1. Framing Green and Blue Infrastructure

European urban areas are home to over two-thirds of the population, with a level of urbanisation that is expected to increase to approximately 83.7% in 2050. Most European cities are often characterised by a high concentration of economic activities and wealth, but they are increasingly vulnerable to pandemics, environmental and economic crises, social disaggregation, and climate change related impacts. Additionally, there is a growing concern about biodiversity loss and its implications on health, well-being, climate, economy, degradation of nature, and social inequality (Anguelovski et al. 2018). Ecosystem degradation erodes nature’s ability to support human societies, as ecosystems provide a wide range of services (MEA 2005; TEEB 2010).

Biodiversity loss emphasises the effects of other current crises: climate, economic, and COVID-19. It is essential to start from biodiversity as a strategic component of natural processes providing ecosystems with the possibility to develop the vital functions for social direct or indirect benefits (De Groot 1992), interpreted in terms of ecosystem services (ES) provided to humans (Science for Environment Policy 2015). There is a scientific consensus that without biodiversity, many natural processes (such as climate regulation, limitation of urban heat islands, water and air purification, maintenance of soil fertility, reproduction of species, etc.) and human activities (such as agriculture, fishing, and outdoor recreation) would be impossible (Hooper et al. 2005). In this view, it is urgent to rethink urban planning and design approaches to restore biodiversity as defined in the EU Biodiversity Strategy 2030 within the European Green Deal.

Moreover, the Biodiversity Strategy 2030 calls for a comprehensive change to benefit people, climate and nature. It highlights the role of interconnected protected areas (PAs), green areas, ecological networks, green infrastructure (GI) and green and blue infrastructure (GBI). This interconnection allows for controlling biodiversity loss, enforcing ecosystems, connecting diverse natural and semi-natural areas, and delivering “a wide range of ecosystem services”, maintaining and enhancing at least 15% of degraded ecosystems (EC 2013). Urban and peri-urban PAs and other green areas (such as gardens, yards, vacant lots, pocket parks, and wastelands) are all components of a connected and coherent network able to sustain biodiversity (Trzyna 2014; UNEP-WCMC and IUCN 2021). This multi-scale network must be integrated into the landscape, territorial policies, and urban planning to enhance ecological reticularity and ecosystem functionality (Barabàsi and Bonabeau 2003). Moreover, due to their multifunctionality, PAs and other green spaces play an important social role, bringing people closer to nature (Hockings et al. 2020). Biodiversity loss emphasises the effects of ongoing crises (e.g. COVID-19, economic and climate), making it essential to start with biodiversity as a strategic component of planning and design at diverse territorial scales, even in the light of interdependencies between humans and nature.

In this process, the pandemic event of COVID-19 represents a turning point from different perspectives, impacting economic development, everyday life, habits, planning, and design practices. Current national, EU, and international strategies (such as Biodiversity Strategy 2030, Green Deal, Next Generation EU and the various national plans such as the Italian Piano Nazionale di Ripresa e Resilienza and the French Plan National de Reprise et de Résilience) stress the attention on urban green spaces as one of the main elements determining the quality of life and ecosystem health (Noszczyk et al. 2022). In response to these impacts, planning and design practices are even more forced to rethink the urban project in an ecologically oriented way, restarting from natural and ecological assets.

In this evolving framework, GBI is a socio-ecological system strategically planned and designed for sustainability and resilience (Voghera and Giudice 2019), aimed at managing a large variety of ES (Hansen and Pauleit 2014) and playing a crucial role in halting biodiversity loss. It can sustain the interrelation between “diversity (biodiversity), redundancy (ecological variability), cycles of adaptation (multiple equilibrium states), and interaction between spatial scales (hierarchy) and temporal (activation of different times responses)” (De Lotto et al. 2017, p. 780). Various studies underline the need for carefully planning, distributing, and designing a multifunctional and multi-scale GBI, integrating green (soils) and blue (water) spaces that can improve biodiversity values, the related ecological functionality, and socio-economic values.

Given the current situation of the COVID-19 pandemic emergency, GBI has become an urgent topic of the contemporary cultural, planning, and design approaches. Even though it is recognised as “planning and design-related measures” for urban resilience (Sharifi 2020), it still appears poorly developed in research and everyday practices. Given this gap, the book aims to develop an integrated approach connecting cultural and environmental features with planning and design dimensions, investigating both academic and practitioners’ perspectives emphasising public policy innovation.

