Checklist of alien plant species in a natural protected area: Anaga Rural Park (Tenerife, Canary Islands); effect of human infrastructures on their abundance

Background and aims - Invasive alien (exotic) species are one of the most serious threats to the conservation of biodiversity on the planet. This is especially true on islands, given the fragility of their ecosystems and high levels of endemicity in both species and ecosystems. The problem is particularly acute in the Canary Islands, a biodiversity 'hot spot', where there is widespread high endemicity and unique biodiversity. This paper presents the first comprehensive inventory of alien plant species in Anaga Rural Park (ARP) (Tenerife, Canary Islands, Spain) a Natural Protected Area, currently proposed as a UNESCO Biosphere Reserve. Anaga is also outstanding for including a relict Tertiary era laurel-forest ecosystem that hosts a large number of palaeoendemics. Methods - Surveys were conducted along itineraries through the different ecosystems of ARP to determine the alien plant species in areas with different levels of human impact. Key results - Two hundred and sixteen alien species were identified, belonging to 53 families and 141 genera, especially concentrated in the most anthropic areas, noting the possibly competitive coexistence of aliens and local endemics of importance in the ecosystem. This is the first overall comprehensive study on the importance of alien species in ARP. Surveys confirmed how human infrastructure and activities significantly favour the presence and diversity of exotic species. Using multivariate statistical analysis, significant differences were found between the species diversity of alien flora and the proximity of anthropic areas. The presence of Cuscuta campestris Yunck was detected, being a second record for the Canaries and the first for ARP. Conclusions - A large number of alien plant species inhabit ARP, affecting all its ecosystems. This is largely the result of the human activities within it, and poses a risk to its conservation and the survival of numerous endemic taxa s. str.