Street Trees Research Articles

Functional urban ground-cover plants: identifying traits that promote rainwater retention and dissipation

Urban vegetation can influence urban hydrology and reduce the risk of flooding. Urban forestry studies have suggested that tree type and species choice affect the amount of rainwater intercepted and retained. Little information exists, however, for other landscape typologies, and the sorts of ground-cover plants that are best used to retain/detain rainwater during storm events. This is important as many urban spaces are too small to facilitate trees, but can accommodate roadside vegetation, buffer strips, rain gardens, green roofs and stormwater planters. Thus, this research aimed to determine how choice of ground-cover taxa affected rainwater interception and retention. Six model species with contrasting leaf morphologies were used to determine how well rainwater was intercepted, but also dissipated through evapotranspiration (ET). A pot-based system was used to determine how plant water balance changed during late summer in the UK, with the aim to understand how leaf traits affected hydrological processes. Plant choice was important, with fine-leaved taxa, Festuca glauca and Dianthus ‘Haytor White’ showing best rainwater interception and Festuca demonstrating highest rates of dissipation from the substrate. Overall, compared to non-planted pots, those with plants present were more effective at capturing water (by 2.3–3.0x), and evapo-transpiring water (by 2.5-4.0x). Results indicate that ground cover vegetation has potential to aid urban water management in those localities where space is limited for trees. Plant choice and community-structure should be considered, especially when there is a desire to dry out soil/substrate quickly and restore maximum soil moisture holding capacity.

Hydrothermal pretreatment of Platanus orientalis Linn fallen leaves: effects of process conditions on anaerobic digestion

ABSTRACT Platanus orientalis Linn is widely distributed as a famous street tree, and its fallen leaves are a rich biomass resource. The fallen leaves of Platanus orientalis Linn (FLPOL) can be resourcefully treated by generating biogas through anaerobic digestion. This study aimed to assess the anaerobic digestion (AD) performance of FLPOL under different hydrothermal pretreatment (HTP) conditions (solid–liquid ratio 2–10%, residence times 0.5–2.5 h, and temperatures 120–200°C). The solid–liquid ratio, residence time, and temperature determined by energy balance calculation were 6%, 2.0 h, and 180°C, respectively, and the energy balance was 1.823 kJ/g biomass. Under these conditions, the methane yield of the process water was 56.85 mL/g·VS. The methanogenic potential, hydrolysis rate, maximum methanogenic rate, and the lag period obtained by the Fitzhugh first-order kinetic model and the modified Gompertz model were 101.803 mL/g·VS, 0.130 d−1, 14.207 mL/(g·VS·d) and 1.332 d, respectively. The research results suggest that HTP has an important role in promoting the large-scale AD application of FLPOL.

Aptness of Seedling Age of Important Avenue Woody Species of Uttar Pradesh, India

Trees are an important component of our ecosystem, as far as ecological services provided by them are concerned. Especially in urban ecology, their role becomes more significant where they mitigate negative impacts of urbanization like deforestation; loss of wetlands; acquirement of agricultural lands; loss of biodiversity due to habitat clearing; degradation and fragmentation of the landscapes, etc. Trees make urban areas more resilient to these adverse impacts. Avenue plantation is an important part of Urban Forestry. In Avenue plantation, mostly tall seedlings are used. But planting very tall seedlings may affect the secondary growth of the tree, whereas planting small seedlings may be grazed by the animals. It is very important that the planting stock must be able of high rates of survival and good field performance to justify the expense of reforestation efforts. Therefore the present study is focused on the suitable planting age of some important preferred tree species of the Uttar Pradesh Forest Department and their growth performance in field conditions. The selected tree species were Shisham (Dalbergia sissoo), Imli (Tamarindus indica) Kathal (Artocarpus heterophyllus), Jungle Jalebi (Pithecellobium dulce), Kat sagaun (Haplophragma adenophyllum) and Karanj (Pongamia pinnata). These are the major woody species presently being planted in urban forestry. The species with large crown are planted in government garden, city garden, etc. Different age groups of these tree species were planted and their growth performance was studied under different field conditions. Aptness and importance of seedling age were recommended for studied trees for avenue plantation. It was concluded that species like Jungle Jalebi (Pithecellobium dulce), Katsagaun (Haplophragma adenophyllum), and Shisham (Dalbergia sissoo ) seedlings performed well for one year old age as well as for two year old age ones but species like Karanj( Pongamia pinnata), Imli ( Tamarindus indica ) and Kathal (Artocarpus heterophyllus), performed well more for one year old seedling. Therefore all these may be planted after one year of age in nursery to avoid the extra expense of maintaining these seedlings in the nursery stage.

