$D:\My Journal\Logo\kam logo.JPG$	Journal of Contemporary Urban Affairs
2024, Volume 8, Number 1, pages 121–140 Original scientific paper Towards Biodiverse Urban Public Spaces: A Morphological Study in Milan ^1Assistant Prof. Dr. Fabio Lepratto* , ²Assistant Prof. Dr. Francesca Zanotto ^{1& 2}National Biodiversity Future Center, Department of Architecture and Urban Studies, Politecnico di Milano, Italy ¹E-mail: Fabio.lepratto@polimi.it , ²E-mail: Francesca.zanotto@polimi.it
ARTICLE INFO: Article History: Received: 9 April 2024 Revised: 18 June 2024 Accepted: 25 June 2024 Available online: 30 June 2024 Keywords: Urban Biodiversity; Architectural Composition; Urban Design; Public Spaces; Urban Morphology.	ABSTRACT This study explores the role of architectural composition and urban design in enhancing urban biodiversity, which is crucial for improving ecosystem services and overall urban sustainability. It addresses a gap in the literature by providing empirical evidence on how specific morphological characteristics in urban regeneration projects can support biodiversity, emphasizing the overlooked potential of architectural morphologies in urban greening strategies. Focusing on five recent urban regeneration projects in Milan, the study conducts a detailed analysis of built volumes and green areas. Quantitative measurements, such as green area compactness, perimeter edge continuity, and building front permeability, were combined with qualitative assessments to identify correlations between urban morphology and biodiversity potential. The analysis revealed three distinct urban morphologies—"Central Park," "Fluid Park," and "Garden Between Houses"—each offering unique conditions for accessibility and biodiversity development. These morphologies demonstrate varying capacities for conserving, promoting, and implementing urban biodiversity, depending on their interaction with the surrounding urban fabric. By establishing a clear correlation between urban morphology and biodiversity potential, this research highlights the critical role that architects and urban designers play in addressing the emerging challenge of enhancing urban biodiversity. It provides valuable insights for future urban regeneration projects aimed at fostering sustainable and biodiverse urban environments.

This article is an open-access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) $C:\Users\Hourakhsh\Desktop\CC_By_2020_licnece1.jpg$ Publisher’s Note: Journal of Contemporary Urban Affairs stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.
	JOURNAL OF CONTEMPORARY URBAN AFFAIRS (2024), 8(1), 121-140. https://doi.org/10.25034/ijcua.2024.v8n1-7 www.ijcua.com Copyright © 2024 by the Author(s).
Highlights:		Contribution to the field statement:
- Architectural composition in urban design can significantly enhance biodiversity in public spaces by optimizing morphological characteristics. - Distinct urban morphologies, such as "Central Park," "Fluid Park," and "Garden Between Houses," influence biodiversity potential through their interaction with surrounding urban fabric. - Urban regeneration projects with increased green area compactness and perimeter edge continuity foster higher biodiversity and ecological connectivity. - Milan's urban regeneration efforts demonstrate that specific settlement forms can successfully integrate biodiversity with accessible, visible public spaces.		By identifying the correlation between urban morphology and biodiversity potential, this research contributes to the field of urban studies and architectural studies by shedding light on the role that architectural composition and urban design – and therefore architects and urban designers - can play in the emerging challenge of designing urban spaces aimed at conserving and enhancing urban biodiversity, facilitating ecosystem services provision and creating accessible, safe and inclusive public spaces.

*Corresponding Author:

National Biodiversity Future Center, Department of Architecture and Urban Studies, Politecnico di Milano, Italy