Rooted in the tradition of the twentieth century city since the earliest hygiene-based urban reflections (e.g. parks and gardens system by Jean-Claude Nicolas Forestier, public parks and parkways by Frederick Law Olmsted, garden city experience), GBI provides consolidated assets that refer to an environmental approach in spatial and landscape planning (“old wine in new bottles”, Davies et al. 2006, p. 6). Later on, the American greenways movement relaunched the idea of creating a system of parks and parkways that integrated “corridors of private and public recreation lands and waters and to provide people with access to open spaces close to where they live, and to link together the rural and urban spaces in the American landscape” (Americans Outdoors 1987).

Nowadays, it is powerfully invoked as operative support in developing the resilient, sustainable, safe, inclusive, and climate-responsive contemporary city (Mell 2009). Furthermore, it has a key role in the ecologically and landscape-oriented design of public spaces (see Andreas Kipar interview) and is considered a fundamental element for urban regeneration strategies (see interviews with Magali Volkwein and Sébastien Roussel and Carlo Gasparrini).

GI appears to have several conceptualisations focused mainly on “(1) a greenspace planning, (2) an urban ecology concept, and (3) a water/stormwater management concept” (Matsler et al. 2021, p. 2). With regard to the first aspect, GBI tends to be an “integrated system” (Landscape Institute 2009) of green spaces that bring plenty of benefits, focusing on landscape multifunctionality (Lovell and Taylor 2013). It is thus configured as a system that links landscapes and ecological networks, penetrating the tissues of the consolidated city. This system also insists on urban metabolism based on resource recycling, identity reappropriation and care for the landscape commons. It implies a design action that brings into play different scales of landscape design, considering building materials, eco-friendly public spaces, water cycle, vegetation performance, slow mobility systems, and settlement types. Furthermore, it also entails different forms of inclusive and innovative governance to activate green and circular economies.

The multidimensional and transcalar strategy of GBI grounds the design of cities and territories in landscape quality to trigger urban regeneration by redesigning vacant lands and open spaces (Secchi 1986; Lanzani 2015). This paradigm shift needs to move out of “sectoriality” and integrate ecological, environmental and landscape issues into the territorial project, according to a model now consolidated in theoretical elaboration, emerging practices, and international policies. These reflections fall under the second conceptualisation related to urban ecology.

The third conceptualisation is quite a narrow vision of GBI, and it needs to be further deepened to include the already mentioned characteristic of multifunctionality. Indeed, EU policies define GBI as a “strategically planned network of natural and semi-natural areas with other environmental features designed and managed to deliver a wide range of ecosystem services” (EC 2013). This definition led many researchers to deal with multifunctionality. In this context, GBI can be considered a producer of multiple benefits (Ahern 2011; Hansen and Pauleit 2014; Lovell and Taylor 2013) for health and life quality. The international literature highlights that the several benefits and services supplied to urban environments by GBI contribute to climate change mitigation and adaptation (Demuzere et al. 2014). Additionally, the multifunctionality of GBI can mitigate the urban heat island effect, flood risk, and ecosystem resilience (Sussams et al. 2015).

Furthermore, the concept of GI “differs from conventional approaches to open space planning because it looks at conservation values and actions in concert with land development, growth management and built infrastructure planning” (Benedict and McMahon 2002, p. 5). Here, the inclusion of a sustainable development perspective in addition to a preservative one is evident. The various connotations given to GBI in the different disciplinary approaches configure GBI as a “boundary object” (Brand and Jax 2007).

GBI can be used to enforce ES (Arcidiacono and Ronchi 2021) through its integration into the landscape and regional planning (Voghera and Giudice 2021; Giudice et al. 2021), dealing with a multifunctional approach in planning and design (Austin 2014), or it can be a policy itself (Gasparrini 2015; Clergeau and Blanc 2013) implementing the EU biodiversity strategy for 2030, the COP 10 decision X/2 Strategic Plan for Biodiversity 2011–2020.

