*2.2. Categorization of Alien Species*

First, naturalized alien species were categorized into invasive and non-invasive following Bezeng et al. [20,21] as their study provides the most recent and comprehensive record and categorization of alien woody species in South Africa. In South Africa, the NEMBA list of alien plants is the official list of species considered as invasive and noninvasive (naturalized) in South Africa. The list is generated, through a lengthy process, by the governmen<sup>t</sup> of South Africa through the Department of Environment, Forestry and Fisheries (DEFF). The process through which the list of alien species is generated can be summarized as follows: An Alien Species Risk Analysis Review Panel (ASRARP) is established and tasked to conduct the invasion risk analysis of alien species in the country. This panel, formed of various experts in the field of biological invasion, uses the framework of [35] for alien invasion risk analysis. This framework is grounded on the following five risk assessment criteria: background (of the alien species), likelihood (of the species being introduced to the country, naturalized and invasive), consequences (environmental and

socio-economic), managemen<sup>t</sup> (of the alien species) and reporting (summary of the risk assessment and risk recommendation). Before ASRARP makes a final decision on the risk status of a given species, the opinions of at least two experts, generally one local and one international, are consulted. The list of South Africa's alien species used in the present study emanated from this process and additional expert consultations [21].

### *2.3. Record of Services of Woody Flora (Native and Alien) in South Africa*

We documented through an intensive literature search the different services these species (native and alien) provide to humans in South Africa. First, we used the Web of Science (WoS) to retrieve existing scientific ethnobotanical studies in the region. Second, we searched for each species by using combinations of keywords such as "scientific name of species", "Southern Africa", "Botswana", "Mozambique", "Namibia", "South Africa", "Swaziland", "Lesotho", "Zimbabwe", "uses", "usages", and "benefit". We also made use of Google and Google Scholar for scientific and grey literature using similar keywords to retrieve online resources such as regional and country-specific journals, proceedings, technical reports, herbarium and commercial websites informing on the uses of woody plants in our dataset. The Southern African Plant Invaders Atlas (http://www.agis.agric.za/wip/, accessed on 1 March 2017) was also consulted. In addition, we consulted key books on the regional flora such as *Trees of Southern Africa*, *Field Guide to Trees of Southern Africa*, and *Guide to Trees Introduced into Southern Africa* [33,36,37]. Additionally, plant uses in South Africa were retrieved from the *Prelude Database for Medicinal Plants in Africa* (http://www.africamuseum.be/collections/external/prelude; accessed on 10 February 2017), a unique database where medicinal plants and uses across the entire African continent since 1847 are documented and frequently updated. Finally, services of plants were updated by consulting the global dataset of plant uses of plants documented on the WEP database (National Plant Germplasm System GRIN-GLOBAL; https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearcheco.aspx, accessed on May 2021) and Diazgranados et al. [38]. All the different services (uses) retrieved from this wide and intensive literature search were grouped into 12 distinct categories of services (Table S1).

### *2.4. Phylogeny of the Southern Africa's Woody Flora*

The phylogenetic tree used in this study is the most comprehensive DNA-based phylogeny ever assembled for both native and alien woody flora of Southern Africa in one of our recent papers [21]. In summary, this phylogeny was based on a matrix of the two DNA barcode regions *matK* (942 bp) and *rbcLa* (552 bp) generated in two recent studies (ref. [34] for native flora and ref. [21] for alien flora; sequences available since 2015 on www.boldsystems.org;). Although four markers are proposed as plant barcodes, the two regions *matK* and *rbcLa* have been shown to be efficient in several ecological studies, e.g., [21,34]. The phylogeny includes 1400 native and alien taxa representing 117 families and 562 genera. The reconstruction of the phylogeny follows the classical widely established Bayesian method (see details in [21]). Importantly, four independent runs of MCMC were performed, each for 100 million generations, sampling every 1000 generations. The MCMC log files for convergence using the effective sample size (ESS) statistics in Tracer v.1.5 [39] were evaluated, and all ESS values >100. Finally, the resulting tree files from the four runs were combined in LogCombiner v.1.7.5 [39], down sampling 1 in 20,000 trees, and discarding the first 25% trees as burn-in. The maximum clade consensus (MCC) phylogeny was generated with TreeAnnotator v.1.7.5 [39]. This MCC phylogeny is used for all phylogenetic analyses in the present study.
