Trees In Urban Areas Research Articles

Urban trees left high and dry – Modelling urban trees´ water supply and evapotranspiration under drought

Abstract Long-lasting extreme weather conditions are expected to occur more frequently in the future owing to climate change, as demonstrated by the recent heat waves. In particular, the decrease in precipitation during the summer months had a significant impact on urban tree water availability. Therefore, it is imperative to develop methodologies for determining the available water supply and evaporation rates for urban trees. We mapped data from 49 urban small-leaved linden trees with varying characteristics including groundwater levels, shading situations, tree pit sizes, pavement materials, and sealing ratios. By combining these data with an adapted Penman-Monteith method to calculate evapotranspiration, we simulated the soil water storage and evapotranspiration rates of these trees during the very dry year of 2018 as an example. Model validations were performed using lysimeter and sap-flow studies on Tilia cordata trees in 2022.
During the growing season, most trees experienced water stress on > 85% of the days because of weak precipitation events that failed to refill soil water storage. In contrast, trees with additional water supply through capillary rise reached water stress approximately 45 d later. The model results suggest that many trees will require additional water supply during predicted droughts in the future, which could have significant implications for urban forestry management. This model approach can be used to test and refine future water supply management strategies, making it a useful planning tool for improving the water efficiency of trees in urban areas and blue-green infrastructure.

Camphor tree detection in urban environments using RGB-DSM data fusion

ABSTRACT Individual tree detection in urban areas using unmanned air vehicles (UAVs) RGB imagery poses challenges due to the diverse shapes and structures of urban trees and the complexity of urban forests. The digital surface model (DSM) provides elevation data, and the fusion of UAV RGB imagery with elevation data has emerged as a promising approach for tree detection. Here, we constructed a novel network structure based on the faster region-based convolutional neural network (Faster R-CNN) to detect camphor trees in urban environments using RGB-DSM data. First, an attention fusion module was proposed to effectively fuse the RGB and DSM features by leveraging their complementarity. Second, the bidirectional feature pyramid network (BiFPN) was introduced to enhance the model performance in detecting camphor tree crowns of varying sizes. The results showed that our approach could effectively detect urban camphor trees and achieved an AP of 85.7%. Notably, our approach yielded an AP of 81.3% in urban green spaces. The analysis indicated that our approach was feasible for detecting camphor trees in urban areas and demonstrated its potential to facilitate urban forestry research and applications.

Perempuan dan Kesadaran Arti Pohon: Studi Kasus Etnobotani

The issue of global warming resulting from carbon emissions of greenhouse gas is a concern for nations inthe world including Indonesia. The Indonesian government has launched several programs for mitigation, including planting trees in urban areas. In 2007, Indonesia introduced Women Planting Trees and Management, WomenPlanting Trees Movements and Food Resilience Program (GPT-PKP), and other programs. Research explored theprogram implementation in Indonesia by collecting data and analyzing women's knowledge, perceptions, awareness,and actions for planting trees and their management. Surveys were conducted for data on the meaning of treessocially, economically, and environmentally. After completion surveys, the good participants were interviewed deeply and observed to prove their genuine awareness and action for planting and maintaining trees in their daily lives. Research revealed planting trees did not provide social and economic benefits. Trees taproots damaged walls and buildings, leaves made yards dirty, and lack of appreciation for being an environmentally friendly person by planting trees. Keywords: Awareness of trees, Indonesian government program, social and economic benefits, women,

Higher tree species richness and diversity in urban areas than in forests: Implications for host availability for invasive tree pests and pathogens

Urban and forest trees provide valuable ecosystem services. However, they are increasingly threatened by invasive forest pests and pathogens. Trees in urban areas are often the first potential hosts non-native tree-feeding insects and tree pathogens (“pests”) encounter after introduction in a novel region. If the trees encountered are suitable hosts, these pests can establish and become invasive – eventually also in surrounding forests. Here, we compared tree species and genus composition between urban areas and surrounding forests and examined the implications for host availability for forest pests and potential effects on invasibility. We compiled and standardised 26 urban tree inventories, containing ∼ 500.000 individual trees. We used multivariate analyses to compare urban tree composition with forest tree composition from forests surrounding each municipality (10 km radius), derived from the Swiss National Forest Inventory. With > 1300 different tree species, species richness of urban trees was 17 times higher than species richness in surrounding forests. Linear models and multivariate analyses revealed that host availability for forest quarantine pests is significantly higher in urban areas than in forests, with large differences in host suitability for different quarantine pests between urban and forest tree assemblages. This indicates that differences in species composition in urban and forest trees can result in increased host availability, possibly facilitating the establishment of quarantine forest pests.

