ABSTRACT The integration of urban dwellings and the forest proposed by Alvar Aalto is regaining attention, especially in relation to unbridled global urbanization and its impacts on the socio-ecological environment. Aalto’s approach fosters a deeper connection with nature in everyday life and is credited with significant physiological and psychological benefits for residents. Various scholarly works have explored Aalto’s forest-inspired methods in architecture and design, but there has been a distinct lack of research on the quantitative spatial integration of dwellings and forests within his planning concepts. This study aims to bridge that gap through a detailed four-level spatial analysis of how dwellings are integrated with forests in Aalto’s General Town Plan of Imatra (1947-53), a key project from his mature period. Based on the findings, the plan has a significant level of spatial integration, characterized by factors such as mixing degree, adjacency, proximity, and accessibility between residential areas and surrounding forests. These outcomes illuminate Aalto’s consistent application of his forest-centric philosophy across different design fields. The lessons learned from Aalto can inspire new urban development patterns that favour residents’ access to and interaction with urban forests, ultimately enhancing residents’ connection to the natural environment.

Mediterranean cities are home to more than 10% of the global population and more than 1298 urban tree species. These regions are highly vulnerable to climate change and are facing extreme climatic events such as droughts, heat waves, and flash floods. Urban trees play a key role in mitigating and reducing the effects of these events; however, it remains poorly understood how urban trees might cope with them. This review synthesizes the existing literature evaluating the effects of climatic and weather-related extremes on urban trees in Mediterranean cities. We screened more than 3000 studies, yet only 13 met the criteria of this review. Among the analyzed studies, most focused on drought and heat waves, with only one addressing the effects of extreme wind on tree mortality. Most studies employed remote sensing data and analytical methods, while a smaller number used experimental, field-based, or dendrochronological approaches. Since ten studies addressed droughts, the Standardized Precipitation–Evapotranspiration Index (SPEI) was calculated to contextualize and compare drought characteristics and outcomes across the analyzed cases. Our synthesis reveals that climatic extremes consistently impaired urban tree functioning across multiple scales and methods: remote sensing analyses detected declines in canopy greenness and cover, field-based studies documented reductions in leaf area and photosynthesis and simulation approaches highlighted the loss of evaporative cooling in irrigated trees under water restriction. Overall, the results reveal a significant and concerning research gap in understanding how climatic extremes might influence tree physiology, growth, and adaptive capacity within Mediterranean regions and urban environments. Advancing the knowledge of species and single tree level response to climatic extreme events is crucial for resilient urban forest management, particularly to inform sustainable tree species lists and help predict tree damage and failure, as well as sustain their provision of ecosystem services. • Out of 3,000+ screened studies, only 13 investigate the impact of extreme climatic events on urban Mediterranean trees, while 34 adopt an anthropocentric focus, examining trees through the lens of human exposure, risk, and benefit. • Climatic extremes reduce canopy cover, greenness, leaf area, photosynthesis, tree growth, and evaporative cooling. • Studies focus most on drought as a climatic extreme, using a wide variety of characterization indexes. • Remote sensing dominates the field, which is why most evidence reflects community-level responses rather than species or individual trees, which are crucial for practical applications that enhance the resilience of urban forests.

Recent research revealed that city dwelling coyotes select den sites regardless of proximity to human development and showed that attacks were most frequent near dens and in the denning months. Denning in human-dominated landscapes likely favors human and coyote encounters during pup rearing, yet den site selection can vary across urban contexts with different green-space configurations. Here, we used resource selection functions to analyze den site selection in suburban areas of the Chicago Metropolitan Area and investigate whether similar selection patterns are exhibited by the species when urban forests are comparatively abundant. Our conditional regression functions compared used and available den sites and revealed a marked preference for forested sites and avoidance of developed ones. Our results did not support any effect of wetlands, open natural land cover or agriculture on den site selection. Selection patterns for forests were exhibited at the local (30 meters around den site) and patch scale (200 meters around den site), but patch scale models had better performance at predicting den site use indicating that selection likely happens at a wider scale. These results indicate that coyotes preferentially den in forested patches and avoid developed areas in cities where sufficient forest cover exists, suggesting that urban forests may reduce human-coyote conflict in cities. Whether these patterns causally translate into differences in conflict rates will require linking den distributions with human activity and conflict report data across a gradient of forest cover in anthropogenic landscapes.

