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29 September 2023

Global Assessment on Invasive Alien Species and their Control – Effective Management of Invasive Alien Species in Protected Areas is Possible

Invasive alien species are one of the top five threats to biodiversity, including threatened and endangered species and ecosystems. Protected areas and national reserve systems, therefore, become critically important from an invasive alien species management perspective.

The first global Assessment on Invasive Alien Species and their Control by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES et al. 2023) was recently approved in Bonn, Germany, by representatives of the 143 member States. The Assessment found that invasive alien species threats and impacts are underappreciated, underestimated, and often unacknowledged in many regions and biomes around the world.

IPBES Invasive Alien Species Launch Key Message

The report is the most comprehensive assessment of invasive alien species ever undertaken. It was produced by 86 experts from 49 countries, working for more than four years. It draws on more than 13,000 references, examining 195 country checklists covering more than 37,000 established alien species and 3,500 invasive alien species, of which 2,400 were found on indigenous lands. About 1,000 reports of invasive alien species concerns, impacts and responses were evaluated through Indigenous and local knowledge workshops with over 50 participants from IPLCs in over 20 countries.

The Assessment documented that invasive alien species have had a role to play in 60% of all extinctions globally and were the sole driver for 16% of extinctions. The Assessment also found that the impacts of invasive alien species have increased by at least four times every decade since 1970 also severely affecting the livelihoods of indigenous peoples and local communities. The Assessment, however, also emphasises that existing invasive alien species impacts can be controlled and future invasive alien species, and their impacts, can be prevented or rapidly responded to. This however requires effective integrated governance supporting well-resourced management strategies and action plans to address the invasive alien species challenge, from potential sources to impact suppression within protected areas.

Professor Anibal Pauchard (Chile), co-chair of the Assessment together with Prof. Helen Roy (United Kingdom), and Prof. Peter Stoett (Canada) stated that “The good news is that, for almost every context and situation, there are management tools, governance options and targeted actions that really work”, further noting that, “Prevention is absolutely the best, most cost-effective option – but eradication, containment and control are also effective in specific contexts”.

The authors highlighted that those areas protected for nature conservation, are also vulnerable to the adverse effects of biological invasions and that remoteness and protection status do not necessarily prevent biological invasions or their impacts.

South African National Parks’ Prof. Llewellyn Foxcroft, one of the lead authors in Chapter 5 on Management; challenges, opportunities and lessons learned (Sankaran et al. 2023), also stated that “protected areas are an important component of conserving nature, nature’s contributions to people and good quality of life, but the immense impacts of invasive alien species are eroding the ability of protected areas to sustain these essential services. However, there are many management options available to managers to deal with the challenges being faced”.

The four phases in the biological invasion process [reproduced from IPBES (2023) Figure SPM 1]Conceptual diagram of management-invasion continuum

Biological invasions are comprised of four main phases: Transport, Introduction, Establishment and Spread. All these processes are important for protected areas as targeting each of the phases will provide the highest likelihood of achieving successful long-term outcomes. This includes management 1) prior to the species’ introduction, 2) at the introduction of an alien species, 3) during the establishment, 4) and spread phases, and 5) preventing widespread dispersal and potentially severe impacts. This is usually more easily achievable for terrestrial plants and animals, whereas in marine and connected freshwater systems prevention is the only feasible method of managing invasive alien species.

The Management objectives panels (A and B) show the generalized invasion curve without management and the expected changes in the trajectory of the invasion curve with appropriate management actions in (A) terrestrial and closed water systems (including lakes and coastal systems such as salt marshes) and (B) marine and connected water systems (including rivers). [reproduced from IPBES (2023) Figure SPM 6]

Prior to the introduction of an alien species, management needs to focus on preventative measures and preparedness. Numerous decision-making frameworks have been developed and can be adopted by protected area managers, for example, risk analysis, horizon scanning, pathway analysis, impact assessments and learning from case studies. These frameworks can assist managers to prioritise pathways of invasion, priority species, and sites that may be particularly susceptible or sensitive to invasive alien species. Upon arrival of an alien species and during the establishment phase, early detection and rapid response is important to attempt eradication of localised populations or extirpation of the alien species from the protected area entirely. Many databases with information on alien species have been developed and can be used to assist in aspects such as identification and providing insights into environmental requirements or potential impacts. Adequate surveillance and monitoring systems need to be in place along major pathways, such as rivers and roads, as well as increasing awareness for potential ornamental plant and pet species escaping into protected areas from neighbouring lands. As the species continues to spread, containment programmes need to be implemented, with the aim of preventing the alien species from invading the protected area and all suitable habitats. Management tools are available that can work across a range of taxa and ecosystems. Long-term, cost-effective programmes are needed to maintain the potential impacts as low as possible. Although not equally available or implementable, sophisticated technological advances in management options are growing, and as this technology evolves it will become more readily implementable across larger areas.

Management of invasive alien species in protected areas raises important additional complexities that need to be incorporated, as they need to be approached within a complex social-ecological context that can influence where, and under what conditions, these tools and technologies can be applied. Engagement across all sectors, including the private sector and Indigenous Peoples and Local Communities, is required if the governance of biological invasions in protected areas and surrounding habitats is to be successful.

Integrated governance of biological invasions. A context-specific Integrated governance approach of biological invasions is enabled by a governance system with properties that support integration, and a set of strategic actions that together are designed to bring about the progress needed to meet national and international goals systems that support the strategic actions (above) to be achieved. [reproduced from IPBES (2023) Figure SPM 7]

References

IPBES (2023) Summary for Policymakers of the Thematic Assessment Report on Invasive Alien Species and their Control of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Roy, H. E., Pauchard, A., Stoett, P., Renard Truong, T., Bacher, S., Galil, B. S., Hulme, P. E., Ikeda, T., Sankaran, K. V., McGeoch, M. A., Meyerson, L. A., Nuñez, M. A., Ordonez, A., Rahlao, S. J., Schwindt, E., Seebens, H., Sheppard, A. W., and Vandvik, V. (eds.). IPBES secretariat, Bonn, Germany. https://doi.org/10.5281/zenodo.7430692

Sankaran, K. V., Schwindt, E., Sheppard, A. W., Foxcroft, L. C., Vanderhoeven, S., Egawa, C., Peacock, L., Castillo, M. L., Zenni, R. D., Müllerová, J., González-Martínez, A. I., Bukombe, J. K., Wanzala, W., and Mangwa, D. C. (2023). Chapter 5: Management; challenges, opportunities and lessons learned. In: Thematic Assessment Report on Invasive Alien Species and their Control of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Roy, H. E., Pauchard, A., Stoett, P., and Renard Truong, T. (eds.). IPBES secretariat, Bonn, Germany. Zenodo. https://doi.org/10.5281/zenodo.7430733