In this study we explore species richness and traits across two urban gradients in the City of Cape Town. The first is the natural-urban boundary and the second is a socio-economic gradient informed by historical race-based apartheid planning. Plant species and cover were recorded in 156 plots sampled from conservation areas, private gardens, and public open green space. The socio-economic gradient transitioned from wealthier, predominantly white neighbourhoods to poorer, predominantly black neighbourhoods. The socio-economic gradient was selected to fall within one original vegetation type to ensure a consistent biophysical template. There is a marked shift between the natural and urban plant communities in the City of Cape Town, with little structural affinity. Urban landscapes are dominated by grass, with low diversity compared to natural counterparts. A significant ecological gradient of reduced biodiversity, traits, and in turn functionality, was found across the socio-economic gradient. Wealthier communities benefit from more private green space, more public green space, and a greater plant diversity. Poorer communities have limited green space on all fronts, and lower plant and trait diversity. Plant communities with limited diversity are less resilient and if exposed to environmental perturbation would lose species, and associated ecosystem services faster than a species rich community. These species-poor plant communities mirror historical apartheid planning that is resistant to change. Based on how biodiversity, functionality, and associated ecosystem services and ecosystem stability are linked, the results of this study suggests how significant environmental injustice persists in the City of Cape Town.

Cities, as home to the majority of the world’s people, are significant sites for addressing challenges of achieving sustainability and securing human wellbeing. Urban environments are complex social-ecological systems, and meeting these challenges requires better understandings of the interactions of social and ecological elements. While there are many possible lenses through which to study social-ecological systems, this thesis examines the potential of a traits approach as one way to link ecological elements to social values. 

In ecology, functional traits have been defined as the characteristics of organisms that determine how organisms respond to the environment, and how they affect ecosystem processes, functions, and services. While functional traits have an established history of being linked to ecosystem processes and functions, they have only recently been extended to social aspects through the operationalization of the ecosystem services concept. As such, there is a distinct gap in identifying traits that are relevant and important to people. This interdisciplinary thesis attempts to bridge some of this lacuna, through empirical studies conducted in two cities: Cape Town, South Africa, and Stockholm, Sweden. 

Paper 1 addresses connections between traits and social values generally across cities through a literature review that examines connections between traits and cultural ecosystem services. Paper 2 explores preferences for traits and reasons for plant selection in the context of Cape Town. Paper 3 examines vegetation patterns and the expression of socially-valued traits across different land cover and land use classes in Stockholm. Paper 4 serves as a synthesis and comparison piece between Cape Town and Stockholm, and brings together social data on plant preferences and ecological data on plant patterns gathered in both locations under two different projects. 

Overall, responses from social surveys of preferences suggest that people actively select for a variety of different plant traits in the urban environment, and have a multitude of reasons for selecting the plants that they do, related both to qualities of the plants themselves, as well as broader external factors at multiple scales. Vegetation surveys of plant patterns suggest that trait preferences may be inscribed by people in the landscape, though to differing degrees. 

Using traits as an approach to link ecological elements to social values exhibits advantages in that traits are a spatial unit that is easily understood by citizens and environmental managers. However, it presents limitations in terms of scale, as traits are most useful in connecting to pin-point characteristics in the landscape, and social values associated with broader scales may be overlooked. Collectively, however, the papers in this thesis suggest that traits may serve as one useful approach for discerning human values in the urban landscape, and can be used as indicators of social function. In management applications, particular traits can be incorporated into landscaping interventions to provide for urban areas of greater social meaning. In this way, traits may serve as one tool within the evolving toolbox of social-ecological system study, and thus can contribute to future urban landscapes that exhibit robust social and ecological function.

Städer, hem till majoriteten av jordens befolkning, är betydelsefulla platser för att uppmärksamma utmaningar med att nå hållbarhet samt säkerställa mänskligt välbefinnande. Urbana miljöer är komplexa socialekologiska system och för att möta dessa utmaningar krävs bättre förståelse för samspelet mellan de sociala och ekologiska elementen. Medan det finns många möjliga synsätt genom vilka socialekologiska system kan studeras, så undersöker denna avhandling potentialen av växters egenskaper, som ett sätt att länka ekologiska element med sociala värderingar. 

