scholarly journals A Comparison of the Shading Effectiveness of Five Different Street Tree Species in Manchester, UK

2013 ◽  
Vol 39 (4) ◽  
Author(s):  
David Armson ◽  
Mohammad Asrafur Rahman ◽  
Anthony Roland Ennos
Keyword(s):  
Tree Species ◽  
Urban Areas ◽  
Urban Landscape ◽  
Urban Trees ◽  
Area Index ◽  
Pyrus Calleryana ◽  
Human Thermal Comfort ◽  
Surface Temperatures ◽  
Street Tree ◽  
Crataegus Laevigata

One major benefit of urban trees is the shade they provide on sunny days; this reduces the heat stored in engineered surfaces and lowers the heat load on people, increasing their comfort. This study compared the shading effectiveness of five small street tree species within the urban landscape of Manchester, UK. The area of shade produced by each tree during early and midsummer 2012 was calculated from morphological measurements, such as canopy height, width, and aspect ratio. The effect of tree shade on air, mean radiant and surface temperatures was also compared and related to the leaf area index (LAI) of the canopy. It was found that tree shade reduced mean radiant temperatures by an average of 4°C, though neither tree species nor LAI had a significant effect. Tree shade reduced surface temperatures by an average of 12°C, and the tree species and LAI both had significant effects. Tree species with higher LAI, Crataegus laevigata and Pyrus calleryana, provided significantly more cooling than the other species, and surface temperature reduction was positively correlated with LAI. This study has shown that trees are useful in improving both human thermal comfort and reducing surface temperatures in urban areas, and that selection of tree species with high LAI can maximize the benefits they provide.

scholarly journals Effects of Drought on the Phenology, Growth, and Morphological Development of Three Urban Tree Species and Cultivars

2019 ◽  
Vol 11 (18) ◽  
pp. 5117 ◽  
Author(s):  
Stratópoulos ◽  
Zhang ◽  
Häberle ◽  
Pauleit ◽  
Duthweiler ◽  
...  
Keyword(s):  
Water Supply ◽  
Tree Species ◽  
Urban Areas ◽  
Selection Criterion ◽  
Root Systems ◽  
Urban Trees ◽  
Morphological Development ◽  
Root:Shoot Ratio ◽  
Exclusion Experiment ◽  
Mitigation And Adaptation

: Under changing climatic conditions, drought may become a critical constraint for trees in urban areas, particularly at roadsides and highly paved squares. As healthy urban trees have proven to be an important mitigation and adaptation tool for climate change as well as a significant provider of ecosystem services, there is a need for planting species and cultivars capable of coping with the limited water supply. However, data on species’ and cultivars’ response to drought, particularly their water supplying root systems remains rare. To consider the whole plant responses to drought situations, we studied the growth and phenology of three frequently planted tree species and cultivars with a diameter of 5–6 cm during a one-year rainfall exclusion experiment conducted in a nursery field as well as the dry biomass of the compartments branch, stem, and root after excavation. Our results revealed that species’ and cultivars’ performance were linked to their within-plant carbon partitioning. A high tolerance to drought was noted for Acer campestre, with a particularly high ratio of root:shoot ratio, which made it presumably less susceptible to droughts. Tilia cordata ‘Greenspire’ was highly affected by the reduced water availability visible through prematurely leaf senescence, while Carpinus betulus ‘Fastigiata’ suffered from losing a considerable part of its root biomass, which resulted in the lowest root:shoot ratio of all species and cultivars. This study demonstrated the need for investigating the reaction patterns of species and cultivars by considering both the above-and the below-ground plant parts. We recommend that, for future tree plantings at harsh and challenging urban sites, an important selection criterion should be species’ and cultivars’ capability to develop and retain strong and dense root systems even under limited water supply, as that is believed to be an important trait for drought tolerance.

A Tree Selection Survey of Tree City USA Designated Cities in the Pacific Northwest

2020 ◽  
Vol 46 (5) ◽  
pp. 371-384
Author(s):  
Joshua Petter ◽  
Paul Ries ◽  
Ashley D’Antonio ◽  
Ryan Contreras
Keyword(s):  
Pacific Northwest ◽  
Tree Species ◽  
Urban Areas ◽  
Urban Forest ◽  
Urban Trees ◽  
Species Selection ◽  
Invasive Pests ◽  
The Pacific ◽  
Canopy Volume ◽  
The Right

