal diversity

Ectomycorrhizal fungi (EMF) are key symbiotic microbial components for the growth and health of trees in urban greenspace habitats (UGSHs). However, the current understanding of EMF diversity in UGSHs remains poor. Therefore, in this study, using morphological classification and molecular identification, we aimed to investigate EMF diversity in three EMF host plants: Cedrus deodara in the roadside green belt, and C. deodara, Pinus massoniana, and Salix babylonica in the park roadside green belt, in Guiyang, China. A total of 62 EMF Operational Taxonomic Units (OTUs) were identified, including 13 EMF OTUs in the C. deodara roadside green belt, and 23, 31, and 9 EMF OTUs in the park green belts. C. deodara, P. massoniana, and S. babylonica were respectively identified in park green belts. Ascomycota and Basidiomycota were the dominant phylum in the EMF communities in roadside and park green habitat, respectively. The Shannon and Simpson indexes of the C. deodara EMF community in the park green belt were higher than those in the roadside green belt. EMF diversity of the tree species in the park green belt was P. massoniana > C. deodara > S. babylonica. Differences in EMF community diversity was observed among the different greening tree species in the UGSHs. UGSHs with different disturbance gradients had a significant impact on the EMF diversity of the same greening tree species. These results can be used as a scientific reference for optimizing the design and scientific management of UGSHs.

Whose forest, whose values? Planning for Atlanta’s “South River Forest”

ABSTRACT Atlanta, Georgia's (USA) proposed South River Forest (SRF) is a 3,500-acre area straddling southeast Atlanta and parts of neighboring DeKalb County that would include non-contiguous greenspace and developed land uses. Catalyzed by the 2017 Atlanta City Design process, the SRF concept recognizes the ecologically rich, urban forest patches in this predominantly African American part of the metro area. SRF advocates point to the climate and environmental equity benefits of green space conservation for underserved communities and the personal benefits of having wildland-like outdoor recreation areas within the city. To gauge public perceptions of the SRF, promoters conducted the South River Forest Consensus Building & Stakeholder Engagement process in 2022, which included an online survey querying respondents' interactions with and personal relationship to the SRF. The findings showed overwhelming support for the preservation effort; however, eighty percent of respondents identified as white and just nine percent as black. This composition contrasts sharply with most SRF neighborhoods, which question whether black ways of being in nature were captured by the engagement process. Our analysis also brings attention to an alternative, black-led vision for the area that was not reflected in the engagement process and the implications of this erasure for recognition justice.

Scale-Dependent Effects of Urban Canopy Cover, Canopy Volume, and Impervious Surfaces on Near-Surface Air Temperature in a Mid-Sized City

Cities are significantly warmer than their surrounding rural environments. Known as the ‘urban heat island effect’, it can affect the health of urban residents and lead to increased energy use, public health impacts, and damage to infrastructure. Although this effect is extensively researched, less is known about how landscape characteristics within cities affect local temperature variation. This study examined how tree canopy cover, canopy volume, and impervious surface cover affect daytime near-surface air temperature, and how these effects vary between different scales of analysis (10, 30, 60, 90 m radii), ranging from approximate street corridor to city block size. Temperature data were obtained from a car-mounted sensor, with traverse data points recorded during morning, afternoon, and evening times, plotted throughout the city of Portland, OR. The variability in near-surface air temperature was over 10° F during each traverse period. The results indicate that near-surface air temperature increased linearly with impervious surface cover and decreased linearly with tree canopy cover, with canopy volume reducing the temperature by 1° F for every 500 cubic feet of canopy volume for evening temperatures. The magnitude of the effect of tree canopy increased with spatial scale, with 60 and 90 m scales having the greatest measurable effect. Canopy volume had a positive relationship on presumed nighttime and early-morning temperatures at 60 and 90 m scales, potentially due to the impacts of wind fluctuation and air roughness. Canopy cover still contributed the largest overall decrease in street-scale temperatures. Increasing tree canopy cover and volume effectively explained the lower daytime and evening temperatures, while reducing impervious surface cover remains critical for reducing morning and presumed nighttime urban heat. The results may inform strategies for urban foresters and planners in managing urban land cover and tree planting patterns to build increased resiliency towards moderating urban temperature under warming climate conditions.