Inom ekologin så definieras funktionella egenskaper som en organisms kännetecken, vilka avgör hur organismer svarar på miljön samt hur de påverkar processer i, funktioner av och tjänster från ekosystemet. Medan funktionella egenskaper har en vedertagen historia av att vara länkade till ekosystemprocesser och -funktioner, så har sociala aspekter bara nyligen blivit inkluderat, detta genom operationaliseringen av begreppet ekosystemtjänster. Därigenom finns ett påtagligt gap i identifierandet av egenskaper, som är relevanta och viktiga för människor. Denna tvärvetenskapliga avhandling försöker därmed brygga delar av detta gap genom empiriska studier utförda i två städer – Kapstaden, Sydafrika och Stockholm, Sverige. 

Artikel 1 adresserar sambandet mellan växtegenskaper och sociala värderingar generellt i städer genom en litteraturgenomgång, som undersöker sambandet mellan växtegenskaper och kulturella ekosystemtjänster, och föreslår att begreppet ’växtegenskap’ kräver en utvidgning för att kunna rymma hela skalan av samband med olika sociala värderingar. Artikel 2 undersöker preferenser för olika växtegenskaper och skäl för val av växter i Kapstaden, Sydafrika. Artikeln belyser att människor väljer växter och motsvarande växtegenskaper i relation till temana estetik, nytta, miljömässig lämplighet och personligt symboliska värden. Artikel 3 granskar vegetationsmönster och uttrycket för värderingar av växtegenskaper i olika marker och markanvändningsklasser i Stockholm, och finner att ett socialt kännemärke i urbana miljöer, som har en multifunktionell prakt av värderade växtegenskaper, uppvisade särskilt i de markklasser som förvaltas av individer och för individer. Artikel 4 är en syntes och jämförelse mellan Kapstaden och Stockholm, och för samman sociala och ekologiska data samlad på båda platserna under två olika projekt. Sociala enkäter av preferenser avslöjar att det finns en delad växtegenskapspreferens och skäl för växtval på båda platserna – relaterade till temana estetik, nytta och miljömässig lämplighet, dock förekommer också några unika preferenser till respektive plats. Enkäter för vegetationstyp avslöjar ett skifte från ursprunglig bevarad vegetation till gräsmattor från en stadsnära till urban gradient i både Kapstaden och Stockholm. Men, människors uttalade preferenser för växtegenskaper ger ingen förståelse för denna observerade dominans av gräsmattor, vilket föreslår att andra faktorer än preferenser, potentiellt på andra nivåer, troligen är lika inflytelserika. 

På det hela taget föreslår svaren från våra enkätintervjuer att människor aktivt väljer en variation av olika växtegenskaper i den urbana miljön och att de har en uppsjö av skäl för valet av växter de gör, vilka grundar sig i både kvaliteterna hos själva växterna så väl som bredare externa faktorer på flera olika nivåer. Vegetationsenkäter föreslår att preferenser kopplade till växtegenskaper kan vara formade av människor i landskapet, dock till varierande grad. 

Att använda växtegenskaper som ett synsätt hjälper oss att visa fördelar med en rumslig enhet, vilken är lättförståelig för invånare on förvaltare. Men, synsättet visar också begränsningar i termer av den tid och resurser som krävs för att analysera mer ekologi-orienterade växtegenskaper samt i skalnivå, genom att växtegenskaper är mer användbara för att sammanlänka utpekandet av kännetecknande drag i landskapet. Kollektivt visar studierna i denna avhandling trots detta att växtegenskaper kan användas som ett meningsfullt verktyg för att urskilja mänskliga värderingar i det urbana landskapet samt skulle kunna användas som en indikator för sociala funktioner. Som verktyg i förvaltningen kan särskilda växtegenskaper slås samman med landskapsåtgärder för att ge urbana områden större socialt värde. På detta sätt kan växtegenskaper fungera som ett verktyg i en ständigt utvecklande verktygslåda i studiet av socialekologiska system och på så sätt bidra till att framtida urbana landskap innehar robusta sociala och ekologiska funktioner. 