As urban areas expand, there are a greater number of urban trees; however, development often leads to a reduction in urban trees in many areas. A reduction in the canopy volume of trees results in a reduction in the number of benefits. Additionally, urban trees can have additional stressors and must be more actively managed to maintain those services. Selecting tree species for the right site can lead to greater benefits and longer-lived trees. Increasing diversity of urban trees can help to mitigate some of the threats facing urban forests, such as invasive pests and climate change. We surveyed Tree City USA designated cities across Oregon and Washington to explore how they are selecting tree species for their municipalities. Responses were recorded for 79 out of 151 municipalities for a 52.3% response rate. Both open-ended questions and descriptive statistics were used to triangulate how managers are selecting tree species. Emergent themes in open-ended responses indicate a variety of justifications for tree species selection and the challenges of balancing those criteria. There is evidence to suggest that these municipalities are actively diversifying the urban forest; however, there are still 10 municipalities that reported ash (Fraxinus spp.) in their top 5 most frequently planted species in 2016. Many municipalities are still planting large quantities of maple (Acer spp.). Overplanting certain genera and species can lead to an increase in susceptibility to pests and pathogens. We recommend an increase in consideration for the diversification of tree species in urban areas.

scholarly journals The Removal Efficiencies of Several Temperate Tree Species at Adsorbing Airborne Particulate Matter in Urban Forests and Roadsides

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 960 ◽  
Author(s):  
Myeong Ja Kwak ◽  
Jongkyu Lee ◽  
Handong Kim ◽  
Sanghee Park ◽  
Yeaji Lim ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Tree Species ◽  
Morphological Characteristics ◽  
Urban Forests ◽  
Urban Trees ◽  
Widespread Species ◽  
Area Index ◽  
Canopy Density ◽  
Leaf Surfaces ◽  
Removal Efficiencies

Although urban trees are proposed as comparatively economical and eco-efficient biofilters for treating atmospheric particulate matter (PM) by the temporary capture and retention of PM particles, the PM removal effect and its main mechanism still remain largely uncertain. Thus, an understanding of the removal efficiencies of individual leaves that adsorb and retain airborne PM, particularly in the sustainable planning of multifunctional green infrastructure, should be preceded by an assessment of the leaf microstructures of widespread species in urban forests. We determined the differences between trees in regard to their ability to adsorb PM based on the unique leaf microstructures and leaf area index (LAI) reflecting their overall ability by upscaling from leaf scale to canopy scale. The micro-morphological characteristics of adaxial and abaxial leaf surfaces directly affected the PM trapping efficiency. Specifically, leaf surfaces with grooves and trichomes showed a higher ability to retain PM as compared to leaves without epidermal hairs or with dynamic water repellency. Zelkova serrata (Thunb.) Makino was found to have significantly higher benefits with regard to adsorbing and retaining PM compared to other species. Evergreen needle-leaved species could be a more sustainable manner to retain PM in winter and spring. The interspecies variability of the PM adsorption efficiency was upscaled from leaf scale to canopy scale based on the LAI, showing that tree species with higher canopy density were more effective in removing PM. In conclusion, if urban trees are used as a means to improve air quality in limited open spaces for urban greening programs, it is important to predominantly select a tree species that can maximize the ability to capture PM by having higher canopy density and leaf grooves or trichomes.

scholarly journals IDENTIFICATION AND MAPPING OF TREE SPECIES IN URBAN AREAS USING WORLDVIEW-2 IMAGERY

2015 ◽  
Vol II-2/W2 ◽  
pp. 175-181 ◽  
Author(s):  
Y. T. Mustafa ◽  
H. N. Habeeb ◽  
A. Stein ◽  
F. Y. Sulaiman
Keyword(s):  
Support Vector Machine ◽  
Tree Species ◽  
Urban Areas ◽  
Vegetation Indices ◽  
Urban Forestry ◽  
Urban Trees ◽  
Support Vector ◽  
Classification Methods ◽  
Tree Detection ◽  
Consistent Information

Monitoring and mapping of urban trees are essential to provide urban forestry authorities with timely and consistent information. Modern techniques increasingly facilitate these tasks, but require the development of semi-automatic tree detection and classification methods. In this article, we propose an approach to delineate and map the crown of 15 tree species in the city of Duhok, Kurdistan Region of Iraq using WorldView-2 (WV-2) imagery. A tree crown object is identified first and is subsequently delineated as an image object (IO) using vegetation indices and texture measurements. Next, three classification methods: Maximum Likelihood, Neural Network, and Support Vector Machine were used to classify IOs using selected IO features. The best results are obtained with Support Vector Machine classification that gives the best map of urban tree species in Duhok. The overall accuracy was between 60.93% to 88.92% and κ-coefficient was between 0.57 to 0.75. We conclude that fifteen tree species were identified and mapped at a satisfactory accuracy in urban areas of this study.