Incipient decay in beech (Fagus sylvatica L.) and linden (Tilia cordata Mill.): An interspecific static and dynamic material analysis

With increasing awareness of the ecological value of trees in urban areas, there is a growing need to preserve mature specimens often colonised by wood-decay fungi. Nonetheless, cases of stem collapse or uprooting of such trees under adverse weather conditions remain a significant issue requiring further investigation. Depending on the decay type and the wood structure of the host tree, different combinations of wood-decaying fungi and host species can have varying impacts on the mechanical and vibroacoustic properties of green wood. This study compares the physical and mechanical properties of green European beech (Fagus sylvatica L.) and small-leaved linden (Tilia cordata Mill.) artificially exposed to Fomes fomentarius (L.) Fr. and Kretzschmaria deusta (Hoff.) P.M.D. Martin after different exposure periods. Mass loss (ML) caused by both fungi differed according to the wood species. A statistically significant difference between the two fungal species was observed in beech wood, but not in linden. Significant differences in the modulus of rupture (MOR) and dynamic bending modulus of elasticity (MOED) were observed among the fungus-wood combinations, also depending on the exposure time. The relationships between ML and MOR varied according to the fungal species, where at the same ML values, K. deusta caused a higher MOR loss in both wood species. Strong relationships between MOED and MOR were demonstrated for all fungus-wood combinations, without significant differences related to the decay type. The MOED is a reliable parameter for predicting MOR loss even at incipient degradation stages, irrespective of the type of decay. The presented results can lead to better prediction of the impact of fungal colonization on standing trees and improve non-destructive methods used for tree stability assessment.

Risk of wind destruction to urban trees: Prediction workflow and relative importance of influencing factors

During typhoons, risk of wind destruction to trees is harder to predict for trees in urban areas than for those in plains, and the influencing factors are more intricate. This study integrated a simplified HWIND mechanistic model for trees, computational fluid dynamics simulations for airflow, and quantified tree morphology indicators to predict the risk of wind destruction to urban trees. The workflow was demonstrated using three typical streets in Guangzhou, China. The workflow was verified based on the observed damage states of case trees in the study areas after Typhoon Mangkhut. Original critical wind speed in plains (CWSP(10)) and urban regions (CWS(10)) at a height of 10 m were introduced to evaluate the wind resistance and destruction risk to urban trees. The relative influence of various factors on CWS(10) and CWSP(10) was evaluated through Relative Weight Analysis and Random Forest. For urban trees with uprooting as the primary destruction mode, wind resistance is mainly influenced by tree height and total root-soil length in terms of tree morphology indicators, while the decisive factor affecting wind destruction risk is the “built environment indicator,” defined as BEI=CWS(10)/CWSP(10).

High-resolution satellite images reveal the prevalent positive indirect impact of urbanization on urban tree canopy coverage in South America

Trees in urban areas act as carbon sinks and provide ecosystem services for residents. However, the impact of urbanization on tree coverage in South America remains poorly understood. Here, we make use of very high resolution satellite imagery to derive urban tree coverage for 882 cities in South America and developed a tree coverage impacted (TCI) coefficient to quantify the direct and indirect impacts of urbanization on urban tree canopy (UTC) coverage. The direct effect refers to the change in tree cover due to the rise in urban intensity compared to scenarios with extremely low levels of urbanization, while the indirect impact refers to the change in tree coverage resulting from human management practices and alterations in urban environments. Our study revealed the negative direct impacts and prevalent positive indirect impacts of urbanization on UTC coverage. In South America, 841 cities exhibit positive indirect impacts, while only 41 cities show negative indirect impacts. The prevalent positive indirect effects can offset approximately 48% of the direct loss of tree coverage due to increased urban intensity, with full offsets achieved in Argentinian and arid regions of South America. In addition, human activity factors play the most important role in determining the indirect effects of urbanization on UTC coverage, followed by climatic and geographic factors. These findings will help us understand the impact of urbanization on UTC coverage along the urban intensity gradient and formulate policies and strategies to promote sustainable urban development in South America.

