Guidance for Practitioners When Selecting Low-growing Shrubs for Challenging Urban Sites: A Systematic Literature Review of Information on Drought Tolerance and Ecosystem Services

Urban sites are often characterized by limited space and harsh growing conditions, which present many challenges for plants. Shrubs constitute a significant proportion of the plant material used in urban plantings. Because of their variability in size, form, and habitat requirements, they are helpful design elements for the greening of cities. Therefore, it is incumbent on practitioners to have detailed information about the tolerance of shrubs to environmental stresses to inform their choices. The increasing prevalence of dry and unpredictable rainfall patterns further compounds these. The issue of water stress represents a significant constraint for plants in urban environments. Consequently, those responsible for selecting plants for such areas must consider drought tolerance when making their choices. The objectives of this study were to ascertain the current availability of information regarding drought tolerance and the provision of ecosystem services of selected shrub species and to evaluate the extent to which this information provides guidance to practitioners. To achieve this, books, nursery catalogues, and academic articles were subjected to a review process. A total of 10 European nurseries were consulted to select five common and five uncommon low-growing shrub species for the subsequent literature screening. The species-specific information was extracted by considering findings concerning the tolerance to environmental stresses, the provision of ecosystem services, the recommendations for use in urban environments, and the natural habitat of the species. The findings indicated that extant information was available for most species. However, this information was frequently generic, contradictory, concerned with botanical characteristics rather than site-related information, or excessively focused on a singular stress factor in a controlled setting, thereby limiting its utility for practitioners. The knowledge documented in books is predominantly unsubstantiated and based on the author’s experiences and qualitative observations. These findings underscore the necessity for reliable quantitative assessments of stress tolerance in numerous widely used shrub species to inform professionals’ plant selections for urban environments and ecosystem services.