Matching Items (3)

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Characterizing sustainable performance and human thermal comfort in designed landscapes of Southwest desert cities

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During summer 2014, a study was conducted as part of the Landscape Architecture Foundation Case Study Investigation to analyze features of three sustainably designed landscapes. Each project was located in

During summer 2014, a study was conducted as part of the Landscape Architecture Foundation Case Study Investigation to analyze features of three sustainably designed landscapes. Each project was located in a southwest desert city: Civic Space Park in Phoenix, AZ, the Pete V. Domenici US Courthouse Sustainable Landscape Retrofit in Albuquerque, NM, and George "Doc" Cavalliere Park in Scottsdale, AZ. The principal components of each case study were performance benefits that quantified ongoing ecosystem services. Performance benefits were developed from data provided by the designers and collected by the research team. The functionality of environmental, social, and economic sustainable features was evaluated. In southwest desert cities achieving performance benefits such as microclimate cooling often come at the cost of water conservation. In each of these projects such tradeoffs were balanced by prioritizing the project goals and constraints.

During summer 2015, a study was conducted to characterize effects of tree species and shade structures on outdoor human thermal comfort under hot, arid conditions. Motivating the research was the hypothesis that tree species and shade structures will vary in their capacity to improve thermal comfort due to their respective abilities to attenuate solar radiation. Micrometeorological data was collected in full sun and under shade of six landscape tree species and park ramadas in Phoenix, AZ during pre-monsoon summer afternoons. The six landscape tree species included: Arizona ash (Fraxinus velutina Torr.), Mexican palo verde (Parkinsonia aculeata L.), Aleppo pine (Pinus halepensis Mill.), South American mesquite (Prosopis spp. L.), Texas live oak (Quercus virginiana for. fusiformis Mill.), and Chinese elm (Ulmus parvifolia Jacq.). Results showed that the tree species and ramadas were not similarly effective at improving thermal comfort, represented by physiologically equivalent temperature (PET). The difference between PET in full sun and under shade was greater under Fraxinus and Quercus than under Parkinsonia, Prosopis, and ramadas by 2.9-4.3 °C. Radiation was a significant driver of PET (p<0.0001, R2=0.69) and with the exception of ramadas, lower radiation corresponded with lower PET. Variations observed in this study suggest selecting trees or structures that attenuate the most solar radiation is a potential strategy for optimizing PET.

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Date Created
  • 2016

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Soil biogeochemical consequences of the replacement of residential grasslands with water-efficient landscapes

Description

As a result of growing populations and uncertain resource availability, urban areas are facing pressure from federal and state agencies, as well as residents, to promote conservation programs that provide

As a result of growing populations and uncertain resource availability, urban areas are facing pressure from federal and state agencies, as well as residents, to promote conservation programs that provide services for people and mitigate environmental harm. Current strategies in US cities aim to reduce the impact of municipal and household resource use, including programs to promote water conservation. One common conservation program incentivizes the replacement of water-intensive turfgrass lawns with landscapes that use less water consisting of interspersed drought-tolerant shrubs and trees with rock or mulch groundcover (e.g. xeriscapes, rain gardens, water-wise landscapes). A handful of previous studies in experimental landscapes have shown that converting a turfgrass yard to a shrub-dominated landscape has the potential to increase rates of nitrate (NO3-) leaching. However, no studies have examined the drivers or patterns across diverse management practices. In this research, I compared soil nutrient retention and cycling in turfgrass and lawn-alternative xeriscaped yards along a chronosequence of time since land cover change in Tempe, Arizona, in the semi-arid US Southwest. Soil inorganic extractable nitrogen (N) pools were greater in xeriscapes compared to turfgrass lawns. On average xeriscapes contained 2.5±0.4 g NO3--N/m2 in the first 45 cm of soil, compared to 0.6±0.7 g NO3--N/m2 in lawns. Soil NO3--N pools in xeriscaped yards also varied significantly with time: pools were largest 9-13 years after cover change and declined to levels comparable to turfgrass at 18-21 years. Variation in soil extractable NO3--N with landscape age was strongly influenced by management practices that control soil water availability, including shrub cover, the presence of sub-surface plastic sheeting, and the frequency of irrigation. This research is the first to explore the ecological outcomes and temporal dynamics of an increasingly common, ‘sustainable’ land use practice that is universally promoted in US cities. Our findings show that transitioning from turfgrass to water-efficient residential landscaping can lead to an accumulation of NO3--N that may be lost from the soil rooting zone over time, through leaching following irrigation or rainfall. These results have implications for best management practices to optimize the benefits of water-conserving residential yards.

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Date Created
  • 2015

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Exploring resident's xeriscaping preference: the influence of ecological world view and place identity

Description

For the last 10 years, the American Southwest has been experiencing the most persistent drought conditions on record. Based on future climactic predictions, there is a dire need to reduce

For the last 10 years, the American Southwest has been experiencing the most persistent drought conditions on record. Based on future climactic predictions, there is a dire need to reduce water usage within Phoenix. An environmentally responsible behavior such as low water use landscaping (xeriscaping), has been shown to reduce household water consumption by 40%-70%. While much is known regarding the relationship between socio-demographics and xeriscaping choices, the influence of other variables remains to be explored. Using data from the 2017 Phoenix Area Social Survey, this study investigates the influence of two additional variables - ecological worldview and place identity on xeriscaping choice. Data was analyzed using two models - Ordinary Least Squares (OLS) and Linear Probability Model (LPM). Ecological worldview and place identity, along with income, ethnicity, and gender, were all found to be positively related to xeriscape preference. Additionally, when compared to the LPM, the traditional OLS was found to still be the most robust and appropriate model when measuring landscape preference. Finally, results suggested that programs to foster identity with the local desert mountain parks may help to increase xeriscaping in the Valley and thus lower residential water use.

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Date Created
  • 2018