Exploring risk factors for insect borer attack in Georgia's (USA) urban landscapes.

Urban trees are at risk of stress due to heat island effects and the increased proportion of impervious areas surrounding them. Among pests of trees, insect borers such as bark beetles (Coleoptera: Curculionidae) and flatheaded borers (Coleoptera: Buprestidae) are some of the most devastating, frequently colonizing stressed trees. The objective of this study was to explore the effects of biotic and abiotic risk factors on borer attacks on trees in urban areas. In the summer of 2021 and 2022, this study was conducted in 50 urban sites in Atlanta and Augusta, Georgia (USA). Specific factors explored include overall tree health, differentially warmer maximum and minimum temperatures of sites compared to surrounding areas, tree species, and the percentage of impervious surface surrounding trees. Generalized linear models and zero-inflated models explored how these factors were related to damage from these borers. The number of borer attacks on trees increased with higher percentage impervious area. As the two most commonly encountered trees, Acer rubrum was found to be significantly more susceptible to attack from borers than Ulmus parvifolia. Unhealthy trees were more likely to experience more frequent and more severe borer attack. Trees with increased impervious cover around them as well as those with differentially warmer daily maximum and minimum temperatures relative to surrounding were more likely to be attacked.

First report of Root rot in Cerasus subhirtella Caused by Fusarium solani and Fusarium oxysporum in China.

Cerasus subhirtella (Miq.) Sok. is a widely used ornamental tree in urban areas around China and has a high ornamental value. From 2018 to 2020, a root rot disease was observed in C. subhirtella in Meitan County, Weng'an County, and Guiyang city of Guizhou, China (106.71 E, 26.57 N). Diseased C. subhirtella trees exhibited wilting with leaf chlorosis accompanied by brown to black root discoloration. In an area of 100 ha in total, with disease incidence ranging from 60 to 80%. Six symptomatic plants with root rot were randomly collected from three locations where disease symptoms were observed for pathogen isolation. Fifty fragments of diseased roots (5×5mm) were disinfected in 3% sodium hypochlorite for 30 s and 75% alcohol for 60 s, rinsed three times in sterile distilled water, plated on potato dextrose agar (PDA; BoWei, Shanghai), and incubated at 28 °C in the dark for 7 days. Eighteen isolates were purified by single spore culturing. Typical Fusarium spp. colonies were obtained from all root samples. On PDA, the colonies showed white and the hyphae were dense, while the colony of isolate YH15 showed pale yellow on the back, radial growth and produced chlamydospores. The macrospores (YH15) were straight to subarcuate, measured 15.3 to 25.1 × 2.5 to 6.2 μm (n=50). The microconidia (YH26) were ellipsoid to ovoid, measured 8.6 to 12.7 × 1.6 to 5.1 μm (n=50). These morphological characteristics were consistent with Fusarium spp., as described recently in Vitullo et al. (2014). To confirm the morphological diagnosis, genomic DNA from the isolates was extracted. The internal transcribed spacer (ITS) (White et al, 1990) region of rDNA and a β-tubulin (Varga et al, 2011) gene fragment were amplified with the primers ITS1/ITS4 and Bt2a/Bt2b, respectively, and were subsequently sequenced. Maximum likelihood analysis was carried out using MEGA 11.0. BLAST analysis revealed that the ITS and β-tubulin sequences of isolate YH15 were 100% homologous with F. oxysporum, and the isolate YH26 had a 99.69~100% homology with F. solani. Sequences of isolate YH15 and YH26 were deposited in GenBank (ITS: OQ363005 and OQ363049; β-tubulin: OQ398187 and OQ398180). The isolate YH15 was thus identified as F. oxysporum by the morphological characteristics and sequences analysis, and the isolate YH26 was identified as F. solani. A reconstructed phylogenetic tree also confirmed their phylogenetic position. The healthy 2-year-old C. subhirtella plants grown in autoclaved acid yellow soil were used for the pathogenicity tests. Then, 50 mL of conidial suspension (2.0×105 conidia/mL, in medium) of 7-day-old isolates YH15 and YH26 were gently applied to the soil in each of the 10 pots as the treatment. A sterilized fungal culture matrix (PDB; BoWei, Shanghai) was applied to each of 10 pots as a control. All pots (30 cm high, 25 cm upper diameter, 15 cm base diameter) were placed in a greenhouse (25 °C, 12 h photoperiod). After 30 days of inoculation, all plants inoculated with the isolates showed wilting symptoms, and the roots showed light-brown to dark-brown lesions. No symptoms were observed in the controls. The pathogen was reisolated from all symptomatic roots and identified as F. oxysporum and F. solani as described above. The pathogenicity test was repeated twice with similar results. Although this fungus was previously reported to cause root disease in many hosts (Li et al., 2020; Gibert et al., 2022), this is the first report of F. oxysporum and F. solani causing root rot in C. subhirtella in China.