Urban Green Development and Resilient Cities: A First Insight into Urban Forest Planning in Italy

The research proposes an application of a modification of the 3–30–300 rule to identify areas that require Urban Forestry implementation in small and medium-sized Roman and/or medieval urban areas. The selected case study is that of Asti in Piedmont, Italy. An open source, cross-platform desktop geographic information system is used to process geospatial datasets via qualitative analyses of electoral sections (or wards). An analysis of the number and distribution of trees around each building is performed, in addition to the calculation of tree canopy cover and distance between buildings and green spaces. Findings reveal that 64 out of 70 wards have an average of at least three trees per building and sufficient green areas of at least 0.5 hectares within 300 m of the buildings. Additionally, the tree canopy cover ranges from approximately 0.6% (lowest) to about 55% (highest) for the electoral sections. Lastly, findings suggest that the highly built-up urban fabric in these areas may significantly affect the availability and quality of green spaces. In conclusion, the case study proves the benefits of applying the 3–30–300 rule to small and medium-sized urban areas using an integrated assessment approach based on nature-based solutions and ecosystem services.

Allergenic tree pollen in Johannesburg and Cape Town as a public health risk: towards a sustainable implementation framework for South African cities

South Africa’s urban population is increasing, and in parallel, urban green infrastructure has shown an increase in alien tree species, e.g., mulberry (Morus sp.), oak (Quercus spp.) and plane trees (Platanus spp.) to name a few. This causes ecological problems since alien trees are often more water-demanding and competitive than indigenous trees, but they also increase the abundance of respiratory diseases often triggered by an allergic reaction towards the pollen of those alien taxa. In the current study, utilizing 7-day volumetric spore traps, we illustrate that the most abundant tree pollen in the two largest cities of South Africa, Cape Town and Johannesburg, is produced by alien trees with a high risk of allergenicity. This adds another aspect related to public health when evaluating plant species composition in urban forestry and urban ecology, which underlines the urgency of more intense monitoring. More importantly, this—for South Africa—newly emphasized risk for public health underlines the applicability of current directives [i.e., Spatial Development Frameworks (SDFs), localized Precinct Plans, Land Use Schemes (LUSs)] and implementation options in urban planning. Here, we present ideas that may be implemented in such a framework. From both a public health and an ecological perspective, it is recommended to plant indigenous trees like Combretum erythrophyllum, Vachellia and Senegalia spp. that have fewer ecosystem disservices, like a lower impact on public health due to lower allergenicity/lower pollen occurrence and providing more ecosystem services such as lower water needs.

Pursuit of environmental justice in urban forest planning and practice

IntroductionThere is a growing demand for urban forest management that prioritizes genuine community involvement, acknowledges power imbalances within society, and embraces the principles of environmental justice. To assess current initiatives and share better/best approaches, examining how environmental justice principles are applied in urban forest planning and practice is crucial. This study aims to understand the perspectives of urban foresters on the factors that either facilitate or impede the attainment of environmental justice goals.MethodsInterviews were conducted with urban foresters from non-profit organizations and municipal government in San Francisco, California, and Seattle, Washington. The interviewees were asked to identify and discuss their tree planting and maintenance strategies, public engagement protocol, and inter-organizational collaboration processes. To provide a contextual understanding of environmental injustice in the study cities, the historical racist practice of neighborhood redlining was examined alongside current tree canopy cover, locations of environmental hazards, and the spatial distribution of persons of color and those living in poverty.ResultsThe findings revealed that urban forestry professionals in each city approached environmental justice in distinct yet complementary ways: San Francisco prioritized distributional justice, while Seattle focused on elements of procedural and recognitional justice. The Race and Social Justice Initiative in Seattle and Proposition E in San Francisco have been instrumental in identifying and addressing inequities in urban forest planning and practice.Discussion/conclusionCreating fair and inclusive urban forestry practices that prioritize disadvantaged neighborhoods has been a difficult task for both cities. Acknowledging and addressing past policies and cultural perspectives that have led to marginalization is crucial for building trust with these communities. Moving forward, prioritizing recognitional justice in urban forest planning and management should be a top priority.

