Abstract
Protected areas play an important role as refuges from invasive species impacts on biodiversity. Within the MOSAIK (Monitoring Savanna Biodiversity in the Kruger National Park) project, plant species were recorded in a representative set of 60 plots, 50 × 50 m in size, across the entire KNP, distributed so as to cover a range of savanna habitats, i.e. perennial rivers, seasonal rivers and dry crests, and two main bedrock types (granite and basalt). The data were used to assess the role of rivers in the dispersal of alien plants and study whether the alien plant species spread from rivers to open dry savanna. The resulting dataset provided the first thorough information on the spatial distribution of naturalised alien plants in KNP. In total, we recorded 20 plant species that are alien to the park, four of them considered invasive: Parthenium hysterophorus, Opuntia stricta, Xanthium strumarium and Zinnia peruviana. The most widespread species in KNP was Tridax procumbens, recorded in 11 plots (i.e. 18% of all sampled), four other species were found in > 10% of the plots. One species, Bidens bipinnata, was not previously reported from the park and represents a new record. The majority of aliens were concentrated along perennial rivers (60% of all occurrences), but some were repeatedly recorded at seasonal rivers as well and two of the most invasive species in KNP, Opuntia stricta and Parthenium hysterophorus, occurred also on dry crests away from water. The average number of alien species per plot was low (1.6), as was their mean percentage contribution to all species in a plot (2.2%), but some plots harboured as many as seven species and contributed up to 11.9%. Moreover, only 21 plots (35%) were alien-species free. In terms of the total species number per habitat, perennial rivers had significantly more aliens than crests and were marginally significantly richer than seasonal rivers. By recording all naturalised alien species occurring in the plots – many of them are not invasive but may become so in the future – and by using the GloNAF database of global distribution of naturalised species, we assessed the invasion potential of the recorded species.
Highlights
The majority of protected areas worldwide are vulnerable to invasions, with very few completely free of alien species (Foxcroft et al 2017; Moodley et al 2020) and many suffering various impacts at the species and community levels
The situation is not improving over time, as shown by Shackleton et al (2020). These authors compared how the threat by and management of invasive species have changed in a representative set of 21 protected areas that were included in the international SCOPE programme on biological invasions in the mid-1980s (Drake et al 1989)
Four of the species recorded are considered invasive in Kruger National Park (KNP): Parthenium hysterophorus, Xanthium strumarium, Opuntia stricta and Zinnia peruviana
Summary
The majority of protected areas worldwide are vulnerable to invasions, with very few completely free of alien species (Foxcroft et al 2017; Moodley et al 2020) and many suffering various impacts at the species and community levels These impacts include the alteration of habitats, ecosystem regime shifts and losses to native species abundance, diversity and richness (Foxcroft et al 2013; Hulme et al 2014; Pyšek et al 2020). The situation is not improving over time, as shown by Shackleton et al (2020) These authors compared how the threat by and management of invasive species have changed in a representative set of 21 protected areas that were included in the international SCOPE programme on biological invasions in the mid-1980s (Drake et al 1989). Amongst the taxonomic groups analysed, invasive plants pose the greatest continued threat, as documented by increased numbers in 31% of the protected areas over ~30 years from 1980s to the present (Shackleton et al 2020)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
