What solutions can be used for large cities to achieve the best solution in terms of urban pollution, pleasant climate, and water scarcity, and what is standard urban planning? What role do vegetation and artificial lakes play in urban planning?

Cities face increasing environmental, social and economic challenges that together threaten the resilience of urban areas and the residents who live and work there. These challenges include chronic stresses and acute shocks, amplified by climate change impacts. Nature-based solutions have emerged as a concept for integrating ecosystem-based approaches to address a range of societal challenges. Nature-based solutions directly address and contribute to increased urban resilience. However, implementing nature-based solutions is inherently complex, given the range of ecosystem services, their multi-functionality and the trade-offs between functions, and across temporal and spatial scales. Urban planning can play a substantial role to support the implementation of nature-based solutions and to manage trade-offs and conflicts, as well as how social equity dimensions are considered. This paper presents a framework that guides the application of urban planning to nature-based solutions’ implementation, by addressing key trade-offs across temporal, spatial, functional and social equity aspects. The framework highlights the key questions, and the supporting information required to address these questions, to underpin the inclusion of nature-based solutions for urban resilience. We find that while urban planning can contribute substantially, there are continuing gaps in how the inherently anthropocentric urban planning processes can give voice to non-human nature.Cities are facing increasing environmental, social and economic challenges that together threaten the resilience of urban areas and the residents who live and work there. These challenges include both chronic stresses and acute shocks. Climate change impacts are amplifying these challenges. Nature-based solutions have emerged as a concept for integrating a range of ecosystem-based approaches to address a range of societal challenges. Nature-based solutions directly address and contribute to increased urban resilience, but understandings of the mechanisms and vehicles for their implementation in cities are still being developed. There is potential for mainstreaming nature-based solutions through integration into urban planning approaches, but these are not yet well developed in either research or practice. This conceptual paper demonstrates how nature-based solutions contribute to building urban resilience, and the roles required of urban planning in operationalising or implementing nature-based solutions. To do this, the paper reviews and brings together three bodies of literature to propose a framework for urban planning approaches to implementation of nature-based solutions. We first review the development of concepts of urban resilience and nature-based solutions and ecosystem services. We highlight the complexity of delivering nature-based solutions through the lens of ecosystem services, and nature-based solutions’ multifunctionality. Our review highlights key gaps in nature-based solutions’ conceptual framing, namely how social equity is addressed, and the range of trade-offs between functions and services and across time and space. Following this, we discuss the roles of urban (land-use) planning in the planning and management of cities, and how urban planning addresses trade-offs. We bring together the three bodies of literature to propose a framework for integrating naturebased solutions into urban planning, and demonstrate its application for strengthening urban resilience.The resilience of cities is dependent upon their ability to adjust and adapt in the face of change (Alberti & Marzluff, 2004; Alberti et al., 2003; Pickett, Cadenasso, & Grove, 2004). Resilience encompasses responding to the gradual change and chronic stresses, often of socioeconomic nature, and the abrupt change or acute shocks, often related to natural disasters (Resilient Melbourne, 2016). In this sense, ‘resilience’ is about more than recovering or rebuilding (Campanella, 2006; Elmqvist, Barnett, & Wilkinson, 2014). Resilience describes the ability of a system to “thrive during times of stability, and to adapt, organise and grow in response to change or disruption” (Gardner, 2019, p. 10). Urban resilience, according to Elmqvist et al. (2014) “is therefore about navigating a desirable system trajectory and state rather than avoiding abrupt change and collapse” (p. 22). Resilience has become an important issue in urban policy (Davoudi et al., 2012). As ‘resilience’ has grown in influence, a wide range of international, national, metropolitan, and urban initiatives have been established (Wilkinson, 2011). Building urban resilience requires longterm, integrated approaches to urban planning and development (Antrobus, 2011), as well as a diverse range of disciplines, perspectives, and mechanisms, which bring together different approaches to explore viable transition pathways (Coaffee, 2013; Collier et al., 2013; Elmqvist et al., 2014; Meerow, Newell, & Stults, 2016). Recent literature around the operationalisation and implementation of urban resilience argues the need to reframe resilience, better understand the trade-offs, and link to issues of institutional embedding of new practices and policies (Chelleri, Waters, Olazabal, Minucci, & Urbanization, 2015; Coaffee et al., 2018). Furthermore, acknowledging the interlinkages between resilience and sustainability can better support desirable trajectories for urban transitions (Elmqvist et al., 2019). Governance also needs to shift towards more anticipatory and proactive approaches (Coaffee et al., 2018), and connecting different actors and sectors in order to focus on “mainstreaming a resilience approach in all the city-level decision making” (Coaffee et al., 2018, p. 404). Studies show that despite the growing popularity of resilience, there is an implementation gap between resilience as an ambitious objective, and the capacity to govern resilience in practice at the urban level (Wagenaar & Wilkinson, 2015, p. 1265). Others have identified a gap in terms of the transformative potential of resilience initiatives, as many continue to reproduce the status quo, neglecting the implications for social justice and equity (Anguelovski, Connolly, & Brand, 2018; Fainstein, 2018). In reframing urban resilience, it is critical to focus on the politics of resilience, such as resilience from what, to what, and who gets to decide, as well as where, when, and why (Meerow & Newell, 2016; Meerow et al., 2016). 