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Visual Programming Aided Urban Vegetation Design
Abstract
Advancements in computational design are leveraging Urban Design by reducing human input and increasing multi-layer integration from different discipline into one platform. Therefore in this paper, a design tool has been developed using visual programing to generate vegetation models in urban streets using a bottom-up approach called (Tdesign). The tool provides environmental analysis, construction technical details in order to aid the urban design in the planning stage. City guides and greenery regulations are embedded within the server system of the tools. A case study in Seoul city, south Korea was tested and initial results are gathered and analyzed. The results depict that automatic modeling tool Tdesign is able to produce variety of vegetation models that might aid urban design decision making process. In the future this tool will be simplified for city citizens to use without prior knowledge of scripting in order to shape their city by themselves.
Communities in Phoenix are confronted with numerous challenges that adversely affect human health and safety, with disproportionate impacts on low-income communities. While some challenges are being addressed at the city level, new alliances at the neighbourhood level are initiating community development programmes and projects. This article reports on an intervention study carried out in collaboration with community representatives, city staff, and non-profit organisations to mitigate adverse effects of urban sprawl in the Sky Harbour Neighbourhood in Phoenix. Participatory research was conducted to design and test a tree and shade intervention. Challenges associated with navigating community desires and broader principles of sustainable development are discussed. The study offers a replicable and adaptable intervention research design aimed at empowering communities to meet urban challenges.
Urban forest management is being increasingly recognized as a viable policy vehicle for improving community health, sustainable development, and well-being for city dwellers. To improve our understanding of public concern for the local urban forest, a theoretical framework employing concepts traditionally explored in social–psychological and environmental concern studies was tested using data from a public opinion survey of 800 homeowners living in a major urban area in Southern Appalachia, USA. Publicly available geographic information system (GIS) data were analyzed to measure tree canopy density around survey respondents’ properties. Structural equation modeling was used to test the validity of the hypothesized relationships among the survey-derived constructs and the spatial data as predictors of public support for urban forest protection policy. The results suggest that homeowners living around urban trees place greater importance on various attributes of trees, and that tree knowledge and experience are indirectly and positively related to support for urban forest protection.
In Queensland, land is cleared at high rates to develop pastures for enhanced production and the associated monetary gains. However, pasture production declines over time in cleared pastures until a new equilibrium is reached. The present study focussed on elucidating the reasons for decline in pasture production and finding the key soil properties that are affected due to clearing. Paired sites for cleared and uncleared pastures were selected to represent 3 dominant tree communities of the semi-arid tropics in central Queensland, i.e. Eucalyptus populnea, E. melanophloia, and Acacia harpophylla. The cleared pastures were chosen to represent 3 different durations of time since clearing (5, 11–13, and 33 years) to evaluate the temporal impact of clearing on soil properties. Various soil parameters were studied: macronutrients—available N (NH4⁺and NO3–), total N, and available P; micronutrients—Cu, Fe, Zn, and Mn; exchangeable cations—Ca, Mg, Na, and K (also macronutrients); pHw; and electrical conductivity. Of these, pHw showed a significant response to time of clearing for all 3 tree communities. Soil pHw increased significantly at cleared sites relative to uncleared (native woodland) pastures, and the increase was highly correlated with concentrations of exchangeable Ca, Mg, and Na. The change in soil pHw and exchangeable cations was more evident at >0.30 m soil depth. The increase in soil pHw in cleared pastures decreased the availability of soil nutrients for plant growth and, hence, pasture productivity. The interactions of different soil properties down the profile as a result of changes caused by clearing are important when interpreting the effects of clearing on soil properties.
