Explore the vast range of titles available.

The context in which trees and forests grow in cities is highly variable and influences the provision of ecological, social, and economic benefits. Understanding the spatial extent, structure, and composition of forests is necessary to guide urban forest policy and management, yet current forest assessment methodologies vary widely in scale, sampling intensity, and focus. Current definitions of the urban forest include all trees growing in the urban environment, and have been translated to the design of urban forest assessments. However, such broad assessments may aggregate types of urban forest that differ significantly in usage and management needs. For example, street trees occur in highly developed environments, and are planted and cared for on an individual basis, whereas forested natural areas often occur in parkland, are managed at the stand level, and are primarily sustained by natural processes such as regeneration. We use multiple datasets for New York City to compare the outcomes from assessments of the entire urban forest, street trees, and forested natural areas. We find that non-stratified assessments of the entire urban forest are biased towards abundant canopy types in cities (e.g. street trees) and underestimate the condition of forested natural areas due to their uneven spatial arrangement. These natural areas account for one quarter of the city's tree canopy, but represent the majority of trees both numerically and in terms of biomass. Non-stratified assessments of urban forest canopy must be modified to accurately represent the true composition of different urban forest types to inform effective policy and management.

Urban flooding is a widespread and impactful natural hazard, presenting considerable challenges to urban areas. Integrating peri-urban forests (PUFs) into flood management strategies has emerged as a promising approach to mitigate flood hazards. Citizen engagement in PUF management can enhance flood risk reduction efforts. A notable research gap exists in understanding the factors influencing citizens’ intentions to participate in PUF management for flood mitigation. To address this gap, this study investigates the determinants shaping citizens’ intention to engage in PUF management efforts. Using an extended Theory of Planned Behavior framework—which incorporates environmental awareness and risk perception—this research surveyed visitors to PUFs in Tehran. Structural equation modeling with SmartPLS was applied to examine the relationships among these variables. The findings reveal that attitudes, subjective norms, perceived behavioral control, and environmental awareness significantly influence citizens’ intentions. In contrast, perceived risk had no significant effect. This study highlights the importance of fostering positive attitudes toward PUF management, creating a supportive social environment, empowering individuals with knowledge and resources, and emphasizing environmental awareness in flood hazard reduction. The results provide empirical evidence supporting the inclusion of environmental awareness as a key determinant in an extended behavioral model. Enhancing citizens’ understanding of the immediate benefits of PUFs is crucial for promoting active participation in flood mitigation initiatives.

Street trees are public resources planted in a municipality’s right-of-way and are a considerable component of urban forests throughout the world. Street trees provide numerous benefits to people. However, many metropolitan areas have a poor understanding of the value of street trees to wildlife, which presents a gap in our knowledge of conservation in urban ecosystems. Greater Los Angeles (LA) is a global city harboring one of the most diverse and extensive urban forests on the planet. The vast majority of the urban forest is nonnative in geographic origin, planted throughout LA following the influx of irrigated water in the early 1900s. In addition to its extensive urban forest, LA is home to a high diversity of birds, which utilize the metropolis throughout the annual cycle. The cover of the urban forest, and likely street trees, varies dramatically across a socioeconomic gradient. However, it is unknown how this variability influences avian communities. To understand the importance of street trees to urban avifauna, we documented foraging behavior by birds on native and nonnative street trees across a socioeconomic gradient throughout LA. Affluent communities harbored a unique composition of street trees, including denser and larger trees than lower-income communities, which in turn, attracted nearly five times the density of feeding birds. Foraging birds strongly preferred two native street-tree species as feeding substrates, the coast live oak (Quercus agrifolia) and the California sycamore (Platanus racemosa), and a handful of nonnative tree species, including the Chinese elm (Ulmus parvifolia), the carrotwood (Cupaniopsis anacardioides), and the southern live oak (Quercus virginiana), in greater proportion than their availability throughout the cityscape (two to three times their availability). Eighty-three percent of street-tree species (n = 108, total) were used in a lower proportion than their availability by feeding birds, and nearly all were nonnative in origin. Our findings highlight the positive influence of street trees on urban avifauna. In particular, our results suggest that improved street-tree management in lower-income communities would likely positively benefit birds. Further, our study provides support for the high value of native street-tree species and select nonnative species as important habitat for feeding birds.