The Impact of Urbanization on Tree Growth and Xylem Anatomical Characteristics.

In the context of the intensification of global urbanization, how urbanization (urban heat island effect and air pollution) affects urban tree growth is not fully understood. In this paper, the radial growth and xylem anatomical characteristics of three different tree species (Quercus mongolica, Fraxinus mandshurica, and Pinus sylvestris var. mongolica) in urban and rural areas of Harbin were compared by means of tree-ring anatomy. The results showed that there were significant differences in the growth of both broadleaf trees and conifers between urban and rural areas. The vessel number, cumulative area of vessels, and theoretical hydraulic conductivity of all tree species in rural areas were higher than those in urban areas, indicating that urbanization may have the effect of slowing down growth. However, broadleaf trees in urban areas had higher vessel density and a greater percentage of a conductive area within xylem and theoretical xylem-specific hydraulic conductivity. The thickness of cell walls and cell wall reinforcement index of P. sylvestris var. mongolica were strongly reduced by air pollution, implying that it may be more sensitive to urbanization. Compared to Q. mongolica, F. mandshurica showed less sensitivity to urbanization. Warming and drying climate in Harbin may be an important factor affecting tree growth.

Hazard Assessment of Urban Trees along the Bagmati River Corridor: A Case Study from Kathmandu Metropolitan City, Ward Number 8.

Urban trees are extremely significant and provide numerous advantages for both the environment and people. In order to provide a healthy and sustainable environment, green spaces have long been seen as a crucial component of contemporary cities. Nevertheless, as urbanization and population growth have accelerated, environmental challenges have become a major worldwide issue. This study mainly focuses on the assessment of hazardous trees along the Bagmati river corridor and documents major tree species for urban forestry. The study was conducted in ward number 08 of Kathmandu metropolitan city. Total enumeration was carried out by recording information on trees through direct observation of the whole site. The International Society of Arboriculture (ISA) tree hazard evaluation method was used as a tree risk assessment tool. A total of 74 trees were recorded from the study site. Grevillea robusta, Cinnamomum camphora, Ficus bengalensis, F. religiosa, and so on were the major species planted along the Bagmati corridor. The trees were categorized in varying degrees of hazard. Forty-seven trees were less hazardous, 24 were semihazardous, and 3 were hazardous with hazard rates of 2.91, 6.04, and 9, respectively. Jasminum nudiflorum was the only hazardous species recorded followed by semihazardous species such as Morus alba and F. religiosa among other species, and Eucalyptus camaldulensis, Citrus limon, Psidium guajava, Alnus nepalensis, and so on were least hazardous tree species. The hazardous tree in urban areas increases the risk to people and public as well as private properties. There is a need for the removal of such hazardous trees and planting the right species at the right time. Moreover, regular inspection and a clear policy for urban trees are needed.

