Plants and People in Urban Green Space (PAPPUS)

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

In the face of pressures such as urban densification 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 (UGS), 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 UGS, largely because the links between the biophysical and human factors driving plant assemblages in cities remain underexplored. As a result, we still do not know how to manage the diversity, composition, and attributes of plants in UGS to realize both human and ecological benefits, such as habitat provision for insects and regulation of temperatures. Understanding how these benefits are realized requires an interdisciplinary approach that addresses the social and ecological processes behind stakeholders’ decision making.

The goal of the project PAPPUS is to understand how decision-makers affect plant assemblages present in different UGS, and how their decisions affect the ecological and human benefits that can be realized from UGS in a changing climate.

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

  • RQ1: 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?
  • RQ2: Which plants grow in different UGS and how do they affect insect biodiversity and human benefits?
  • RQ3: How do plants grown in UGS affect local microclimate and how does climate affect these plants?
  • RQ4: Which plants would grow in these UGS in the future given different scenarios and how will this alter ecological and human benefits?

These research questions are addressed in their respective work packages (WP) (see Figure 1): People, Plants, Microclimate, and Integrated Scenariosthat, together, aim to integrate the social, ecological, and climatological aspects of urban green spaces. To do so, plant traits (attributes) and assemblages present in UGS are used as the basis for communication between ecologists, climate modelers, and social scientists. WP1 People (Dr. Marcel Hunziker, WSL) assesses plant-related preferences and behaviors of decision-makers responsible for various UGS in Switzerland (we use the term “plant-related” to cover preferences and behaviors regarding plant species, traits, and assemblages), while WP2 Plants (Dr. Marco Moretti, WSL) assesses how planting and management decisions affect current plant assemblages, insect biodiversity and human benefits in different UGS. WP3 Microclimate (Dr. Lauren Cook, Eawag) explores how plant traits and assemblages affect the thermal regulation in UGS in a current and future Swiss climate. Finally, 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.

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 to assess societal preferences and management practices related to vegetation in different UGS and their effects on biodiversity, microclimate, and human benefits. Ultimately, we will gain social, ecological, and microclimatic knowledge needed to ensure that UGS 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.

PAPPUS: 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 (Tassacum officinalis).