Email address: Fabio.lepratto@polimi.it

1. Introduction

1.1 Background and Context

The preservation and promotion of urban biodiversity are crucial for achieving the objectives outlined in the European Union’s Biodiversity Strategy for 2030: ecosystem restoration, ecological balance, human well-being, and overall urban sustainability (European Commission, Directorate-General for Environment, 2021). With a population share of about 50% in 2020, projected to increase to 58% over the next 50 years, the responsibility for the majority of the world’s carbon emissions (Moran, et al., 2018) and ongoing threatening dynamics as urban sprawl, irreversible land-use changes, resource and energy-intensive consumption patterns, urban areas are a critical field of study to understand how to conserve and improve biodiversity globally (Luederitz, et al., 2015) and, at the same time, learn how to intervene in the built environment to provide cities with ecosystems services: a range of benefits granted by natural ecosystems (Millennium Ecosystem Assessment, 2005) (Danley & Widmark, 2016), involving in cities the improvements in air quality and microclimate regulation, recreational opportunities for nature experience and sports activities, water regulation and stormwater runoff control (Ronchi & Salata, 2022). The enhancement of green infrastructure is also connected with multiple health benefits (Dipeolu, Akpa, & Fadamiro, 2020) and can also promote crucial investment and business opportunities to foster Europe’s economic recovery following the COVID-19 crisis (European Commission, Directorate-General for Environment, 2021).

This research is situated within the scientific activity of the National Biodiversity Future Center (NBFC), one of the five centres supported by the Italian post-pandemic National Recovery and Resilience Plan, focusing on frontier research aligned with European research priorities. The NBFC’s goal is to generate knowledge for conserving, restoring, monitoring, and enhancing Italian and Mediterranean biodiversity. NBFC’s Spoke 5 focuses on the generation of knowledge regarding the conservation and improvement of urban biodiversity. Urban public spaces in Italy still exhibit a considerable lack of biodiversity. Nevertheless, documents such as Law No. 10 of January 14, 2013, “Regulations for the Development of Urban Green Spaces”, the National Strategy for Public Green Areas ^[1] issued in 2018, and the integration of the EU’s Biodiversity Strategy for 2030 into a national strategy ^[2], reveal a regulatory and cultural context where the role of urban biodiversity is acknowledged as crucial for creating sustainable and resilient urban environments. Therefore, the city of Milan serves as a significant context for the investigation presented in this paper: it boasts a high-quality, consolidated urban environment that has experienced rapid growth and densification over the last two decades, particularly in regeneration areas within and around the city centre. This growth has highlighted the prominent role of architecture in embodying the city’s economic and cultural development. Simultaneously, both the municipality and the metropolitan city are committed to improving the quality of public spaces through forestation policies and naturalization programs.

1.2 Problem Statement and Research Gap

Several frameworks and disciplinary approaches have been developed globally in recent years to design greener and more biodiverse cities while ensuring their functionality and livability (Beatley & Newman, 2013; Garrard, et al., 2018; Kirk, et al., 2021; Dizdaroğlu, 2022). In such models, the architectural composition is often relegated to a peripheral role in favour of larger-scale, ecology-related tools and systemic approaches, which are believed to be more effective in addressing complex, multifaceted, and extensive issues related to the integration of nature in the built environment in a comprehensive manner. However, architectural composition can provide substantial contributions to the challenge of envisioning urban public spaces that conserve and implement biodiversity and, at the same time, are also beautiful, safe and accessible for citizens.

The paper explores the disciplinary contribution that architectural composition and urban design can provide to the conservation and enhancement of urban biodiversity. It investigates the possibility of morphological definition of open spaces and spatial conditions that are potentially conducive to the development of organic components, the increase of biodiversity, and the provision of ecosystem services while, at the same time, outlining highly accessible and visible public green spaces. Combining the tradition of morphological and typological studies (Muratori, 1963; Caniggia, 1979) with the more recent research on urban biodiversity is an interdisciplinary approach that remains underdeveloped yet holds great potential. In recent years, a relatively limited number of studies have attempted this combination. Among these, Ståhle (2005) and Marcus (2008) have explored the connections between urban form and its influence on environmental ecology. Marcus and Colding (2011) discuss how to shape urban development towards more sustainable directions. Benelli and Pellegrini (2013) propose a methodology to relate settlement forms to different climatic and environmental performances. Andersson and Colding (2014) delve into how built urban forms influence biodiversity by comparing different suburban residential patterns in relation to their surroundings. More recently, Palazzo (2022) reflected on the potential to bridge urban morphology and urban ecology, starting from conceptualising cities as urban landscapes (Andersson, 2006; Forman, 2008; Forman, 2014) to identify patterns that better support urban resilience within the historic city framework. Much like the present study, these studies share a common trait: the development of geometric descriptions of urban forms pertinent to ecosystem services and environmental issues. They all advocate for a more interdisciplinary approach, where each discipline must acknowledge its potential role and express its limits to foster collaboration. This investigation aims to further contribute to the relationship between urban form and biodiversity potential, particularly by closely examining newly constructed contexts in medium-to-high-density urban areas resulting from regeneration projects.

