## 2 Materials and Methods  
### Study Area and Dataset  
The study area is represented by the city of L'Aquila, situated in the Abruzzo region (central Italy) (Figure 1). This territorial scope includes both the natural system composed by protected areas (PAs), established at the local and national/international level (Natura 2000 network, local protected areas, Important Birding Areas, Ramsar areas, etc. ), and by the anthropic system, consisting mostly of artificial areas. However, the latter do not have net defined boundaries due to the territorial morphology that not only influences aspects of the planning action, such as the dynamics of urban development and the protection of the natural matrix, but also contributes to mixing up the functionalities and the intrinsic characteristics of the two systems, resulting in a more complex pattern [25]. In this peculiar context, the sustainable development principle entails a fundamental prerogative for the planning policies, to the point that several projects and plans are envisaged for this and other neighboring territorial scopes. LIFE IMAGINE is an integrated LIFE project aimed at sustaining the development of an integrated and unified strategy for the management of the Natura 2000 network in the Umbria region through actions to foster the connection, protection and enhancement of agricultural lands, forest habitats and wetlands, and the conservation of severe animal species [26]. Similarly, the \"Sustainability, resilience, adaptation for the protection of the ecosystems and the physical reconstruction in central Italy\" (SostEng&Re) project that concludes in autumn 2022 represents an important experience for the Abruzzo, Marche and Umbria regions in the formulation of guidelines to promote the implementation of the National Strategy for sustainable development [27]. The accomplishment of these projects brings the planning policies to a new level of concern about the aspects of sustainable development, creating new tools and supporting strategies to help local administration implement sustainable development goals set by both the national and international levels [28]. Despite this, on the other hand, municipalities manage territorial transformations with planning tools drafted, in certain cases, almost fifty years ago, defining threats and/or pressure on the network formed by all the possible connections between PAs. The city of L'Aquila does not escape these dynamics, which results in even more complexity if considered in a territorial scope, for which different thrusts of development subsist. Indeed, to put in place solutions aimed at enhancing the best planning practices, different projects and tools set both at the national and EU levels are envisaged; e.g., NextGenerationEU established two important instruments with the aim of involving member states in significant changes both from an environmental and a social point of view (Recovery and Resilience Facilities and Recovery Assistance for Cohesion and the Territories of Europe) [29]. These two instruments, aimed at the sustainable development of European Union member countries and the revitalization of their own economy, were followed up in Italy by the National Recovery and Resilience Plan (PNRR), which, in its current state, stimulates a series of interventions for the development of the country [30]. Figure 1: Study area. In the depicted framework, studies such as the current one, aimed at distinguishing urbanized cells from the natural ones, play a fundamental role as tools to address and formulate efficient planning policies. The dataset utilized to perform the analyses is the Urban Atlas (UA), a product from the Copernicus Land Monitoring Service, in which the categories represent different Functional Urban Areas (FUA). The year of the utilized UA is 2018, and the spatial resolution is of 0.25 hectares for the first class and of 1 hectares for the other ones (class 2-5), with a minimum mapping width of 10 m [31].