The establishment of interdisciplinary Master’s and PhD programs in sustainability science is opening up an exciting arena filled with opportunities for early-career scholars to address pressing sustainability challenges. However, embarking upon an interdisciplinary endeavor as an early-career scholar poses a unique set of challenges: to develop an individual scientific identity and a strong and specific methodological skill-set, while at the same time gaining the ability to understand and communicate between different epistemologies. Here, we explore the challenges and opportunities that emerge from a new kind of interdisciplinary journey, which we describe as ‘undisciplinary.’ Undisciplinary describes (1) the space or condition of early-career researchers with early interdisciplinary backgrounds, (2) the process of the journey, and (3) the orientation which aids scholars to address the complex nature of today’s sustainability challenges. The undisciplinary journey is an iterative and reflexive process of balancing methodological groundedness and epistemological agility to engage in rigorous sustainability science. The paper draws upon insights from a collective journey of broad discussion, reflection, and learning, including a survey on educational backgrounds of different generations of sustainability scholars, participatory forum theater, and a panel discussion at the Resilience 2014 conference (Montpellier, France). Based on the results from this diversity of methods, we suggest that there is now a new and distinct generation of sustainability scholars that start their careers with interdisciplinary training, as opposed to only engaging in interdisciplinary research once strong disciplinary foundations have been built. We further identify methodological groundedness and epistemological agility as guiding competencies to become capable sustainability scientists and discuss the implications of an undisciplinary journey in the current institutional context of universities and research centers. In this paper, we propose a simple framework to help early-career sustainability scholars and well-established scientists successfully navigate what can sometimes be an uncomfortable space in education and research, with the ultimate aim of producing and engaging in rigorous and impactful sustainability science.

As cities increasingly become the dominant settlement form across the world, it is critical to gain a deeper insight into their dynamics, in order to better direct environmental management towards enhancing urban sustainability and environmental quality. People are a key driver shaping the ecological makeup of cities, not least through landscaping actions and choices. In this study, we explore social factors shaping plant selection in Cape Town, South Africa through interviews with stakeholders responsible for managing and landscaping across three land use types: private residential gardens, public parks and open space, and conservation areas. We combine an interdisciplinary, multi-scalar framework on residential landscape dynamics and a plant traits lens to structure our approach to examining the influence of social factors on plant selection across spatial and institutional scales in the city, from a bottom-up perspective. Residents name a variety of reasons for plant selection at the household scale related to plant traits, including aesthetics, utility (e.g., food provision), environmental suitability, and personal symbolic meanings. Parks managers select for ecological suitability as well as aesthetic concerns, and conservation managers select chiefly for ecological integrity. All stakeholders describe factors at other scales (e.g., property structure, government policies) that influence their plant selection. We indicate that a complementary patchwork of private gardens and public open spaces could serve as a source of trait diversity and provide a variety of ecosystem functions and services in the urban landscape, and suggest that management and policy efforts can focus on leveraging synergies towards this end. This study contributes to a greater understanding of the social-ecological dynamics in a global south city and biodiversity hotspot.

Cities are currently experiencing serious, multifaceted impacts from global environmental change, especially climate change, and the degree to which they will need to cope with and adapt to such challenges will continue to increase. A complex systems approach inspired by evolutionary theory can inform strategies for policies and interventions to deal with growing urban vulnerabilities. Such an approach would guide the design of new (and redesign of existing) urban structures, while promoting innovative integration of grey, green and blue infrastructure in service of environmental and health objectives. Moreover, it would contribute to more flexible, effective policies for urban management and the use of urban space. Four decades ago, in a seminal paper in Science, the French evolutionary biologist and philosopher Francois Jacob noted that evolution differs significantly in its characteristic modes of action from processes that are designed and engineered de novo (Jacob in Science 196(4295):1161-1166, 1977). He labeled the evolutionary process tinkering, recognizing its foundation in the modification and molding of existing traits and forms, with occasional dramatic shifts in function in the context of changing conditions. This contrasts greatly with conventional engineering and design approaches that apply tailor-made materials and tools to achieve well-defined functions that are specified a priori. We here propose that urban tinkering is the application of evolutionary thinking to urban design, engineering, ecological restoration, management and governance. We define urban tinkering as:<disp-quote>A mode of operation, encompassing policy, planning and management processes, that seeks to transform the use of existing and design of new urban systems in ways that diversify their functions, anticipate new uses and enhance adaptability, to better meet the social, economic and ecological needs of cities under conditions of deep uncertainty about the future.</disp-quote>This approach has the potential to substantially complement and augment conventional urban development, replacing predictability, linearity and monofunctional design with anticipation of uncertainty and non-linearity and design for multiple, potentially shifting functions. Urban tinkering can function by promoting a diversity of small-scale urban experiments that, in aggregate, lead to large-scale often playful innovative solutions to the problems of sustainable development. Moreover, the tinkering approach is naturally suited to exploring multi-functional uses and approaches (e.g., bricolage) for new and existing urban structures and policies through collaborative engagement and analysis. It is thus well worth exploring as a means of delivering co-benefits for environment and human health and wellbeing. Indeed, urban tinkering has close ties to systems approaches, which often are recognized as critical to sustainable development. We believe this concept can help forge much-closer, much-needed ties among engineers, architects, evolutionary ecologists, health specialists, and numerous other urban stakeholders in developing innovative, widely beneficial solutions for society and contribute to successful implementation of SDG11 and the New Urban Agenda.

