ARPHA Preprints, doi: 10.3897/arphapreprints.e156737

An evidence-based protocol for developing lists for tree planting

Luke John Potgieter^‡§, Marc W. Cadotte^|, Sabrina Kumschick^§¶, Trudy Paap^#, Francois Roets^§¤, John Ross Wilson^§¶, David Richardson^§

‡ Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Canada§ Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa| Department of Biological Sciences, University of Toronto – Scarborough, Toronto, Canada¶ Kirstenbosch Research Centre, South African National Biodiversity Institute, Cape Town, South Africa# Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa¤ Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, Stellenbosch, 7600, Stellenbosch, South Africa

Corresponding author: Luke Potgieter ( lukepotgieter@sun.ac.za )

This is an open access preprint distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Citation: Potgieter L, Cadotte MW, Kumschick S, Paap T, Roets F, Wilson JR, Richardson D (2025) An evidence-based protocol for developing lists for tree planting. ARPHA Preprints. https://doi.org/10.3897/arphapreprints.e156737

Abstract

Tree planting is increasingly being promoted for urban greening, carbon sequestration, and to enhance biodiversity. However, poorly planned and executed tree-planting schemes can inadvertently contribute to biological invasions which often have detrimental effects on local ecosystems, economies, and human well-being. Therefore, sustainable, rigorous, repeatable and transparent species selection strategies need to be employed to maximise ecosystem benefits.

Using the Polyphagous Shot Hole Borer (PSHB, Euwallacea fornicatus) invasion in South Africa as a case study, we used a multi-criterion approach, incorporating national lists of regulated invasive plant species, records of their invasiveness in other regions, and data on PSHB susceptibility to develop a strategic decision protocol for identifying tree taxa that can be safely considered in planting schemes. Using a recently published national planted tree inventory, we apply this protocol to the City of Cape Town, South Africa, a metropolitan municipality experiencing widespread tree and PSHB invasions.

Among the 445 planted tree taxa evaluated in Cape Town, 85 are regulated nationally as invasive species (and so must not be used), while 49 are deemed suitable candidates for planting initiatives (i.e., a safe list).

This protocol provides evidence-based guidance for tree planting to mitigate the risk of tree invasions and to reduce the spread and impact of associated pests and pathogens. It can provide support for environmental planners and managers in making informed decisions to safeguard ecosystems and optimise ecosystem services. This protocol is replicable and adaptable for use in other regions and offers a robust model for sustainable planting, restoration planning, and invasive species management.

Keywords

biological invasions, ecosystem services, green infrastructure, pest management, treescapes, tree invasions, tree planting, urban greening