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PDF, English - main document Download (2MB) | Lizenz: Strategies of Managing Urban Tree Vegetation: A Study of Cities in Taiwan by Anders, Katharina ; Weise, Teresa ; Aeschbach, Nicole ; Höfle, Bernhard underlies the terms of Creative Commons Attribution 4.0

Abstract

Urban regions are particularly affected by increasing heat waves due to climate change. Vegetation, particularly trees, are an important factor to the local climate (i.e. microclimate) within cities. However, urban trees are subject to increasing heat stress during hot summers, which may impede their positive effects on the urban climate and – worst case – lead to dying of trees. With increasing requirements to curate trees and limited resources (e.g., water, human power) there is increasing relevance to develop new strategies, for example, using digital geotechnologies for urban tree management. Cities in geographic regions with overall hotter climate (than in central Europe) are already more adapted to conditions of strong heat than German or central-European cities. This study gathers insights about strategies of urban tree management in Taiwan. This entails a survey of literature and publicly available resources, and direct interviews. Interviews are conducted with two scientific partners from Taiwan. In the frame of this survey, it was not possible to conduct interviews with stakeholders (formal requests were made to several city governments). According to public resources and the information gained with the interviews, urban trees in Taiwan play an important role for different aspects: they have a function for aesthetics and culture, but also for thermal comfort and provision of shade during periods of high temperatures. There is increasing awareness of the importance of trees in the population in the environmental context. Linked to this, an increasing number of actions to avoid the removal of trees, for example, for construction can be observed. The management of urban vegetation is handled by different departments in the cities. Generally, the maintenance of urban trees, particularly trimming and irrigation, are outsourced to contractors. Irrigation mainly relies on watering trucks and human power, and may be limited in dry periods when there is low availability of water. Mostly fresh water is currently being used, some cities already changed to using gray water for irrigation. So far, in Taiwanese cities the deployment of geotechnology in urban vegetation management regards mapping of trees for cadasters, with additional in-situ measured structural parameters. In current research projects in cooperation with city planning, meteorological data is recorded for monitoring the urban microclimate. These existent monitoring setups could be integrated for an improved understanding on the status of urban trees, by linking to new observation parameters, such as soil humidity at the position of individual trees or spatial information on the vitality of trees via (airborne) image acquisition. Similar to the current standard approach of urban tree management in Germany, there seems to be large potential for adopting new strategies of monitoring and managing trees. The situation in Taiwan shows various similarities to current strategies of tree management, mainly irrigation, in German cities. For example, in most cases watering trucks and expert-based scheduling of irrigation at street level are used. Therein, the capacity of irrigation during dry periods is limited by the availability of water and the capacity of human power. Both countries may hence greatly benefit from investigating new strategies of integrating digital geotechnologies to monitor urban vegetation for more targeted requirements of water and further maintenance.