Urban trees provide important ecosystem services (ESS), but their contributions are often undervalued and less acknowledged due to the complexity of quantifying them. Therefore, ESS assessment for urban trees at the individual tree level using ESS models is crucial for a more knowledge-based management of urban green spaces. In this study, we used very high-resolution aerial and satellite-based remote sensing imagery to derive the geospatial input for the CityTree model to estimate regulating ESS from over 160,000 individual trees in Munich, Germany. Our assessment includes both, trees on public and private land and enables fine-scale spatial modeling of eight ESS (carbon storage, carbon sequestration, CO 2 sequestration, evapotranspiration of trees, runoff under the tree, transpiration, cooling by transpiration and shading). We found that public trees, especially those in recreational areas such as parks and woodlands, contribute largely to ESS provision. Private trees also play a meaningful role by contributing around one third of the total ESS. A statistical comparison with the tree inventory data revealed good agreement between the two datasets. However, we also found systematic measurement differences, possibly due to rounding in field measurements and limitations in remote sensing datasets. However, the size effect of these differences is small in practical terms, indicating that both data sources are comparable and complementary. Our findings support the use of remote sensing as a scalable, area-wide, consistent, and resource-efficient approach for urban ESS estimations.

Urban trees are widely recognized as effective nature-based solutions for urban heat mitigation, yet current design strategies focus predominantly on optimizing summer cooling, leaving their potential for winter thermal regulation understudied. This oversight raises a question: Do tree configurations optimized for summer cooling remain thermally beneficial in winter? To address this issue, this study conducted a parametric study using ENVI-met to evaluate the seasonal thermal performance of urban trees in subtropical coastal city Hong Kong under extreme summer and winter conditions. Multi-scenario simulations were run, incorporating eight urban canyons characterized by discrete sky view factors (SVF=0.1–0.8) from typical morphological categories in previous research, two street orientations (N-S, E-W), and two tree species (evergreen Ficus microcarpa , deciduous Lagerstroemia speciose ). Results indicate that both evergreen and deciduous trees provided comparable cooling in summer, with mean differences of 0.21 °C in PET and 0.35 °C in UTCI. A consistent peak cooling of up to 8 °C in PET and 5 °C in UTCI was observed at SVF = 0.7 for both species. In winter, evergreen trees improved comfort by wind shielding in deep, low-SVF canyons (up to 1 °C in PET; 6 °C in UTCI), while deciduous trees enhanced comfort through solar access in shallow, high-SVF canyons (over 0.3 °C PET; 1 °C in UTCI). For subtropical coastal context, our findings suggest that tree selection and placement should be seasonally adaptive. This study provides a methodological framework and preliminary insights for climate-adaptive planting strategies in urban canyons from a year-round perspective.

Urban forest carbon storage and sequestration on the Qinghai-Tibetan plateau: Machine learning analysis and management implications for Xining, China

Intelligent classification of dominant tree species in urban forests based on UAV hyperspectral remote sensing images

Urbanization alters riverine fluorescent dissolved organic matter characteristics in a forested city - metropolitan Atlanta, Georgia (USA).

As cities continue to densify, opportunities to introduce green areas decrease. Small urban green spaces, such as pocket parks, often represent the only remaining non-built-up areas within compact urban fabrics. Through shading, evapotranspiration, and the enhancement of air circulation, these spaces can provide microclimatic benefits; yet the cooling capacity of pocket parks and the role of their internal forest structure remain insufficiently explored. This study quantifies the association between forest structure, configuration, and species composition of urban pocket parks and morning cooling performance during a heat wave in the city of Barcelona, Spain. Moving beyond the conventional emphasis on tree canopy cover alone, the role of vertical structure of 627 urban trees was investigated. Five cooling indices—Park Cooling Distance (PCD), Park Cooling Area (PCA), Park Cooling Efficiency (PCE), Park Cooling Intensity (PCI), and Park Cooling Gradient (PCG)—were used to evaluate 18 pocket parks in densely built-up areas of the city. Statistical analyses assessed relationships between internal park characteristics and cooling performance, identifying the structural configurations with the strongest association. Results showed an average PCD of 55.8 m, PCA of 1.44 ha, PCE of 7.9, PCI of 1.2 °C, and PCG of 0.02 °C∙m⁻¹ in the studied pocket parks. Tree height, tree density, percentage of tree cover, and vertical structural variability were significantly correlated with PCE, PCI, and PCG, whereas no significant relationships were observed with PCD. The pocket parks exhibiting the strongest cooling performance association shared distinct structural characteristics, i.e., dense (>150 trees∙ha -1 ), predominantly monospecific trees concentrated in the upper canopy layer (>8.6 m) and were characterized by high canopy cover (>86%). These findings reveal that internal tree structure correlates to pocket park cooling performance. Design and management-oriented actions, focused on forest structure, may significantly enhance urban cooling and thermal comfort, contributing to climate adaptation strategies in compact urban environments. • High-performing pocket parks combine dense plantings, wide crowns, and continuous canopy • PPs are associated with a measurable differences in morning LST patterns • Smaller green spaces show higher cooling efficiency per unit area than larger parks • Tree height, density, and canopy cover are consistently related with cooling indices • High canopy cover in upper tree layers and low crown ratios are related to cooling • Design benchmarks suggest ≥150 trees/ha and canopy heights above 8.6 m