scholarly journals Temperature Reduction in Urban Surface Materials through Tree Shading Depends on Surface Type Not Tree Species

Forests ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1141
Author(s):  
Kaluarachichi T.U.N. ◽  
Tjoelker M.G. ◽  
Pfautsch S.
Keyword(s):  
Urban Space ◽  
Tree Species ◽  
Austral Summer ◽  
Bare Soil ◽  
Urban Surface ◽  
Surface Material ◽  
Free Standing ◽  
Area Index ◽  
Surface Temperatures ◽  
Surface Materials

Trees play a vital role in urban cooling. The present study tested if key canopy characteristics related to tree shade could be used to predict the cooling potential across a range of urban surface materials. During the austral summer of 2018–2019, tree and canopy characteristics of 471 free-standing trees from 13 species were recorded across Greater Sydney, Australia. Stem girth and tree height, as well as leaf area index and ground-projected crown area was measured for every tree. Surface temperatures were recorded between noon (daylight saving time) and 3:00 p.m. under the canopy of each tree in the shade and in full sun to calculate the temperature differential between adjacent sunlit and shaded surfaces (∆Ts). The limited control over environmental parameters was addressed by using a large number of randomly selected trees and measurement points of surface temperatures. Analyses revealed that no systematic relationship existed among canopy characteristics and ∆Ts for any surface material. However, highly significant differences (p < 0.001) in ∆Ts existed among surface materials. The largest cooling potential of tree shade was found by shading bark mulch (∆Ts = −24.8 °C ± 7.1), followed by bare soil (∆Ts = −22.1 °C ± 5.5), bitumen (∆Ts = −20.9 °C ± 5.8), grass (∆Ts = −18.5 °C ± 4.8) and concrete pavers (∆Ts = −17.5 °C ± 6.0). The results indicate that surface material, but not the tree species, matters for shade cooling of common urban surfaces. Shading bark mulch, bare soil or bitumen will provide the largest reductions in surface temperature, which in turn results in effective mitigation of radiant heat. This refined understanding of the capacity of trees to reduce thermal loads in urban space can increase the effectiveness of urban cooling strategies.

Watering our cities

2012 ◽  
Vol 37 (1) ◽  
pp. 2-28 ◽  
Author(s):  
Andrew M. Coutts ◽  
Nigel J. Tapper ◽  
Jason Beringer ◽  
Margaret Loughnan ◽  
Matthias Demuzere
Keyword(s):  
Thermal Comfort ◽  
Urban Design ◽  
Urban Areas ◽  
Urban Landscape ◽  
Heat Exposure ◽  
Climate Change Impacts ◽  
High Heat ◽  
Future Climate Change ◽  
Surface Cooling ◽  
Human Thermal Comfort

Urban drainage infrastructure is generally designed to rapidly export stormwater away from the urban environment to minimize flood risk created by extensive impervious surface cover. This deficit is resolved by importing high-quality potable water for irrigation. However, cities and towns at times face water restrictions in response to drought and water scarcity. This can exacerbate heating and drying, and promote the development of unfavourable urban climates. The combination of excessive heating driven by urban development, low water availability and future climate change impacts could compromise human health and amenity for urban dwellers. This paper draws on existing literature to demonstrate the potential of Water Sensitive Urban Design (WSUD) to help improve outdoor human thermal comfort in urban areas and support Climate Sensitive Urban Design (CSUD) objectives within the Australian context. WSUD provides a mechanism for retaining water in the urban landscape through stormwater harvesting and reuse while also reducing urban temperatures through enhanced evapotranspiration and surface cooling. Research suggests that WSUD features are broadly capable of lowering temperatures and improving human thermal comfort, and when integrated with vegetation (especially trees) have potential to meet CSUD objectives. However, the degree of benefit (the intensity of cooling and improvements to human thermal comfort) depends on a multitude of factors including local environmental conditions, the design and placement of the systems, and the nature of the surrounding urban landscape. We suggest that WSUD can provide a source of water across Australian urban environments for landscape irrigation and soil moisture replenishment to maximize the urban climatic benefits of existing vegetation and green spaces. WSUD should be implemented strategically into the urban landscape, targeting areas of high heat exposure, with many distributed WSUD features at regular intervals to promote infiltration and evapotranspiration, and maintain tree health.

scholarly journals DEVELOPING MALAYSIAN ROADSIDE TREE SPECIES SELECTION MODEL IN URBAN AREAS