Ecological adaptations among spruce species along an environmental gradient in urban areas

Knowledge about current state of the trees in urban areas may be important for foresting and green planting of city landscapes and for improving environmental quality in these areas. The object of this study were to screen a range of morphometric, physiological and biochemical parameters among species of the genus spruce (Picea A. Dietr.) in urban areas of Kryvyi Rih City and to assess the ecological adaptations among species of the genus spruce (Picea A. Dietr.) along an environmental gradient in urban areas of Kryvyi Rih City. During 2017-2021, the 7 research plots in Kryvyi Rih City urban areas along an environmental gradient (low, moderate and high levels of the environmental impact) and 1 research plot in the background area (control) were established. The 30–40-year-old trees of indigenous spruce species (Norway spruce (Picea abies (L.) Karst.)) and non-native spruce species (Colorado blue spruce (Picea pungens var. ‘Glauca’)) were investigated. The morphometric characteristics of trees, vitality of trees and chlorophyll a, chlorophyll b content in needles were studied. The results showed that in background area the tree height (14.5-15.1 m and 11.7-12.5 m for Norway spruce and Colorado blue spruce), diameter at breast height (25.3-28.1 cm and 24.6-27.2 for Norway spruce and Colorado blue spruce), chlorophyll a content (0.75-1.04 mg/g of wet weight and 0.96-1.24 mg/g of wet weight for Norway spruce and Colorado blue spruce) and chlorophyll b content (0.33-0.41 mg/g of wet weight and 0.42-0.50 mg/g of wet weight for Norway spruce and Colorado blue spruce) were typical of mature 30-40-year-old spruce trees. In Kryvyi Rih City urban areas the ecological stress along an environmental gradient decreased the values of growth, vitalyty and photosynthetic activity of the trees by 15-50%. Colorado blue spruce trees (non-native species) exhibit greater ecological tolerance and ecological adaptations than Norway spruce trees (indigenous species). Colorado blue spruce is less sensitive to environmental impact and have a better ecological adaptive balance of pigment content than Norway spruce. Our results confirm that from a sustainable development of the urbane areas perspective it is necessary to using the Colorado blue spruce for greene planting.

The overlooked contribution of trees outside forests to tree cover and woody biomass across Europe.

Trees are an integral part in European landscapes, but only forest resources are systematically assessed by national inventories. The contribution of urban and agricultural trees to national-level carbon stocks remains largely unknown. Here we produced canopy cover, height and above-ground biomass maps from 3-meter resolution nanosatellite imagery across Europe. Our biomass estimates have a systematic bias of 7.6% (overestimation; R = 0.98) compared to national inventories of 30 countries, and our dataset is sufficiently highly resolved spatially to support the inclusion of tree biomass outside forests, which we quantify to 0.8 petagrams. Although this represents only 2% of the total tree biomass, large variations between countries are found (10% for UK) and trees in urban areas contribute substantially to national carbon stocks (8% for the Netherlands). The agreement with national inventory data, the scalability, and spatial details across landscapes, including trees outside forests, make our approach attractive for operational implementation to support national carbon stock inventory schemes.

Interlinking the silos: How to stimulate a new debate on more greenery in cities

To address the current and future impacts of climate change on urban inhabitants, the development and benefits of urban green areas have been widely investigated – including parks, open unsealed spaces, residential gardens and street trees. However, the provision of urban green spaces can be used by private developers or private-public partnerships as a marketing tool to increase real-estate values. This presents a disadvantage for low-income households who may not be able to stay where they are or move to buildings or areas less affected by heat waves. Another key challenge reflects land-use conflicts created by the need to plant more trees, as opposed to other urban needs such as more parking spaces. At present, in several cities, policy and planning instruments remain inadequate in providing enough green spaces such as urban trees to lessen the heat stress in cities (for example, in poorer neighborhoods and new urban transformations led by private developers). The need for the proliferation of urban trees faces multiple expectations and challenges from several perspectives: 1) the crucial need for adaptation to climate change; 2) the partial presence (or total absence) of trees in areas undergoing densification and future transformations to readdress within effective planning strategies and tools; and 3) the relevance of social consequences (counteracting socio-spatial inequalities and considering residents’ perspectives) linked to green gentrification and environmental justice. The aim of this paper is to investigate these three perspectives (which are currently independent, for the most part), in order to interlink the silos and address the need for an interdisciplinary perspective of trees in urban areas. We suggest that the integration of these three aspects would help us fill the current knowledge gaps and enable a comprehensive perspective on social and environmental policies required in the complex urban system, and therefore also encourage new research paths, as well as a higher social acceptance by homeowners and renters.

