Environmental, socio-economical, or sanitary crises constantly question our adaptability as individuals within a community. How can we overcome the present situation? How to mitigate future crises? What role can we, citizens, play in this collective effort? More and more research and international reports point to the key role of human communities, especially at the level of cities, to increase our societal resilience. In this thesis, I therefore investigate some of the mechanisms leading to more community resilience in cities. This thesis focuses a broadly spread collective action practice which occurs in the urban space, extensively described from the point of view of individual cases or from specific disciplines, with yet no significant attempt to generate a loosely constrained overview of this practice, called the urban commons. @en

This paper presents an agent-based model that explores the conditions for ongoing participation in community gardening projects. We test the effects of Ostrom’s well-known Design Principles for collective action and use an extensive database collected in 123 cases in Germany and two case studies in the Netherlands to validate it. The model uses the Institutional Analysis and Development (IAD) framework and integrates decision mechanisms derived from the Theory of Reasoned Action (TRA). This allows the analysis of volunteer participation in urban community gardens over time, based on the garden’s institutions (Design Principles) and the volunteer’s intention to join gardening. This intention is influenced by the volunteer’s expectations and past experiences in the garden (TRA). We find that not all Design Principles lead to higher levels of participation but rather, participation depends on specific combinations of the Design Principles. We highlight the need to update the assumption about sanctioning in such systems: sanctioning is not always beneficial, and may be counter-productive in certain contexts.

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This study is a comprehensive literature review about the field of the urban commons and its diversity, which we investigate through the lens of the new commons. Acknowledging a potential for adaptive capacity in the urban commons, we classify its traits into ecosystem, socio-economic and institutional factors. To make our work more practical, we further arrange them as benefits, challenges or supports. Our literature review highlights the need to further study the institutions which have an impact on the urban commons, as well as the individual and collective behaviour mechanisms at stake in the emergence and management of this commons. In addition, more light needs to be shed on the property-regimes relevant to the urban commons, with a focus on the access or use rules, rather than on ownership.@en

In order to better understand the mechanisms leading to resilient urban gardening systems, we revisit Ostrom’s institutional design principles with an agent-based model (ABM) and implement behavioural dynamics as structured by the theory of reasoned action. Our experiments show that sanctioning bad behaviour in general increases the group cohesion and leads to longer collective action. Higher success rates occur for cases in which volunteers join for socialising rather than just taking crop yield. However, the design principles are not blueprints leading de facto to robust gardening systems: the combination of these principles is instead determining.

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In this paper, we investigate the potential of urban commons for building community resilience. We focus on the issue of adaptability to socio-ecological issues, which depends on the social capital built by the local community of practice. We measure this capital through the variables of volunteer involvement, perceived trust, and social cohesion in an agent-based model, which simulates the dynamics of participation in collective activities. We anchor our model with the case of KasKantine in Amsterdam, a cooperative and restaurant run by volunteers. Our model shows that both trust and social cohesion emerge from the interactions in the cooperative, especially when group sizes are kept small. This contributes to the adaptability of such social-ecological systems, helping their communities build social resilience.@en