UrbanGaia Project

More than half of the global population is living in cities. The need for resilient and healthy ecosystems, fostering biodiversity and maintaining human wellbeing is particularly pressing in urban contexts where the highest population densities are coinciding with highest environmental impacts. Urbanisation provokes fragmentation and degradation: ecological connectivity and ecosystem condition (quantity as well as quality) are heavily affected. This decreases ecological resilience, ecosystem functioning and biodiversity.

In turn, it affects the supply of ecosystem services and all potential benefits related to them. Cities are complex socio-ecological systems, and the needs and desires to improve well-being are highly variable within and between cities, as well as over time. The demand for – and use of - ecosystem services is therefore equally diverse and context-dependent, and as such, transdisciplinary approaches are required, not only to capture this complexity, but also to be able to scale up findings to higher spatial and institutional levels.

Urban Green-Blue Infrastructures (U-GBI), ranging from technical solutions with an ecological component to entirely nature-based solutions, are hypothesised to increase ecological connectivity and quality, improve biodiversity and functioning, deliver multiple ecosystem services and direct improvements of human wellbeing. Moreover, U-GBI have an indirect well-being effect by mitigating the negative urbanisation cascade described above (fig. 1). U-GBIs are defined here as sets of ecosystems of one type, linked into a spatially coherent system through flows of organisms, and interacting with the landscape matrix in which it is embedded, which can be used to conserve and sustain or enhance biodiversity, ecosystem functions,

and to provide services to human populations (e.g., Opdam et al. 2006).

UrbanGaia will contribute to the socio-ecological knowledge base on critical features of U-GBIs, and provide tools for guiding their establishment, management and evaluation. Applying an innovative two-way approach of smartphone supported citizen science including spatial data mobilisation on the one hand, and on the other the transdisciplinary valuation and co-creation of U-GBIs by a range of stakeholders, UrbanGaia will be able to go beyond the state of the art and provide new insights on effective U-GBI implementation.

Resilient ecosystems are essential for the maintenance of biodiversity and the continued support of ecosystem services under global change scenarios. Ecological quality consists of different components (energy fluxes, matter flows, diversity aspects) which all contribute to the integrity, stability and resilience of ecosystems. Urbanization, as the main driver for habitat degradation, impacts several of these components, but till now attempts to measure or estimate ecological quality of urban systems are scarce. A major concern is that urban socio-ecological systems can cross biotic and/or abiotic thresholds [Ramalho & Hobbs 2012], with severe implications for the risk for destructive events. Connectivity is essential for resilient ecosystems: dispersal and other movements of organisms are recognized as key processes for the survival of small isolated populations, and the shrinking of semi-natural areas is assumed to be partially mitigated by increasing connectivity between habitat patches.

However, on-going fragmentation and habitat isolation results in a decline of populations and decreased species richness. Fragmentation also alters the delivery of ecosystem services dependent on biodiversity [e.g. pollination: Tylianakis et al. 2008]. Urban zones are ecologically characterized by habitat patches that are small, fragmented and isolated [Goddard et al. 2009], and urbanisation and infrastructure development have been main drivers for fragmentation of natural and semi-natural areas, river networks and associated wetlands. Connectivity is dependent on the type of landscapes and species involved [Kindlmann & Burel, 2008]. The challenge is to connect advanced spatial datasets, ecological theory and local validation with the aim to understand how complexity and heterogeneity interact either to threaten or to secure and strengthen biodiversity and ecosystem services.

Ecosystem functioning and biodiversity are essential components of ecological quality defined in the former section. In this step of the UrbanGaia theoretical framework, both are defined as the specific functions or functional groups/biodiversity which support the supply of ecosystem services. This responds to the category of supporting services (e.g. habitats for species, maintenance of genetic diversity). For species, the trend towards greater extinction risk for several taxonomic groups shows no sign of decrease. Where ecosystem services have been assessed, many are found to be in decline. Urban areas can support high levels of biodiversity and this urban diversity plays an important role in long-term ecosystem functioning [Alvey 2006].

The biodiversity of highly urbanized areas can act as an important reserve of biodiversity [Araújo 2003], harbouring endangered species [Alvey 2006]. Especially the loss and fragmentation of natural habitat sharply reduced the richness of taxa in the urban core [McKinney 2002]. Global changes exert additional pressures on ecosystems, and reduced resilience (quality & connectivity) of urban ecosystems renders them especially vulnerable to these pressures. The main challenge is to disentangle the production functions and priority functional groups which support the services relevant for the urban context. This requires ecological understanding as well as a prioritisation based on the societal importance of the services and species being supported, which can only be captured via place-based and contextual socio-ecological research methods.

Ecosystems are used by humans. This ecosystem use always invokes an investment, be it intellectual capital (e.g. contemplating a beautiful landscape), labour (e.g. biking in a park, maintaining treelines) or energy (e.g. fuel input in agricultural production). Therefore, managed ecosystems are situated on a continuum from nature-based to technology [Maes & Jacobs, 2015]. In this sense, all ecosystem services-uses are a combination of nature-based, human and fuel-based inputs. Green and blue urban networks fulfil a broad range of economic, social and ecological services, and the management (‘investment’) or the actual use of these areas will determine the final bundle of services humans and the ecosystem will derive from them. Urban infrastructures with a natural component are therefore able to produce a number of (economic, social, ecological) co-benefits which their ‘grey’ counterparts do not.

With some exceptions [e.g. Elmqvist et al. 2013], the relationships between urban ecosystems/infrastructures and biodiversity levels required to enhance or maintain key services have rarely been studied with the purpose of designing improved / optimal use or management, with many residents/users taking part in nature management, enjoying and valuing ‘natural’ areas [Svendsen & Campbell 2008] with different purposes. The challenge is to map and value (not in monetary but in societal sense) services of urban areas and infrastructures based on ecological, social, economic values held by different stakeholders, which is a particular research challenge due to the high spatial heterogeneity, multi-functionality and multiple use of U-GBI in urban areas [Gómez-Baggethun et al Barton, 2013]. Once the relevant services are valued, the extent to which they depend on ecosystem functioning and biodiversity needs then to be clarified to adapt the use to ecological as well as social sustainability criteria and indicators.

Once the ecological, social and economic values of ecosystems have been determined for a certain context, the management can be adapted. However, urban contexts are highly complex, with sharp spatial gradients in well-being and human needs. This immediately invokes ethical questions of distribution: who benefits and how to balance the needs of one stakeholder to the wants of another. Also, choices concerning inter-generational issues have to be made, especially in the context of global change and conservation of ecosystem resilience to serve the next generations by restricting use by this generation.

Effectiveness of tools and operationalization of findings also depends on a large number of governance and communicative factors. These issues can only be tackled in a local, place-based and in-depth participatory research approach. The challenge is to percolate these findings upstream into the theoretical framework and practical work by co-designing the research based on this transdisciplinary approach, while safeguarding comparability between local contexts.