The tree population within the City of Syracuse was assessed using a random sampling of plots in 1999, 2001 and 2009 to determine how the population and the ecosystem services these trees provide have changed over time. Ecosystem services and values for carbon sequestration, air pollution removal and changes in building energy use were derived using the i-Tree Eco model. In addition, photo interpretation of aerial images was used to determine changes in tree cover between the mid-1990s and 2009. Between the mid-1990s and 2003, tree cover in Syracuse exhibited a decline from 27.5 to 25.9 %, but subsequently increased to 26.9 % by 2009. The total tree population exhibited a similar pattern, dropping from 881,000 trees in 1999 to 862,000 in 2001, and then increasing to 1,087,000 trees in 2009. Most of this increase in the urban tree population is due to invasive or pioneer trees species, particularly Rhamnus cathartica , which has more than tripled in population between 2001 and 2009. Insects such as gypsy moth and emerald ash borer pose a substantial risk to altering future urban forest composition. The annual ecosystem services provided by the urban forest in relation to carbon sequestration, air pollution removal and reduction in building energy use are estimated at about $2.4 million per year. An improved understanding of urban forests and how they are changing can facilitate better management plans to sustain ecosystem services and desired forest structure for future generations.

Cities are increasingly focused on expanding tree canopy cover as a means to improve the urban environment by, for example, reducing heat island effects, promoting better air quality, and protecting local habitat. The majority of efforts to expand canopy cover focus on planting street trees or on planting native tree species and removing nonnatives in natural areas through reforestation. Yet many urban canopy assessments conducted at the city-scale reveal co-dominance by nonnative trees, fueling debates about the value of urban forests and native-specific management targets. In contrast, assessments within cities at site or park scales find that some urban forest stands harbor predominantly native biodiversity. To resolve this apparent dichotomy in findings, about the extent to which urban forests are native dominated, between the city-scale canopy and site-level assessments, we measure forest structure and composition in 1,124 plots across 53 parks in New York City’s 2,497 ha of natural area forest. That is, we assess urban forests at the city-scale and deliberately omit sampling trees existing outside of forest stands but which are enumerated in citywide canopy assessments. We find that on average forest stand canopy is comprised of 82% native species in New York City forests, suggesting that conclusions that the urban canopy is co-dominated by nonnatives likely results from predominantly sampling street trees in prior city-scale assessments. However, native tree species’ proportion declines to 75% and 53% in the midstory and understory, respectively, suggesting potential threats to the future native dominance of urban forest canopies. Furthermore, we find that out of 57 unique forest types in New York City, the majority of stands (81%) are a native type. We find that stand structure in urban forest stands is more similar to rural forests in New York State than to stand structure reported for prior assessments of the urban canopy at the city scale. Our results suggest the need to measure urban forest stands apart from the entire urban canopy. Doing so will ensure that city-scale assessments return data that align with conservation policy and management strategies that focus on maintaining and growing native urban forests rather than individual trees.

Aesthetic experience in a forest can typically be associated with attractive forest scenery that gives people a sense of visual pleasure. Characterized as a visual product based on people’s reactions towards various combinations of landscape settings, features, and objects, this type of natural visual pleasure may benefit people’s well-being, promotes natural and cultural heritage preservation, and encourages the growth of the eco-tourism industry. While most research on forest aesthetics focuses on non-urban settings, this study examines aesthetics in the context of urban forests. This study aims to systematically review landscape aesthetic assessment studies to propose a model for urban forests. We conducted a systematic review of research articles published from 2014 to 2020 by using three research journal databases, Science Direct, Scopus, and MDPI. In total, 55 research articles were identified and qualified for review based on the screening requirements. An additional 26 research articles were also included by using the snowball method to provide better understanding and outcomes for the study. The results were organized into these categories: definitions, benefits, philosophies, approaches, and variables for the aesthetic quality assessment in urban forest areas. In addition, we also found that aesthetic quality in urban forests is highly influenced by visual composition, visual sense, and visual conditions, which have also been proven to be important parts of forest functions and values that could contribute towards the preservation of urban green spaces.