Alternative scenarios for urban tree surveys: Investigating the species, structures, and diversities of street trees using street view imagery

Grasping information about street trees can assist urban environmental managers in quantifying and evaluating their costs and ecological benefits. Street view imagery has the potential for urban street tree surveys. However, few studies have been conducted on the inventory of street tree species, size structures and diversity based on street view imagery at the urban scale. In this study, we tried to conduct a survey of street trees in urban areas of Hangzhou using street view images. First, we constructed a size reference items system and determined that using it for street view measurements of street trees was comparable to field measurements results (R2 = 0.913–0.987). On this basis, we investigated the distribution characteristics and differences of street trees in Hangzhou using Baidu Street View and found that Cinnamomum camphora was the dominant tree species in Hangzhou (46.58 %), and the high proportion made urban street trees susceptible to ecological hazards. In addition, surveys conducted separately in various urban districts revealed that the diversity of street trees in new urban areas was smaller and less uniform. Additionally, as the gradient got further away from the city center, the street trees are smaller, the diversity first increased and then decreased, and the evenness gradually decreased. This study analyzes the use of Street View to investigate the distribution of species, size structure, and diversity of urban street trees. The use of street view imagery will simplify the collection of data on urban street trees and provide urban environmental managers with a foundation for strategy development.

Kentsel alanlarda büyük boyutlu ağaçların taşınması (İstanbul Çengelköy örneği)

Kentsel doku içerisinde var olan yeşil alanların geliştirilmesi veya yeni yeşil alanların oluşturulmasında bitkilerin ekim – dikim çalışmaları yanında ağaç taşıma çalışmaları da söz konusu olmaktadır. Ağaçların taşınması çalışmalarında; taşıma zamanları, ağaç türü, boyu, göğüs çapı, tepe tacının büyüklüğü, gövde yapısı ve taşıma çalışmalarının maliyeti çok önemlidir. Ağaçların bulunduğu yerden yeni yerine taşınması çalışmaları ön hazırlık, ağacın sökülmesi, taşıma, dikim ve bakım çalışmalarından oluşmaktadır. Ağaç taşıma çalışmalarında mekanik ağaç taşıyıcıları, balyalama ve kasalama şeklinde farklı araçlar ve yöntemler kullanılmaktadır. Bu çalışmada İstanbul ili, Çengelköy bölgesinde yapılan konut proje sahasındaki dört adet büyük boyutlu ağacın taşıma çalışmaları incelenmiştir. Ağaçlar proje sahası içerisinde mevcut yerlerinden alınarak 48 – 77 m mesafede farklı bir yere taşınmışlardır. Ağaç boyutlarının büyük olması nedeniyle kasalama yöntemi tercih edilmiş ve 400 ton kapasiteli bir vinç yardımıyla ağaçlar taşınmıştır. Ağaçların taşınması sırasında meydana çıkan toplam maliyet 87250 $ olarak belirlenmiştir.

How green is an urban tree? The impact of species selection in reducing the carbon footprint of park trees in Swedish cities

IntroductionPlanting trees in urban areas can mitigate some of the emissions generated in cities by carbon sequestration (annual uptake of CO2 through the process of photosynthesis) and carbon storage (amount of carbon stored in the tree's biomass throughout its lifespan). The aim of this study was to calculate the carbon footprint from nursery production to final establishment of different tree species grown for planting in urban parks in a northern European context.Material and methodsThe analysis included a cradle-to-gate approach and investigated the amount of carbon the adult trees needed to sequester in order to compensate for initial carbon emissions and which temporal perspectives are of concern. Greenhouse gas emissions were estimated based on an inventory of consumption of fuels, energy, materials and other production inputs during cultivation, delivery, planting and establishment of three different tree species in three different locations in Sweden. The tree species considered in the analysis (Salix alba, Quercus rubra, Pinus sylvestris) were selected due to significant differences in their growth rates. Salix alba is a competitive strategist in resource-rich habitats, and is proficient at converting these resources into vigorous growth. Pinus sylvestris is a pronounced stress strategist with good ability to handle resource-limited habitats, and invests in traits accordingly, resulting in significantly slower development. Quercus rubra has its main distribution in cool and moderately resource-rich habitats, but has relatively high stress tolerance and can be considered intermediate between the other two species in terms of growth rate.Results and discussionThe results showed that within 16 years of planting, all species in all three cities, except Pinus sylvestris planted in Umeå, compensated for initial carbon emissions, i.e. showed net absorption of CO2 after emissions from cultivation, delivery, planting and establishment of the trees had been deducted. There was a clear link between the time by which compensation of initial carbon emissions was achieved and growth rate of the different species, with the fast-growing Salix alba showing the best results. The single largest source of emissions among all activities carried out during cultivation, delivery and planting of all species, regardless of the city in which they were planted, was fuel consumption during tree planting.

