Effect of tree shades in urban planning in hot-arid climatic regions

Muñoz, Víctor Manuel Gómez; Porta-Gándara, Miguel Ángel; Fernández, José-Luis

doi:10.1016/j.landurbplan.2009.09.002

Cited by 89 publications

(29 citation statements)

References 15 publications

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“…Two possible parameters, tree height and crown volume, have already shown positive correlations with climatic cooling. With increasing tree size and crown, the trees blocked more radiation [30]. Likewise, the density of the crown affected the amount of blocked radiation and surface cooling [10].…”

Section: Estimation Of Surface Cooling Using Tree Characteristicsmentioning

confidence: 99%

Mutual Influences of Urban Microclimate and Urban Trees: An Investigation of Phenology and Cooling Capacity

Stanley

Helletsgruber

Hof

2019

Forests

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This paper presents an empirical study on urban tree growth and regulating ecosystem services along an urban heat island (UHI) intensity gradient. The UHI effect on the length of the growing season and the association of cooling and shading with species, age, and size of trees was studied in Salzburg, Austria. Results show that areas with a low UHI intensity differed from areas with a medium or high UHI intensity significantly in three points: their bud break began later, the leaf discoloration took longer, and the growing season was shorter. After leaves have developed, trees cool the surface throughout the whole growing season by casting shadows. On average, the surfaces in the crown shade were 12.2 • C cooler than those in the sun. The tree characteristics had different effects on the cooling performance. In addition to tree height and trunk circumference, age was especially closely related to surface cooling. If a tree's cooling capacity is to be estimated, tree age is the most suitable measure, also with respect to its assessment effort. Practitioners are advised to consider the different UHI intensities when maintaining or enhancing public greenery. The cooling capacity of tall, old trees is needed especially in areas with a high UHI intensity. In the future, species differences should be examined to determine the best adapted species for the different UHI intensities. The present results can be the basis for modeling future mutual influences of microclimate and urban trees. of heat and thus evaporate the water they store. Through evapotranspiration, the plants not only cool themselves but also the air temperature in the immediate vicinity [4]. Furthermore, urban trees provide indirect temperature cooling by shading the surface. The crown blocks the solar radiation and the surface heats up less. Therefore, due to less radiation, the air temperature under the crown heats up much less as well [5].The extent of the cooling effects depends on various environmental factors and plant characteristics [4]. Many studies deal with the positive benefits of large green spaces, such as city parks, whereas urban trees are rarely in focus. Yet even individual trees show a cooling effect [6]. One study identified correlations between air temperature cooling and leaf color, foliage density, leaf thickness, and structure of the leaves [7]. Another study about surface cooling showed that with an increasing leaf area index (LAI), the asphalt temperature decreases, with this effect being independent of tree species; however, there was no corresponding effect on a grassy surface [8]. Mao et al. studied two streets, one lined with deciduous trees and the other lined with coniferous trees [9]; due to a higher evapotranspiration capacity of the deciduous trees, the temperatures on this street were lower. Differences in cooling performance occur even between different tree species. These differences are related to the trees' characteristics, such as height or crown shape [6]. Gillner and colleagues [10] compared six species of trees...

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Section: Estimation Of Surface Cooling Using Tree Characteristicsmentioning

confidence: 99%

Mutual Influences of Urban Microclimate and Urban Trees: An Investigation of Phenology and Cooling Capacity

Stanley

Helletsgruber

Hof

2019

Forests

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“…wildlife habitats) (Costanza et al 1997;Akbari et al 2001;Grahn and Stigsdotter 2003;Tyrväinen et al 2005;Gill et al 2007;Morgenroth et al 2016). Since large healthy trees have the greatest capacity to deliver these services (Xiao and McPherson 2002;Gratani and Varone 2006;Gómez-Muñoz et al 2010), maintenance of existing trees and planning for future tree plantings are critically important in order to utilise the full scope of potential ecosystem services.…”

Section: Introductionmentioning

confidence: 99%

Vulnerability of ten major Nordic cities to potential tree losses caused by longhorned beetles

Sjöman

Östberg

2019

Urban Ecosyst

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Urban forest and urban trees are currently facing several challenges arising from a changing climate, complex inner-city environments and severe threats of pathogen and insect attacks. The latter have already had serious consequences for many cities, with outbreaks of diseases and pests causing large-scale tree losses that will take a long time to resolve. The pest species Asian longhorned beetle (Anoplophora glabripennis) and citrus longhorned beetle (A. chinensis) have large numbers of host species and genera and can hence be classified as one of the most serious future threats to the urban (and natural) tree landscape. The question is not whether these new threats will arrive in northern Europe, but rather when an infestation will occur and how well prepared are cities to deal with it. This study presents an up-to-date compilation of the urban tree population in 10 major Nordic cities, based on recent tree inventories, and investigates and discusses the effects of an outbreak of the two longhorned beetle species, based on information taken from a review of 35 papers presenting host-related data on these species. Evaluation of the data on host susceptibility to the two longhorned beetles revealed clear differences in tree losses between scenarios, with predicted tree losses of 15-98% in the different cities.

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“…However, in cities, this analysis can prove complex [23], due to several interactions existing, including those with neighboring buildings or the effect of the trees [33] and the fact that each neighborhood must be studied independently [34].…”

Section: Introductionmentioning

confidence: 99%

A Methodology for Buildings Access to Solar Radiation in Sustainable Cities

et al. 2019

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The growing need to improve the environmental and energy sustainability of buildings involves the use of solar radiation incident on their surfaces. However, in cities, this task is complicated due to the constructive geometry that leads to shading between buildings. In this context, this work presents a study of solar access to the façades of buildings in cities. The methodology is based on the determination of the incident annual solar radiation in 121 significant points of each façade considering the twelve representative days of the year. To characterize the influence of the different city typologies on solar access, the urban solar coefficient is proposed. A study of two neighborhoods in Cordoba (Spain) with different urban settings have been analyzed. Specifically, two typologies of neighborhoods have been compared: one with “L-shaped” and “U-shaped blocks” and another with “Grouped blocks”. For both of them, the Urban Solar Coefficient has been calculated, obtaining a higher mean value for the neighborhood with “L-shaped” and “U-shaped blocks” (0.317) than for the one with “Grouped blocks” (0.260). Accordingly, the results show that urban morphology can influence the Urban Solar Coefficient and solar access. Finally, a regression model for each neighborhood has been obtained in order to determine the dependence of the Urban Solar Coefficient on neighborhood geometry factors.

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Effect of tree shades in urban planning in hot-arid climatic regions

Cited by 89 publications

References 15 publications

Mutual Influences of Urban Microclimate and Urban Trees: An Investigation of Phenology and Cooling Capacity

Mutual Influences of Urban Microclimate and Urban Trees: An Investigation of Phenology and Cooling Capacity

Vulnerability of ten major Nordic cities to potential tree losses caused by longhorned beetles

A Methodology for Buildings Access to Solar Radiation in Sustainable Cities

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