Assessing biological invasions in protected areas after 30 years: Revisiting nature reserves targeted by the 1980s SCOPE programme

Abstract

Invasive alien species pose a major threat to biodiversity and natural ecosystems globally and negatively affect conservation efforts in protected areas. They can negatively alter biodiversity and ecological regimes and are a financial burden. Because of their negative impacts, it is important to better understand the threat and management of invasive alien species in protected areas (PAs) globally, and to know how these factors have changed over time. We give an update and compare how the threat and management of invasive species has changed in 21 PAs that were analysed as part of the international SCOPE programme on biological invasions in the mid-1980s. Of all the taxa analysed, invasive plants pose the greatest continued threat, and their numbers have increased in 48% of the PAs. Conversely, mammal invasions now represent less of a threat due to effective management in many PAs; 48% of PAs show a decrease in listed invasive alien mammal taxa. Invasions of amphibians, reptiles, birds and fish have remained stable over the three decades; around half of the PAs show no change for these taxa. Managers of most PAs consider the threat of invasions to be increasing, despite many (55%) PAs having sustained long-term management programmes and 45% having implemented additional ad hoc approaches. We draw on lessons from this analysis to support the future management of biological invasions in conservation areas. In particular, better monitoring and collation of data is needed, followed by increased preventative measures and the promotion of biological control for widespread species.

Scientists' warning on invasive alien species

“…These trends have sometimes been reversed following the implementation of control efforts (Simberloff et al ., 2011, 2018; Shackleton et al ., 2020), and several studies have shown that protected area boundaries provide some resistance to colonization by alien plants (Lonsdale, 1999; Pyšek, Jarošík, & Kučera, 2003; Foxcroft et al ., 2011). However, as human populations adjacent to many protected areas are growing rapidly (Wittemyer et al ., 2008), colonization and propagule pressures will increase.…”

“…Nevertheless, integrated efforts involving science, management, and policy for dealing with IAS in protected areas are insufficient. The extent and overall impact of invasive species in protected areas is increasing worldwide, especially for invasive plants, despite some notable successes in dealing with such invasions (Shackleton et al ., 2020). New initiatives are needed to pave the way for monitoring trends, revising legislation and policies, and improving management interventions to reduce the impacts of invasive alien species in protected areas (Genovesi & Monaco, 2013; Foxcroft et al ., 2017).…”

What Will the Future Bring for Biological Invasions on Islands? An Expert-Based Assessment

“…Given their isolated nature and limited spatial extent, biosecurity measures are substantially easier to implement compared to mainland regions. For example, on the Galapagos Islands, where nature-based tourism is a vital part of the local economy, IAS management is a top priority, with the highest allocated budget of 2.5 million US$/yr in a study of 21 protected areas globally (González et al, 2008;Self et al, 2010;Shackleton et al, 2020). Similarly, New Zealand has some of the strictest biosecurity protocols regarding IAS and an ambitious governmental program ("Predator-Free NZ") aiming to eradicate a selection of invasive predators by 2050 (Russell et al, 2015).…”

Distribution and impact of invasive alien plant species in Bardia National Park, western Nepal

“…Regions with extreme climatic conditions such as the high mountains and poles, and those with low anthropogenic disturbance levels such as protected areas (PAs), are often thought to have low susceptibility to biological invasions. However, such regions with low numbers of alien species are also witnessing a recent increase in the numbers of alien species (Pauchard et al 2009, Wasowicz et al 2019, Shackleton et al 2020). Of particular interest are PAs because of their disproportionately high conservation values.…”

“…Of particular interest are PAs because of their disproportionately high conservation values. While many PAs globally are poorly managed, with unchecked deforestation rates and other environmental degradation (Leberger et al 2020), an overall increase in the threat of invasive alien species in PAs constitutes an extra burden to management authorities (Shackleton et al 2020).…”