Abstract The impact of feral Asian water buffalo (Bubalus bubalis) and season of fire on growth and survival of mature trees was monitored over 8 years in the eucalypt savannas of Kakadu National Park. Permanently marked plots were paired on either side of a 25-km-long buffalo-proof fence at three locations on an elevational gradient, from ridge-top to the edge of a floodplain; buffalo were removed from one side of the fence. All 750 trees ≥ 1.4 m height were permanently marked; survival and diameter of each tree was measured annually; 26 species were grouped into four eco-taxonomic groups. The buffalo experiment was maintained for 7 years; trees were monitored an additional year. Fires were excluded from all sites the first 3 years, allowed to occur opportunistically for 4 years and excluded for the final year. Fires were of two main types: low-intensity early dry season and high-intensity late dry season. Growth rates of trees were size-specific and positively related to diameters as exponential functions; trees grew slowest on the two ends of the gradient. Eucalypt mortality rates were 1.5 and 3 times lower than those of pantropics and of arborescent monocots, respectively, but the relative advantage was lost with fires or buffalo grazing. Without buffalo grazing, ground level biomass was 5–8 t ha−1 compared with 2–3 t ha−1, within 3 years. In buffalo-absent plots, trees grew significantly slower on the dry ridge and slope, and had higher mortality across the entire gradient, compared with trees in buffalo-present plots. At the floodplain margin, mortality of small palms was higher in buffalo-present sites, most likely due to associated heavy infestations of weeds. Low-intensity fires produced tree growth and mortality values similar to no-fire, in general, but, like buffalo, provided a ‘fertilization’ effect for Eucalyptus miniata and Eucalyptus tetrodonta, increasing growth in all size classes. High-intensity fires reduced growth and increased mortality of all functional groups, especially the smallest and largest (>35 cm d.b.h.) trees. When buffalo and fires were excluded in the final year, there were no differences in growth or mortality between paired sites across the environmental gradient. After 8 years, the total numbers of trees in buffalo-absent plots were only 80% of the number in buffalo-present plots, due to relatively greater recruitment of new trees in buffalo-present plots; fire-sensitive pantropics were particularly disadvantaged. Since the removal of buffalo is disadvantageous, at least over the first years, to savanna tree growth and survival due to a rebound effect of the ground-level vegetation and subsequent changes in fire-vegetation interactions, process-orientated management aimed at reducing fuel loads and competitive pressure may be required in order to return the system to a previous state. The ‘footprint’ of 30 years of heavy grazing by buffalo has implications for the interpretation of previous studies on fire-vegetation dynamics and for current research on vegetation change in these savannas.
Preferences for urban spaces were studied as a function of spatial category and nine predictor variables: spaciousness, refuge, enclosure, coherence, legibility, complexity, mystery, typicality, and age. A non-metric factor analysis of the preference ratings yielded four categories of urban spaces: Open-Undefined, Well-Structured, Enclosed Settings, and Blocked Views. These categories are similar to the spatial categories proposed for natural environments by S. Kaplan (1979, Assessing Amenity Resource Values. USDA Forest Service General Technical Report RM-68), who stressed openness and spatial definition as bases for categorization. The Well-Structured category was best liked, with the other categories not very well liked and about equal in preference. Regression analyses revealed three variables as consistent predictors of preference. Coherence and complexity were positively related to preference, and age was negatively related. Overall, the results support the Kaplans' proposal that both spatial and non-spatial factors are important in categorizing environments and in explaining environmental preferences.
A modeling study using hourly meteorological and pollution concentration data from across the coterminous United States demonstrates that urban trees remove large amounts of air pollution that consequently improve urban air quality. Pollution removal (O3, PM10, NO2, SO2, CO) varied among cities with total annual air pollution removal by US urban trees estimated at 711,000 metric tons ($3.8 billion value). Pollution removal is only one of various ways that urban trees affect air quality. Integrated studies of tree effects on air pollution reveal that management of urban tree canopy cover could be a viable strategy to improve air quality and help meet clean air standards.
This paper investigates the use of solar energy in urban areas as exemplified by Famagusta in Cyprus. All the climatic and geographic factors were analyzed to compute the solar energy potential for Famagusta City. Next, the solar energy utilization potential in the Social Housing Complex (SHC) district of Famagusta was investigated in detail. The effective parameters of solar energy, including climatic factors, radiation types, geographic parameters, orientation techniques, height to width ratio (H/W) and landscape analysis, were evaluated based on Famagusta using DuffieBeckman and Stephenson's cousin methods. The rate of irradiation solar energy was analyzed for horizontal, vertical and tilted surfaces of blocks and routes in the SHC in Famagusta City using Ladybug for Rhino and MS Excel software programs. The results of this study showed that the district landscape is very poor from a solar energy point of view. While there is a great source of solar energy producing extreme heat, the solar energy is not utilized properly, as the district is not walkable, especially in the afternoons. It is recommended that pedestrians be helped by adding hardwood trees, by using solar panels to generate renewable power for lightning, and by using permeable materials for pavements.
