Carlos Bartesaghi Koc

Urban voids, such as vacant lots, brownfields, fallow land, wasteland, and the spaces between buildings, have the potential to serve as habitats for a diverse range of plants. However, their value for plant conservation remains understudied because of their informal and neglected nature. The aim of this systematic review is to consider the potential for urban voids to contribute to urban plant biodiversity. A total of 55 studies from 14 countries were analysed for geographical trends, factors influencing plant biodiversity, research methods, and relevant environmental parameters. The results of this study show that the factors influencing the plant diversity of urban voids can be divided into three main categories: biophysical, temporal, and landscape factors. Biophysical factors, such as size, age, soil, and vegetation structure, as well as temporal factors, including site management and human interventions, are the most important at the site-level scale. In contrast, landscape factors, such as the location and distance from other green spaces, are more dominant at the larger urban scale. The review has identified a significant limitation in the available literature, with relatively few studies examining the influence of urban voids’ shape, ownership, and microclimate on biodiversity. With respect to research methods, the results suggest a recent increase in the use of GIS-based and remote sensing techniques to investigate the plant diversity of urban voids. The findings discussed in this paper indicate the need for further research to comprehensively understand the factors that promote urban vegetation diversity in urban voids.

Urban and building typologies have a serious impact on the urban climate and determine at large the magnitude of the urban overheating and urban heat island intensity. The present study aims to analyze the impact of various city typologies and urban planning characteristics on the mitigation of the urban heat island. The effect of the building height, street width, aspect ratio, built area ratio, orientation, and dimensions of open spaces on the distribution of the ambient and surface temperature in open spaces is analyzed using the Sydney Metropolitan Area as a case study for both unmitigated and mitigated scenarios. Fourteen precincts are developed and simulated using ENVI-met the simulation tool. The ambient temperature, surface temperature, and wind speed are extracted. The parameter ‘Gradient of the Temperature Decrease along the Precinct Axis’ (GTD) is introduced to study the cooling potential of the various precincts. In the mitigated precincts, the GTD ranges between 0.01 K/m to 0.004 K/m. In the non-mitigated precincts, the GTD ranges between 0.0093 K/m to 0.0024 K/m. A strong correlation is observed between the GTD of all the precincts, with and without mitigation, and their corresponding average aspect ratio, (Height of buildings to Width of streets). The higher the aspect ratio of the precinct, the lower the cooling potential. It is also observed that the higher the Built Area Ratio of the precincts, the lower the cooling contribution of the mitigation measures.

The local climate zones (LCZ) scheme has attracted the interest of climate researchers as it enables the standardized study of urban heat islands by combining thermal and physical parameters of built and natural structures. Most recent work on LCZ has concentrated on understanding air temperature differences, adapting the scheme to different contexts and improving satellite-based classification methods. However, studies using very high-resolution imagery, including 3-D descriptors and analyzing their land surface temperature (LST) variability are scarcer. Since a correct delineation of LCZ implies significant temperature differences among classes, the aims of this study are 1) to test a GIS-based method for the classification of LCZ based on cut-off values valid to the Australian context; and 2) to examine the quality of classifications by analyzing the LST variability among LCZ using high-resolution airborne remote sensing data. Results show that diurnal and nocturnal mean LSTs significantly differ among most LCZs. Welch's ANOVA and subsequent post hoc tests for pairwise comparisons also demonstrate that these differences prevail for 71.8% of zones during the daytime and 73.6% of zones at night. Overall, LCZs A, 8, and 3 are the most distinguishable zones during the daytime and LCZs D, G, 1, 4, and 5 are well differentiated at night. In contrast, LCZs 1 and 4 are the least distinguishable at daytime and LCZs 10, A, and E are not well differentiated at night. The present study has successfully validated the present airborne-based classification method which is contingent on further accuracy assessment and improvements.

There is ample evidence of the cooling effects of green infrastructure (GI) that has been extensively documented in the literature. However, the study of the thermal profiles of different GI typologies requires the classification of urban sites for a meaningful comparison of results, since specific spatial and physical characteristics produce distinct microclimates. In this paper, the Local Climate Zones (LCZ), a scheme of thermally relatively homogeneous urban structures proposed by Stewart and Oke, was used for mapping and classifying the urban morphology of a study area in Sydney, Australia. A GIS-based workflow for an automated classification based on airborne remote sensing data is presented. The datasets employed include high resolution hyperspectral imagery, LiDAR (light detection and ranging), and cadastral information. This paper also proposes a standardised and replicable workflow that can be applied by researchers and practitioners from novices to experts. The results presented here provide evidence that LCZ can be effectively derived from multiple airborne remote sensing datasets, which can then be used to identify morphological profiles to support varied climatological studies. Future stages of this research include coupling this method with a newly developed GI typology for a more comprehensive analysis of the cooling effects of GI by taking into account the morphological disparities of LCZ.