Assessing Climate Change Impacts on the Vegetation of the Canton of Zurich

Abstract

Climate on our planet is changing. The canton of Zurich, in following the global trend, is expected to face warmer temperatures throughout the year and dryer summers in most parts of the canton. These climatic changes have an effect upon ecosystems and biodiversity, and pose major challenges for many species. As a consequence, the canton of Zurich has developed a series of action plans to address the risk of biodiversity loss. This thesis aims at supporting the canton of Zurich in its climate adaptation strategy regarding management tasks to reduce the climate change impact on plant biodiversity loss. For that purpose, we identified potentially threatened and favored plant species within the canton of Zurich by means of ecological indicator values from Flora indicativa and plant surveys. Furthermore, we assessed how the site conditions the plant species can find today are expected to change under different climate change scenarios. Finally, we identified regions in the surrounding Europe that exhibit a similar current climate compared to the climate we would expect to see in the future in Zurich. Studying the ecosystems of the identified places could provide insight into complex ecosystem dependencies, such as interactions among species and between trophic levels. The resulting lists of sensitive species distinguish between climate change effects due to rising temperature and decreasing soil moisture, whereby the results seem to be meaningful as judged by botanical experts of WSL and the canton of Zurich. However, they only represent a first assessment and the definition of species-specific management goals requires further investigation. Further, we found that in accordance to the climatic changes the environmental conditions are expected to become more preferable for species with dryer and warmer requirements than today. The third analysis revealed that the locations with similar future Zurich climate can be found in few cases in Switzerland, but most often in neighbouring countries, as well as in Slovenia, Croatia and Bosnia and Herzegovina. However, only very few regions show a climate that tightly matches the projected future climate of Zurich. In order to explore in more detail existing ecosystems that are likely to resemble future ecosystems in Zurich, further investigations are needed, and analyse need to consider computed distances and other important factors, such as bedrock or wind.