Brown leaf spot of Cunninghamia lanceolata Caused by Colletotrichum kahawae in Sichuan province, China.

Chinese fir (Cunninghamia lanceolata) is an important timber species that has been widely cultivated in southern China. It is extensively applied in medicine, environmental monitoring, furniture, urban (e.g., street trees) and rural landscaping, windbreak forest, soil and water conservation. In January 2022, distinct leaf spot symptoms were observed in Chinese fir in Hongya Forestry (29°45'N, 103°11'E) Meishan City, Sichuan Province, China. Field surveys showed that the disease was widespread, with around 70% disease incidence. The typical symptoms initially appeared as yellowish-brown necrotic lesions on the margin of the leaves. Subsequently, lesions gradually expanded and developed into larger necrotic areas with red-brown irregular shape. The lesions later expanded throughout the leaf. Infected leaves turned dark brown and wilted, leading to seeding's death. Diseased leaves with typical symptoms were collected for pathogen isolation and identification. Infected tissues from ten samples were cut into small pieces of 2 × 2 mm. Infected tissues were surface disinfected with 3% sodium hypochlorite and 75% ethanol for 30s and 60s, respectively, and rinsed with sterile water 3 times. They were blotted dry with autoclaved paper towels and incubated on potato dextrose agar (PDA) with streptomycin sulfate (50 μg/mL) for 5 ~ 8 days at 25°C. and 12 h light/dark period. The diameter of the colonies reached 65.7 to 75.9 mm, with a gray to black center, and white edges while the reverse sides were gray to orange. Conidia were single-celled, colorless, straight, cylindrical, bluntly rounded at both ends, Conidia dimensions varied from, 7.3 μm to 15.7 μm in length and 3.3 μm to 6.1 μm in width (n = 100). For molecular identification, the genomic DNA of isolate SM2290708, SM229070801 and SM229070802 were extracted using a fungal genomic DNA extraction kit (Beijing Solarbio Science & Technology Co., Ltd., City, China). The internal transcribed spacers of the ribosomal RNA (ITS) [ITS1/ITS4 (White et al., 1990), calmodulin (CAL) (Weir et al., 2012), β-tubulin (TUB2) (O'Donnell et al., 1997), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (Templeton et al. 1992) were amplified. Sequences were deposited in GenBank (ITS: ON564877, OQ535027 and OQ535028; CAL: ON583827, OQ538101 and OQ538102; TUB2: ON583830, OQ538104 and OQ538105; and GAPDH: ON583831, OQ538108 and OQ538109). BLAST results showed that our ITS, CAL, TUB2 and GAPDH sequences were >99% identical to the corresponding sequences of Colletotrichum kahawae deposited at NCBI (GenBank JX010231, JX009642, JX010444, and JX010012). Identification was confirmed by Bayesian inference using MrBayes (Fig 2). The conidial suspension (1 × 106 conidia/ml) was used for inoculation by spraying leaves of ten 3-year-old Chinese fir plants for pathogenicity test. Fifteen leaves of each plant were inoculated. An equal number of control leaves was sprayed with sterilized distilled water as a control. Finally, all potted plants were placed in a greenhouse at 28°C under a 16 h/8 h photoperiod and in 73% to 79% relative humidity. After fifteen days, the symptoms observed on the inoculated plants were similar to those of the original diseased plants, but the controls remained asymptomatic. Colletotrichum kahawae was re-isolated from the infected leaves and identified by both morphological characteristics and DNA sequence analysis. The pathogenicity test was repeated three times, which showed similar results, confirming Koch's postulates. To our knowledge, this is the first report of brown leaf spot on C. lanceolata caused by C. kahawae in China. The results of this study provide basic information for diagnosis of the pathogen and developing prevention strategies to manage C. lanceolata leaf spot disease.

