Urban Forest Research Articles

Climate change and urban forests: generational differences in women’s perceptions and willingness to participate in conservation efforts

Climate change and urban forests: generational differences in women’s perceptions and willingness to participate in conservation efforts

A new approach for quantification of total above-ground heartwood and sapwood volume of trees

Key messageTerrestrial laser scanning data of trees combined with models of heartwood content proportion of woody disks can provideprecise characterization of total aboveground tree sapwood and heartwood volume.Quantifying sapwood and heartwood content of trees is challenging. Previous studies have primarily characterized main stem wood composition, while branches have rarely been studied. Terrestrial Laser Scanning (TLS) can provide precise representations of the entire above-ground tree structure, non-destructively, to help estimate total tree sapwood and heartwood volume. In this study, we used TLS to scan above-ground portions of twenty-four open-grown, urban Gleditsia triacanthos trees on Michigan State University campus. TLS data were used to generate quantitative structure models that provided comprehensive characterizations of the total tree woody surface area (WSA) and volume. A subsample of trees was harvested (after scanning) and main stem and branch woody disks were collected to build models of heartwood content proportion. Models were applied to measurements from TLS to quantify complete heartwood and sapwood volume of each tree, including main stem and branches. From the base to the top of the trees, the largest portion of stem vertical cumulative volume was heartwood, whereas vertical cumulative volume of branches showed the opposite pattern. Absolute heartwood volume declined monotonically toward zero from stem base to stem top, while absolute sapwood volume declined sharply from stem base up to near the crown base and then remained relatively constant within crown. We also found that tree WSA increased with sapwood volume for both branches and main stem. This study developed a novel, general method for quantifying total aboveground sapwood and heartwood volume of trees and provided new insights into urban tree growth and structure.

There Goes the Neighbourhood-A Multi-City Study Reveals Ticks and Tick-Borne Pathogens Commonly Occupy Urban Green Spaces.

Humans acquire tick-borne pathogens (TBPs) from infected ticks contacted during outdoor activities. Outdoor activity is at its highest in urban green spaces, where the presence of tick populations has increasingly been observed. Consequently, more insight into factors influencing the presence of ticks therein is needed. Here, we assess the occurrence of ticks and several TBPs in urban green spaces in Finland, estimate related human hazard and assess how landscape features influence tick and TBP occurrence therein. Ticks collected from five cities during 2019-2020 were utilised. Borrelia, Rickettsia, Neoehrlichia mikurensis, Anaplasma phagocytophilum, Babesia and TBEV were screened from ticks using qPCR. Various landscape features were calculated and utilised in generalised linear mixed models to assess their contribution towards tick and TBP occurrence in green spaces. Finally, human population density proximate to each study site was calculated and used to create population-weighted risk indices. Borrelia were the most common pathogens detected, with 22% of nymphs and 43% of adults infected. Increasing forest cover had a positive effect on the densities of nymphs and adults, whereas forest size had a negative effect. Middling percentages of artificial surfaces predicted higher nymph densities than low or high values. Human population-weighted risk estimates were highly varied, even within cities. A positive correlation was observed between total city population and risk indices. Ticks and TBPs are commonplace in urban green spaces in Finland. Enzootic cycles for Borrelia and Rickettsia appear to be well maintained within cities, leading to widespread risk of infection therein. Our results suggest that nymph densities are highest in urban forests of medium size, whereas small or large forests show reduced densities. Green spaces of roughly similar risk can be found in cities of different sizes, emphasising that the identification of areas of particularly high hazard is important for effective mitigation actions.