2.2. Nature-based solutions and ecosystem services Ecological systems provide a wide range of functions which benefit humans and the cities in which they live. ‘Nature-based solutions’ has emerged as a concept, or umbrella term, for ecosystem-based approaches to address the societal challenges of climate change, natural disasters, food and water security, human health and well-being, and economic and social development (Cohen-Shacham, Walters, Janzen, & Maginnis, 2016; EC, 2015). Nature-based solutions address these societal challenges through the delivery of ‘ecosystem services’. The MEA (2003) identified four categories of services: provisioning, regulating, cultural and supporting. Gómez-Baggethun et al. (2013) utilised the concept to highlight the provision of ecosystem services in urban areas that contribute to a city’s resilience. The ecosystem services framework, in providing a simple, clear and useable typology, has been widely adopted in research literature (McDonough, Hutchinson, Moore, & Hutchinson, 2017), is being operationalised in policies, planning and practice (Ainscough et al., 2019; Jax et al., 2018), and acts a ‘boundary object’ to facilitate communication and collaboration between disciplines and sectors (Abson et al., 2014). However, the concept is not without its criticisms. These revolve around the conceptualisation of ecosystem services being fundamentally anthropocentric and grounded in an economic approach that as a result excludes the intrinsic values of nature and non-human species, potentially leading to commodification of nature, and exploitative human-nature relationships (Schröter et al., 2014). While earlier applications of the term often focused on economic valuations of ‘natural capital’ (Costanza et al., 1997), considerable research since then has contributed to substantially more complex, holistic and inter disciplinary understandings and applications (McDonough et al., 2017). The complexity of ecological processes that can span both services and ‘disservices’, sometimes simultaneously, has also been highlighted (Lyytimäki, 2015; Saunders & Luck, 2016). However, Saunders and Luck (2016) suggested that resorting to simplified dichotomies should be resisted, instead advocating for adoption of a “more nuanced, holistic approach” that addresses complexity and the temporal and spatial context of specific ecosystems. Others have raised questions in relation to how the concept addresses issues of the distribution of wealth, power, equity and access to urban ecosystems (for example Kull, Arnauld de Sartre, & Castro-Larrañaga, 2015). Addressing these dimensions, particularly in urban contexts, reinforces the roles for urban planning and governance in the implementation of ecosystem services and nature-based solutions, and in considering trade-offs and how they can be resolved or managed. 2.3. Relationship between urban resilience and nature-based solutions Urban resilience is increased through the inclusion of nature-based solutions and their associated delivery of ecosystem services in urban areas (Table 1). Ecosystem services contribute to thriving cities during times of stability, particularly through the provision of cultural ecosystem services that bring social, cultural and community benefits and wellbeing. Nature-based solutions and urban green spaces provide the location for recreation, social interaction, building community cohesion and contributing to physical and mental health and wellbeing (Jennings & Bamkole, 2019). These services contribute to enhanced resilience to the chronic stresses and gradual changes to which cities are exposed. Increasingly, the contributions of ecosystems services are also being recognised as contributing to resilience to sudden change, disruptions and natural disasters (Cohen-Shacham et al., 2016). Ecosystems can buffer cities and enhance their resilience by mitigating the impacts of climate change, including heatwaves and storms (Kabisch et al., 2016). Compared with conventional, engineered adaptation measures that are often associated with “high costs, inflexibility and conflicting interests” (Brink et al., 2016, p. 111), nature-based solutions and “ecosystembased adaptation” are potentially more resilient and cost-effective (Kabisch et al., 2016; Temmerman et al., 2013). Nature-based solutions effectively act as decentralised, distributed systems of infrastructure service provision, which are usually inherently more resilient than large, centralised grey infrastructure (Depietri & McPhearson, 2017). Any discussion of the links between resilience and nature-based solutions should also be extended to encompass the resilience (or vulnerability) of ecosystems themselves. Climate change has major impacts on ecosystems (Li, Wu, Liu, Zhang, & Li, 2018). Ecosystem resilience focuses on maintaining the health and capacity for ecosystems to continue to function and provide ecosystem services (Xu, Marinova, & Guo, 2015), even in the face of both biophysical and ‘societal challenges’ highlighted previously. This