During the next decades, humanity will have to cope with climatic changes and increasing urbanization. To facilitate urban planning in the face of these issues, we developed a software tool for the selection of trees in urban areas. The tool not only incorporates the characteristics particular to each tree species but also accounts for common planning practices, health issues (particularly in regard to air quality and allergy potential), and subjective assessments of city residents.
Which trees are to be planted where within a city? What are the criteria used to make these decisions? How can tree selection be both economically efficient and ecologically beneficial? How can urban trees help to reduce CO₂ emissions? What makes urban green attractive for city residents, and how can it provide benefits to their health?
Tree plantings on unfavorable sites need extra maintenance e.g. by irrigation and fertilization and tend to be more vulnerable against pests and pathogens. This causes higher mortality of planted trees as well as higher costs. Furthermore it has to be considered that plants can be toxic or trigger allergies.
Taking all these aspects of urban forestry into account is a difficult and complex challenge for urban planners. To address these issues, we built a database serving as an information base and decision-making aid for planners - hoping to improve urban green, thereby enhancing quality of life for city residents as well as increasing floristic urban biodiversity. The underlying research was conducted in Dresden, Germany. The database shows characteristics for more than 390 species and varieties which can be potentially planted in central Europe.
An approach this complex task called for interdisciplinary collaboration: Thus, the Department of Forest Botany, the Department Forest Biometry and Systems Analysis (both: School of Civil and Environmental Engineering, TU Dresden), and the Centre for Interdisciplinary Research in Technology Development (School of Humanities and Social Sciences, TU Dresden) joined efforts. Within the project, scientists from different academic backgrounds collaborated in developing this solution for urban forestry at the intersection of environment, health and urban planning.
In psychological studies, we identified the outward tree characteristics that are relevant for lay people in their perception of urban trees. We also researched how these characteristics relate to which trees are preferred over others. This research provides the basis “popularity” value in the tree profiles: Three basic tree characteristics (distinction between coniferous and deciduous trees, crown shape, maximum tree height) can be used to estimate tree popularity. Please beware that human reactions can almost never be predicted perfectly. Above that, there may be outliers, that is, our prediction may be far off for certain species if they feature rare characteristics which influence popularity but are not considered in our statistical popularity prediction model. Specifically, it may be further influenced b individual preferences, unusual species characteristics, or certain properties of the planting site. However, the popularity values may be used as a rough guideline for species popularity among lay people.