STINGLEES BEES AND URBAN SPACES: AN INVESTIGATION OF THE CONDITIONS FOR ADAPTATION TO CITY BUILDINGS AND LANDSCAPING

Stingless native bees are essential for the preservation of ecosystems as they contribute to the maintenance of biodiversity and the stability of forest fragments. Information on how these species behave in urban environments is still scarce in Brazil. For this reason, the aim of this study was to investigate the occurrence of stingless bees in the urban area of the city of Realeza (PR) through the localization of nests and active and passive capture methods. Sampling was conducted between October and December 2022, a period of peak nectar-producing species flowering in the region. The searches were carried out in five sectors, covering both public and private areas, and aspects of the landscape such as floral species, physical characteristics of buildings, and nesting substrates were recorded. During the survey, 23 nests of Tetragonisca angustula and Scaptotrigona depilis were recorded, and foraging activities of Scaptotrigona bipunctata and Plebeia spp. were also detected. The urban forest fragments of Realeza face challenges for stingless bees due to urbanization and exotic vegetation. Tetragonisca angustula adapts to artificial substrates, while Scaptotrigona depilis depends on natural cavities. Wooden houses favor nesting, and strategies such as artificial shelters, native plants, and sustainable cultural practices are essential for conserving pollinators and ecosystem services.

Protecting trees in the urban forest: a systematic review of literature on acts, bylaws, ordinances, and regulations

Trees contribute to the livability of cities. To preserve the urban forest, many governments have turned to regulatory mechanisms, ranging from local bylaws and ordinances to state and federal legislation. To understand the history, scope, perspectives, successes, and challenges of disincentive-based tree protection legislation, a systematic review was conducted using PubMD, EBSCOHost, Web of Science, and Scopus. The review, which was not geographically constrained but contained only English-language articles, included 114 publications. The literature highlights that the history of urban forest legislation is long. However, tree protection regulations were popularized more recently, built on years of more general environmental policies. While the adoption processes for tree protection legislation vary across both cities and countries, it is often driven by appreciation of urban forests and led by municipalities with the support of the public and non-governmental organizations. Tree protection legislation defines what trees are to be protected, typically based on size, species, or land use, although cultural or heritage trees are often protected as well. Some tree protection legislation includes replanting clauses and enforcement procedures to increase their effectiveness. The protection of large, culturally important trees and replanting requirements are largely supported by both the public and urban foresters, although support is greater in urban areas. However, whether the legislation actually works is unclear. Conflicting evidence and study limitations preclude direct causal relationships, although areas where tree protection legislation was removed experienced subsequent tree loss. On-going challenges at the local level include underenforcement, conflicting legislation, and underfunded programs. Tree protection legislation is also vulnerable to socio-political changes that prioritize private property rights and development over private tree protection. Amidst widespread urban tree loss, further research that provides a better understanding of the successes of tree protection legislation will help justify their continued use in urban forestry programs globally.

Automated Tree Detection Using Image Processing and Multisource Data

This paper presents a method for the automatic detection and assessment of trees and tree-covered areas in Katowice, the capital of the Upper Silesian Industrial Region in southern Poland. The proposed approach utilizes satellite imagery and height maps, employing image-processing techniques and integrating data from various sources. We developed a data pipeline for gathering and pre-processing information, including vegetation data and numerical land-cover models, which were used to derive a new method for tree detection. Our findings confirm that automatic tree detection can significantly enhance the efficiency of urban tree management processes, contributing to the creation of greener and more resident-friendly cities.

Artificial Light at Night (ALAN) as an Emerging Urban Stressor for Tree Phenology and Physiology: A Review

Artificial light at night (ALAN) is an expanding environmental issue, particularly in urban areas. This review aimed to present the state of the art regarding the impact of ALAN on specific and interrelated aspects related to physiological processes and life cycle events in tree species. The reviewed studies highlighted the multifaceted effects of artificial light on plants, offering insights and perspectives to guide future research in this evolving and stimulating field. ALAN disrupts circadian rhythms, alters photoperiodic responses, and affects photosynthesis and carbohydrate metabolism. Changes in phenology such as delayed senescence and altered budburst timing demonstrated species-specific responses, often compounded by other urban stressors like heat and drought. Despite an increased interest, knowledge gaps remain concerning the species-specific responses and the effects of light spectra as well as the long-term consequences on tree physiology. These gaps highlight the need for integrated research approaches and urban planning strategies to mitigate ALAN effects, ensuring the resilience of urban trees and preserving ecosystem services in the context of growing urbanization and climate change.