2018 ◽  
Vol 16 (7) ◽  
Author(s):  
Ramly Hasan ◽  
Noriah Othman ◽  
Faridah Ismail
Keyword(s):  
Tree Species ◽  
Urban Areas ◽  
Selection Model ◽  
Urban Trees ◽  
Species Selection ◽  
Sustainable City ◽  
Qualitative Approaches ◽  
Living Organisms ◽  
The Right ◽  
The Relationship

Urban trees are living organisms and vital elements of a city’s infrastructure; thus, they should be considered at every stage of planning design and development. In Malaysia, rapid changes in the environment have indirectly influenced the roadside tree condition such as fallen trees. This is reflected with the statistic increment of public complaints by 39% from 2014 until 2016 regarding the roadside tree problems, which are very worrying for the local authorities. This study aims to develop a Malaysian Roadside Tree Species Selection for guidance in selecting the right tree species for a sustainable city. The objectives of this study are (i) to determine additional attributes in roadside tree species selection, (ii) to examine the relationship between existing and additional attributes and (iii) to develop a Malaysian Roadside Tree Species Selection Model based on these attributes. This research applied the quantitative and qualitative approaches. The results produced a Malaysian Roadside Tree Species Selection Model.

Is Street Tree Diversity Increasing in New York State, USA?

2021 ◽  
Vol 47 (5) ◽  
pp. 196-213
Author(s):  
F.D. Cowett ◽  
N.L. Bassuk
Keyword(s):  
New York ◽  
Tree Species ◽  
Diversity Index ◽  
New York State ◽  
Economic Benefits ◽  
Tree Diversity ◽  
Urban Trees ◽  
Street Trees ◽  
York State ◽  
Street Tree

Diversity in tree populations is viewed as essential for protecting the public investment in urban trees and for preserving the environmental, social, and economic benefits that these trees provide. It is therefore crucial for officials responsible for the management of municipal trees to know the diversity of their municipal tree populations and whether their efforts to increase diversity have been effective or should be modified. We assessed street tree diversity in New York State, USA by analyzing municipal street tree inventory data from two data sets, the first comprised of 75 inventories collated from municipalities, and the second comprised of 32 sets of inventories conducted at multiple points in time. This analysis builds on two previous papers containing similar assessments by analyzing more current data and by calculating diversity index statistics and relative abundance percentages for prevalent street tree species and genera. Findings indicate that there has been substantial progress to increase street tree diversity in New York State. This progress is correlated with reductions in the dominance of Norway maple (Acer platanoides), the state’s most prevalent street tree species (17% of street trees statewide), and in the dominance of maple (Acer), the state’s most prevalent street tree genus (35% of street trees statewide). Work remains to be done to further increase species and genus diversity so as to meet the challenges posed to municipal street tree populations by invasive pests and climate change. Strategies are proposed for accomplishing this.

scholarly journals Identifying Tree Traits for Cooling Urban Heat Islands—A Cross-City Empirical Analysis

Forests ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1064
Author(s):  
Carola Helletsgruber ◽  
Sten Gillner ◽  
Ágnes Gulyás ◽  
Robert R. Junker ◽  
Eszter Tanács ◽  
...  
Keyword(s):  
Ecosystem Services ◽  
Leaf Area ◽  
Tree Species ◽  
Urban Trees ◽  
Cooling Effect ◽  
Site Conditions ◽  
Area Index ◽  
Tree Management ◽  
Urban Heat ◽  
Tree Traits

Research Highlights: This paper presents a cross-city empirical study on micro-climatic thermal benefits of urban trees, using machine-learning analysis to identify the importance of several in situ measured tree physiognomy traits for cooling. Background and Objectives: Green infrastructure and trees in particular play a key role in mitigating the urban heat island (UHI) effect. A more detailed understanding of the cooling potential of urban trees and specific tree traits is necessary to support tree management decisions for cooling our progressively hot cities. The goal of this study was to identify the influence and importance of various tree traits and site conditions. Materials and Methods: Surface temperature, air temperature at 1.1 m and at tree crown height, as well as wet bulb globe-temperature of shaded and fully sun-exposed reference areas, were used to study the cooling effect of seven different urban tree species. For all 100 individuals, tree height, crown base, trunk circumference, crown volume, crown area, leaf area index (LAI) and leaf area density (LAD) were measured. Measurements were conducted in the cities of Dresden, Salzburg, Szeged, and Vienna as representatives for middle European cities in different climate zones. Results: Beside site conditions, tree species, height, height of crown base, as well as trunk circumference, have a great influence on the cooling effect for city dwellers. The trunk circumference is a very valuable indicator for estimating climate regulating ecosystem services and therefore a highly robust estimator for policy makers and tree management practitioners when planning and managing urban green areas for improving the availability and provision of ecosystem services.

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