Together with ecosystem-based solutions, GBI-based planning is recognised as a relevant approach to addressing climate change in the EU strategy on adaptation. Indeed, GBI discourses are also strictly connected to disaster risk management and its relationship with the environment (we refer primarily to the Sendai Framework for Disaster Risk Reduction 2015–2030). The topic is also strategically relevant to implementing some of the UN Sustainable Development Goals: no. 3 “Good health and well-being”, no. 11 “Sustainable cities and communities”, no. 13 “Climate Action”, no. 14 “Life below water”, no. 15 “Life on land”. To fulfil these objectives, GBI development requires “both the conservation of existing biodiversity-rich ecosystems in good condition and the restoration of degraded ecosystems” (EC 2019, p. 2). In addition, it is also necessary to create a new GBI to valorise and create landscapes and values (as interpreted by the European Landscape Convention, CoE 2000). However, there is an increasing need to further integrate GBI synergistically and organically into ordinary and sectorial planning tools at different scales (e.g. river basin management plans and rural development programmes) and into voluntary agreements between regional and local authorities (for example, French Contrats Verts et Bleus and Italian Contratti di Fiume). Indeed, most of the spatial planning tools (above all, the ones developed at the local scale) don’t include GBI as a “standard part” (EC 2019). Only a few countries, such as France, have decided to integrate GBI as a specific recognised part of their spatial planning tools (from regional strategy to local plan).

In particular, the book frames GBI within the conceptual contexts of sustainability and resilience. This background takes the cue from former research led by two of the proposing editors (Voghera and Giudice) and published in Sustainability in 2019. These contexts are also strictly connected to the social-ecological systems approach (on this issue, the work by the Stockholm Resilience Centre is exemplary). Existing literature on GBI, social-ecological systems, resilience, and sustainability show how GBI mainly applies to stormwater management (Ahern 2013), but it can contribute to providing other benefits, such as better air and water quality (Demuzere et al. 2014), urban heat island mitigation (Tzoulas et al. 2007), improved communities values and reduced social vulnerability (Meerow and Newell 2017), greater access to green space (Meerow and Newell 2017), increased landscape connectivity (Zhang et al. 2019), and control of land take (Giudice 2021). Nevertheless, if the role in promoting ecological resilience is consolidated and shared, scientific positions split consensus on its social impact (Anguelovski et al. 2019).

Another essential element of GBI is its multiscalar governance. Despite the absence of an organic and robust structure and reference framework for deploying GBI, many attempts and progresses at different levels have been made to achieve this deployment worldwide. Existing plans and projects often consider GBI only at a specific scale: some projects consider the elements of GBI only at a local scale of intervention without relating them to the surrounding areas. Nevertheless, on the one hand, some Italian experiences attempted to develop a GBI at the municipal level, connecting it with the surroundings and giving connectivity. On the other hand, France established a multilevel planning system in the early 2010s integrating the regional territorial scheme, metropolitan strategy, and local plan. GBI management remains an open issue, which requires focused research and cooperation between policymakers, private stakeholders, and non-governmental organisations.

The description of GBI shows how the topic is still fundamental when speaking of ongoing ecological, social, and economic transformations. GBI represents indeed not only a relevant strategy and policy to promote ecological-related issues but it is recognised that it can potentially have economic and social benefits. With this book, we want to fill this gap by presenting various experiences that show how multifaceted the topic of GBI is and how it can be applied in practical case studies. The first point deals with the necessity to overcome the prevalence of ecological-related issues, including social and economic ones, while the second point allows for evaluating the operationalisation of GBI. To do this, the book discusses the emerging approaches within planning and urban design: not only ecological solutions but also architectural and social ones that contribute to the overall regeneration of territories. This research mainly focuses on French and Italian contexts but also provides some insights from experiences developed worldwide. The choice of France and Italy is not casual. On the one hand, France has developed a national strategy, the so-called Trame Verte et Bleue (see Fournier and Bonnefond chapter; Devillers & Associés interview), to integrate GBI into regional and local planning practices and urban design. On the other hand, Italy is attempting to build a GBI framework by reinforcing its role in the latest Regional Landscape Plans and raising awareness of the Italian National Strategy for Climate Change Adaptation. Other case studies come from England, Portugal, Spain, and the USA in order to put into perspective the French and Italian cases at the international level.

The chapters of this book highlight the innovations introduced by different GBI approaches in the field of territorial planning (part I) and urban design (part II).

The discussion involves experts in different sectors giving their opinion on some issues or presenting how they included the concepts of GBI in their projects and how this integration modifies their approaches to planning, urban project, and public spaces design. From this perspective, we interviewed planners, architects, and landscape architects (part III: Carlo Gasparrini Planning Studio, Studio Land, and Devillers et Associés). These interviews help to develop the link between the design conception and action (implementation and management). Interviewees are all involved in new planning and design forms, putting the GBI project at the centre. Interviews focused on different aspects based on each interviewee’s background and field of experience. Considering the existing literature on this topic, we are trying to develop a multi-disciplinary approach which overarches the entire GBI building process, from planning scopes to the design phase, including management and implementation actions.