Child friendliness of rural school travel road: Improvement strategies based on rural children's perception

IntroductionIn the process of building child-friendly cities, scholars have conducted extensive research on the appropriateness of urban facilities for children in urban regions, while less attention has been paid to rural areas with large numbers of children. This study attempts to explore the friendly planning and design of rural school travel roads from the perspective of children's perception of the current environment. MethodsSixteen school route assessment indices were summarized into four categories: road characteristics (width, pavement type, maintenance, and cleanliness), basic services (sidewalks, non-motorized lanes, recreational facilities, street lights, shops), traffic safety features (traffic signals, crosswalks, speed bumps, slow/speed limit signs, traffic volume), and aesthetic elements (street trees, landscape pieces). Through a face-to-face questionnaire survey of students in 28 rural schools, 992 valid questionnaires were obtained. Then sixteen microscopic road environment indicators were classified by the IPA model, and on this basis, the TOPSIS model was used to prioritize the contents in the improvement area. ResultsThere were differences between the children's perception of the importance and satisfaction of the rural school travel environment, and the actual situation of each indicator did not reach the expected level. The priority of the five environmental factors needing improvement were sidewalks > crosswalks > slow/speed limit signs > traffic signals > speed bumps. ConclusionsInterventions should be considered from the perspective of children's perception, which can provide a reference for the optimization and upgrading of rural roads, and for the theory and practice of the further construction of child-friendly villages.

Integrated metabolomics and transcriptomics analysis reveals that the change of apoplast metabolites contributes to adaptation to winter freezing stress in Euonymus japonicus

Euonymus japonicus, a common urban street tree, can withstand winter freezing stress in temperate regions. The apoplast is the space outside the plasma membrane, and the changes of metabolites in apoplast may be involved in plant adaptation to adverse environments. To reveal the molecular mechanism underlying the winter freezing stress tolerance in E. japonicus, the changes in physiological and biochemical indexes, apoplast metabolites, and gene expression in the leaves of E. japonicus in early autumn and winter were analyzed. A total of 300 differentially accumulated metabolites were identified in apoplast fluids in E. japonicus, which were mainly related to flavone and flavonol biosynthesis, and galactose metabolism, amino acid synthesis, and unsaturated fatty acid synthesis. Integrated metabolomics and transcriptomics analysis revealed that E. japonicus adjust apoplast metabolites including flavonoids such as quercetin and kaempferol, and oligosaccharides such as raffinose and stachyose, to adapt to winter freezing stress through gene expression regulation. In addition, the regulation of ABA and SA biosynthesis and signal transduction pathways, as well as the activation of the antioxidant enzymes, also played important roles in the adaptation to winter freezing stress in E. japonicus. The present study provided essential data for understanding the molecular mechanism underlying the adaptation to winter freezing stress in E. japonicus.

Morphological diversity of pollen grains within the flowering stages of Tecoma stans (L.) Juss. ex Kunth

The study of the morphology of pollen grains is essential to understand plant evolution, adaptation, diversity and discrimination of taxa. This study aims to determine the importance of choosing the perfect stage of flower development in the study of pollen morphological characters as a taxonomical tool. In this work a woody, perennial street tree Tecoma stans was chosen as a model species belonging to family Bignoniaceae. Tecoma stans has many polymorphic forms native to North America and flourished in hot climates. This tree is commonly planted in both Cairo and Alexandria streets. Samples of flower buds in nine different stages were gathered from five to six different trees from March to June 2023. Non-acetolysed pollen grains were investigated using both light and Scanning electron microscopes. The results showed that pollen density, size, shape beside colpi length as well as their state varied between the different developmental flowering stages and cannot be relied on taxonomical decisions, while exine ornamentation slightly differed between the pollen grains from stage two to nine, but it was faint in immature flower bud (stage one). This study confirms that we must be precise in choosing the correct flower stage in pollen morphological studies to obtain significant morphological description. The results obtained revealed that the aperture type is more stable than pollen shape and size.

