Exploring expert perception of protected areas’ vulnerability to biological invasions

Invasive alien species are considered a major threat to biodiversity and seriously impact the economy and public health of recipient regions. Identifying the determinants of protected areas’ vulnerability to the establishment of invasive alien species (IAS) may improve management, prevention and early warning systems of biological invasions. We elicited the perceptions of 106 experts working in 56 protected areas located in 6 European countries, to gather insights on the determinants of ecosystem vulnerability to IAS. We implemented an online questionnaire to understand the following: i) the expectations and perceived drivers of the future entry of IAS to protected areas, ii) the most common policy frameworks and management options used, and iii) the main challenges encountered when managing or preventing biological invasions. Experts project an increased entrance of IAS in protected areas located in Corsica, Portugal, and Spain. Areas where the entry of IAS is expected to increase comprise i) low to average anthropogenic disturbance, ii) average biodiversity richness, with endemic/threatened/protected species, iii) current presence of IAS, and iv) anthropogenic activities in surrounding regions. Respondents expecting increased entrance of IAS in protected areas also consider corridors as the main pathway of their entry, whereas those expecting IAS entrance to decrease believe IAS enter protected areas mainly through intentional introductions. Our results also underline the complexity of IAS management, which is often hampered by the lack of clear policies, shortage of economic resources and specialised staff, and poor awareness of biological invasions. Future research should further strive to understand which areas are more vulnerable to IAS, especially in regions with free trade and movement agreements, such as the EU. Meanwhile, vulnerability to IAS can be minimized through a stricter management of both protected areas and surrounding anthropogenic activities, and by raising manager and citizen awareness of the ecological and economic problems caused by IAS.