Swiss Federal Institute for Forest, Snow and Landscape Research WSL

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Avalanche Bulletin

Plants and People in Urban Green Space (PAPPUS)

Project lead

Marco Moretti, WSL (Project leader)
Marcel Hunziker, WSL (Deputy)
Lauren M. Cook, Eawag 
Bertrand Fournier, Potsdam Universität 

Project duration

2023 - 2027

Financing
Figure 1: Allotment garden, as an example of an urban green space (Click on the image to enlarge it)

How human and biophysical factors jointly shape biodiversity and human benefits in cities

In the face of pressures such as urban densification, biodiversity loss, and climate change, there is a growing consensus that cities should be transformed to restore biodiversity, regulate microclimate, and increase human quality of life. Urban green spaces, such as parks and private gardens, can help to achieve these multiple goals, primarily due to the properties and types of vegetation grown there. Unfortunately, we do not yet fully understand what dictates the plant communities present in urban green spaces, largely because the links between the biophysical and human factors driving plant assemblages in cities remain underexplored. As a result, it remains unclear how to manage the diversity, composition, and attributes of plants in urban green spaces to realize both human and ecological benefits, such as habitat provision for insects and temperature regulation. Understanding how these benefits are realized requires an interdisciplinary approach that addresses the social and ecological processes behind stakeholders’ decision making.

Goal and research questions

The goal of the project PAPPUS1 is to understand how decision-makers (e.g., owners and managers of public and private green spaces, gardeners, and lay people) affect plant assemblages present in different urban green spaces, and how their decisions affect the ecological and human benefits that can be realized from urban green spaces. This is done in a context characterized by urban densification, biodiversity loss, and climate change to ultimately propose sustainable measures to best address the current and future challenges of cities.

We will achieve this goal by examining the human and biophysical drivers of planting decisions in private, semi-public and public urban green spaces. Of particular relevance is whether decisions can be influenced by external factors (e.g., public preference or knowledge of biodiversity crisis and climate change) and how the decisions so influenced would alter the functional composition of plant assemblages in urban green spaces under current and future climate and urban densification scenarios.

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1 The pappus is the light feathery appendix of some fruits having the function of favoring the dispersion of the seeds by the action of the wind, as in the well-known dandelion (Tarassacum officinalis).

 

PAPPUS will evaluate the following four research questions:

  1. Which plants do decision-makers purchase and plant, and how do they manage them, given their and other stakeholder group's preferences and different external considerations?
  2. Which plants grow in different urban green spaces and how do they affect insect biodiversity and human benefits?
  3. How do plants grown in urban green spaces affect local microclimate and how does climate affect these plants?
  4. Which plants would grow in these urban green spaces in the future given different scenarios and how will this alter ecological and human benefits?

Project design

The project started in 2023 and will run until 2027. Three Swiss cities (Lugano, Geneva and Zurich) are involved, representing three different biogeographical regions, languages, and socio-cultural realities. The project focuses on the main types of urban green spaces (private gardens, family gardens, parks, real estates, and ruderal areas), with a total of 60 sites per city and 180 sites in total (see Figure 2).

Figure 2: A) The three cities included in the project PAPPUS; B) The five most representative urban green space types selected in each city; C) The stakeholder groups involved in the project. (Click on the image to enlarge it)

 

These research questions are addressed in their respective work packages (WP) (see Figure 3): Society (WP1), Biodiversity (WP2), Microclimate (WP3) and Integrated Scenarios (WP4 ):

Figure 3: Project structure, showing links between external factors and work packages (WP), as well as relevant influences and feedback. (Click on the image to enlarge it)

WP1 Society (Dr. Marcel Hunziker, WSL) assesses plant-related2 preferences and behaviors of decision-makers responsible for various urban green spaces in Switzerland.  

WP2 Biodiversity (Dr. Marco Moretti, WSL) assesses how planting and management decisions together with biophysical factors affect current plant assemblages, insect biodiversity and human benefits in different urban green spaces.

WP3 Microclimate (Dr. Lauren Cook, Eawag) explores how plant traits and assemblages affect the thermal regulation in urban green spaces in a current and future Swiss climate.

WP4 Integrated Scenarios (JProf. Betrand Fournier, University of Potsdam) quantifies and models the trait-mediated response of plant assemblages and associated ecological and human benefits.

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2We use the term “plant-related” to cover preferences and behaviors regarding plant species, traits, and assemblages.

Scientific and social relevance

The originality of PAPPUS lies in the strong integration of social, ecological, and climatological theories and methods, together with its use of a mechanistic and predictive modelling approach that uses plants traits to quantify to assess societal preferences and management practices related to vegetation in different urban green spaces and their effects on biodiversity, microclimate, and human benefits. Ultimately, we will gain social, ecological, and microclimatic knowledge needed to ensure that urban green spaces continue to provide crucial co-benefits in the face of climate change, biodiversity loss, and urban densification given differing needs of plants, biodiversity, and humans.

Progress of the Projects

Activities 2023: We selected 60 urban green spaces in each of the three cities. In each of them, we carried out vegetation surveys, while in 15 of them (5 per city) we measured relevant microclimate variables. We also interviewed a representative selection of owners and managers of these green spaces. From the plant suppliers, we obtained lists of commercially available species, which together with the native species present in Switzerland, form the global species pool of more than 4,000 species that will be used to investigate the selection criteria from the various decision-makers.

Activities 2024: In 60 green spaces in the city of Zurich, we sampled plant-related insects and collected flowers and leaves for analysis of their chemical composition. We prepared the sociological survey to be carried out among the 180 owners and managers of green spaces and nationwide. We started the microclimate modelling and also collected additional microclimate data in 15 green spaces in the city of Zurich. With the data on all plants in Switzerland and on the market, we finally analysed the species present in the city and identified some of the reasons for this selection.

Figure 4: PAPPUS interdisciplinary research team. From left, standing: Lauren Cook (WP3 leader), Sebastian Ruile, Gabriele Manoli, Joan Casanelles-Abella, Aline von Atzigen, Marcel Hunziker (WP1 leader), Anna Hersperger, Vivien Grothe, Louise Dädlow; squatting: Marco Moretti (PI, WP2 leader), Noemi Buri, Bertrand Fournier (WP4 leader), Yuxin Yin, Nicolas Mouquet, Zélie Stauffer
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