1.3 Objectives and Contribution to the Field

This research has multiple objectives: 1) define a new methodology for the morphological analysis of urban open spaces aimed at recognizing biodiverse potentials in urban morphologies; 2) identify urban and architectural morphologies that are more conducive to supporting the conservation and development of urban biodiversity, as well as the provision of ecosystem services, and to generating more favourable conditions for citizens’ interaction with nature; 3) generate useful knowledge to enhance biodiversity in new constructions and interventions in the existing built environment as a basis for the future definition of design guidelines; 4) considering the multidisciplinary of this issue, raise questions that can be addressed collaboratively with other disciplines to proceed in the direction of defining design guidelines.

The research focuses on five case studies selected from the Atlas of Urban Regeneration of the Municipality of Milan ^[3], on which quantitative analysis was performed at the urban and architectural scale, combined with qualitative remarks.

This study’s expected contribution to the field of architecture, and more broadly, to the challenge of designing more biodiverse urban public spaces, revolves around the generation of new knowledge on the role that architectural composition and urban design can play in conserving and enhancing urban biodiversity and in the facilitation of ecosystem services provision. Additionally, the present research aims to provide guidance for integrated design approaches beneficial to designers and public administrations dedicated to enhancing urban biodiversity and ecosystem services in their cities (especially aimed at contexts similar to Milan).

1.4 Significance and Structure of the Paper

This research paper is organized into six parts. Following an introduction, the second part emphasizes the marginal role that architectural composition still plays in initiatives to enhance biodiversity in urban spaces. The third part introduces the analysis methodology, covering also the choice of the case study of Milan, highlighting its importance as a highly significant research context due to the rapid expansion of buildings over the last two decades and the attention given to environmental performances of open spaces. The analysis methodology is based on a quantitative approach, combined with qualitative remarks, applied to five case studies within the city of Milan. Parts four and five present the findings and their discussion. Finally, the sixth part outlines conclusions regarding the main contribution of this paper to the field, presenting the limitations of the current study and the main perspectives for development towards a comprehensive and more robust research methodology.

2. Architectural Composition for Urban Biodiversity: An Overlooked Potential

In recent years, several frameworks and disciplinary approaches have been developed globally to design greener cities. Landscape Urbanism (Mostafavi & Najle, 2003) (Waldheim, 2006) proposes planning cities through the design of the landscape rather than buildings and infrastructure, imagining new relationships and possibilities among the elements involved, reasoning with horizontal alignments rather than vertical development and introducing an understanding of the dimension of time and the changing nature of environments into the planning process (Corner, 2006). Ecological Urbanism (Mostafavi & Doherty, 2010), stemming from Landscape Urbanism, bends the focus towards envisioning and planning cities not only as cultural constructs but also as artificial ecosystems, to be designed and organized based on their demand and supply of resources (Hagan, 2014).

Within these approaches, the architectural scale is often overlooked among the levels of intervention at which it is possible to make substantial contributions to envisioning biodiverse urban public spaces. Architecture is a critical field in the challenge to make cities more sustainable and biodiverse: the construction sector is responsible directly and indirectly for more than one-third of global energy and process-related CO2 emissions (Aste, Del Pero, & Leonforte, 2022), and buildings play a crucial role in the formation of urban heat islands; furthermore, architectural design holds the potential to shape the built environment and therefore drive or support greening strategies and integrated and sustainable models for urban biodiversity. Several recent innovations in the practice show through prototype buildings the feasibility of integrating trees and greening in architecture, especially in the framework of NBS at the building scale (World Bank, 2021), entailing the construction of new green roofs and green façades on new buildings or existing buildings. Biophilic design, on the other hand, poses humans’ innate connection to nature as the foundation of an approach aiming to incorporate natural elements and references into the built environment to improve physical and mental well-being, enhance productivity, and promote a sense of harmony (Kellert, Heerwagen, & Mador, 2008). However, as far as efficient systems, in most cases, these strategies are not involved in the compositive conceptualization of the building: they represent “applied” solutions that are integrated into the design process at a later stage than other fundamental disciplinary tools of architectural design. A similar issue exists with the framework known as Animal-Aided Design (Hauck & Weisser, 2019) which, despite looking at the urban environment as an integration of scales and dimensions, including architecture, this approach is more oriented towards applied strategies on and around buildings, rather than investigating the effect of their outlining, composition and massing towards biodiversity.

