Report: SANParks Global Environmental Change Project: Alien species Summary Report

Objective: This assessment aims to determine the relative risk posed to South African National Parks (SANParks) by invasive alien species. Specifically, the assessment aims to collate existing information and knowledge of alien and invasive species (excluding disease causing agents) in and around parks, in an attempt to synthesise this knowledge, and provide the information in a form that is usable for management and policy development.

Driver status: An extensive investigation produced a list of 813 alien species recorded in SANParks, of which 80% are alien plants. Kruger (398 species) and Table Mountain (291 species) National Parks are worst affected, whereas the arid parks tend to be least invaded (e.g. Richtersveld 14, and Kalahari Gemsbok 15 species).

Assessment methods: Of the 813 alien species listed, a subset of 49 animal and 139 plant species considered as potentially the most damaging to the diversity of indigenous species, ecosystems and related services protected under the mandate of the organisation, were selected. These data were examined for both the likely pathways of introduction into a park and the kinds of impacts that may be expected, for animals and plants.

Key results: The most common pathways of introduction of alien animals, namely agriculture and aquaculture, and the ornamental and pet trade can bring in alien species both intentionally and unintentionally, with the high impacting species more likely to be introduced intentionally. For alien plants, the use of alien species as ornamentals is the most common pathway of introduction into parks, followed by rivers, and roads, trails and pathways. The most common impacts by alien animals are herbivory, predation and spread or hosting of diseases. Importantly however, results show that alien animal species may not currently be realising their full range of potential impacts.

Monitoring Implications: An important gap highlighted through the assessment is the paucity of basic information required to assess long-term trends and support decision making. A mapping project, already nearing completion in the Cape cluster, needs to be rolled out to other parks urgently to set baseline data for the monitoring programme.

Management recommendations: The assessment provides 10 key outcomes (described in detail on p. 20), which can contribute to improving various areas of the organisations alien species management operations. A general outcome is the need for a corporate level framework to guide all aspects of the organisations operations, which can then be adapted as new knowledge evolves. Future introductions may be reduced by focusing on a few priority pathways, such as use of ornamental plants and intensifying surveillance along high priority pathways, such as specific rivers and roads/tracks/trails. Key impacts being exerted on the system include direct competition between alien and indigenous species and alteration of a habitats physical structure, thus highlighting priority species. Little is known about the impact of invasive alien species on rare or threatened species, and should be a priority avenue for further investigation.