Observations and modelling of urban carbon and water fluxes to aid cities in climate mitigation and adaptation

Urban green areas have multiple benefits extending from heat mitigation and carbon sinks to human well-being. Due to their multi-benefits, they are an attractive natural solution to aid climate change adaptation and mitigation. In cities of Helsinki and Tampere located in Finland, intensive observations and modelling of urban water and carbon dioxide (CO₂) fluxes have taken place to improve our understanding of the functioning and carbon sequestration potential of different urban green areas and provide science-based evidence for decision-makers on how urban green areas should be planned and constructed to maximize their climate benefits.

Extensive eco-physiological observations were collected from different vegetation types (urban forest, park, garden, and street vegetation) in Helsinki during summers 2020-2022. The observations were made in the vicinity of the ICOS Associated Ecosystem Station FI-Kmp where eddy covariance (EC) measurements presenting the ecosystem level are conducted. The measurements included photosynthesis, sap flow, soil respiration, phenology, fine root growth, meteorology and soil properties. FI-Kmp represents mixed land use and vegetation, and to get more information of the behavior of lawns, additional EC measurements were conducted over urban lawn in the city of Espoo in 2021-2022. The observations are complemented by ecosystem modelling using SUEWS (Surface Urban Energy and Water balance Scheme). SUEWS is used to examine the impact of different urban green area planning options on carbon sinks and storages with focus on the city of Tampere. 

This work will highlight some of the findings made so far and provide examples on the carbon and water fluxes in different urban green areas. We also demonstrate how science-based knowledge can aid decision-making concerning urban green areas.