The Multi-functionality of urban nature: An overview of methods to assess urban ecosystem services

The urban population is increasing around the globe, and while nature provides social, health and aesthetic benefits for humans, the natural and urban worlds are sometimes viewed as contrasting matters. Cities are often seen as human spaces without areas for nature to flourish, free from human intervention. The world faces challenges of disasters such as climate crisis, biodiversity loss, pandemics, and loss of lives due to polluted atmospheres. If we want cities to remain habitable, a different balance between cities and nature must be struck. But what are the advantages and benefits of (urban) ecosystem services? And how can these be assessed and qualified?

Johannes Langemeyer (https://www.bcnuej.org/johannes-langemeyer-bio/), Universitat Autònoma de Barcelona is an established researcher at the Institute of Environmental Science and Technology (ICTA) (https://www.uab.cat/icta/) , Barcelona, and a research fellow at the geography department at the Humboldt University in Berlin. He gave us an overview of methodologies and tools for quantifying, mapping, and valuing (urban) ecosystem services during his lecture at our Master’s in City Resilience Design and Management at UIC Barcelona.

Urban nature: what is it and why is it important?

The concept of urban nature may appear controversial, since we are not used to see urban areas as natural (green) spaces. As Johannes stated during one of his lectures on challenges of an urbanizing planet, we might even be speaking of the ‘extinction of (nature) experience’, meaning that humankind might be forgetting what nature looks like and therefore losing their experience with natural environments. With our urban lifestyle and activities, we are living on an urbanizing planet in which more than 50% of the world’s population live in cities. The expected growth in urban citizens by 2050 is 3.000 million inhabitants.

Next to that, more than ever, we are depending on natural resources since 60-70% of all greenhouse gas emissions come from urban inhabitants.

Ecosystem services in practice: the case study of Barcelona

To understand and assess ecosystem services, we need to consider three different families of services: ecological, sociocultural, and economic/utilitarian values, as shown in the figure below. The use of the concept of urban ecosystem services can play a critical role in reconnecting cities to the biosphere and reducing the ecological footprint and ecological dept of cities while enhancing resilience, health, and quality of life for their inhabitants.

Ecosystem services are grouped in four major categories: provisioning, regulating, habitat and cultural services. To start with, Provisioning services include all the material products captured from ecosystems, such as food, fiber, and freshwater. The regulating services are all the benefits obtained from the regulation by ecosystem processes, including the regulation of climate, water, and some human diseases. Cultural services are the non-material benefits people collect from ecosystems through spiritual enrichment, cognitive development, reflection, and aesthetic experience. Finally, supporting habitat services are the necessary services to produce all other ecosystem services, such as biomass production, nutrient cycling, water cycling, etc.

Valuing ecosystems means dealing with numerous, and often clashing benefit dimensions. Economic valuing of ecosystem services can be divided into use-values, indirect-values, and non-use values. The use-values are based on the way people use the environment, such as: hunting, fishing, bird watching, and hiking. Other people however might enjoy the indirect use of the environment’s values such as: watching television shows about the area and its wildlife. Non-use value refers to the fact that people appreciate that something exists, but they will never use it, such as: paying to protect a wildlife area without ever going there.

Sociocultural values are aspects that people bring to relate to the urban environment. These can be material, moral, spiritual, and aesthetic values. Sociocultural benefits may be more difficult to measure since this often needs various approaches and methods. Sociocultural valuation approaches specifically explore human attitudes and perceptions regarding ecosystem services. Therefore, they are a relevant tool for valuing ecosystem services in landscapes that have been shaped by long-term human impacts.

Ecological values often provide powerful information to guide urban planning. For example, various ecological data of urban green areas have been used for guiding planning processes in cities. These measures can be production of food per year, water flow, cover density of vegetation, species diversity, number of aged trees, and so on.

However, in contrast to the ecological data, a rapidly growing number of ecosystem functions have been characterized as services, valued in monetary and non-monetary terms. Therefore, the use of the ecosystem services concept has transcended from the academic field to policy, non-profit, private, and financial sectors. The valuation of ecosystem services is a way to apprehend and show the importance of non-material benefits from nature that matter to humans. This valuation can be used within the planning process of green infrastructure. However, because people have various perceptions of valuing ecosystem services in urban areas, monetary and non-monetary valuation techniques can be useful. Monetary in this sense can be hedonic pricing, contingent valuation, choice experiments, and travel cost methods. Non-monetary on the other hand can be methods based on observational studies, stated well-being, self-reported physiological health, time allocation and preference ranking approaches.

An example Johannes gave us during his lecture based on the case study of Barcelona is a method used to obtain people’s preferences on urban gardens. For the collection of this data, interviews were done, as to be seen on the image below.  The outcome of this survey is that social cohesion and integration, education, and food supply (quality food) were the main drivers for people to join community gardens.

Furthermore, stakeholder process/scenario development can be used as a method for ecological valuation. This way of valuing is a useful tool to trigger a debate between groups of people. This can be practiced through participatory mapping, whereby people can physically put marks on a map and thereby point out which parts of the metropolitan area are important to look at regarding the different ecosystem services. The remaining methods for ecological valuing Johannes presented are conducting people’s opinions through a survey, or through social media data. However, we must consider the many limitations that come with assessing data from social media. These methods are useful to get a larger picture, compensating on the limitations that a direct survey might have as well as social media interpretations might present.

Ecosystem services for whom? The social justice perspective

What is the value of greening and why do people care about it? Urban greening is not necessarily a good thing. Quantification gives us a picture on this, measuring specific impacts of urban greening on different citizens or groups. An example given during Johannes’s lecture is the effect of green gentrification in Barcelona, the implementation of the (super)blocks on the crossing in Sant Antoni, as shown on the following image.

During this research, data from the prices on Airbnb (main drivers of gentrification in Barcelona) were used to see the green gentrification process at this location. The superblocks in this case did have an influence on the prices of the Airbnb’s in this area. The rising of the prices in this area of Sant Antoni already started from the moment that this project was announced. This means that even before the construction started, the Airbnb owners increased the prices of their properties. This often leads to an increase in social injustice.

What are the main findings?

While the importance of ecosystem services is widely recognized, research methods to assess these services might still have some gaps. While there might be a positive relation between aesthetic values, recreational values and cultural ecosystem services, the social justice perspective is something that needs more various ways of research to measure. Ecosystem services work well as a boundary object to allow people from different backgrounds to have a common language, even though we must be very aware of its limitations. The economic and ecological valuation legacies are reflected within the normative goal of maintaining ‘natural capital’ for future generations; an idea that prioritizes justice between people of the present generation and justice between people of different generations. Very often, the relationship between the two is being ignored and that can lead to an imbalance in the prioritization of temporal dimensions of ecosystem services.

The takeaway for resilience is that assessing ecosystem services has multiple benefits but not infinite benefits. The strength of ecosystem services is that they facilitate the assessment of multiple benefits and tradeoffs across different management options. However, when it comes to assessing multifunctionality and tradeoffs between ecosystem services in the context of urban planning, better consideration of the different dimensions, roles, and stakeholders is necessary. To make it more resilient, a more holistic and dynamic approach should be promoted. This means integrating a more adaptive and plural strategy, considering evaluation loops, broadening participation, and building supervision capacities.

Author: Cato Pos

 

List of references:

Ecosystem Services

Johannes Langemeyer Bio

https://www.uab.cat/icta/
https://drive.google.com/drive/u/0/folders/1Zpitt6VLo5N3Y2UT5UAjTjtNlw5vmKUK
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