Assessing the association of pathways of entry and alien plant impacts in protected areas
Assessing the potential pathways of introduction of invasive alien plants into protected areas can direct surveillance and enhance detection strategies. Additionally, predicting those species with the highest potential impact can also act to preserve native biodiversity and target resources to those species with the highest potential impacts. The study focused on the South African National Parks (SANParks) estate which has 752 alien plant species recorded across its 19 national parks. The SANParks estate covers an area of 39 000 km2 encompassing nine biomes. 139 transformer species defined as ‘those alien species that change the character, condition, form, or nature of ecosystems over a substantial area relative to the extent of that ecosystem’, and had the highest potential impact were selected for the study. Their potential for entry into the protected areas was assessed for eight pathways (rivers; road, paths, trails, tracks; contamination by construction material, equipment, soil; ornamental plants; agriculture; clothing; food or produce; and animal dispersal). In addition, their potential impact on five main categories was evaluated (impact on ecosystem processes, impact on community structure, impact on community composition, impact on individual indigenous species, species interactions). The similarity of impact and pathway types between species was assessed using statistical methods. Nearly 80 % of the species were ornamental species and 60 % were dispersed along rivers, highlighting the importance of managing ornamental species and monitoring along rivers. There was a positive relationship between the number of potential pathways and the variety of impact categories the species can have impacts in. – which highlights species which can use multiple pathways can reach a wider range of habitats and have different kinds of impacts.
Sources
Foxcroft LC, Spear D, van Wilgen NJ, McGeoch MA (2019) Assessing the association between pathways of alien plant invaders and their impacts in protected areas. NeoBiota 43, 1–25. https://doi.org/10.3897/neobiota.43.29644