The City of Toronto (Ontario) is Canada’s largest urban area in population and areal extent. As a result, elevated activity from urban, industrial, and transportation sectors has increased atmospheric carbon-12 ( 12 C) and carbon-13 ( 13 C) from fossil fuel combustion. Excess 12 C and 13 C mask natural levels of atmospheric carbon-14 ( 14 C), a phenomenon known as the Suess Effect. Consequently, measurements of atmospheric 14 C can be used to quantify anthropogenic fossil fuel contributions. With southern Ontario having an air sampler run by Environment and Climate Change Canada (ECCC) in northern Toronto, there is opportunity to expand our understanding of the atmospheric carbon inventory. Using dendrochronological methods, tree-ring 14 C measurements were obtained and compared with background 14 C levels to assess urban 14 C-depletion across Toronto via six trees representing different urban microclimates. One tree located near the ECCC air sampler closely tracked measured atmospheric 14 C levels (Spearman’s ρ=0.93). While most samples analyzed were 14 C-depleted, some years also experienced 14 C-enrichment due to elevated 14 C emissions from the Pickering Nuclear Generating Station. Trees located in urban parks recorded 14 C levels closer to background levels. In general, tree rings effectively record 14 C variations, reflecting both fossil fuel and nuclear contributions. Meteorological analysis indicates that proximity to the Pickering Nuclear Generating Station and lake-influenced air masses affects 14 C uptake, suggesting that Toronto’s atmospheric carbon inventory is spatially complex and that urban sampling sites must be evaluated individually. • Tree-ring and air sampler radiocarbon measurements track one another closely. • Most tree-ring radiocarbon measurements in the City of Toronto are depleted in radiocarbon. • Tree rings enriched in radiocarbon align with nuclear emission peaks/maintenance.

Solid biofuel production from torrefaction of urban tree pruning biomass using a combined mixture-process experimental design

Assessment of Urban Tree Effectiveness for Submicron Soot Aerosols Reduction through Combined Deposition and Resuspension Experiments.

Urban forests are strategic components of urban green space systems because they provide ecological, recreational, and educational functions that collectively support sustainable urban environmental quality. This study aims to formulate an ideal model of an urban forest concept as a sustainable educational tourism site based on empirical findings derived from visitor perceptions and the ecological conditions of the Pekanbaru Urban Forest. The research employed a simple mixed-method approach dominated by descriptive quantitative analysis involving 96 respondents, complemented by ecological observations and in-depth interviews with site managers. The results indicate that cleanliness and comfort received positive assessments (scores 4.21 and 4.12), whereas environmental education facilities (3.88), educational activities (3.45), and promotional efforts (3.22) fell within the moderate to low categories. These findings highlight a significant gap between the ecological potential of the area and the development of its educational functions. A synthesis of empirical data and theoretical insights produced six components of the ideal urban forest concept: (1) adaptive ecology, (2) environmental education facilities, (3) interpretive trails, (4) sustainable educational tourism programs, (5) inclusive accessibility, and (6) collaborative governance. Policy analysis further demonstrates that strengthening the educational function aligns with the mandates of Law No. 26/2007 on Spatial Planning, SDG 11.7 targets regarding inclusive green spaces, and the Pekanbaru Strategic Environmental Assessment (KLHS) emphasizing the enhancement of environmental quality. This study concludes that the integration of ecological planning, educational development, and collaborative governance forms the essential foundation for positioning urban forests as centers of sustainable environmental learning