Increasing recognition of the importance of urban forest ecosystem services calls for the sustainable management of urban forests, which requires timely and accurate information on the status, trends and interactions between socioeconomic and ecological processes pertaining to urban forests. In this regard, remote sensing, especially with its recent advances in sensors and data processing methods, has emerged as a premier and useful observational and analytical tool. This study summarises recent remote sensing applications in urban forestry from the perspective of three distinctive themes: multi-source, multi-temporal and multi-scale inputs. It reviews how different sources of remotely sensed data offer a fast, replicable and scalable way to quantify urban forest dynamics at varying spatiotemporal scales on a case-by-case basis. Combined optical imagery and LiDAR data results as the most promising among multi-source inputs; in addition, future efforts should focus on enhancing data processing efficiency. For long-term multi-temporal inputs, in the event satellite imagery is the only available data source, future work should improve haze-/cloud-removal techniques for enhancing image quality. Current attention given to multi-scale inputs remains limited; hence, future studies should be more aware of scale effects and cautiously draw conclusions.

ContextTree canopy connectivity is important for supporting biodiversity. In urban landscapes, empirical examinations of habitat connectivity often overlook residential land, though yards and gardens often comprise a large portion of urban forests.ObjectivesWe quantify structural composition (patches and paths), connectivity and fragmentation of an entire tree canopy network spanning 1220 Boston’s neighborhoods to assess the configuration of the urban forest potentially affecting tree-dependent wildlife species, such as some birds and arboreal mammals.MethodsThe urban landscape was classified by land use, and residential yards were further subdivided into front yards, backyards, and corner yards. Structural composition, connectivity and fragmentation of the tree canopy was assessed using morphological spatial pattern and network analysis. Canopy metrics were then related to the land use of 349,305 property parcels.ResultsBack yard tree canopy cover was 65.23%. The majority of canopy links were on residential land (60.95% total), and particularly in backyards. Back yards contained the highest number of canopy fragments (48.65% total). Fragmentation of the canopy network peaked at ~ 23% of total canopy cover. Canopy fragmentation, distance among patches and their shape complexity were lower in neighborhoods with more tree canopy.ConclusionsThe important role that yards have in sustaining canopy connectivity across urban landscapes poses challenges and opportunities. Urban land management and planning need to protect connectivity links within urban forests when located on private residential realm. A prioritization strategy aimed at expanding urban tree cover could focus on yards to ensure that urban landscape connectivity is maintained and increased.

Understanding the biomass, characteristics, and carbon sequestration of urban forests is crucial for maintaining and improving the quality of life and ensuring sustainable urban planning. Approaches to urban forest management have been incorporated into interdisciplinary, multifunctional, and technical efforts. In this review, we evaluate recent developments in urban forest research methods, compare the accuracy and efficiency of different methods, and identify emerging themes in urban forest assessment. This review focuses on urban forest biomass estimation and individual tree feature detection, showing that the rapid development of remote sensing technology and applications in recent years has greatly benefited the study of forest dynamics. Included in the review are light detection and ranging-based techniques for estimating urban forest biomass, deep learning algorithms that can extract tree crowns and identify tree species, methods for measuring large canopies using unmanned aerial vehicles to estimate forest structure, and approaches for capturing street tree information using street view images. Conventional methods based on field measurements are highly beneficial for accurately recording species-specific characteristics. There is an urgent need to combine multi-scale and spatiotemporal methods to improve urban forest detection at different scales.