Keynote and Invited Speakers

"Ecosystem services of urban forests in the context of water security and climate change - a GIS-based analysis in the German metropolis Cologne" Prof. Dr. habil. Heidi Elisabeth Megerle University of Applied Forest Sciences Rottenburg, Germany

The worldwide process of urbanization, with more than 50% of world’s population already living in urban areas, leads to rapid climate and environmental changes in cities as well as on a global scale. Cities are a key contributor to climate change, as urban activities are major sources of greenhouse gas emissions. Estimates suggest that cities are responsible, directly and indirectly, for 80 percent of global greenhouse gas emissions. At the same time, cities are especially vulnerable to impacts of climate change. Therefore it is important not only to invest in climate protection, but also to make climate adaptation a priority in cities, to ensure the quality of life of citizens. In this regard ecosystem services of urban forests might play an essential role, but are not yet in the research focus.

Our research project focused on the ecosystem services of urban forests, especially air particle filtration, temperature and water regulation. Using the city of Cologne (Germany) as a case study, the ecosystem services of the city owned forests, which were created at the beginning of the twentieth century in the previously forest-free city, are highlighted, with a special focus on water storage capacity, temperature regulation and filtration of air particles. The processing with GIS consists of the basic analyzes and the in-depth analyzes. The basic analyzes were also carried out in line with the NRW guidelines, the in-depth analyzes go beyond this application and provide additional details in order to further differentiate the results. The goal had been on one hand to test the practicability of the NRW guidelines and on the other hand to provide the city council with a means to communicate the importance of the city’s forests and to advise the forestry department on methods of management regarding the forest’s ecosystem services.

The resulting maps depict the ecosystem services of air particle filtration, temperature regulation and water regulation. In addition to many other aspects, the water storage capacity of urban forests has a broad impact: floods after heavy rainfall events are mitigated, the stored water causes a microclimatic cooling effect via evapotranspiration and the forest floor filters pollutants out of the water.

Furthermore, the findings show that the city’s afforestation efforts in the last century are fulfilling their intended purpose and are benefitting the population greatly. The outer green belt on the western side of the river Rhine is of particular importance as it provides all analyzed ecosystem services at the same time. The results may serve as a stimulus for other major cities to protect and, if possible expand their forest areas.