Apart from these innovations, there is a general lack of attention to integrating urban biodiversity targets among the main challenges in the field of architecture. Furthermore, urban greening plans or strategies rarely involve the architectural scale: research developed within Activity 3.1 of NBFC Spoke 5 reveals that urban Green Plans ^[4] (Pastore & Lazzarini, 2024) in Italy have a scarce commitment to implementation (Lazzarini, Mahmoud, & Pastore, 2024), highlighting, among the rest, a weak ability of planning instruments to engage with the architectural and urban design scale and domain. Given the multidimensional nature of urban challenges, it is crucial to increase knowledge on the possible role of architecture in better integrating design solutions at different scales for more sustainable and biodiverse urban environments. Architectural composition can make a key contribution to the challenge of designing biodiverse urban public spaces by employing disciplinary fundamentals such as morphological study and typological methods: it can integrate ecological and qualitative requirements of urban public spaces, creating the conditions for biodiversity to thrive while ensuring that these spaces are safe, allergy-free, easy to maintain, welcoming, and accessible, suitable for developing high-quality uses and fostering meaningful relationships.

Figure 1. Extract from the Atlas of Urban Regeneration of the Municipality of Milan. The online Atlas map provides an overall and periodically updated view (Credits: Municipality of Milan).

3. Materials and Methods

3.1 Study Design and Setting

The methodology's first step involves choosing a context of study. The NBFC Spoke 5 research units are based in Milan (Politecnico di Milano, Università degli Studi di Milano-Bicocca), Florence (Università degli Studi di Firenze), Rome (Sapienza Università di Roma) Campobasso (Università degli Studi del Molise), and the different locations where Consiglio Nazionale delle Ricerche – CNR is based. Milan is the spatial context where the majority of Spoke 5 researchers are based, and the city has been chosen as the context of this study due to the potential usefulness of the results to further Milan-based research within Spoke 5. Furthermore, the city of Milan was chosen as it offers a compelling example for studying the role of urban open spaces in medium and large-scale developments, focusing on the existing relationships between biodiversity and different urban morphologies, for a large amount of land developed or re-developed over the past 30 years, which amounts around 10 square kilometres ^[5]. Milan has undergone multiple large and medium-scale transformations, continuously following one another: a rare occurrence at the Italian national level and a prominent case also at the European level.

At the same time, the city of Milan is characterized by local regulations, such as the Piani di Governo del Territorio (territorial government plans) along with actions resulting from public-private negotiations (PRU - Urban Redevelopment Program, Programma di Riqualificazione Urbana - and PII – Integrated Intervention Program, Programma Integrato di Intervento), which have consistently considered the need to improve public green spaces and parks; initiatives such as “Nine Parks for Milan”^[6] (Comune di Milano, Laboratorio di progettazione urbana, 1995) (Marinoni, 2007) and, more recently, “20 Parks for Milan”^[7], the strategic policy document “Future Landscapes - Milan: open spaces in a metropolitan vision”^[8], the “Public Green Regulations of the Municipality of Milan”^[9], “Forestami”^[10] project, the “Guidelines for the design of the public space”^[11] and many other initiatives demonstrate, together with a vibrant public debate, how urban planning and implementation tools for urban development have strengthened environmental parameters and, at the same time, have oriented public interest towards recognizing the benefits of urban nature and advocating for a more widespread presence of green spaces in the city of Milan. The rapid pace of building activity in Milan has transformed the city’s landscape within a few years. This speed also allows us to observe how, over a short period, the evolution of public discourse about the benefits of urban nature – both in Milan and at the European and global levels – has influenced, or failed to influence, architectural morphologies and settlement layouts.