Abstract Background Trees near construction sites and roads are exposed to an increased risk of stem injuries, and urban trees are also vulnerable to vandalism. Such injuries can result in large wounds, leading to reduced water and nutrient transport, taking several years to occlude, and the apparent risk of decay. Covering the wounds with plastic wrapping has been discussed over the years, but the evidence for its efficacy is not complete. During winter 2020/2021 a total of 248 trees were systematically vandalised in Malmö, Sweden. The two organisations responsible for these trees handled the injuries differently; one wrapped the stem wounds with plastic, and the other did not. This provided a rare opportunity to compare the treatment outcomes in urban field conditions. Methods We studied the effects of plastic wrapping on tree wounds by comparing data from measurements that were performed in 2021 with measurements in 2023. The study focused on 3 genera: maple ( Acer ), birch ( Betula ), and linden ( Tilia ). Results Tree wounds in both linden and maple wrapped in plastic occluded faster than unwrapped trees, but no benefit of wrapping could be seen in birch. There was an overall difference of occlusion rate between the genera, where the linden trees wrapped in plastic occluded faster than the wrapped trees of maple and birch. Conclusions Plastic-wrapping can benefit urban trees with stem wounds. However, the effect is at least genera, if not species, specific. This highlights the need for further studies of differences across different genera and species.

ABSTRACT Urbanization is a key driver of biodiversity change globally, reshaping species composition, ecosystem functions, and spatial diversity patterns. In this study, we investigated how urbanization influences the taxonomic and functional beta diversity of dung beetles in the eastern Amazon. Sampling was conducted along a preserved–rural–urban gradient using baited pitfall traps during the rainy season. We focused on three functional traits closely linked to dung beetle ecosystem functions and characterized landscape structure around each site using four land‐use and land‐cover types. Taxonomic and functional beta diversity, along with their replacement and gain/loss components, were calculated and related to urbanization effects. In total, we collected 4298 individuals from 66 species, with both richness and abundance declining from preserved to urban sites. A nested pattern in taxonomic diversity and evidence of nested functional diversity emerged along the gradient, suggesting that urbanization acts as a filtering process that progressively excludes species with unique trait combinations. Functional differences among environments were largely driven by nestedness, indicating that urban assemblages represent subsets of species from less disturbed habitats rather than functionally distinct assemblages. Additionally, the positive relationship between environmental dissimilarity and taxonomic beta diversity underscores the influence of landscape changes across the gradient on dung beetle assemblages. Our results demonstrate that urbanization reduces both taxonomic and functional beta diversity in Amazonian dung beetles, reinforcing the importance of conserving forest cover. Implementing sustainable policies, such as protecting urban forest remnants, can help preserve biodiversity and the ecosystem processes it supports within tropical cities.

Despite global concern over microplastic (MP) pollution, only a few studies have systematically evaluated the deposition and retention of atmospheric MP on urban tree foliage at the city scale, particularly in densely populated regions of South Asia. Here, the study present the first comprehensive assessment of foliar MP deposition in Lahore, Pakistan, examining the influence of leaf surface morphology and canopy height across 15 plant species at 44 locations along a major urban corridor. The leaves of the selected tree species were identified for smooth, leathery, hairy, and glossy surfaces, and the presence of trichomes (hair-like structures) was taken into account. Microplastic particle concentration on leaves varied between 0.93 n/cm2 to 9.23 n/cm2; the highest MPs were quantified on the Morus alba leaves (i.e., 9.23 n/cm2), and the lowest were noted on Lagerstroemia indica leaves (i.e., 0.93 n/cm2). Morphologically, the highest number of MPs (4.8 n/cm2) was adhered to the hairy surface leaves (n = 9), followed by smooth surface leaves (3.8 n/cm2) (n = 10), glossy surfaces (2.7 n/cm2) (n = 13), and the lowest was on the leathery surface leaves, i.e., 2.6 n/cm2 (n = 12), and were not statistically different. The spectral analysis confirmed that fibers of polyethylene terephthalate (61.25%) were the dominant polymer, followed by polyphenylene sulfide (17.67%) and aramid polymer (10.43%). An inverse relationship of MPs with the height where leaves were sampled, signifying lesser deposition above 1m. There have been other studies within cities, and other publications have noted the influence of the tree and leaf morphology. Lower heights in the canopy are closer to ground-level emissions source or they accumulate microplastic particles that leach (wash off) from the upper canopy. Among all the plant species, Morus alba (n = 5) are most suitable species having complex venation, waxy, and hairy leaf morphology that can enhance biomonitoring and potentially mitigate airborne plastic pollution in rapidly growing cities.