The impact of air pollution control measures and the COVID-19 pandemic on photosynthesis in urban trees

Phytotoxic air pollutants such as atmospheric nitrogen dioxide (NO2) are among the major stresses affecting tree photosynthesis in urban areas. We clarified the relationship between NO2 concentrations and photosynthetic function for three major urban trees, Prunus × yedoensis, Rhododendron pulchrum, and Ginkgo biloba, planted in Kyoto and surrounding cities, combining our published data and new data collected from 2020 to 2023. High NO2 increased long-term water use efficiency for all species. High NO2 decreased photosynthesis in P. yedoensis and R. pulchrum, while for G. biloba, NO2 imposed little effect on photosynthesis. We then focused on the decrease in NO2 due to (1) air pollution control measures from 2005 to 2023 and (2) the economic recession caused by the COVID-19 pandemic, and examined whether these factors improved photosynthesis in urban trees. The historic decrease in NO2 improved leaf photosynthesis for P. yedoensis and R. pulchrum, while the COVID-19 pandemic reduced NO2 by only 0.3 ppb and did not further improve photosynthesis in these tree species. This report shows that air pollution control measures improved photosynthesis in urban trees over several years in Japan, and is valuable because it demonstrates that air pollution control measures can increase CO2 uptake by urban trees.

Optimizing Thermal Comfort in Urban Squares of Hot-Humid Regions: A Case Study Considering Tree Growth, Species, and Planting Intervals

The worsening urban thermal environment has become a critical challenge in many cities. Trees, as vital components of urban green spaces, provide multiple ecosystem services, especially in improving the microclimate. However, limited studies address how morphological changes during tree growth influence their cooling benefits. This study combined the tree growth model with ENVI-met to simulate 27 scenarios in a subtropical urban square, considering three planting intervals, three urban tree species, and three growth stages to evaluate their daytime thermal impacts. The key findings include: (1) Tree size and planting intervals are more important than tree quantity in enhancing thermal comfort. (2) Reducing intervals by 2 m enhances cooling effects but minimally affects PET (physiological equivalent temperature). (3) Increasing DBH (diameter at breast height) significantly improves cooling. For every 10 cm increase in DBH, Michelia alba, Mangifera indica, and Ficus microcarpa L. f. reduced solar radiation by 19.54, 18.09, and 34.50 W/m2, and mean radiant temperature by 0.61 °C, 0.68 °C, and 1.35 °C, respectively, while decreasing PET by 0.23 °C, 0.23 °C, and 0.46 °C. These findings provide empirical evidence and practical recommendations for designing comfortable open spaces in subtropical cities.

Impact of urban trees on carbon dioxide exchange: Mechanistic pathways, environmental controls, and feedback.

The increase of carbon dioxide (CO2) concentration in the atmosphere is held responsible for global climate changes. To meet the objective of achieving carbon neutrality and keeping global warming in check, many cities, as hotspots of CO2 emissions, have been promoting the use of urban greenery, urban trees in particular, to mitigate carbon emissions from the built environment. However, there remain large uncertainty and divergence of the potential of urban trees for carbon mitigation, with the underlying mechanisms poorly understood. In this study, we conducted a comprehensive survey of the biophysical functions, their environmental controls, and possible heat-carbon-water feedback that mechanistically govern the CO2 exchange processes of trees in the built environment. This review helps to clarify some disparities and enables us to gain clearer insights into the participatory role of urban trees in the dynamics of CO2 exchange. In addition, we proposed a few guidelines for urban planning and management strategies of using trees to promote the sustainability of urban ecosystems.

How perception of environmental and social justice drive citizen's satisfaction and intention to engage with urban forests management?