A Simulation Study on the Influence of Street Tree Configuration on Fine Particulate Matter (PM2.5) Concentration in Street Canyons

Because motor vehicles emit a large amount of PM2.5 pollution, traffic-related emissions have always been an important part of PM2.5 pollution. To better understand the influence of street trees on traffic-related PM2.5 pollution, our study focused on camphor trees, common evergreen urban street trees in central and southern China. We used ENVI-met for the simulation of PM2.5 pollution and to build a model to show the distribution of PM2.5 pollution along a section of Xinyao North Road in downtown Changsha City in central China. Based on this model, we constructed four other models with different heights, quantities, and distances between street trees, where each model had high feasibility and aimed to determine how these affect the PM2.5 concentration on the designated block. We performed simulations within different time frames in the year. We found that the wind can promote the diffusion of PM2.5 in the street canyon. Too dense a distribution of tall street trees will have a negative impact on PM2.5 concentration in street canyons. A moderate distance between street trees is conducive to the dispersion of pollutants. Because the crown of 5 m high street trees is small, its negative impact on the dispersion of wind and PM2.5 is relatively small, so further increasing the number of 5 m high street trees in street canyons with densely distributed tall street trees will have only a little more negative impact on PM2.5 concentration in street canyons. The PM2.5 concentration in the street canyon is generally better when the street trees are 5 m long, even if the number of 5 m high street trees is relatively large. Although the crown size of 15 m high street trees is larger than that of 10 m street trees, the vertical distance between the canopy of 15 m high street trees and the ground is usually greater than that of 10 m high street trees. The distance between the canopy of 15 m high street trees and the breathing zone is usually greater than that of the 10 m street trees. Longer distances lead to a weakening of its impact on PM2.5. When the 15 m high and 10 m high street trees are more scattered in the street, their effects on the PM2.5 concentration at the height of the breathing zone (1.5 m) are generally similar.

More than greening: Using a novel index to assess restorative nature and vulnerability relationships.

Urban living limits access to nature yet spending time in nature is crucial for human health and well-being. To overcome this, urban planners and policymakers are actively looking for different ways to conserve and create more urban nature through parks, street trees, and other greening strategies. However, research shows that in most cities, these greening efforts are not equitably distributed, nor are they equal in terms of their quality or benefits they provide. Creating more equitable access to urban nature is a challenge and a priority in the next decade, and so is improving the quality of urban nature and associated benefits for urbanites. To address this challenge and contribute at both practical and conceptual levels, we propose a new Local Restorative Nature (LRN) index for geospatially assessing the "restorative quality" of urban nature that can support mental well-being. To contextualize the LRN index, we map the distribution of restorative nature in relation to social vulnerability in Vancouver, Canada. The novel LRN index provides critical insights showing that many neighborhoods with vulnerable populations in Vancouver have less exposure to restorative nature to support mental health and highlights where to strategically prioritize urban greening investment in areas that need it the most. The LRN index is scalable and can be used by urban planners in other cities and contexts to improve equitable distribution of restorative nature and better support urbanites' well-being.

Prediction of Urban Trees Planting Base on Guided Cellular Automata to Enhance the Connection of Green Infrastructure

Urbanization and climate change pose significant challenges to urban ecosystems, underscoring the necessity for innovative strategies to enhance urban green infrastructure. Tree planting, a crucial aspect of green infrastructure, has been analyzed for optimized positioning using data metrics, priority scoring, and GIS. However, due to the dynamic nature of environmental information, the accuracy of current approaches is compromised. This study aims to present a novel approach integrating deep learning and cellular automata to prioritize urban tree planting locations to anticipate the optimal urban tree network. Initially, GIS data were collated and visualized to identify a suitable study site within London. CycleGAN models were trained using cellular automata outputs and forest mycorrhizal network samples. The comparison validated cellular automata’s applicability, enabled observing spatial feature information in the outputs and guiding the parameter design of our 3D cellular automata system for predicting tree planting locations. The locations were optimized by simulating the network connectivity of urban trees after planting, following the spatial-behavioral pattern of the forest mycorrhizal network. The results highlight the role of robust tree networks in fostering ecological stability and cushioning climate change impacts in urban contexts. The proposed approach addresses existing methodological and practical limitations, providing innovative strategies for optimal tree planting and prioritization of urban green infrastructure, thereby informing sustainable urban planning and design. Our findings illustrate the symbiotic relationship between urban trees and future cities and offer insights into street tree density planning, optimizing the spatial distribution of trees within urban landscapes for sustainable urban development.