requires dynamic urban systems that are adaptive to impacts of climate change as well as other environmental changes and impacts of urbanisation. The extent to which urban ecosystems, as isolated pockets of green space within the built environment, can themselves be resilient may be limited, but could be supported with active management, selection of temperature-adapted species, creation of connected networks and control of habitat disturbance and destruction processes (Garrard, Williams, Mata, Thomas, & Bekessy, 2017; Kendal et al., 2018; Parris et al., 2018). We have shown how nature-based solutions have central roles in building and maintaining many aspects of urban resilience. However, there are key gaps in the framing of nature-based solutions, as well as in research on nature-based solutions for urban resilience, in the areas of equity and trade-offs. Brink et al. (2016), in a review of research on ‘ecosystem-based adaptation’, a concept closely aligned with ‘naturebased solutions’ (Dorst, van der Jagt, Raven, & Runhaar, 2019), found that few articles considered equity, and that the normative and ethical aspects require more attention. Furthermore, when nature-based solutions are planned and managed to primarily address single function priorities (such as heat mitigation, carbon sequestration or biodiversity habitat provision), there are trade-offs between priority functions and the multiple other functions and services (Mexia et al., 2018).

Cities are expanding and becoming denser. Urban densifications may significantly impact access to direct or scattered sunlight, which may result in increased usage of electric light and limited potential of installing photovoltaic solar panels on building roofs and facades. Additionally, urban densifications often lead to less green areas which, in turn, can affect public health (World Health Organization 2023) and cause environmental problems such as increased exposure to noise (Skovbro 2002). This situation calls for strategic planning of the remaining green infrastructure in the urban planning process. To facilitate appropriate urban planning and enable cities to grow sustainably, it is important that the geospatial community provides adequate vegetation information, e.g., as part of a 3D city model. 1.2 Aim The general aim of this paper is to discuss the need for storing vegetation information in 3D city models from an urban planning perspective. The focus is set on examining if and how vegetation should be included in the new Swedish specifications for 3D city models. The following research questions are addressed: • What urban vegetation information is collected today in Sweden for urban planning applications? What is the main use of this vegetation data? • What possibilities does CityGML provide for storing vegetation data? And what studies have been conducted to extend the CityGML specifications for vegetation? • Which urban planning applications do require vegetation information? Which type of vegetation information is needed for these applications? • How much does vegetation information affect daylight and solar energy simulations? In this study, as well as in the abovementioned specifications, we do not consider vegetation information required for e.g.: management of the green infrastructure (such as operational systems for park areas), tree inventories, and more advanced ecosystem modelling (e.g., carbon uptake and evapotranspiration modelling).While mitigation seems easier to achieve at local levels, because in synergy with energy constraints and orientations, adaptation requires more specifc appropriation work, based on existing institutional mechanisms. The question is how to make territories resilient to climate change efects (Berdoulay and Soubeyran 2014). In the literature, many examples of adaptation measures can be found: – Green infrastructure shape adaptation preferences among residents in Rotterdam (Derkzen et al. 2017), opportunities and gaps for urban green infrastructures planning in Europe (Davies and Lafortezza 2017). – Cartography of heat islands in Graz based on GIS indicators (Reischl et al. 2018) – Land use planning related to sea level rise and extreme weather events (McClure and Baker 2018) – Summer thermal comfort related to urban form and compactness in Berlin (Straka and Sodoudi 2019). – Cloutier et al. (2014) organized in Quebec a design workshop with professionals who identifed 18 sectoral planning measures of 4 types: (1) coating materials (color, texture, albedo, etc.), (2) urban form (height of buildings, street orientation, etc.), (3) natural cover and (4) building architecture. Those examples show that adaptation is mainly carried out into sectoral activities. But adaptation has not yet been seen as really transversal program driving land use planning. According to Cloutier et al. (2014), adaptation can become a mean of innovation for planning process, which does not involve to initiate new actions or processes but to improve and orient the existing ones toward climate change issues. It can even become a new gateway to sustainability science in land use planning (Bertrand and Richard 2015). In this perspective, new approaches should be proposed for land use planning instruments, dealing with municipal land use revision, new neighborhoods developments, open spaces planning in existing neighborhoods. This involves working on a global and transversal framework, and not only sectoral, and to investigate how far such integrated approaches could be transposed into the regulations at diferent levels. Propositions in this matter will be made through the article using the Swiss context. Levers and barriers of taking into account climate change in urban governance One of the main challenges is to modify land use planning practices in order to systematically consider climate change issues. Diferent authors