The bottom line: impacts of alien plant invasions in protected areas

Phrases like “invasive species pose significant threats to biodiversity. . .” are often used to justify studying and managing biological invasions. Most biologists agree that this is true and quantitative studies support this assertion. Protected areas are the foundation of conservation initiatives in many parts of the world, and are an essential component of an integrated approach to conserving biodiversity and the associated ecosystem services. The invasion of alien plants constitutes a substantial and growing threat to the ability of protected areas to provide this service. A large body of literature describes a range of impacts, but this has not been assessed within the context of protected areas. We do not aim to review the state of knowledge of impacts of invasive plants; rather, we collate examples of work that has been carried out in protected areas to identify important patterns, trends and generalities. We also discuss the outcomes of various studies that, while not necessarily undertaken in protected areas, are likely to become important for protected areas in the future. We discuss the range of impacts under five broad headings: (i) species and communities; (ii) ecosystem properties; (iii) biogeochemistry and ecosystem dynamics; (iv) ecosystem services; and (v) economic impacts.LCF thanks South African National Parks for supporting work on this book and for general support. LCF and DMR thank the DST-NRF Centre of Excellence for Invasion Biology (C•I•B), the National Research Foundation (South Africa) and Stellenbosch University for support. This work benefitted from financial support from the C•I•B and the Working for Water Programme through their collaborative research project on “Research for Integrated Management of Invasive Alien Species”. PP was supported by long-term research development project no. RVO 67985939 (Academy of Sciences of the Czech Republic), institutional resources of Ministry of Education, Youth and Sports of the Czech Republic, and acknowledges the support by Praemium Academiae award from the Academy of Sciences of the Czech Republic. We thank Zuzana Sixtova´ for technical assistance