Disservices of urban trees

Ecosystem services provided by urban green areas have been recognised to an increasing degree following the turn of the millennium (MEA, 2003; Gómez-Baggethun and Barton, 2013). Urban trees in particular provide urban dwellers with a variety of ecosystem services (see Chapter 4 of this volume). However, urban trees are also the source of various types of harm, nuisance and costs. These ‘bad’ aspects may be labelled as ecosystem disservices. The concept of ecosystem disservice is a recent one and there is no widely agreed definition for it. On a general level, ecosystem disservices can be defined as the functions, processes and attributes generated by the ecosystem that result in perceived or actual negative impacts on human wellbeing (Shackleton et al., 2016). Both ecosystem services and disservices are inherently anthropogenic concepts, putting emphasis on the human valuation of ecosystem properties and functions. What is perceived as beautiful and beneficial by one person may be considered ugly, useless, unpleasant or unsafe by another. For example, biodiversity-rich, semi-natural areas inside city limits are often experienced as suffering from a lack of maintenance, as opposed to intensively maintained but biodiversity-poor urban parks