Forest restoration has primarily been evaluated through changes in aboveground communities, while belowground microbial communities-critical drivers of ecosystem functions-remain less understood. Moreover, studies of soil microbes have focused largely on community structure, which does not necessarily reflect the recovery of functional capacity and stability. To determine how forest restoration affects microbial community structure and function and how microbial diversity relates to ecosystem multifunctional potential and stability, we analysed soil microbial communities from 79 urban forest restoration sites across New Zealand, spanning 0-63years since initial plantings. Shotgun metagenomic sequencing was used to characterize taxonomic composition and functional potential, with diversity quantified using alpha and beta metrics. To evaluate links between diversity and ecosystem function, we assessed ecosystem multifunctional potential (EMF) which describes the ecosystem's capacity to simultaneously provide multiple functions, and we developed a novel functional insurance (FI) index grounded in ecological theory as an indicator of functional stability and resilience. To calculate FI in microbial systems from sequencing data, we quantified functional overlap by estimating over 250 million species-function correlations per sample. Contrary to our expectations, only beta diversity, not alpha diversity, was positively associated with EMF and FI, indicating that community composition and dissimilarity rather than species richness underpins microbial functional capacity and stability. EMF and FI were positively correlated, showing that high functional diversity and functional overlap can co-occur in microbial systems. In addition, archaeal turnover increased with closing forest canopies, contributing to higher EMF and FI, while bacterial turnover was only weakly associated with restoration parameters. Notably, restoration time did not play a role in shaping microbial diversity, EMF and FI. Our findings demonstrate that microbial compositional turnover, rather than increases in species richness, are critical for restoring soil ecosystem functions. Incorporating microbial functional metrics like the FI index into restoration frameworks that recognise both above and belowground dynamics could promote resilient and multifunctional urban forests.

Modelling the impacts of soil sealing and climate change on urban tree growth and cooling in public squares of Munich

Urban trees represent valuable renewable biomass sources, but traditional allometric equations inadequately capture structural variability in urban environments. Therefore, considering tree structure is crucial for accurate biomass measurement. While LiDAR-based 3D modeling can reflect tree architecture, generating reliable models from dense foliage point clouds has remained difficult. To address this challenge, we developed the Skeleton Generative Method (SkeletonGM), which reconstructs tree trunks and primary branches from mobile laser scanning data even under heavy foliation. SkeletonGM produces a clarified skeletal point cloud that is subsequently converted into 3D tree models using AdTree; aboveground woody biomass is then calculated by combining the estimated volume with species-specific wood density. To validate the proposed method, we applied SkeletonGM to 33 hinoki cypress trees in a forest stand and 25 dawn redwood trees in a park, and compared the resulting biomass estimates with values derived from allometric equations. The results showed strong agreement with the reference equations (R² = 0.95 and 0.94; mean absolute percentage error = 14.1% and 14.6%). These findings indicate that the proposed method has strong potential to improve the accuracy of biomass assessment for urban trees.

Abstract Cities are warming rapidly and urban heat is already affecting liveability, labour productivity, and human health. Nature-based solutions (NbS) such as green roofs, increased urban tree cover, and demarcating space for urban parks are identified as promising strategies to adapt to increasing urban heat. However, the NbS literature pays relatively lower attention to examining how smaller urban green spaces, such as fragmented urban greens and rooftop home gardens, contribute to hyperlocal temperature regulation. We examine whether rooftop home gardens in Bangalore, India regulate indoor temperature and provide thermal comfort. We draw on perception-based data through a household survey and in-depth interviews, and modelled scenarios data to examine heat regulation potentials of different types of rooftop home gardens. Overall, people perceive rooftop farms/gardens providing thermal comfort in the rooms directly below, with reported air-conditioner use declining after starting rooftop gardening. The modelling analysis (using 7 scenarios from no green cover to complete green cover with a 100% soil bed on the roof) shows that heat reduction benefits from rooftop gardens range from 1.5°C to 14°C, depending on foliage type and density, and extent of green cover. Given most rooftops are used for multiple purposes, a more realistic temperature reduction is of 1.5°C to 3°C (scenario with 50% roof covered in dense foliage). The findings from Bangalore provide early insights into the role of urban home gardens in regulating urban heat and have relevance for national policies on retrofitting and planning for climate-resilient and liveable homes and cities.