The equitable distribution of urban forests in cities and the inclusive consideration of all citizens' voices, regardless of their socioeconomic differences, are prime examples of social and environmental justice in urban areas. The citizens' perception of social and environmental justice can influence their satisfaction with urban forests and this satisfaction can, in turn, affect their intention to participate in the urban forests management. This study aimed to investigate the role of perceived environmental and social justices on citizens' satisfaction with urban forests and the impact of this satisfaction on their behavioral intention to engage in the urban forests management. A survey of 453 citizens was conducted to collect the data. Structural equation modeling was used to analyze the data. The results showed that the two variables of perceived environmental and social justice significantly influence citizens' satisfaction with urban forests, explaining 71% of the variance in citizens' satisfaction. Furthermore, citizens' satisfaction, influenced by these two factors, had a positive and significant effect on their behavioral intention to participate in the management of urban forests, explaining 50% of the behavioral intention. The findings highlight the importance of environmental and social justice in the distribution and management of urban forests. Attention to the equitable distribution and the inclusive consideration of all stakeholders in the management of these forests can facilitate citizens' engagement in the of urban forests management.

Actor and power analysis in urban forests and green spaces management. Insights from the Garden City of West Africa

Actor and power analysis in urban forests and green spaces management. Insights from the Garden City of West Africa

Life Cycle Analysis and species-specific net CO2 assimilation model to assess when a new urban forest becomes a carbon sink in a Mediterranean city

Life Cycle Analysis and species-specific net CO2 assimilation model to assess when a new urban forest becomes a carbon sink in a Mediterranean city

Coexistence of multiple leaf nutrient resorption strategies in urban forests

Coexistence of multiple leaf nutrient resorption strategies in urban forests

Invasive pests and pathogens as potential drivers of urban forest distributional inequalities and inequities

Invasive pests and pathogens as potential drivers of urban forest distributional inequalities and inequities

Legacies of past housing discrimination in the present-day urban forest of a moderate-sized US city

Legacies of past housing discrimination in the present-day urban forest of a moderate-sized US city

Collaborative approaches to urban tree biosecurity: Stakeholder’s perceptions, actions and social networks

Collaborative approaches to urban tree biosecurity: Stakeholder’s perceptions, actions and social networks

Visual Evaluation of Tree Health in Belgrade’s Urban Forest: Čukarica Case Study

A visual assessment of tree conditions is essential for public safety and health because urban trees increase attractiveness and provide other benefits, including reducing global warming and air filtration. Unhealthy or damaged trees pose a concern, emphasizing the importance of comprehensive inspections to identify hazards such as decay or dead branches. The assessment of the trees within the green infrastructure of the brownfield in Belgrade, Serbia, indicated that 35.1% of the examined trees failed to satisfy the basic preservation standards, emphasizing the necessity for proactive strategies for management.

Detecting and measuring fine-scale urban tree canopy loss with deep learning and remote sensing

Detecting and measuring fine-scale urban tree canopy loss with deep learning and remote sensing

Comparison of Canadian urban forest perceptions indicates variations in beliefs and trust across geographic settings

ABSTRACT Urban forests are characterized by relationships between people and trees, where urban trees provide benefits to people and people make decisions impacting trees. People’s perceptions of urban forests are related to the cognitive processes that underpin benefits received from trees, while also influencing support for or against trees and their management. A growing literature has considered urban forest perceptions, but most studies are limited to a single geographic area and focus on socio-economic influences, with less consideration of location and cultural influences. This study explores the relationship between where people live, the language they speak, and multiple perception responses associated with urban forests (i.e. values, beliefs, trust, satisfaction) to better understand commonalities and differences across distinct geographic settings and populations. We conducted an online survey about urban forest perceptions in three Canadian urban regions, allowing us to explore perceptions between regions, locations on an urban gradient and language spoken. We found geographic and language differences primary for beliefs held about urban trees and trust in municipal government’s decision-making about those trees, while values and satisfaction with trees and their management were more stable across geographic settings and language spoken. Our findings suggest that some perceptions vary between populations. Additionally, our findings reinforce the need for urban forest managers to understand the specific perceptions held by different populations, rather than assume universality of perception, to ensure specific and differential urban forest management objectives are in place to supports local people and ecological elements.