In an increasingly urbanized world, air pollution mitigation is considered one of most important issues in city planning. Urban trees help to improve air quality by facilitating widespread deposition of various gases and particles through the provision of large surface areas as well as through their influence on microclimate and air turbulence. However, many of these trees produce wind-dispersed pollen (a known allergen) and emit a range of gaseous substances that take part in photochemical reactions – all of which can negatively affect air quality. The degree to which these air-quality impacts are manifested depends on species-specific tree properties: that is, their “traits”. We summarize and discuss the current knowledge on how such traits affect urban air pollution. We also present aggregated traits of some of the most common tree species in Europe, which can be used as a decision-support tool for city planning and for improving urban air-quality models.
Many inhabitants of cities throughout the world suffer from health problems and discomfort that are caused by overheating of urban areas, and there is compelling evidence that these problems will be exacerbated by global climate change. Most cities are not designed to ameliorate these effects although it is well-known that this is possible, especially through evidence-based climate-responsive design of urban open spaces. Urban parks and green spaces have the potential to provide thermally comfortable environments and help reduce vulnerability to heat stress. However, in order for them to provide this function, parks must be designed within the context of the prevailing climate and predicted future climates. To analyze the effects of elements that alter microclimate in parks, we used human energy budget simulations. We modelled the outdoor human energy budget in a range of warm to hot climate zones and interpreted the results in terms of thermal comfort and health vulnerability. Reduction of solar radiant input with trees had the greatest effect in all test cities. Reduction in air temperature was the second-most important component, and in some climates was nearly as important as incorporating shade. We then conducted similar modelling using predicted climates for the middle of the century, emphasizing the importance of city-level efforts for park design to assist in minimizing future climate-related urban health risks. These simulations suggested that heat waves in many climates will produce outdoor environments where people will be in extreme danger of heat stress, but that appropriately designed parks can reduce the threat.
This study aimed to explore people's perception of tree planting in street canyons and the perceived tree impacts through a questionnaire survey. Also, by using a discrete choice experiment, it aimed to reveal how people performed tradeoffs among three streetscape attributes: namely permeability (i.e. spacing between buildings), aspect ratio (i.e. ratio of street width to building height), and tree planting. A secondary aim was to determine respondent's willingness to pay for streetscape features and tree planting. Despite published research results that indicate tree planting can have a negative impact on air quality, the survey results from 509 respondents in Hong Kong indicated that the majority of them held positive views of tree planting in street canyons. The probability of having an overall positive view was found to be higher if an individual perceived that trees could improve air quality, provide shading or did not obstruct footpaths. The preferred streetscape was high permeability, regardless of whether respondents thought that trees could or could not contribute to improving air quality. However respondents who perceived that trees could improve air quality preferred tree planting at both sides of the street over lower aspect ratio whereas those who perceived that trees did not improve air quality preferred low aspect ratio over tree planting at both sides of the street. Both sets of respondents did however agree on the preferred order of tree planting options, namely planting on both sides of the street was preferred to planting at the center of the street which in turn was preferable to no tree planting at all. The overall willingness to pay was estimated to be HK132.4 and HK$121.1 per month for high permeability, street-level tree planting and low aspect ratio, respectively. The study clearly identifies high permeability as the most preferred planning option. However, the perception held by the majority of respondents that trees can improve air quality is contrary to recent research findings. This poses a dilemma for urban planners in that schemes that may be more beneficial, i.e. low aspect ratio, may face more public opposition than less beneficial schemes involving tree planting. Although the study was conducted in Hong Kong the findings should be applicable to other modern metropolises characterized by high rise buildings.
