Citation: Abuseif, M.; Dupre, K.; Michael, R.N. Trees on Buildings: A Tree Selection Framework Based on Industry Best Practice. Land 2023, 12, 97. https://doi.org/10.3390/ land12010097 Academic Editor: Thomas Panagopoulos Received: 29 November 2022 Revised: 15 December 2022 Accepted: 26 December 2022 Published: 28 December 2022 Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). land Article Trees on Buildings: A Tree Selection Framework Based on Industry Best Practice Majed Abuseif 1,2 , Karine Dupre 1, * and Ruby N. Michael 1,2 1 School of Engineering and Built Environment, Griffith University, Gold Coast, QLD 4222, Australia 2 Green Infrastructure Research Labs (GIRLS), Cities Research Institute, Griffith University, Gold Coast, QLD 4215, Australia * Correspondence: k.dupre@griffith.edu.au; Tel.: +61-7-5552-7269 Highlights: What are the main findings? • A four-stage tree selection framework is proposed to increase implementation success; • Planting strategies, microclimate analysis and maintenance planning are essential for success; What are the implications of the main findings? • Soil volume selection should be evidence-based and suitable for trees at maturity; • A balance between exotic and native species in green roof settings at the city scale is needed. Abstract: Trees on buildings have received increased interest, and installations have multiplied over recent years, yet there is limited literature and policies guiding the successful implementation of projects relating to trees on buildings. This study investigates the tree selection process for implementation on buildings, using a survey and follow-up interviews with experienced experts to reveal current worldwide industry best practice, and provides a systematic framework for selecting the most appropriate tree species. A tree selection framework is proposed that consists of four stages: identifying the purpose of the tree; analysing the site context and its conditions; evaluating the risk of implementation; and investigating the characteristics of the candidate trees. Decision-makers can use the developed framework to inform design, implementation, and policy development of trees on buildings to reduce implementation risks. In addition, this paper provides useful insights to inform future research about trees on buildings. Keywords: trees on buildings; tree selection; green roof; city policies; framework 1. Introduction Green infrastructure has received increasing attention over the last decade to mitigate the negative impacts of urbanisation and climate change [1]. Diverse types of plants with different implementations define the current types of green infrastructure systems available, including green roofs and green walls. Of the existing vegetation and plant types, trees show higher environmental and thermal performance [2] through air pollution reduction [3], urban heat island mitigation [4], increased shading and biodiversity [5], and improved thermal comfort [6]. However, trees on buildings have received less attention in green infrastructure studies [7] compared with low canopy vegetation. The few existing articles investigating trees rarely mention tree species or provide a holistic overview regarding their selection, although research application is broad (e.g., it might concern thermal performance, health, wildlife, etc.). For example, in their study regarding bird and butterfly diversity, Wang et al. [8] inventoried 126 plant species, tree height and tree crown, but since tree species are not mentioned, it is difficult to evaluate the benefits of one type of tree. The same phenomenon is observed in Tian and Jim [9] and Mohammadi and Land 2023, 12, 97. https://doi.org/10.3390/land12010097 https://www.mdpi.com/journal/land