In many countries in the European Union (EU), the popularity of communal urban gardening (CUG) on allotments and community gardens is on the rise. Given the role of this practice in increasing urban resilience, most notably social resilience, municipalities in the Global North are promoting CUG as a nature-based solution (NbS). However, the mechanisms by which institutional actors can best support and facilitate CUG are understudied, which could create a gap between aspiration and reality. The aim of this study is therefore to identify what governance arrangements contribute to CUG delivering social resilience. Through the EU GREEN SURGE project, we studied six CUG initiatives from five EU-countries, representing different planning regimes and traditions. We selected cases taking a locally unique or innovative approach to dealing with urban challenges. A variety of actors associated with each of the cases were interviewed to achieve as complete a picture as possible regarding important governance arrangements. A cross-case comparison revealed a range of success factors, varying from clearly formulated objectives and regulations, municipal support, financial resources and social capital through to the availability of local food champions and facilitators engaging in community building. Municipalities can support CUG initiatives by moving beyond a rigid focus on top-down control, while involved citizens can increase the impact of CUG by pursuing political, in addition to hands-on, activities. We conclude that CUG has clear potential to act as a nature-based solution if managed with sensitivity to local dynamics and context.

Functional traits have been proposed as a more mechanistic way than species data alone to connect biodiversity to ecosystem processes and function in ecological research. Recently, this framework has also been broadened to include connections of traits to ecosystem services. While many links between traits and ecosystem processes/functions are easily and logically extended to regulating, supporting, and provisioning services, connections to cultural services have not yet been dealt with in depth. We argue that addressing this gap may involve a renegotiation of what have traditionally been considered traits, and a targeted effort to include and expand upon efforts to address traits-cultural ecosystem services links in traits research. Traits may also offer a better way to explore the recognition and appreciation of biodiversity. Drawing upon examples from outside the explicit traits literature, we present a number of potential connections between functional traits and cultural ecosystem services for attention in future research. Finally, we explore considerations and implications of employing a traits approach in urban areas, and examine how connections between traits and ecosystem services could be developed as indicators in a research and management context to generate a robust and resilient supply of ecosystem services.

In order to contribute to urban sustainability and the generation of enjoyable, multifunctional spaces for city residents, it is crucial to gain a better understanding of the environments that are being shaped in urban areas. This study examines patterns of vegetation structure and cover, as well as tree species and socially-valued tree traits across the urban landscape of Stockholm, Sweden. It uses the lenses of two different land classes for this investigation: (1) seven categories of urban morphology, and (2) three categories of land management: private, public, and remnant reference vegetation sites. Results indicate significant differences across urban morphology, with the greatest extents of tree and ground cover layer in forests, the least in industrial and contiguous closed urban sites, and a near absence of shrub layer across all classes. Ground cover indicates a shift from an herbaceous mix to a combination of grass and impervious cover from more exurban to urban sites. A diversity of socially-valued tree traits is exhibited most strongly across those spaces most intensely managed for use by humans. Similar functions may be provided by different species in the landscape. While tree species differed when comparing public and private land use, their functional profiles were similar, indicating potential for response diversity and resilience across the urban area of Stockholm in the face of environmental change. Overall, this study serves as a pilot for using traits as an indicator tool for discerning and mapping social-ecological value in urban areas. We suggest that future investigations further explore the potential of using traits as both social and ecological value indicators and as cues for management actions.