account for levers and barriers of taking into account climate change in planning processes. United Nations Intergovernmental Panel on Climate Change (IPCC) distinguishes between physical and ecological limits, technological limits, fnancial barriers, informational and cognitive barriers, and social and cultural barriers (IPCC 2007). Important works and surveys were carried out to identify barriers and levers. For instance, Olazabal and De Gopegui (2021) studied planning in 59 cities worldwide, and Simonet and Leseur (2019) conducted 75 semi-structured interviews among 75 actors in 10 French cities. The following table (Table 1) gives a selection of frequent occurrences of barriers and levers classifed into three main topics: knowledge sharing, fnancial resources, organization and regulation: Faced with the observation of these barriers and levers, the question is how urban governance could evolve to facilitate the consideration of climate change in the development of cities (Bulkeley and Betsill 2013).fnally the presentation of the results of the survey (Section 4.2). Afterward, sequences of work in pairs and then jointly allowed the participants, including the research team (both authors), to formulate their point of view on the blocking factors (barriers) to the integration of climate change into urban planning. Finally, the participants were asked to identify, in pairs and then jointly, a frst set of courses of action and levers to address the identifed obstacles. The second focus group, which took place on October 17, 2019 in Lausanne, started with a reminder of the results obtained in the frst session. Afterward, participants were asked to select one or two courses of action (called “Measure”) in order to describe in more detail their content and implementation process. Appendix 2 provides an example of a form completed by one of the groups on one of the identifed action lines. Each focus group was designed to produce diversifed and directly exploitable results (factsheet, schemes). It was therefore not necessary to transcribe the discussions between participants; however, during each focus group a notetaker was present to produce a summary note which was returned to the participants for validation. Results Climate change instruments and tools in Switzerland The analysis of the documentation collected and processed according to the grid presented above (Table 2) provides useful lessons on the implementation of territorial and climate governance in Switzerland at the local level. The main results are presented below, using the headings of the analysis grid. Mitigation vs. Adaptation (see rubric 2 in Table 2) Until recently, climate policy in Switzerland was closely linked to energy policy and mainly focused on the mitigation of GHG emissions. This focus on mitigation is probably due to the direct and logical link between efcient use of renewable energies and emission reductions. Thus, more than 400 municipalities (in 2019), supported by the Confederation, have committed themselves to establish an exemplary energy policy through the Energy City label (Swiss contribution to the European Energy Award program). Recently, mitigation and adaptation seem to be more closely linked in Swiss climate policy. One example is the new criteria catalog of the “Cité de l'énergie” label, which integrates requirements relating to quality of life and the fght against global warming in public spaces and buildings, as well as adaptation measures accordingly. Land use planning is gradually becoming a major axis of action in relation to climate change, both on the mitigation side (reducing CO2 emissions in terms of mobility, construction and rational use of energy) and on the adaptation side (urban development in relation to natural risks, adapted urban forms). The successive Climate Plans of the Canton of Geneva (2015, 2017, 2021) is one of the frst signifcant illustrations of how climate issues can be taken into account in a spatial planning instrument. This evolution at the cantonal level (region) is to be underlined but it is still only slowly refected at the lower levels.Overall, the climate issue is still rarely mentioned explicitly in the objectives of the urban plans. It appears rather implicitly and indirectly through the various disciplines concerned with climate and in particular adaptation: green and public spaces, urban climate, health, energy and mobility. This interdisciplinary framework highlights apparent conficts, in particular between adaptation and urban density. Indeed, high urban densities, which are encouraged by urban planning policies in Switzerland, constitute particular challenges in terms of heat islands or vulnerability to climatic hazards. This delicate link between urban planning and climate policy (Xu et al. 2019, Biesbroek et al. 2009) is well illustrated in Zurich where a wind map shows that light winds and breezes, especially at night from nearby forests and mountains, have difculty circulating in dense urban areas, thus accentuating night-time warming (Stoiber 2019). Thus, planners are becoming increasingly aware of the importance of integrating climate measures into the construction and densifcation process. For example, the Climate plan of Geneva highlighted the benefts of climate action in all three areas of sustainable development (echoing the link observed by Bertrand and Richard 2015, between sustainability science and adaptation). At the social level, the measures envisaged can contribute to improving air quality, fghting sedentary lifestyles or strengthening food security. From the environmental point of view, they contribute to preventing foods, strengthening biodiversity, increasing soil fertility or preserving natural resources. As for the economic efects, these measures contribute to supporting the local economy, developing new skills or reducing material damage.