With the aim of uncovering which urban morphologies are most conducive to creating space and conditions for biodiversity to thrive, as well as providing ecosystem services while ensuring high accessibility and visibility, the research focuses on five case studies of architectural and urban development in Milan conducted in the last three decades, chosen among a broader selection, to investigate how their building morphology influences their interactions between open and built spaces. A quantitative-qualitative analysis is conducted at the urban scale, involving tracing the perimeter of open space in each case study, examining their shape, compactness articulation, and continuity conditions that the perimeter edges can establish with the elements of the adjacent urban fabric. The quantitative investigation includes: 1) the connectivity established within each case with existing or potential ecological corridors and/or green infrastructures at the municipality level; 2) the connectivity established within each case with green areas at the neighbourhood level; 3) the extension of building fronts (intended also as windowed fronts, which allow for overlooking outside) generated by each case within the masterplan; 4) the extension of building fronts from the existing urban fabric with which each case establish connectivity; 5) the “compactness” of each open space. Qualitative remarks are then expressed to supplement the quantitative findings.

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Figure 2. Planimetric extract of the 15 urban-scale interventions detailed for this study. The park area is highlighted in red on the aerial photo. The projects, listed vertically from top left, are: Merezzate, Figino Borgo Sostenibile, Ex Macello, Ex Trotto, City Life, Cascina Merlata, Ex Scalo Porta Romana, Ex Scalo Farini, Porta Nuova, Ex OM, Adriano, Palizzi, Santa Giulia, Ex Calchi Taeggi, Ex Piazza d'Armi. (Aerial photos: Google Earth; edited by the authors with Michele Porcelluzzi).

3.2 Materials

Five case studies carried out in the last three decades were selected from the Atlas of Urban Regeneration of the Municipality of Milan (Figure 1). Among the regeneration areas listed in the Atlas, the selection criteria excluded transformation areas under 10.000 sqm, those under construction, those that did not involve an increase in the volume of residential use, those that did not provide substantial associated open spaces, and those presenting non-recurring morphologies deemed irrelevant for building a thesis due to their infrequency. The results of this initial selection identified 15 regeneration areas (Figure 2), from which 10 were excluded due to their unique characteristics (such as the presence of heavy infrastructure, the presence of a water body, the recreation of historical layouts), making them less comparable to the others. Consequently, five case studies were selected as they presented comparable spatial conditions. The five selected case studies are the districts named PII Santa Giulia, PII Cascina Merlata, PII CityLife, PII Garibaldi-Repubblica, PII Calchi Taeggi e Bisceglie. With the exception of Cascina Merlata, which was built on former agricultural land, the cases studied have in common that they are developed on land previously occupied by other functions, often called brownfields. These include former industrial areas released by relocations, as seen in the cases of Santa Giulia and Calchi Taeggi; former urban macro-functions, as in the case of City Life, which replaces the old pavilions of the Milan Trade Fair; and urban voids created by the transformation of the railway system, as in the case of Garibaldi-Repubblica. This means that, in most cases, the start of the transformation is preceded by land reclamation from polluting sources. In examining their location in relation to the more consolidated parts of the city, the selection includes areas located in densely built-up central areas, immediately adjacent to the consolidated city, and more rarefied peripheral contexts, as seen in the other three cases.

3.3 Procedures and Data Analysis

The cases were examined using publicly available project documents, orthophotos, and direct observations during visits. The perimeter of the open space in each area was traced using AutoCAD software (Figure 5). The Municipal Ecological Network map ^[12] of Comune di Milano (Figure 3) was superimposed onto each area to evaluate the compliance with existing or potential ecological corridors and the openings' width (Figure 6). Connectivity towards four elements (existing or potential ecological corridors and/or green infrastructures at the municipality level, green areas at the neighbourhood level, building fronts within the masterplan, and building fronts from the existing urban fabric) was visually represented in schemes using different lines and symbols, to aid in visualizing the conditions of each perimeter (Figure 7).