The selection of suitable tree species in cities is based on many different criteria covering different demands and requirements. In the GrüneLunge 1.0 project, trees were investigated with regard to their ecosystem services and their effect on human health, as well as the growth potential of different tree species depending on site conditions and extreme weather events. In the follow-up project, a tool is now to be developed that will make it easier for municipalities to select suitable tree species based on scientific findings and taking into account the individual requirements of the municipality. So far, the climate species matrix (Roloff et al., 2008; Knopf et al., 2015), the citree planning database based on it (TU Dresden Professorship of Forest Botany, 2020), and the street tree list of the German Conference of Garden Authority Managers (Arbeitskreis Stadtbäume, 2020) are available for this purpose. These methods have specific application areas and already take into account criteria such as drought tolerance, frost hardiness, crown characteristics and susceptibility to pathogens. The first goal of this subproject is to add to these compilations the criteria investigated in GrüneLunge 1.0 to conduct a new, proprietary literature review especially with respect to ecosystem services. As a second goal, the existing methodology of suitability assessment will be further developed. In order to adequately incorporate the variety of criteria to be considered, multi-criteria procedures are suitable. By means of a multicriterial decision analysis (MCDA), a table tool is created that is relatively easy to use. Such a table contains the suitability criteria for each tree species. Based on this, municipalities can enter their specific weightings for the criteria so that regional characteristics or individual requirements can be taken into account in tree species selection. Such prioritizations, also known as preference articulation, can be drought tolerance, shade, irrigation, or human health, for example.
The result of the subproject is a tool that has been extended by some criteria and further developed by methodological aspects to support the complex decision situation "tree species selection in urban areas under climate change". The tool is being developed with the participation of test municipalities and the Garden Authorities Conference.
Essential for this subproject is the cooperation with the Working Group Urban Trees of the German Conference of Garden Authorities (GALK e. V., Dr. Joachim Bauer, City of Cologne). Suitable and interested test communities are to be identified and selected at the beginning of the project. These should cover as wide a variety of conditions as possible (size, stock of street trees, requirements). The aim is to work with at least three municipalities.