Flow and dispersion of traffic-emitted pollutants were studied in a generic urban neighborhood for various avenue-tree layouts by employing 3D steady RANS simulations with the realizable k-ε turbulence model. In comparison to the tree-free situation quantitative and qualitative changes with flow reversal in the wind field were observed. Low to moderate increases (<13.2%) in the neighborhood-averaged pollutant concentration were found at pedestrian level. An approximately 1% increase in the neighborhood-averaged concentration was obtained with each percent of the street canyon volumes being occupied by vegetation for occupation fractions between 4 and 14%. The overall pattern of concentration changes relative to the tree-free situation was similar for all avenue-tree layouts. However, pronounced locally restricted decreases or increases in concentration (-87 to +1378%) occurred. The results indicate the necessity to account for existing or planned avenue-trees in neighborhood scale dispersion studies. Their consideration is prerequisite for reliable urban air quality assessment.
Copyright © 2014 Elsevier Ltd. All rights reserved.
To determine if trees in urban or ornamental plantings are more susceptible to attack and receive more damage to foliage by herbivores than trees in natural forests, we compared the amount of leaf damage caused by several guilds of insects feeding on seven species of native, broadleaf trees in two geographic locations.
Total leaf damage did not differ significantly between urban or ornamental and natural forests, although trees in natural forests tended to have slightly higher levels of leaf damage.
Damage caused by chewing insects was consistently higher on trees in natural forests than in urban or ornamental plantings. All other feeding guilds showed no consistent pattern in levels of damage between the two habitats.
Total damage levels were highest on canopy trees and lowest on understorey trees.
These results are inconsistent with the view that trees in urban or ornamental settings are more susceptible to insect attack than trees in natural forests.
The lower level of foliar damage caused by chewing insects on trees in urban or ornamental plantings may arise because of low rates of dispersal by insects into urban environments, higher levels of plant resistance to insect attack in urban or ornamental plantings, or lower survival rates of herbivorous insects in urban environments.
This paper first discusses the aerodynamic effects of trees on local scale flow and pollutant concentration in idealized street canyon configurations by means of laboratory experiments and Computational Fluid Dynamics (CFD). These analyses are then used as a reference modelling study for the extension a the neighbourhood scale by investigating a real urban junction of a medium size city in southern Italy.
A comparison with previous investigations shows that street-level concentrations crucially depend on the wind direction and street canyon aspect ratio W/H (with W and H the width and the height of buildings, respectively) rather than on tree crown porosity and stand density. It is usually assumed in the literature that larger concentrations are associated with perpendicular approaching wind. In this study,
we demonstrate that while for tree-free street canyons under inclined wind directions the larger the aspect ratio the lower the street-level concentration, in presence of trees the expected reduction of street-level concentration with aspect ratio is less pronounced.
Observations made for the idealized street canyons are re-interpreted in real case scenario focusing on the neighbourhood scale in proximity of a complex urban junction formed by street canyons of similar aspect ratios as those investigated in the laboratory. The aim is to show the combined influence of building morphology and vegetation on flow and dispersion and to assess the effect of vegetation on local concentration levels. To this aim, CFD simulations for two typical winter/spring days show that trees contribute to alter the local flow and act to trap pollutants. This preliminary study indicates that failing to account for the presence of vegetation, as typically practiced in most operational dispersion models, would result in non-negligible errors in the predictions.
Evidence suggests that allergic respiratory diseases such as hay fever and bronchial asthma have become more common world-wide in the last two decades, and the reasons for this increase are still largely unknown. A major responsible factor could be outdoor air pollution, derived from cars and other vehicles. Studies have demonstrated that urbanization and high levels of vehicle emissions and westernized lifestyle is correlated with the increasing frequency of pollen-induced respiratory allergy. People who live in urban areas tend to be more affected by pollen-induced respiratory allergy than those from of rural areas. Pollen allergy has been one of the most frequent models used to study the interrelationship between air pollution and respiratory allergic diseases. Pollen grains or plant-derived paucimicronic components carry allergens that can produce allergic symptoms. They may also interact with air pollution (particulate matter, ozone) in producing these effects. There is evidence that air pollutants may promote airway sensitization by modulating the allergenicity of airborne allergens. Furthermore, airway mucosal damage and impaired mucociliary clearance induced by air pollution may facilitate the access of inhaled allergens to the cells of the immune system. In addition, vegetation reacts with air pollution and environmental conditions and influence the plant allergenicity. Several factors influence this interaction, including type of air pollutants, plant species, nutrient balance, climatic factors, degree of airway sensitization and hyperresponsiveness of exposed subjects.
