Project duration: 01/2018 to 05/2020

The aim of the project, taking into account the vulnerability of the critical infrastructure, is to generate specific cluster recommendations for the development of the resilience of urban stocks of trees. This ought to support the development of a preferably high risk-free level concerning the essential ecosystem services with precise implementation proposals for the tree population of the city of Essen with regard to climate change and shall be implemented by means of test pilots. The project is funded by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety to provide measures for adaptation to climate change. It is executed together with the city administration of Essen.

The city of Essen experienced the worst summer storm since the beginning of records so far, it is called ELA and took place in June 2014. According to the first progress report large parts of the urban stock of trees were damaged when the storm hit the city with previously unimagined intensity. This underlines that the vulnerability of the tree population can lead to an impairment or even a complete standstill of the urban infrastructure with significant risks for affected people. With a view to the climate change and probably interrelated more frequent and intensive summer strong wind events a verification, optimisation or rather climate adaptation in the fields of urban forestry is urgently necessary. For this purpose, in the first instance, it can be learned from past events by appropriate analyses to later base upon it the development of concepts for a gradual implementation which on the one hand focuses on the increase of the resilience to such events and on the other hand aims to an optimisation of all ecosystem services of urban trees with regard to climate change.

Against the background of the summer storm ELA with its severe effects on the stock of trees of the city of Essen, the project serves the subsequent analysis of the quantitative changes in dependence of direction of the wind, city structure, structures of the forest and city tree population and orography for the whole urban stock of trees. It is owned by the city of Essen and has 1750 hectares of forest and about 230,000 city trees in the green infrastructure assets of streets, educational institutions, green areas and other properties. It is expected, that a clustering of comparable structures and damage stages can be derived from the analysis.

Simultaneously, the criticality of the urban infrastructure will be examined and analysed, from which a city wide criticality ranking is created. Infrastructures are described to be “critical”, when they are of substantial importance for the functioning of modern societies and their failure or impairment results in persistent disorders in the overall system. On this basis and in connection with the findings of the wind dynamics with their effect on trees, simulated calculations for storm scenarios with different structures of forest and city tree population will be performed in comparable risk structures. The effects concerning changes of the ecosystem services will be qualified and specific recommendations for action will be made. A high transferability can be expected by this project, whereby the risk awareness towards storm events can be increased.