Carbon sequestration potential of street tree plantings in Helsinki

• Published in: Biogeosciences 2022-04, Vol.19 (8), p.2121-2143
• Main Authors: Havu, Minttu, Kulmala, Liisa, Kolari, Pasi, Vesala, Timo, Riikonen, Anu, Järvi, Leena
• Format: Article
• Language: English
• Subjects: Air pollution; Analysis; Atmospheric models; Biomass; Carbon capture and storage; Carbon content; Carbon cycle; Carbon cycle (Biogeochemistry); Carbon exchange; Carbon sequestration; Cities; Climate; Climate action; Climate and vegetation; Climate change mitigation; Ecosystems; Emissions; Environment models; Environmental changes; Environmental conditions; Evaluation; Forest ecosystems; Greenhouse gases; Irrigation; Land surface models; Life span; Microclimate; Mitigation; Modelling; Moisture effects; Photosynthesis; Plant species; Planting density; Respiration; Road construction; Sap; Software; Soil; Soil conditions; Soil moisture; Soil moisture measurements; Soil respiration; Soil types; Soils; Species; Temporal variations; Tilia; Transpiration; Trees; Urban areas; Urban heat islands; Urban microclimates; Vegetation; Water balance
• ISSN: 1726-4189; 1726-4170; 1726-4189
• DOI: 10.5194/bg-19-2121-2022

Cities have become increasingly interested in reducing their greenhouse gas emissions and increasing carbon sequestration and storage in urban vegetation and soil as part of their climate mitigation actions. However, most of our knowledge of the biogenic carbon cycle is based on data and models from forested ecosystems, despite urban nature and microclimates differing greatly from those in natural or forested ecosystems. There is a need for modelling tools that can correctly consider temporal variations in the urban carbon cycle and take specific urban conditions into account. The main aims of our study were to (1) examine the carbon sequestration potential of two commonly used street tree species (Tilia x vulgaris and Alnus glutinosa) growing in three different growing media by taking into account the complexity of urban conditions and (2) evaluate the urban land surface model SUEWS (Surface Urban Energy and Water Balance Scheme) and the soil carbon model Yasso15 in simulating the carbon sequestration of these street tree plantings at temporal scales (diurnal, monthly, and annual). SUEWS provides data on the urban microclimate and on street tree photosynthesis and respiration, whereas soil carbon storage is estimated with Yasso. These models were used to study the urban carbon cycle throughout the expected lifespan of street trees (2002-2031). Within this period, model performances were evaluated against transpiration estimated from sap flow, soil carbon content, and soil moisture measurements from two street tree sites located in Helsinki, Finland.