How can greenery space mitigate urban heat island? An analysis of cooling effect, carbon sequestration, and nurturing cost at the street scale

Rapid urbanization has contributed to urban heat islands, which can potentially lead to increased energy consumption and carbon emissions, further worsening global warming. The U-shaped street canyon is one of the leading causes of urban heat islands, which may block air circulation and lead to urban heat accumulation. The canyon heat issues can be usually mitigated by nature-based solutions, such as street trees. It is important to increase the greenery space benefits (e.g., cooling effect of trees) with limited canyon space. However, there is an absence of refined greenery space design strategy in various street canyons. This work explored the quantitative design of greenery space (e.g., tree spacing) in different street canyons with complex morphological characteristics, in order to effectively improve co-benefits of trees and mitigate urban heat islands. Eighteen morphological types were considered, including symmetrical & asymmetrical shallow, ideal, and deep street canyons. Co-benefit considering cost of different tree spacings were analyzed, to maximize the benefits of cooling effect and carbon sequestration at minimal nurturing cost. Compared with street canyons without trees, ideal street canyon with tree spacing of 0.2W (W is canyon width) achieved the maximum temperature reduction of 6 °C. The positive correlation between tree spacing and co-benefits was found. The maximum co-benefits of street canyon trees occurred at tree spacing of less than 0.7W, which was largely increased by about 14% compared with 0.2W. This work can provide the guideline for efficient greenery space design, which is crucial for mitigating urban heat islands by nature-based solutions.

Street trees and Urban Heat Island in Glasgow: Mitigation through the ‘Avenues Programme’

Glasgow, Scotland, is embarking on an ambitious plan to convert all city centre thoroughfares into tree-lined streets (the ‘Avenues Programme’) to make the city centre more people-friendly, attractive, greener, sustainable and economically competitive. While it is well-known that urban green infrastructure (UGI) is a promising strategy to address overheating in urban areas, evidence for the surface temperature, air temperature and thermal comfort effects of street trees is contradictory. In the context of a city-centre-wide ‘Avenues Programme’ in Glasgow, we explore its co-benefits in terms of temperature and thermal comfort. We used a multi-method approach, combining GIS-based spatial analysis with fieldwork, microclimate modelling and statistical analysis to determine the scale of the overheating problem and the likely role of its mitigation based on the ‘Avenues Programme’ case study. We show that the Surface Urban Heat Island (SUHI) differences within the city are of the same magnitude as the urban-rural anomaly and “hot” spots are localized in the city centre area and are clustered in different patterns depending on the severity of background temperatures. Therefore, small, isolated patches of vegetation would not be effective for cooling the clusters of overheated areas. Air temperature showed non-linear relationship with tree canopy cover and the relationship is stronger at medium scale. The ‘Avenues Programme’ as a whole, could eliminate the UHI effect in the city centre, with some tree species completely eliminating the UHI in the city centre. Once complete, the ‘Avenues Programme’ could significantly improve thermal comfort during heatwaves from the current ‘hot’ category to ‘slightly warm’ across the city centre.

Detection of invasive and native beetle species within trees by chemical analysis of frass

In recent years, several invasive woodborers (Coleoptera: Cerambycidae) have been found in Japan. Aromia bungii is a worldwide important pest of fruits and ornamental species of the genus Prunus. It invaded Japan in the early 2010s and now causes heavy damage to stone fruit trees. Anoplophora glabripennis and Apriona swainsoni are destructive pests of street, ornamental and horticultural trees. The first step in intercepting these beetles is to detect their presence early in their infestation, as accurate identification is crucial for their management. Ejected frass is a major sign of infestation and likely holds information on the insect. We focused on chemicals in both larvae and frass, and conducted a GC–MS analysis of these three invasive beetles and the native Anoplophora malasiaca. In all four species, 4 or 5 species-specific hydrocarbons were detected in both larvae and frass. These results indicate that analysis of hydrocarbons in frass could allow definitive detection of invasive wood-boring pests.