Environmental goods provision and gentrification: Evidence from MillionTreesNYC

Urban trees offer extensive environmental benefits. However, the distribution of trees in urban areas often disproportionately favors higher-income neighborhoods. Implementing tree-planting programs in lower-income neighborhoods may provide environmental amenity values but may also lead to unintended consequences, such as gentrification. This paper focuses on one of the largest tree-planting programs in the U.S., the MillionTreesNYC Program, and estimates the impact of an increased supply of urban street trees on housing values and neighborhood compositions. The results demonstrate that the additional urban street trees did serve as an environmental amenity, resulting in higher housing values and attracting more white, educated, and young households to areas with new trees. However, the gentrification effects of this tree-planting program were relatively small, with minimal change in community composition. These findings suggest that it is possible to provide public goods without significant displacement of the existing population while also reaping the numerous benefits trees offer to urban areas.

Canopy composition drives variability in urban growing season length more than the heat island effect

The elevated heat of urban areas compared to their surroundings makes humid temperate cities a useful preview of future climate effects on natural forest phenology. The utility of this proxy rests on the expectation that trees in urban areas alter their phenology in response to warmer site conditions in spring and fall. However, it is possible that apparent lengthening of the growing season is instead governed by human-driven tree species selection and plant functional type (PFT; trees, shrubs, turfgrass) heterogeneity typical of managed landscapes. Without the use of highly spatially and temporally resolved remote sensing data, the roles of tree taxonomy and local site characteristics (e.g., impervious cover) in controlling phenology remain confounded. To understand the drivers of earlier start of season (SOS) and later end of season (EOS) among urban trees, we estimated individual tree phenology using >130 high-resolution satellite images per year (2018–2020) for ~10,000 species-labeled trees in Washington, DC. We found that species identity alone accounted for 4× more variability in the timing of SOS and EOS compared with a tree's planting location characteristics. Additionally, the urban mix of PFTs may be more responsible for apparent advances in SOS (by between 1.8 ± 1.3 and 3.5 ± 1.3 days) than heat per se. The results of this study caution against associating longer growing seasons in cities—observed in moderate to coarse resolution remote sensing imagery—to within-species phenological plasticity and demonstrate the power of high-resolution satellite data for tracking tree phenology in biodiverse environments.

Fungi associated to Platanus x acerifolia in Uruguay and failure indicators

In the last few years, the interest in keeping the city trees healthy has increased in order to improve their survival and minimize claims due to potential accidents. The pest and diseases, the pollution, and the climate change together with the little genetic diversity of trees in urban areas are some of the factors that contribute to increase the likelihood of death and/or failure of trees in the cities. This work is part of a sanitary and risk of failure assessment of plane street trees (Platanus x acerifolia) carried out between 2019 and 2020. A random sample of 10 city blocks and their 193 plane trees was selected. In these, the presence of cankers, abnormal bark colorations, deformations, and a series of structural attributes that determine likelihood of failure variables were registered. The proportion of individuals with each symptom and the severity main index (SMI) were calculated as a weighted average of the different severity (SEV) levels in the total of evaluated plants. The severity indices were determined according to trunk or branches circumference and the portion of the tree affected (1st, 2nd or 3rd portion from the base). Deformations presented the main incidence (0.6), SMI (1.68) and a correlation with the presence of damages and human injuries. The presence of cankers and reddish bark were the symptoms that most affected the density of the crowns.