Well-designed public open space (POS) that encourages physical activity is a community asset that could potentially contribute to the health of local residents.
In 1995-1996, two studies were conducted-an environmental audit of POS over 2 acres (n =516) within a 408-km2 area of metropolitan Perth, Western Australia; and personal interviews with 1803 adults (aged 18 to 59 years) (52.9% response rate). The association between access to POS and physical activity was examined using three accessibility models that progressively adjusted for distance to POS, and its attractiveness and size. In 2002, an observational study examined the influence of attractiveness on the use of POS by observing users of three pairs of high- and low-quality (based on attractiveness) POS matched for size and location.
Overall, 28.8% of respondents reported using POS for physical activity. The likelihood of using POS increased with increasing levels of access, but the effect was greater in the model that adjusted for distance, attractiveness, and size. After adjustment, those with very good access to large, attractive POS were 50% more likely to achieve high levels of walking (odds ratio, 1.50; 95% confidence level, 1.06-2.13). The observational study showed that after matching POS for size and location, 70% of POS users observed visited attractive POS.
Access to attractive, large POS is associated with higher levels of walking. To increase walking, thoughtful design (and redesign) of POS is required that creates large, attractive POS with facilities that encourage active use by multiple users (e.g., walkers, sports participants, picnickers).
In Chinese cities, air pollution has become a serious and aggravating environmental problem undermining the sustainability of urban ecosystems and the quality of urban life. Besides technical solutions to abate air pollution, urban vegetation is increasingly recognized as an alternative ameliorative method by removing some pollutants mainly through dry deposition process. This paper assesses the capability and monetary value of this ecosystem service in Guangzhou city in South China. The results indicated an annual removal of SO(2), NO(2) and total suspended particulates at about 312.03 Mg, and the benefits were valued at RMB90.19 thousand (US$1.00=RMB8.26). More removal was realized by recreational land use due to a higher tree cover. Higher concentration of pollutants in the dry winter months induced more removal. The lower cost of pollution abatement in China generated a relatively subdued monetary value of this environmental benefit in comparison with developed countries. Younger districts with more extensive urban trees stripped more pollutants from the air, and this capacity was anticipated to increase further as their trees gradually reach final dimensions and establish a greater tree cover. Tree cover and pollutant concentration constitute the main factors in pollutant removal by urban trees. The efficiency of atmospheric cleansing by trees in congested Chinese cities could be improved by planting more trees other than shrubs or grass, diversifying species composition and biomass structure, and providing sound green space management. The implications for greenery design were discussed with a view to maximizing this ecosystem service in Chinese cities and other developing metropolises.
The allergenic content of the atmosphere varies according to climate, geography and vegetation. Data on the presence and prevalence of allergenic airborne pollens, obtained from both aerobiological studies and allergological investigations, make it possible to design pollen calendars with the approximate flowering period of the plants in the sampling area. In this way, even though pollen production and dispersal from year to year depend on the patterns of preseason weather and on the conditions prevailing at the time of anthesis, it is usually possible to forecast the chances of encountering high atmospheric allergenic pollen concentrations in different areas.
Aerobiological and allergological studies show that the pollen map of Europe is changing also as a result of cultural factors (for example, importation of plants such as birch and cypress for urban parklands), greater international travel (e.g. colonization by ragweed in France, northern Italy, Austria, Hungary etc.) and climate change. In this regard, the higher frequency of weather extremes, like thunderstorms, and increasing episodes of long range transport of allergenic pollen represent new challenges for researchers.
Furthermore, in the last few years, experimental data on pollen and subpollen‐particles structure, the pathogenetic role of pollen and the interaction between pollen and air pollutants, gave new insights into the mechanisms of respiratory allergic diseases.
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