Soils are irreplaceable for water and carbon storage. Trees are also important carbon stores and cool their surroundings. Especially in cities soils are exposed to stress due to sealing and compaction - which in turn has a negative impact on the trees growing there and the services they provide to society. The project "City - Tree - Soil" is investigating how the urban environment affects soil and tree growth. The project team from BFW, UBA, BOKU and the Innsbruck University, together with students from three middle schools in Vienna and Tyriolia is providing important findings for climate protection in the city. Anyone in Vienna and Innsbruck who is interested can also take part.

Direct measurements of ‘urban nature’ and digital classification of the soil surface are used. In addition to gaining scientific knowledge, a main goal of the project is to emphasise the importance of urban trees for a healthy microclimate and thus for us all, and to raise public awareness for the important functions of the soil.

The surveys of the Sparkling Science project include:

• The continuous monitoring of the diameter increment of trees using special measuring tapes (dendrometers) by the school children as well as other Citizen Scientists: The readings are sent to a database via a QR code and mobile phone. In this way, periods of stress for the trees (e.g. drought) can be recognised. In addition, the tree growth can be viewed almost ‘live’ by everyone.
  
  
• Addressing tree vitality and the condition of the ground surface (‘green strips with bushes’, ‘soil compacted’, ...) using ‘virtual city walks’ by the students of the participating schools: Here, digital skills are expanded and the city can be experienced from a new perspective.
  
  
• The delineation of surface categories on the aerial photograph by the project team within grid areas, incorporating the data collected by the children.
  
  
• Measuring the height and diameter and assessing the vitality of all ‘public trees’ as well as the condition of the ground surface in nature by the project team.
  
  
• Taking soil samples from the defined surface categories for laboratory analysis as well as measuring the infiltration rate of water: High infiltration capacity is particularly important in the event of heavy rainfall. Exemplary investigations are carried out together with the classes on the school grounds, the other locations are sampled by the project team.

These surveys can be used to extrapolate to the urban areas of Vienna and Innsbruck. This means that urban climate protection measures can be better planned and the results can contribute to improving national greenhouse gas reporting. The sealing rate is a particularly important parameter for a number of climate policy issues, such as the extent to which the soil is available for water and carbon storage and for vegetation growth.