Modelling the spread of tree pests and pathogens in urban forests

Understanding the potential dynamics of tree pests and pathogens is a vital component for creating resilient urban treescapes. Epidemiologically relevant features include differences in environmental stress and tree management between street and garden trees, and variation in the potential for human-mediated spread due to intensity of human activity, traffic flow and buildings. We extend a standard spatially explicit raster-based model for pest and pathogen spread by dividing the urban tree population into roadside trees and park/garden trees. We also distinguish between naturally-driven radial spread of pests and pathogens and human-mediated linear spread along roads. The model behaviour is explored using landscape data for tree locations in an exemplar UK town. Two main sources of landscape data were available: commercially collated aerial data, which have high coverage but no information on species; and, an urban tree inventory, with low, non-random, coverage but with some species data. The data were insufficient to impute a species-specific host landscape accurately; however, by combining the two data sources, and applying either random or Matérn cluster point process driven selection of a subset of all trees, we create two sets of potential host landscapes. We find that combining the two mechanisms of dispersal has a non-additive effect, with the enhanced linear dispersal enabling new foci of infection to be established more rapidly than with radial dispersal alone; and clustering of trees by species slows down the expansion of epidemics when compared with random distribution of tree species within known host locations.

Analysis of key issues and prospects for implementing urban forestry in Lagos State, Nigeria

ABSTRACT Rapid population growth and a high urbanisation rate have led to significant forest and tree losses in Lagos State, which is the smallest of the 36 States in Nigeria. Located on West Africa’s Atlantic Ocean littoral, Lagos State is low-lying and crisscrossed by wetlands and numerous water bodies. These topographical and geographical characteristics render the State highly vulnerable to the sea level rises and flooding that are predicted with a changing climate. In response, the State government has introduced legislation to institutionalise tree planting. This tree mandate is amplified by the Lagos climate action plan and coexists with the State government’s long-standing forestry mandate. It is accepted that urban forestry can improve climate resilience and deliver multifaceted economic, social, and environmental benefits. This article analyses the forestry and tree mandates that are in force in Lagos State and their implications for urban forestry. It identifies the lack of a synergistic approach by the Lagos State government as a major obstacle to successful urban forestry outcomes.

Biochar-biofertilizer combinations enhance growth and nutrient uptake in silver maple grown in an urban soil.

Declining tree health status due to pollutant impacts and nutrient imbalance is widespread in urban forests; however, chemical fertilizer use is increasingly avoided to reduce eutrophication impacts. Biochar (pyrolyzed organic waste) has been advocated as an alternative soil amendment, but biochar alone generally reduces plant N availability. The combination of biochar and either organic forms of N or Plant Growth Promoting Microbes (PGPMs) as biofertilizers may address these challenges. We examined the effects of two wood biochar types with Bacillus velezensis and an inactivated yeast (IY) biofertilizer in a three-month factorial greenhouse experiment with Acer saccharinum L. (silver maple) saplings grown in a representative urban soil. All treatments combining biochars with biofertilizers significantly increased sapling growth, with up to a 91% increase in biomass relative to controls. Growth and physiological responses were closely related to nutrient uptake patterns, with nutrient vector analyses indicating that combined biochar and biofertilizer treatments effectively addressed nutrient limitations of both macronutrients (N, P, K, Mg, Ca), and micronutrients (B, Fe, Mn, Mo, Na, S, and Zn). Biochar-biofertilizer treatments also reduced foliar concentrations of Cu, suggesting potential to mitigate toxic metal impacts common in urban forestry. We conclude that selected combinations of biochar and biofertilizers have substantial promise to address common soil limitations to tree performance in urban settings.

Image-based estimation of crown volume of individual street trees by plane calculation of angle disparity

Street trees provide significant and widespread environmental benefits to the city and its citizens, such as improved air quality and adaptation to climate change. Crown volume (CV) indicates the geometric volume of crown, which is an essential indicator for the ecological service evaluation of street trees. The measurement of CV makes it possible to assess the carbon storage and input cost of urban trees. Because of the particularity of crown shape of street trees, the existing two-dimensional methods of calculating CV of forest trees become difficult except the three-dimensional techniques through the unmanned aerial vehicle, LiDAR equipment, and traditional harvest methods. In this study, a new virtual research method for plane calculation of angle disparity (PCAD) is proposed to calculate the CV of street trees. Two temporal satellite images of the exact location were first collected from Google Earth Pro, and then the angle disparity of images was adopted as a starting point to calculate tree height. Finally, CV was calculated from tree height, stem height, and crown diameter. The feasibility of the method was verified by a sample survey of street trees in Shanghai, China and the relative error of CV calculation by PCAD compared to that by field survey was 17.31 %. PCAD has the advantages of low-cost, quick operation, and suitability for a large area in studying CV of street trees.